White`s V3i Advanced Posts “Book“

White’s V3i
Advanced Posts “Book“
By Forum Members
Slightly organized by Earthmansurfer
Table of Contents
Chapter 1 Tips
Sensitivity Tips
Filter Tips
Iron Tips
Spectragraph Tips
Various Tips
page
page
page
page
page
1
2
2
3
3
Chapter 2
Spectragraph Related
page 5
Chapter 3
Rx Gain & Discrimination Sensitivity
page 11
Chapter 4
Detecting in Iron
page 14
Chapter 5
Probe Related
page 18
Chapter 6
Correlate Related
page 28
Chapter 7
Air Tests
page 35
Chapter 8
Analysis w/ Jeff Foster & more
page 36
Chapter 9
Recovery Delay & Sweep Speed
page 42
Chapter 10 Filter Related
page 53
Chapter 11 Ground Balance
page 57
Appendix
Expert Menu Flowchart
page 59
Pose by Tom Dankowski on V3i
page 63
1
Chapter 1 - Tips
Sensitivity Tips
1. DX – Lower to make less sensitive to small foil, etc.
2. Rx – Run Lower in heavy trash. When increased you should re-ground balance per manual.
3. Rx – Lower the gain to decrease the footprint of the coil and to make it less sensitive to tiny
flakes of foil. (Rx 8, AM 55, DS 65) Or, you can try going slow and not reducing much.
4. Setting Rx w/ Sensitivity Probe - In most cases you should adjust the Rx Gain to
maintain a residual Signal of no more than 30-40%. VX3 will overload at
60%, so it’s still possible that large shallow targets will cause an overload.
5. False signals are an indication that one or more settings are set too high. Neil
6. EMI Check - Pinpointing “the air” is a good method to check for EMI. I have not found that
zoom+sensitivity while holding the coil in the air to be a reflection of EMI.
7. Jimmy Sierra posted recently about RX Gain and Disc adjustments. Per his post Disc is more
important to depth than RX Gain, TX Boost and all metal (if running mixed mode). He also
mentioned that lowering your filter setting when you can will also help detect deeper
targets. (edited per suggestion, can’t find original post)
8. ....run that baby as HOT as you can without falses or smearing showing up....just
remember...the more Disc Setting (usually above 90) will cause more smearing on your
screen than any other setting...I always setup with RX 13 Disc 85...if the area is not falsing..I
crank up the RX to 15...if still good..then I raise up the Disc to 90 then 95..once I see the
smearing showing up frequently..I back off the Disc to get her stable & smooth...also I always
run TX Boost as ON unless I hit an area that is bad...which rarely happens... Robert edited
*Note – Robert’s soil is very mild so he can run this way with Tx boost on! BE CAREFUL here!
9. we have ground here that run the -93 to -88 I been see that if I back off the RX a little it help
a hold lot and run ds at 85 am 65 to 70 getting target at 10 to 11 Q AT 12 when the ground
after a good rain. Little Man
10. RX and Disc - There are different symptoms of having your RX too high vs. having your
Discrimination Sensitivity too high. If you have your discrimination sensitivity too high you
will get erratic readings by just holding your detector at waist level. When your RX is set too
high, you may not get falsing when the unit is held at the waist. You will, however, get false
readings when the coil is being swept on the ground.
What I will do is set both to my usual settings (around RX 12 and Disc Sens 91). If the V3
appears stable at this level, I will inch both a few notches higher. If I get erratic readings at
waist level, I will back the Disc Sens down a notch or two. If I get false readings while
sweeping the coil I will back down the RX Gain. Neil Jersey
11. RX Gain and Discrimination Sensitivity - The Rx gain control is done in hardware which is
done at the Preamp or where the signal from the receive coil goes into the instrument. The
Discrimination gain is done in the software after the signal from the coil has gone through all
the analog hardware (circuitry). The Transmit Boost adjustment is the setting that will boost
the signal going to the transmitter of the coil. Rcsnake
2
Filter Tips
12. Filter Setup - Find a deep target then barely attain target by lowering sensitivity as far as you
can. Then go through the filters and find which one is best. Then, up your sensitivity again.
This allows you to find the optimal filter when two sound close at regular sensitivity.
Remember that sites change with rain, EMI, etc. so this is a good procedure to always follow.
13. You might need to increase your filter by one if you bump up against some noise, and don't
want to drop your RXG. Fox Rebalance after a filter switch!
Moving too fast can cause falsing (more in the lower range of filters).
14. The 5Hz Band Pass filter setting is somewhat of an anomaly in the filter settings. There is a
radical change in stability as far as EMI is concerned. You can achieve noticeably higher RX
and DS settings under this filter setting. As mineralization strength increases you have to
swing slower and slower to achieve good tonal quality and frequency alignment on a coin
target. This one single thing increased my depth more than anything else. I am in moderate
strength soils and this filter designed for sweet ground still works the best for me. Also, the
high band goes slightly deeper than regular. CyberS. (I think he is in mod. Mineralized grnd.)
15. If you are swinging slow and have the filter setting to high you are going to miss some stuff. I
don't think it is going to matter much if you are swinging fast and have the filter set low. I
would recommend a lower filter setting and trying to slow down your swing. If you don't
want to slow down your swing make sure your recovery delay is set properly. Pablo
16. Your swing speed will play a big part in quieting your V3 down. If you are using a low filter
setting and swinging too fast you might as well have a monkey with a tin cup on a leash,
because your detector is going to sound like an organ grinder. Cyber Sage
Iron Tips
17.
18.
19.
20.
21.
22.
23.
Setup - 4 6 8 rule, 4 Rx – 6 AM – 8 Disc (Start from there and work up.)
Deep Targets pinpoint well but iron doesn’t.
You can try running GB slightly (-) to quiet iron.
Dominates 22.5 (blue), BCR (2-6) – More than 4 and you can lose deep whispers
Too much RX will cause more problems with deep iron sounding like good targets.
Heavy Iron & 5Hz filter may chatter. (Note – In my mild ground only when wet.)
Sometimes a target will give the threshold change, but jump into the 80's or 90's on the VDI
scale. If the target has a dominant hump showing 22.5, it is most likely iron. If 2.5 KHz or 7.5
Khz was dominant, it would be a dig-able target. Neil
24. A bouncing signal with hits of a big green signals sometimes means a good target with trash.
High VDI with red dominant has always been deeper iron or a bottle cap. Xzlr8n (Am Det) (Of
course a coin in iron can show some red, so be careful here.)
25. Iron has become really easy to spot by watching for the red on the right of the 2.5 KHZ bar.
Red on the right and it was iron every time. Same with bottle caps. Red on the right of 2.5
KHZ bar. Southwind (Again be careful of coins in iron).
26. Old nails are part of the norm. One thing I haven't seen wrote with all the other advice was to
check the PP analyze screen to see what is dominant. Then move 90 degree and check again,
if it doesn’t match and or center the same location then I would suspect a nail or small iron.
Those 3 bars can tell you a lot. H.H. Yazoo
27. Watch negative numbers - Dug some -20 targets that were about 5 inches down but
pinpointed small alike coins and dang they were coins. Bob@Whites
3
28. Iron Wiggle - The wiggle test is what I use the most. If I get that deep good sound, I pinpoint
with the best accuracy that I can get. Then I just barely wiggle the coil left to right and back
and forth and if its a nail or iron, it will show up as such. I dig very few nails but sometimes I
get that really good tone that I have to dig no matter what my detector tells me and
sometimes its a nail...sometimes its not. Magic
29. Another trait of a VLF unit is to have the threshold drop out over iron, even in ALL METAL
mode. This is especially true on deep iron. Fox (Nails also can double hit)
30. A modulation setting of 2 or 3 (V3i) can greatly reduce the high sharp tones of deep iron,
and, in some cases hot rocks, while leaving the tone of a good target at full volume. This an
alternative way to deal with these issues without using HRR or Discrimination, which in turn
keeps you from loosing depth. CyberSage – I edited modulation settings from V3 to V3i.
31. Effect of iron on VDI readings - In general...........flecks of rust will cause a target to 'upaverage'. . . . whereas... solid iron objects (like nails) will cause targets to 'down-average'.
Mineralization adds to the equation also.
Mineralization is somewhat unique in the fact that it'll cause targets to up-average ... as long
as the targets are shallow-to-medium depths. But..... when the target is fairly deep......
mineralization (in general) will cause a target to ID as 'iron'. Tom Dankowski
Spectragraph Tips
32. Spectragraph - The spectragraph always trumps the VDI number. Jeff Foster
33. Smearing - Anytime you get smearing/falsing on your screen...changing the Filter is always
"one of the items" to check as being the culprit. Robert@Whites
34. Smearing - Getting multiple VDIs, especially in the red (rejected) range is what I call
"smearing" .... Multiple VDIs that are all green could be a deep target, or it could be bunch of
surface trash or something else depending on your setup. Fox
35. “Consistency” (averaging) data to ID foil - I noted today that with a single piece of foil - VDI's
2 to 5, that the 2.5Khz frequency didn't see it very well at all, even though the 7.5 and
22.5Khz freqs were hittin' it pretty consistently. I paid attention to this, watching the
Spectragraph on every under 10 VDI hit. In almost 100% of the cases, the 22.5Khz bar was
consistent, the 7.5Khz bar was "fairly" consistent, and the 2.5Khz bar was very small or nonexistent. Lower numbers require less consistency to build height and give wider spectragraph
patterns for inconsistent target signals. Higher numbers allow less target consistency for an
individual spectragraph to build height.
36. Clean Ground – “single sweep”, uncheck when not clean – “consistency” = averages
Various Tips
37. Salt Comp subtracts noise and also subtracts some signal as well. To use Salt Comp and not
lose any depth, bump your RX Gain and Disc Sense up a bit to regain what you lose in 3-F.
38. Frequency Offset – Can have a BIG affect on quieting unit. Try this first!
39. SAT – set lower (e.g., 2) in low mineralization (in AM or Mixed).
40. Pulltab – 22.5 & 7.5 often superimpose in analyze – check this.
41. Tracking Offset - Tip : Pull the trigger and slowly lower the coil to the ground (make sure no
iron is beneath the coil). Listen to the audio threshold, if it dips you need to raise the tracking
4
offset, what you are looking for is a slight raise in threshold as the coil approaches the soil.
Sometimes you may need a high setting such as +10. – Gary (European)
42. Frequency....3 Freq, enable salt if unstable – Gary (European)
43. Sweep Speed & Recovery - For a given sweep speed, a LONGER delay (higher number) will
give you LESS target separation because Spectra has been given more time to "recover". If
you increase your sweep speed with a longer delay, your target separation will get WORSE.
For a given sweep speed, a SHORTER delay (lower number) will give you MORE target
separation because Spectra has been given less time to "recover". If you slow down your
sweep speed with a shorter delay, your target separation will get BETTER.
Hence - for any Recovery Delay setting, a slower sweep speed improves target separation
and for a given Recovery Delay, a faster sweep speed degrades target separation.
If we break the detection process down into "capture / process / report / release" phases,
the time from the start of "capture" to the end of "release" can be considered "processing
time". It is this time, from the onset of one detection until Spectra is ready to "capture"
another target that is affected by Recovery Delay. Or, in pictagraph form ....
|=======Higher Number=======| vs |===Lower Number===|
T1 <----------- Separation------------->T2 T1-------Separation-------T2
It then follows that the longer Spectra has to "look" at a target, the deeper the target can be
and the more accurate the VDI will be. So - to some degree, Recovery Delay also impacts
detection depth and VDI accuracy, but not to a degree that would offset the benefits of
improved target separation for a given sweep speed. Fox
44.
The pin point mode is far more accurate on deep coins for determining
frequency dominance than the motion mode graphing. As a side note you can determine this
equal bar behavior at any depth by adjusting your All Metal setting up or down. I run with
mine at at 72 to 75. This seems to let the 2.5kHz shine through even on the deep ones. If the
coin is on edge or partially obscured by an adjacent ferrous target the 7.5 will show as the
dominant frequency closely followed by the 2.5 kHz. Combined with a VDI reading of 55 to
70 this is also a sure sign of an Indian Head if deep, or a Zincoln if shallow. Mixed coin spills
will also exhibit this behavior at depth. If the 22.5 is strongest followed by the 7.5 you have a
low conductor target. CyberSage
45.
Hammereds - A trick to make a machine more sensitive to smaller finds is to set
the ground balance slightly positive, on manual ground balance machines this means the
threshold rising slightly as the coil is lowered to the ground, on the whites XLT and DFX this
means setting the Trac offset to at least +1. It's also vital to use the "fast" setting if working
in iron. Roger
46.
Find iron for Hammereds - make sure your sensitivity is turned up fairly high, so
when the head is over iron the machine spits and cracks, you can use all metal to suss out the
iron but I prefer to do it in discrim mode, make a note of where the patches of iron are on
your plan of the field, as this is where the hammered and other goodies are waiting to be
found. Roger (Note – He uses XP detectors, but worth trying).
5
Chapter 2 – Spectragraph Related
Read pages 8, 9, 10 of your Owner's Guide.
What you need to learn to do is to assimilate the DATA that Spectra provides, and in your HEAD,
compile the data into INFORMATION, which you will use in conjunction with your EXPERIENCE to
make a dig / no dig decision. You don't "dig on data" you "dig on information".
By now, you should have a good handle on the "3-S Rule".
Between the "3-S Rule" - (Sound, Shape and Size) and the SpectraGraph data, which includes:
VISUAL:
1. Target VDI (type of metal)
2. Which frequency is hitting the hardest - Another indication of target composition
3. Target Depth
4. Target Size
5. Probability / Confidence of target being what Spectra indicates
6. An Icon representing the probable target
AURAL: (Pinpointing)
7. Sound - Especially with Tone ID = ON
8. Shape
9. Size
You have no less than 9 bits of data at your disposal with which to make a dig / no dig decision.
What you have to do is to learn how various targets respond, what they sound like, what they look
like, how they read on the SpectraGraph. That's practice, practice, practice which yields experience.
And finally, (Data + Experience) = Information.
That's all there is to it .... The best computer is between your ears. Don't depend on technology for
anything but DATA. YOU turn it into the good stuff ..... INFORMATION.
Now you have made a great leap from "helpless" to "enlightened" and "empowered". Go forth and
be successful !!!
- Fox
6
I use the SpectraGraph for data points. Which freq is hitting the hardest? Does it make sense with the
VDI ? Does the tone match the VDI and the SpectraGraph? Which is fading faster? Etc, etc, etc.
The more you know about how the unit works, the more "data points" there are to be gleaned from
the display.
Fox
Consistency – Spectragraph shows consistency of VDI number. Max - 1 – 50 – Adjust the
Spectragraph height (number of specific VDI indications to generate the maximum size of the
bar. This is an accumulated result.
How quickly an individual spectragraph bar builds height is based on the consistency
(average) of the target signal after multiple search coil passes. By adjusting consistency,
spectragraph bars can build quick and narrow, or slow and wide based on the targets
characteristics.
• Max – Higher numbers allow less target consistency for an individual spectragraph bar to
build height. Lower numbers require less consistency to build height and have the effect of
more readily indicating wider spectragraph patterns for inconsistent target signals
Intensity – Shows the intensity of each VDI number indication. Base Threshold - 0 – 90 –
Bottom of graph is this % of the strongest signal. The bottom of the graph is the start of this
signal at that %. For example, a base threshold of 90 will show the top 10% of the highest bar
and any of the other bars within that signal strength range.
In addition to indicating the average target indication, Spectragraph bar also indicates the
intensity. Spectragraph height is based on the (average) of signals and intensity at that
particular VDI number.
• Base Threshold – By adjusting the degree or % the first spectragraph segment represents the
target signal strength, and intensity (height of spectragraph blocks or pattern) can be adjusted
to preference. Fox **********************************************************
Consistency counts up the number of times a VDI has been seen during the course of the target. It's a
lot noisier looking than intensity.
Intensity is how strong the signal is at the seen VDI.
Theoretically for consistency, (although around here I've found it to not be very useful. This may not
be true for areas with no mineralization in the ground) a good target should have lots of the same
VDI whereas an iron target will have lots of scatter. For intensity, if there are various VDI's for the
target, the signal strength will be displayed at each of the VDIs that it sees. In this mode, there will
also be scatter for the iron targets whereas a coin will generally have a good cluster right around the
expected VDI. And the signal strengths for the coin (until you get deep) should be much higher than
the ground effects.
Resolution is how wide the bars are. So say you have a resolution of 7, you will have the same bar for
7 different contiguous VDIs (maybe 81-87 for example). If you have a resolution of 1, then each VDI
gets its own bar, but they're a bit harder to see because they're a lot narrower. (Tradeoffs). So, that's
the horizontal resolution.
Base threshold is how much you set to block out the noise region. If you have a BT of 90, then
only signals that are > 90% of the strongest signal will be shown. So, if you have a strongest signal of
100strengths (not real numbers - using it as a way to explain), any signal that has strength < 90 will
7
not be displayed. 90 and over will be. So, setting the BT down to 65 would not show signals 0-65, but
65 to 100 would be. The BT set to 65 (like in Hi-Pro) is set to show more iron scatter effects. Setting
it to 90 you don't see near the scatter so a nail might appear as a real good target under the right
conditions. So, BT is the vertical resolution control. Ak_1234
Base Threshold –(under intensity) VDI Sens -
% of signal for good target e.g., 90=10%, for depth
try 65 = 35%
(The following is partially correct, then the next paragraph makes things clear): - Basically, it's a
control that controls the resolution of your spectragraph screen. So, hopefully I won't mess up the
explanation. But, if you're only seeing 10% of your signal, you won't see as much of the surrounding
noise (much deeper targets close to the strong target you see might get washed out). But, if you set
it to show 35% of the strongest signal, you'll have more of a chance to see the deeper targets as long
as their strength is > than 65% of the strong signal. And the Hi-Pro program is intended to be running
hot to pick up the deeper targets. But it also means that the surrounding noise can have more signal
showing on your spectragraph. Rcasi44
Actually, you'll still see the deeper targets. It's how much of the strongest signal you want to see. So,
if you have a deep target, you will still see the deep target signal. However, since the surrounding
ground/noise also is significant when compared to your deep target, you'll also get the signals from
the surrounding ground/noise that fits in with the 10% of the deep target signal.
The Hi-Pro program is set to 65 because Bob wants to see more of the surrounding VDI info. It helps
him in distinguishing coins from bottle caps as the bottle caps tend to have VDIs that aren't as
consistent. If it was set to 90, those VDIs wouldn't show for a strong target, but set to 65, he sees a
bunch. But either way, he'd still see the strongest signal - deep or shallow. Ak_1234
A base threshold of 90 will show the top 10% of the highest bar along with any of the other bars
within that signal strength range. A base threshold of 65 will show the top 35% of the highest bar...
Using the same example (a base threshold of 90 = 10% signal showing, a base threshold of 65 = 35%
of signal showing). If you have a base threshold set to 90, it will go off the strongest signal and display
the top 10% of that signal as well as signals that are >90% of the strongest signal. Any deep targets
that are less than 90% of the strongest signal will not be displayed on the spectragraph. However for
a setting of 65, the deeper targets need to be only >65% of the strongest signal to show on the
spectragraph. So, if you don't want to see as much of the surrounding noise, you increase the base
threshold. To catch the deeper targets relative to your strongest signal, lower your base threshold.
Ak_1234
? - IF I follow what your saying then would it make since that it could or would help if you
lowered the threshold as your coil size gets small and raise it if the coil size is larger. CVS
If the smaller coil is less susceptible to noise, then that is true. You don't want to have settings
such that external noise overwhelms the good signals. We don't have knowledge of the future,
so we're adjusting on the fly. So, the bars on the screen are adjusted based on the current
strong signals. If you set the base threshold too low, then you are setting up the detector
to show more noise which will make a good signal not stand out as much (only for the
spectragraph - no effect on any other part of the detector). If you don't have noise, then this is
8
a good thing. So, really it's a setting that you can adjust based on how much of the smaller
signals you want to see. Most programs were set up to not run very hot (well, hotter than the
DFX, but still not as hot as hi-Pro or a couple others).. Bob set his up to run fairly hot and that
means he also wants to see more data. The newcomer might get overwhelmed by all that data,
so it was set higher.
Consistency + Fade Rate = Happy Spectragraph
In conjunction with my efforts to put together a Correlate program, I have been working on
cleaning up the Spectragraph .... Especially with the "hotter" settings.
Today I was able to run ALL my programs - COIN / C&J / Beach / Correlate at RXG=15 and
DS=95 with less falsing, spiking and smearing then I had previously with RXG=13, DS=85.
Running my COIN and C&J programs at RXG=13, DS=80 is close to a "blank screen" as far
as spiking and smearing goes, and with DS=85, you might get a touch of ground noise every
couple of minutes, but generally there is nothing showing on the screen. Running Correlate is
even quieter.
Depth? How's a quarter at 10", dime a 8", penny at 9", all from a hard-hit area sound?
Wouldn't it be nice to be able to look at the display and see that 22.5Khz is hitting ALL the
time, 7.5Khz SOME of the time and 2.5Khz HARDLY AT ALL? (Deep nickel) How about
seein' ONLY 22.5Khz hittin', accompanied by short tones? (Tiny, shallow can slaw). Then
just pull the PP trigger and see how ALL the freqs feel about the target in AM mode.
Here's the ticket. Run Spectragraph in Consistency vice Intensity. Why? Consistency shows
how OFTEN each VDI is being seen. You can set the number of "sees" required to build a
signal bar to a max number. 25 seems to be a good number. Hence, you can watch the
Spectragraph get a hit on a good target, watch the bars build as you sweep, verify the target
with pinpoint, and dig. Or, you can see that little surface target that is just makin' a blip in
22.5Kzh only and move on.
To accommodate the increased sensitivity you'll be able to run at, set FADE RATE = 2. This
will immediately get rid of any "smears" that are caused by ground noise, but won't wipe out
the repeated hits of a good target as it builds up .... The deep quarter today just "hung in there"
with 2.5Khz leading the pack, followed close by two nearly equal bars from 7.5 and 22.5Khz.
This seems to be the "signature" of most deeper coins runnin' this way, but more data would
be helpful to verify.
Using this setup in conjunction with my Correlate program today, I was able to walk more
than 50 - 75 steps, time after time without one false spike showin' up on my screen. That's
close to half the length of a football field w/o falsing. I look back to when I started and I
couldn't get 5 swings w/o noise ....
Oh - you should like this. I eyeballed a bottle cap. Turned it upside down and swept the
6X10"DD over it a total of 10 passes. Nary a peep, squeak, beep, honk, toot or burble. I put a
quarter one coil width away from the bottle cap. 10 swings, 10 hits - Coin, C&J, Beach,
Correlate. Same with nickle, dime, penny.
9
You gotta give this a try. I have already updated ALL my programs with these settings, and
they're posted in the new Programs Thread !!! Fox
Using Consistency Data To ID Foil
Carl posted a note .... "thickness matters" and discussed one layer of foil, then two, then four,
etc ....
I noted today that with a single piece of foil - VDI's 2 to 5, that the 2.5Khz frequency didn't
see it very well at all, even though the 7.5 and 22.5Khz freqs were hittin' it pretty consistently.
I paid attention to this, watching the Spectragraph on every under 10 VDI hit.
In almost 100% of the cases, the 22.5Khz bar was consistent, the 7.5Khz bar was "fairly"
consistent, and the 2.5Khz bar was very small or non-existant.
Since I know that both the C&J and C&J Correlate programs will "see" a small piece of gold
and that all three freqs hit it with a reasonable consistency, you might want to use this tidbit to
help sort out surface foil bits in a trashy area.
Hope this is helpful. Da FoX
? - Do I want all the smearing little "bad" bar targets? I get red smears seemingly on constant hold
around -70. There is loads of iron trash and iron soil about. Occasional probe checks show -93 to -95
often. But when I get jagged or broken "green" bars not in line, I pretty much move on. – aharrison
A - Those little red smears are an indication that you might need to (1) Check your GB, (2) Change
your Ground Filter or (3) Bump up your Bottlecap Reject to around 4, assuming that you have
rejected everything from -95 to -7, and +95. Fox
OK, the two trigger setup can make some interesting combinations. The two trigger positions can
both be set for the spectrograph. That means you can have two search screens. For instance, one
screen could be set to intensity and one could be set to consistency and each could have a different
filter.
Just remember, G/B. For only display differences, G/B does not need to be done between the two
trigger positions. If the filters are different on the two screens G/B is also not required.
The only settings that really require a new G/B if switching between screens are gain, frequency and
TX boost changes. If these are the same for both screens you can just flip back and forth. ROB
Getting Pos VDI, good tone with Red Spectragraph in neg range
I notice that with my other white's units if it was a rejected target it would give me negative numbers
but on this one, for instance, in coin mode (or any other mode) I get +83 colored red....why doesn't it
say -83 like it should, and should I be digging red numbers?...I thought they represented rejected
targets.....very frustrating! DavefromCT
I see the + 83 and I get the good tone with it and when I look at the spectrograph, it has a red bar in
the -83 range. Magic
10
Thanks for your reply Magic, That's what I expected to hear.
Do you have the spectragraph configured to show intensity or consistency?
If you have the spectragraph set up for intensity and you have a very large piece of iron, it will
overwhelm a quarter (or other coin). The Spectragraph showing the strength (intensity) of the signal
is the default value. Iron has a tendency to also show up all over the spectrum, so there will be times
when it reads as a rejected target as well as an accepted target. If you have a fast enough recovery
delay, a large chunk of iron may have some ripple effects that extend beyond the decay timing and
one of the ripples will then be seen as a new target. If that new ripple reads as an accepted target,
the VDI # will be displayed but the signal will be small enough to not register on the spectragraph
because the intensity of the iron at its peak is so overwhelmingly large. Other possibilities exist mostly a large signal will be large enough to prevent the smaller signals from showing up on the
spectragraph - they're still there, just not enough resolution with the eyes or the pixels to see them
compared to the large signal.
Or you may actually have a coin buried with that large chunk of iron. I have a pair of metal scissors. I
ran the scissors and a quarter across the loop. The signal from the scissors was so large that the
signal from the quarter wasn't able to show up on the spectragraph - it was just too small, but I still
saw the +83 VDI # displayed.
I personally like intensity better, but if this is a problem while hunting, trying out the consistency
setting might be an option. It shows a lot more scatter from ground effects though. But, you are
much more likely to see a coin buried with a large chunk of iron too. (Expert menu/configure/Live
search screen/search/spectragraph/consistency) Even with consistency, a large chunk of iron may
still overwhelm the signal for a coin, but I was able to see my quarter most of the time when I ran the
scissors and quarter across (not one on top of the other - the scissors did have a very large influence
on the VDI reading). Depending on the ground, consistency may be unusable though. Ak_1234
11
Chapter 3 – Rx Gain and Discrimination
Discrimination sensitivity doesn't have anything to do with the "level of discrimination", or in other
terms, "what Spectra is seeing". That is set by the VDI's that you ACCEPT (see) or REJECT (don't see).
Discrimination sensitivity sets the level of signal to the discrimination circuits where the phase
comparison actually takes place. INCREASING the number makes the detector MORE sensitive, so it
will "see" DEEPER in the MOTION mode. Increasing the DISC too far can make Spectra (or AC for DFX)
susceptible to EMI and Ground Noise, so if you wanted to increase stability, you would DECREASE
DISC / AC.
However, so long as we are talking, with Spectra, the RX GAIN control has a "finer adjustment" (1 15) than the PAG (1 - 4) on DFX. If I was just a "little too hot" with Spectra, I'd drop RX Gain a couple
of points first, before I took the DISC down.
All Metal (DC) follows the same train of thought, except it is for the NON MOTION (All Metal)
channel. It, in conjunction with RX (PAG) of course, controls how deep you pinpoint, AND the
sensitivity of your DX-1 when you are pinpointing, unless you are deploying DX-1 in the DISC (AC)
mode. If that's the case, then DISC (AC) controls the sensitivity of the DX-1, again, along with RX Gain
(PAG). Fox
RX and Disc - There are different symptoms of having your RX too high vs. having your Discrimination
Sensitivity too high. If you have your discrimination sensitivity too high you will get erratic readings
by just holding your detector at waist level. When your RX is set too high, you may not get falsing
when the unit is held at the waist. You will, however, get false readings when the coil is being swept
on the ground.
What I will do is set both to my usual settings (around RX 12 and Disc Sens 91). If the V3 appears
stable at this level, I will inch both a few notches higher. If I get erratic readings at waist level, I will
back the Disc Sens down a notch or two. If I get false readings while sweeping the coil I will back
down the RX Gain. Neil Jersey
RX Gain and Discrimination Sensitivity - The Rx gain control is done in hardware which is done at the
Preamp or where the signal from the receive coil goes into the instrument. The Discrimination gain is
done in the software after the signal from the coil has gone through all the analog hardware
(circuitry). The Transmit Boost adjustment is the setting that will boost the signal going to the
transmitter of the coil. rcsnake
RX Gain affects both All Metal and Discriminate ....
Set RX first, then increase DS until Spectra starts making noise, then back off about 5 points.
A good starting point is C&J, RX = 6, DS = 80, AM = 60. Work up from there. Fox
12
For the V3 it is better to lower the Rx Gain and raise the Disc to help the V3 run stable while
providing max depth.....I'm currently holding on 95 for my Disc with my Rx Gain at 13-14....been
playing with the Disc set at 100....but I'm not yet ready to leave it there. Robert
Jimmy Sierra posted recently about RX Gain and Disc adjustments. Per his post RX Gain has little to
do with depth. TX Boost, Disc, and all metal (if running mixed mode) have the most effect on the
depth achieved by the V. He also mentioned that lowering your filter setting when you can will also
help detect deeper targets. JimDE
Where's The Noise Coming From ???
A lot of folks are noticing some "spiking" in the negative range, often accompanied by a
positive VDI. Other folks are reporting "noisy" operation. Here's some info I learned from the
engineering staff at Whites this week.
1. "Some" spiking is "normal". It says that Spectra is seeing some iron, AND a positive signal
at the same time. Spectra is programmed to RETAIN that positive signal in case there is a
GOOD target being masked by a ferrous object. If you have falsing where it shows the red
line with a positive VDI # displayed, try disabling visual reject and you'll see a negative VDI
at that point. With visual reject enabled, Spectra doesn't automatically erase the +VDI if it
sees an iron signal and a good VDI.
2. If you drop your RX and DISC sensitivity, you should see a lot of the spiking go away.
Again - "some" is normal. If you watch closely, you will also see this happen on DFX and
XLT. It's just not as prevalent, because those units simply aren't as sensitive as Spectra and
don't process targets nearly as fast.
3. Here's a "quick check" to make sure your detector is "quiet", and that the "noise" you are
seeing is coming from an outside source via the coil:
a. Disconnect the coil
b. Turn Spectra ON
c. Set RX = 5 AM = 55 DS = 80
d. Watch the Spectragraph. It should be quiet with no, or a very, very infrequent spike.
e. A "good" unit will run 5 - 10 minutes or more w/o spiking. (Robert and I tested this).
4. Here's another quick check for external noise - using the Analyze screen as an oscilloscope.
a. Turn Spectra ON
b. Have someone wave a coin under the coil to simulate a "deep" target
c. Note the leading and trailing edges of the "camel hump"
d. If you note that they are "ragged" or "wiggly" - that's external noise impressed on the target
signal
5. Take note of how your machine performs with a freshly charged pack and one that has
10.00 volts or less left on the charge. If you see a MARKED difference in performance, then
you should contact your dealer or Whites for advice.
6. You can get Spectra "about where it wants to be" by "working up". I've found that the best
way to bring Spectra on line is to start with RX Gain = 3, AM = 45 and DISC = 30.
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Swing it. If it's quiet, bring Disc up to 35 and swing it. Keep bringing DISC up until Spectra
starts falsing. Back DISC off 5 points and bring RX Gain up to 5, then 6, etc.
You'll find a "happy place" where Spectra is stable. You are going to see some "spikes" in the
negative range, and maybe a positive VDI now and then. Again, that is Spectra trying to
process iron w/o losing a good target. (See #1 above). Adding a bit of Bottle cap reject (about
+2) and Hot Rock Reject (about +2) helps. You may need more or less depending on your soil
conditions, loop, etc, etc.
Finally - bring your Recovery Delay back to about 50. That will help your target separation.
Hopefully - these "lessons learned" will help Spectra users get their units "quieted down". The
one BIG lesson that I have learned, and the "take-away" from this weeks testing is to simply
FORGET what you know about DFX in terms of sensitivity. The two units are just TOO
different to try to draw parallels. You'll just get frustrated. EG: RX=1 / AM=1 / DS=1 ....
Spectra still isn't "shut down". Depending on the coil, you can see a copper penny at 2 - 4".
Again - Robert and I have verified this on several units.
Don't be afraid to "cool Spectra down". You're not losing a lot of depth between RX = 5 and
RX = 10, but you're GAINING a lot of "quiet". Same / same for DISC. Work RX with DS and
you'll be amazed at what you can achieve.
This week was truly a learning experience for me. I got a lot deeper into Spectra then I ever
did into DFX, and at each level I was more impressed with the potential that exists, and with
the level of thought and engineering that went into the hardware and software that IS Spectra.
Hope this is helpful. Da FoX
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Chapter 4 – Detecting in Iron
Sometimes a target will give the threshold change, but jump into the 80's or 90's on the VDI scale. If
the target has a dominant hump showing 22.5, it is most likely iron. If 2.5 KHz or 7.5 Khz was
dominant, it would be a diggable target. Neil
Another trait of a VLF unit is to have the threshold drop out over iron, even in ALL METAL mode. This
is especially true on deep iron. Another iron trait is a "double hit" on an iron nail. Fox
The High pass filters will pick up more ground noise/iron noise. The Band pass filters help with EMI. It
has been my experience the 5 Hz filter seems to give better depth as opposed to the higher filters.
The lower conductor sounds such as foil seem to come in better with a slower sweep and a slower
sweep speed seems to help cut down on iron noise/ground noise when using the lower filters. Also
the high pass filters seem to be less sweep sensitive than opposed to the band pass filters. RCsnake
A modulation setting of 3 or 4 can greatly reduce the high sharp tones of deep iron, and, in some
cases hot rocks, while leaving the tone of a good target at full volume. This an alternative way to deal
with these issues without using HRR or Discrimination, which in turn keeps you from loosing depth.
CyberSage
Fox, you will eventually figure this out. I spent two hours in the local park this afternoon to make sure
I had my facts straight on modulation with the V3. I turned modulation off and found a deep iron hit
that was wrapping and presenting itself at +94 to +95 It pinpointed to the side just like the nails in
this area that I have dug in the past. I turned modulation on and adjusted until the volume dropped
on the iron hit. Then I dug. It turned out to be a piece of fence wire about 2 inches long with the tip
sticking out of the sidewall of the hole about 9 inches down. I then continued my hunt with the
modulation on with a setting of 4. About 40 minutes later I had a great deep hit. everything looked
good. 7 inches down was a 1924 D Mercury Dime. What a surprise considering how many
detectororist I see here. So the wire put off a muted sound and the Merc sang out loudly. Does this
help you see how you can quiet the iron and still get full volume on coins? I would have been happy
with a Lincoln at 6 inches for my test, but I will gladly take the Merc. For what it's worth I would not
have found that silver dime today if we would not have had our little discussion here on the forum
today. So in a twisted kind of way you helped me find a keeper. Thanks Fox.This an alternative way to
deal with these issues without using HRR or Discrimination, which in turn keeps you from loosing
depth. Cyber Sage
TexasRanger The subject of 'ground readings' on both the White's V3 series and other makes of detectors with
ground monitoring indicators, is only vaguely understood by many people.
That is not surprising, because it is a very complex 'scientific' affair'.
15
That is because of the several variable factors involved.
(1)....The various minerals within the ground's matrix, predominantly the ferrite, and secondly, the
soil's chemical contents, amount of moisture, and its pH value.
(2) ...Secondly, (but not necessarily in order of importance.) the design of the instrument involved in
'measuring' the ground's effect on the unit used.
(3)....Also, the diligence and methodology of the person performing the measurements.
(4)...The importance of the frequency involved, is ultimately reflected in the readings obtained.
The readings indicated by our detectors, are very 'rough value' indicators, and should be viewed
more as an relative guide rather than an absolute measurement.
Their 'benefit' of such data, depends solely on the person's interpretation of how well he
understands the 'basics of metal detecting'.
i.e. How mineralization affects the depth and VDI accuracy of his detector.
The Whites V3 / V3i offer the best opportunity to their owner, to learn in a practical way, something
about the mysteries of what is going on 'under the coil'.
Because the forum's audience may shy from the scientific aspects of what is involved and necessary
to 'prove' the validity of any statements, I offer the more acceptable generalization of the 'outcome'
of what the changing figures imply.
FIRST:- Accept for the purpose of explanations, the REFERENCE figure of say,..... 90 degrees.
Let that be the phase angle for your search head when raised to waist level, IN AIR.
Now we next obtain the change in that reading when the coil is placed on the ground......The
GROUND EFFECT.
If that INCREASES, then the predominant effect is caused by the presence of ferrite in the soil.
If it DECREASES, then the predominant effect is caused by the conductivity of the soil, due to
moisture contents and its acidic state. (Due to chemical and/or composite states).
So, from the 'non technical' point of view , we need only be aware of the relative variations, and then
summarize them to suit our personal interpretation of what they mean.
Minus 91......low Fe mineralization
Minus 92....93....94, increasing to severe mineralization.
DECREASING figures in to the 80's or lower, show probable increase in soil dampness and hence
conductivity.
The consequences of FERRO mineralization is to negatively mask the values of a target's conductive
properties.
The consequences of Increased soil conductivity is to enhance the ground's conductivity factor, and
the target's apparent signature, by an amount dependent on the target's material, shape ratio, and
the frequency involved.
Depending on the absolute circumstances of target characteristics and time buried, will determine
16
the degree of improvement in detectability.
So there are some starting points of conversation in this very intriguing subject of soil science and its
relational effects on detecting
Affect of water at e.g. -89
Any heavy penetration of water into the soil strata, should in theory reduce the -89.
Cybersage on iron falsing - I think your settings of RX=12 and DS=93 are very reasonable for our
hunting conditions. Digging a little iron when your after deep coins is normal. Your going to dig a few
rusty nails, wire bits, and chunks of iron. Most of the time crosschecking your target at 90 degrees
will reveal the tell tale splatter of deep iron. You will soon acquire an ear for deep coins as well.
Listen for a slight drop in tone in the decay of your targets signal response. In other words the tonal
response of a coin will usually roll as opposed to being sharp and cut off. A lot of deep iron will throw
a false pinpoint. Visualize the center of your target in motion mode. If it pulls away from that spot
when you pull the trigger and go into pinpoint mode, your probably over a bad target. Finally, vary
your swing speed just slightly when testing for repeatability and consistency on response from the
target. I wouldn't be afraid to experiment with turning down things a bit. Even with the moderate
mineralization strength of our soil, you can drop to an RX=6 and a DS=90 and still easily hit coins at 7
inches. With lower sensitivity settings you must allow for wrap however. Saturday is looking pretty
nice (in the low 50's). I will probably be headed your direction.
Sounds like big, deep iron. How do they pinpoint? I thinks we've all seen these signals and there are a
few things you can do:
- Pinpoint the signal and sweep directly over it and see if it is iron...sometimes the edge of an iron
signal can sound like a coin
- Sweep the target from all directions and see if it is a repeatable signal in at least one direction
- If the pinpoint is weak and diffuse it is usually iron
- If the pinpoint moves around, it is usually iron
- If you can raise your coil off the ground and still get a signal it is probably a large, deep target
- Stomp on the ground at the target location and see if the signal changes
- If your coil says 0-2" or so and your handheld pinpointer (like a Sunray) hears nothing...probably big
and deep. BeepGoesOn
The only thing that could be added is checking those "iron rebound" VDI spikes for being good
targets. Again, sweep those from multiple directions and heights. (Deep and large aluminum can be
treated similarly, but VDI's stay tight and "too good to be true".) NW1886
Falsing & Autotrac - I do experience more falsing with Autotrac on but I don't think it affects the
depth of targets. That is why I lock autotrac in my ground. Neil
A good tracking speed is one that keeps your threshold steady while you're swing the coil. If you set
it too slow your machine may go silent and can cause a loss of sensitivity and lost targets. The
tracking is trying to accommodate the mineralization changes in the ground, so too slow will allow
the mineralization to generate excess noise. If you set it too fast your machine will try to match
every little change in the ground and you'll get overshoot which can also result in noise and lost
targets.
So if set too fast or slow it cause your problem. Rob
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Ground Tracking - Gary
Default Autotrac settings, then switch to Trac lock if lots of iron present and use a +1 offset
Tip : Pull the trigger and slowly lower the coil to the ground (make sure no iron is beneath the coil)
Listen to the audio threshold, if it dips you need to raise the tracking offset, what you are looking for
is a slight raise in threshold as the coil approaches the soil.
Sometimes you may need a high setting such as +10
Frequency....3 Freq, enable salt if unstable – Gary
Iron has become really easy to spot by watching for the red on the right of the 2.5 KHZ bar. Red on
the right and it was iron every time. Same with bottle caps. Red on the right of 2.5 KHZ bar.
Southwind
Coils - But in non mineral ground concentric have advantages.
Concentric loops have the following advantages:
Can get good targets under bad targets because of their cone shaped field
They are 10% quieter regarding magnetic interference from power lines
They have 10% better trash discrimination on iron - steel bottle caps and foil
They can shape the target without walking around it. Rob
Old nails are part of the norm.One thing I haven't seen wrote with all the other advice was to check
the PP analize screen to see what is dominant.Then move 90 degree and check again, if it doesnt
match and or center the same location then I would suspect a nail or small iron.Those 3 bars can tell
you a lot. H.H. Yazoo
Iron Wiggle - The wiggle test is what I use the most. If I get that deep good sound, I pinpoint with the
best accuracy that I can get. Then I just barely wiggle the coil left to right and back and forth and if its
a nail or iron, it will show up as such. I dig very few nails but sometimes I get that really good tone
that I have to dig no matter what my detector tells me and sometimes its a nail...sometimes its not.
Magic
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Chapter 5 – Probe Related
Rob - "PHASE ANGLE" is the measured difference between the transmitted signal and the signal
received from the target. Different materials have different characteristics (resistivity, reflectivity,
conductivity, density, etc) which affect the signal that is returned from that specific target. It is this
difference between the transmitted and returned signal (phase angle) that is measured by.
The detector only reports VDIs converted from positive phase angles (0 to 180 degrees). The negative
angles aren't valid assuming that the machine is calibrated correctly. In the ground probe screen, you
may see negative angles if you are holding the coil in the air so there is no real signal coming in - just
noise, or you haven't zeroed it first. Once you zero the machine and lower it to the ground, or read
your target, your phase angles should come in between 0 and +180 (as with anything there will be
exceptions - ground conditions, noise, what have you). A ferrite bead will come in very close to 180
degrees (-95 VDI) which is close to where most normal ground comes in and pure conductors will
come in around 0 degrees (+95 VDI). Salt water (wet beach or fields with lots of fertilizer and wet)
comes in close to 90 degrees (0 VDI) Approximate numbers.
Ground should fall between 0 and 180 degrees. In air, when you zero the detector, you will see
phases of both positive and negative values - those are just noise and don't pay attention to them. If
you are getting a negative phase for any of the frequencies when you lower the loop to the ground
however, you probably have an overload problem. Most ground that we see is 178 (-94) to 165
degrees except salt which falls close to 90 degrees (VDI 0).
Nonferrous targets (coins and such).VDI 0 - +95
The VDI reading is converted from the ground phase normalized to standard VDI units. It's either
going to be from the strongest signal if the detector is running best data, or the average of the two
strongest signals if correlate is selected. If you have ground coming in at -94(VDI) with a signal
strength of 2% and another ground coming in at -91 with a signal strength of 7%, it would seem to
me that the ground coming in at -91 is more mineralized even though it is a less negative VDI. 010%=low mineralization, 11-25%=moderate and 25% on up = high/very high. Try to keep it at 20% or
less. The lower the mineralization, the slower one should sweep - which may mean a lower filter
should be selected. The phase tells you composition (between purely ferrous and purely salt), while
the signal strength tells you the concentration (more mineralized).
To get the phase of your target, put the coil on the ground away from the target and press the zero
button - that captures the ground for separating its effects from the target. Then put your coil over
the target. That should get you pretty close to the phase of the target. The VDI number at the top is
the normalized reading. The numbers for each of the 3 frequencies are the phases that each
frequency sees for the target. In the ground probe, the phase angles are not normalized, just the VDI.
It was intended to be used to just check out the phase of the ground, but, it can also be used this way
to check out a target if desired.
19
By determining the grounds VDI and the relative strength of the mineralization, changes can be made
that will improve the performance of the detector. The high mineralization can cause smearing and
spiking in the high negative VDI range and may cause a loss of depth due to signal loss, and some
falsing of high VDI signals.
If you find yourself in a highly mineralized ground here are some options available to you to
counteract its affects.
Reduce sensitivity - Use a smaller coil - use a lower sweep speed - Change ground filters - Change to
Correlate Mode
deolslyfox
The "Phase" gives you an idea of how what kind of soil you're looking at .... Magnetic or conductive.
The "Strength" gives you an idea of how strong the mineralization is.
Remember, the TYPE of mineralization (ferrous = iron or conductive = salt beach) or the VDI of the
ground doesn't have anything to do with how STRONG the mineralization is.
Knowing this information can help you select the Ground Filter that best suits your area. However,
the "best" test is the filter that gives you the quietest operation. Also keep in mind that your
"sample" is good for the spot in which you took it. The ground may change drastically in 50 yards.
Mineralization 101
I’ve gotten a few PMs over the last couple of weeks regarding mineralization, so I thought Id put a
top level overview together and post it. Hopefully, this will cover most everyones questions and clear
up some misunderstandings about what mineralization is and isn’t, and provide a few tips on how to
deal with it.
Composition: Mineralization is comprised of two basic types of material. Iron based or ferrous and
wet (dissolved) salt based or conductive.
VDI range: Ferrous mineralization is in the -95 to -75 VDI region. Conductive mineralization such as a
wet salt sand beach is near VDI -15 to +15.
Composite Soil: It is very rare to find a patch of ground that is 100 percent ferrous or 100%
conductive. Generally, you’ll find a composite soil. If you look at the grounds VDI and find that its a 90, you’re seeing a predominance of ferrous material, mixed with a lesser amount of conductive
matter, resulting in a composite VDI of -90. The lower VDI conductive is pulling the VDI towards 0,
away from the -95 ferrous range.
Mineralization Strength: The grounds VDI is NOT an indication of the STRENGTH (severity) of the
mineralization.
EG: If we have one ton of soil that contains one pound of iron filings, it will be ferrous ground, but
the strength of the mineralization will be very low. On the other hand, if the ground contains 250
20
pounds of iron filings, the ground will still be ferrous, but the strength will be much greater. The
same is true with conductive material such as wet salt sand. The higher the concentration of salt, the
stronger the mineralization.
Why is this important?: By determining the grounds VDI and the relative strength of the
mineralization, a seasoned detectorist can make some informed decisions regarding the selection of
Ground Filters, Coil Selection, Sweep Speed, Frequency to use and other settings. When combined
these settings will improve the performance of the detector. While not all these features / functions
/ selections are available to ALL detectors, most of the e-series units (M6 / MXT / MXT PRO / DFX /
V3 / V3i) will allow the user to accommodate various ground conditions to some degree.
How Do I Determine Mineralization Strength?: With Spectra, I have found the following estimates to
be ballpark and will get you close enough to tweak. Based on Signal Loss LOW = 0 to 15%, MODERATE
= 16 to 35% and HIGH = 36% and up. With DFX and MXT, there are processes that can be followed to
measure the ground VDI and strength. They are described in Jeff Fosters books, Digging Deeper With
The DFX and The MXT Edge.
How Does My Detector Deal With Mineralization?: There are two important functions that help your
detector deal with mineralization. Ground Exclusion Balance (G.E.B.) and AutoTrac. G.E.B. measures
the type and strength of the ground mineralization and then does its best to eliminate the effects of
the ground by reducing the machines sensitivity to the grounds VDI. This is the Ground Balance
sequence that you see discussed on the forum. Once the GB sequence is complete, the AutoTrac
system continuously monitors the ground and adjusts the G.E.B. settings to accommodate
mineralization changes as you hunt.
What Will I See If Im In Highly Mineralized Ground?: The predominant effects of high mineralization
include smearing and spiking in the high negative VDI range. You will generally suffer a loss of depth
due to signal loss, and some falsing of high VDI signals in the +95 to + 93 VDI range. This is one reason
to reject +95.
What Do I Do About Moderate To High Mineralization?: If you find yourself in a highly mineralized
patch, that the G.E.B. system cannot completely eliminate, there are numerous options available to
you, depending on the machine youre using. These options include, but are not limited to the
following.
- Reduce sensitivity
- Use a smaller coil
- Slower sweep speed
- Change tracking speed
- Change ground filters (DFX / Spectra)
- Change frequency modes (DFX / Spectra)
- Change to Correlate Mode and adjust Wrap / Span (DFX / Spectra) (Wrap / Span = Spectra only)
- Change to Relic / Prospect Mode (MXT / MXT PRO)
- Change to Salt Tracking Mode (MXT / MXT PRO / M6)
Again this is a top level overview of mineralization. It is something that all of us have to deal with to
some degree or the other. Down here, I am blessed with sweet soil. With the exception of the beach,
21
my ground is slightly ferrous, but very weak. Most of the beaches I hunt are salt, but not so highly
concentrated that the e-series units cant deal with it if properly deployed.
As your conditions change, if you have an understanding of what youre dealing with, youll be better
prepared to use the features / functions provided by your particular detector, combined with your
field experience to overcome the effects of mineralization and have a more productive and enjoyable
hunt.
Smack - So Phase +180 to -180, with ferrous ground at +178, Strength is measured as a percentage of
the maximum signal strength. Typical weak ground will come in below 10%, moderate mineralized
ground 11-25% and highly mineralized ground will come in greater than 25%. Now this is shown in
each frequency, with each frequency responding differently according to the frequency. Some times
they are showing a moderate spread. Which is the best to look at? And what happened to the rest of
the signal strength. Is that removed after it compares the ground balance and the target/soil type.
Polar plot shows me the phase, so it is showing me quickly each frequency phase.
So the box sees the ground phase and signal strength reading of the ground, then when you go over
a target it sees the change in phase and signal strength and calculates the new phase and signal
reading minus the ground reading phase/signal and determines a VDI and can show me the strength
in each of the three frequencies and will, depending if I have the normalize on or off, shows me the
determined or actual VDI.
So if I have the box incorrectly setup, then I get bad data out as the saying goes. If I have autotrack
on, then this should all be taken care of in the background, with some tinkering by me in things like
salt or not, or the speed at which I ask it to track.
Ground balance seems to be the heart of the machine, or at least the occipital lobe of the brain
making sense of what the eyes, loop and box see. RXG/AM/DC/TX boost can make my eyes look
deeper or shallower, or allow or block the noise coming into the box.
Is there a test to see if the ground balance system is working correctly, that I can do at home. The
test to check the loop/coil is available, but to do a ground test you would have to have a standard or
base line to compare it to.
Fox - A "quick check" is to take your detector to a spot and ground balance. Lock the trac. Then with
the trac locked move to another spot that you think might be different - say a wet area - or a
different looking patch of ground. Move the coil over the new patch and see if you get some noise. If
you do, then do another GB and your machine should compensate and be quiet again. If it does, your
GB is working fine.
To check your AT, GB, Lock Trac and "hunt" over to the same spot that had the difference as
discussed above. Turn AT = ON. That will restore the GB to the settings that AT has calculated, but
not applied with AT = OFF.
**************************
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Different frequencies respond to soil conditions differently. Some users look at the % signal loss, and
choose the frequency that is losing the least amount of signal. Some folks prefer to choose the
frequency that is closest to "0". Personal preference, but IMHO, for mineralization, unless it is
SEVERE, you're better off running in 3F and letting the machine take care of the ground for you ....
Take advantage of the dual GB points and the additional target information provided by each
frequency. Especially on the beach, working from wet to dry to wet .
Neil - I think it may be a lot simpler than all of the above. I use a simple method that suits me fine. I
perform a ground balance, and then I lower my coil to the ground while in pinpoint mode. If I get a
depth reading of 11 inches or more, the ground is mild. If I get a reading in the 7-11 inch range I
would say it is moderate ground. Areas with high mineral content tend to read lower readings than 7
inches.
Cont – (wrong) I guess that would be another thing to look at: Scroll over to the Sensitivity on
the Live Menu and hit zoom. Mild soil should have little signal loss and bad soil would have a
high signal loss. It seems simple enough.
Robert - This is not what this feature is for..it's by no means telling you what your Soil
Conditions are from this signal loss feature....granted there are several factors that determine
how much signal loss is occurring...one factor is quality of the coil....and there are several
other factors including EMI go into this %....to prove this..you can hold the detector in the air
waist high and test the % with several coils of the same type....ex: several 6x10's all VRated...and you'll see a range of signal loss percentages from each coil some high/some
lower...and that's In the Air...no ground conditions are being considered...now it may be
possible to lower the coil from this point and see which coil loses the least amount of signal
loss due to the ground conditions which would indicate a Stronger Coil...but yet this still
doesn't indicate how much Mineralization is in the ground as High-Medium-Low...granted it
is a factor when lowering the coil to the ground that affects the signal loss....but where does
one seperate Coil Quality...EMI...Mineralization in a % form ?? (just to name couple factors)
Fox quoting - Neil .... This is a "sample of one" test, but it's better then none for sure .... Its a
process that has been around a long time. We used to listen to how loud the sound was as you
moved the coil towards the ground. Its a function of reflectivity. In other terms, how much of the TX
signal is bouncing back to the coil due only to the ground minerals. It works, but its a SWAG at best.
However, a SWAG is infinitely better then "I have no clue".
EG: Using your numbers, if your
10"DD reads 8", you have moderate mineralization. If you move to another spot, and you read 6" you
can probably safely assume that the mineralization strength has increased.
Robert is also correct. You and I could stand side by side with two different 10"DD coils and get two
different numbers, all other things being equal. If we compared a 10"DD to a 6X10"DD, the
difference would be even more pronounced, and more pronounced yet with a 4X6"DD. If each
person "maps" each of his / her coils, then they'll have a better benchmark when employing your
process.
Jack .... This is reminiscent of the DFX process with one major deviation. The DFX process requires
you to "move the ground balance out of the way" by changing the Coarse GEB setting after a Ground
23
Balance. That lets DFX "read the ground". With the approach that Neil is employing, when the GB is
done, track locked, etc, the ground is still in the mix. I believe what you're thinking about is the
process where you squeeze the PP trigger and read the DC Phase number to get the ground's VDI
number, vice the mineralization strength.
All: Since Spectra provides the capability to actually see WHAT KIND of mineralization is present, and
the effect that it is having on YOUR COIL with YOUR SETTINGS at THAT SPOT, I'd recommend taking
the 15 seconds to let Spectra tell me exactly what its seeing. That way, all of the variables are
cranked in, the actual ground phase is there along with the signal loss is displayed for each frequency
and all the "by guess, by gosh and kentucky windage" is removed.
Once we have this information, what should we do with it? Select filters, sweep speed, and
frequency modes.
One last tip: As long as we are in the SWAG mode, you can come up with a "ballpark" depth estimate
.... EG: What is the Minimum Depth that I should be able to see a 1" target (quarter) with my setup?
Here's what you do.
Min Estimated Depth = ((Coil Size X 1.3) X (1 - Avg % Signal Loss)) X Target size in inches
If your machine is reporting an average of 20% signal loss, a 10" coil can "theoretically" see a quarter
to at least at 10.4".
The same setup with all things equal will see a dime to at least 6.5".
If you get noise down to 10%, the quarter can be seen to at least 11.7" and the dime to at least 7"
Changing coil size to the 6X10"DD with 10% noise yields a minimum 7.0" depth on the quarter and a
minimum 4.3" on the dime.
Max depth estimation is easier. (Coil size X 1.3) X Target Size ....
A 10" coil can see a quarter at 13". A 6" coil can see a quarter at 7.8". 10" coil can see a dime at 8". 6"
coil can see a dime at 5".
The above calculations are conservative. Some folks use 1.5 X coil diameter. Others will say 2X.
Unfortunately as coil size, shape, quality of null, etc come into play, the function is not linear. Again this is a "ballpark" estimate, but will give you some idea of how your setup is working. If you're out in
a spot with your 10"DD, have a good ground balance, and not being saturated with EMI, you should
be seein' a 1" target at around 10". You might do better, but if your signal loss is below 20% and you
can't hit anything below 6", then you need to be lookin' at filter, sensitivity or your coil, because
you're "way outta bed".
That's about all this "rule of thumb" is good for, but it works pretty well, most every place, with most
every coil, and most every machine. is it perfect? Not by a long shot. But like Neil's process - its a
heck of a lot better then "I have no clue". End Fox quoting.
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Rob – What does Zero Do? The right side of the screen reports the phase and strength of the residual
signal and does so for each individual frequency.
This is useful for analyzing the characteristics of the ground, but only if the residual signal consists
purely of ground signal.
This will be true if we can get rid of other residual signals like an imperfect loop null. To get rid of
any residual loop null signal, hold
the loop in the air, TAB to select the Zero button, and press ENTER.
Now you can lower the loop to the ground, careful to avoid targets, and the Phase and Strength
numbers will be that of the
ground.
RCSnake - This is something I use as a rule of thumb that I start out with if I am not familiar with the
ground conditions of the area. This is just a starting point but this is how I use the ground probe to
get me started hunting and then make adjustments to the Rx gain as I am hunting.
Ground Probe: By highlighting the Ground Tracking box on the Live Control Bar and then pressing the
zoom key to bring up the ground probe screen, raise the coil in the air (but must be free of EMI)
Highlight zero if not highlighted and press enter. Then put the loop on the ground in an area free of
trash or targets and then read the screen as it will show the VDI of the ground, signal strength of the
ground at each freq if you are in the 3 frequencies and the phase in degrees of the ground. This
should give you idea of how strong the ground is and the VDI of the ground. The Rx Gain and Tx
Boost, which coil is being used, and three frequencies or single frequency will have an effect ground
strength I consider signal strength of the ground as follows 0 to 10% weak, 10% to 20% Moderate
and 20% and up to be strong. So what do these strength readings tell me? When the ground is
strong, I will lower the Rx gain to around 5 or 6 as a starting point or if the reading is weak to
moderate strength, I will usually start around 10 to 11, and then make adjustments while hunting as
this is just a starting point for the Rx gain. Also the amount or trash in the ground or if it is a tot lot
how close can the loop get to the metal poles will have a big influence on where I set the
gains/sensitivities of the instrument.
The Sensitivity Probe was for trying to give a suggested gain on the Rx Gain but it was inaccurate and
set to low so when the V3i came out the suggested gain was take taken out. THe idea was to keep
the ground signal around 10% but this proved out to be to low. The signal it is measuring is just
coming right of the preamp or the first stage of so try to keep it around 20% and not approach the
100% as this will cuase a overload. However, with that being said I usually do not use or look at this
that much as if in doubt of the area I check the ground probe and then go from there. Most the times
I just start hunting and make adjustments on the fly as I know most the ground where I hunt....
Hmmm maybe it is time to find some new areas. Not much information but I hope this answers your
question.
Neil – Determining Ground Mineralization. The simplest way to determine if your ground is bad is the
depth reading over ground that is free of targets. Once you have performed a ground balance, you
will notice that when you pinpoint over clean ground with light mineralization you will get a deeper
reading from the ground (11- 13 inches) vs. bad ground which will give you much shallower depth
readings (4-6 inches).
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The detector will always detect the ground while in pinpoint mode. Ground Balancing cancels out
most of the signal from the ground that the detector detects...but not all of it. You will notice this
when you pull the trigger back and lower the coil to the ground. If you look at the display as you
lower the coil, you will get some type of depth reading, and possibly a change in the threshold. As the
coil gets very close to the ground with the trigger pulled, look at the depth reading on the display. In
mild soil you may get a depth of 13", in moderate soil it may read 8" in bad soil it might read 5". This
means that targets deeper than the depth reading may be difficult to pull out unless you adjust your
filters accordingly.
Fox - WW .... What Neil is addressing is a variation of the "Coin Inch" measure that is discussed in Jeff
Foster's "Digging Deeper With The DFX". In Jeff's own words, this process is "somewhat arbitrary".
With DFX, the operator can "set aside" the Ground Balance, which allows the ground to be viewed as
a target. Since you can't do this with V3i, the information provided by V3i using the DFX process is
even less accurate then that provided by the DFX method described by Foster's 7-step process. In
addition, the reading you get is affected by coil size, ground moisture, sensitivity and the fidelity of
the ground balance that you started with. You can take a snapshot of the ground, move ten yards,
and get a totally different reading. Likewise, if you left all settings constant, stood still and repeated
the process with the 12" concentric, 9.5" concentric, 6" concentric, 10"DD, 6X10"DD and 4X6"DD,
you would get different readings with each coil.
The steps to "evaluate" the ground with ANY VLF machine, uses the audio as the benchmark, and
goes as follows:
1. Get the best ground balance that you can achieve over a clean area with no targets.
2. Raise the coil to waist height. (Let the machine "track to the air")
3. Pull and hold the pinpoint trigger. (Lock tracking and hold the machine at the "air" measurement)
4. Lower the coil to the ground. (Bring the ground into proximity of the coil, making the ground "the
target")
If the audio increases just a bit, you have "sweet" ground. A bit more is "moderate" and a fairly loud
response is "bad" ground. Jeff Foster alludes to using the audio in his description of the DFX process.
Again, it is aribitrary, and fairly meaningless.
Why meaningless? Because the ground signal has a VDI just like any other target. This VDI is
eliminated when you achieve Ground Balance, and from there, the AutoTrac process continually
updates the GEB setting, thus continuously eliminating the Ground VDI.
V3i provides a better method taking a snapshot of the ground by using the Ground Probe feature,
which is activated by selecting the Ground Tracking Live Control and pressing the ZOOM button.
The Ground Probe feature is described in your User's Guide, so I won't go over it in detail here. It will
remove the system / coil offsets and enable the user to achive a more accurate reading of the
ground. If you press and hold MENU then press ZOOM while you have the Ground Probe activated,
you will be taken to the on-board overview of the Ground Probe function, how to use the function
and the data provided by the Ground Probe.
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While we're here, we might as well hit Sensitivity Probe as well. This function is activated by selecting
the Sensitivity Live Control and pressing ZOOM. You'll see Signal % and Noise %. Again, if you press
and hold MENU then press ZOOM, you'll find an overview of "Sensitivity Probe".
After reading that, arrow down and you'll find "About Sensitivity". Highlight "About Sensitivity" and
Press ENTER. This will take you to the "About Sensitivity" screen. Press and hold MENU and press the
down arrow five (5) times. This will bring you to the detailed explaination of the Sensitivity Probe.
Besides describing the function / information provided, you'll find some tips there.
At the end of the day, the process that Jeff Foster describes for the DFX, Neil's process, the generic
process that I discussed are all "arbitrary snapshots" of that patch of ground under your coil. The
ground can, and most likely WILL change as you walk around hunting. Hence the AutoTrac feature.
Your best success in "fine tuning" your V3i for the area you are going to hunt will come thru trial and
error. When you get to the spot you want to hunt, simply bury a coin at about 6". Check the target
and see how your unit responds. Try changing the Ground Filter setting and see if things improve /
get worse. Same / Same for RX Gain, Disc Sense, AM Sense. "Fine tune" your V3i's performance after
you get the best depth by optimizing the S.A.T., AutoTrac and Recovery Delay.
If you bring all these functions to the Live Controls, you'll find that you can get "set up" to hunt a spot
with "optimized" settings in about 5 minutes or less.
Since RX Gain controls the signal from the coil to the box, I always do that first. Then DISC Sensitivity
(motion) and last, All Metal sensitivity (non motion).
As Warren stated - you will probably have to "touch up" the settings a couple of times to find the
best balance. ESPECIALLY if I change RXG or a filter, I always do a quick Ground Balance before I set
up DS / AM, as the RXG signal also contains the ground noise.
Fox - Signal % = "Percent of signal lost". If, due to mineralization, coil null, all other factors
you are only returning 87% of the transmitted signal, "Signal %" will = 13%.
Noise % = What percentage of the total signal is comprised of noise. From Manual:
• Signal = %. 15% indicates the Spectra is losing 15% of the original transmitted
signal.
In other words 15% of the transmitted signal is being degraded by ground minerals,
electrical
resistance, and other interference. It is rare to find an area where 100% of the
transmitted
signal returns.
• Noise = %. 0.0 indicates there is an unusually low percentage of external noise
(zero) in the
area. With low external noise, and without adverse ground mineral conditions, a
greater degree
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of Rx Gain is possible and recommended. High percentages of Noise suggest a
different
frequency method or Frequency Offset setting should be selected.
Tip #1. – If Signal loss is significant (50% +), the ground is highly mineralized
(contains a lot of natural ground mineral/metal oxides). Conservative sensitivity
settings, multi-frequency operation, and perhaps a smaller accessory search coil, is
highly recommended for such areas.
Tip #2. – If noise is significant (50% +), electrical interference is a major issue for the
area. Conservative Sensitivity settings, offsetting frequencies, selecting different
frequency method or a signal frequency, and perhaps a smaller accessory search
coil should reduce Noise levels.
Tip #3. – Best Rx Gain setting is achieved by an algorithmic calculation as a helpful
reference. Humans can almost always better interpret reasonable or workable
settings. A setting lower than recommended may be needed to achieve smooth
stable results. In others areas, a setting higher than recommended may be usable.
Edit – Rob (In Response to my “How to Set Up the White’s V3i” video).
http://www.youtube.com/watch?v=MykHQ7wob0s
Sensitivity Zoom
In the Sensitivity Zoom window, you see the signal strength at a percentage of when the detector
overloads. This isn't on any specific frequency - the reading is on the incoming signal before it has
been separated into the 3 frequencies. The goal is to keep the ground signal about 20% so that you
still get depth and can still see shallow targets without overload. Signal% doesn't indicate signal
"loss", but rather the amount of residual signal present. If ground + null are the cause, then this
doesn't take away from sensitivity. Instead, it takes away from large/shallow target response,
manifested in a signal overload. None of these are losses, but rather they reduce the available
dynamic range. The lower this % number the stronger the signal will come through or be received.
You can run the RX as high as you want as long as it doesn't cause overload. As long as there isn't
overload it will not affect performance. I myself would not go much higher than 40%. The better the
null on the coil the higher RX you can run. Try setting RX and check the % now try TX boost. The %
will go up and smaller signal could cause you to overload on a target, It shows % before overload.
15% means you have 85% before overload, 40% you have 60% before overload.
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Chapter 6 – Correlate Related
Larry - In Best Data any one of the three frequencies can result in a VDI but Correlate means that the
results from at least two responding frequencies must agree in order to display the VDI number.
Correlate is very good in helping to separate trashy targets from the good ones because two
frequencies must agree that a target is good, Correlate Mode is also good with EMI. Since the V3i
can't use, nor would I want it too, use 22.5 and 2.5 to Correlate, it will choose either 2.5 and 7.5 or
7.5 and 22.5 depending on your targets dominate frequencies. A coin, except a nickel, will use the
2.5/7.5 while a small gold ring might use 7.5/22.5.
Cybersage - The Correlate mode really brings out the magic with the V3/V3i. It's ability to sort
through trash transcends conventional recovery delay beliefs concerning masking caused by near by
targets. As Larry has stated only two of the frequencies must agree within the allowed span setting.
This leaves 7.5 playing the middle man most often. I think you get better results with higher
conductive targets. The 2.5 and the 7.5 are better suited for these targets. The 22.5 is way out there.
Fox - The basis for the Correlate version is to help deal with increased iron mineralization. Because
iron "smears" its VDIs, the signal will not be as consistent as it will from a non-ferrous target such as
a ring or a coin or a bullet or a buckle. And, because V3i correlates the signals from the two
frequencies that are hitting the hardest you are getting the benefit of "best data" anyhow ....
With the added feature of being able to tweak Wrap and Span, you can better accommodate the
amount of iron in your soil.
If you have very low mineralization, you won't see much, if any difference in the operation of the
two programs.
(A reply to me) - Too big a SPAN = More noise. The fact that your nickel is so high tells me that you're
adding a lot of ground signal to the VDI, which is "generally" a sign of an incomplete ground balance.
You may need to drop your RXG a tad to get a good balance. Remember, V3i doesn't get its depth
from "raw horsepower". It’s from improved sensitivity via better nulled coils, improved signal
processors and advanced signal processing. Fox
Neil - For better depth, I prefer single frequency 7.5 KHz. I seem to squeak out a bit more depth,
especially on mid-range targets. It also handles EMI better than either Best Data or Correlate. The
trade off is that my VDI numbers are not as consistent that is to say that my targets tend to jump
29
around on the scale a bit more. Fox - Best Data and Correlate don't have anything to do with EMI.
Those are multifrequency functions. I expect what you are seeing is the quieting down because you
have turned off the 2.5Khz channel. Try the same thing with 22.5Khz and see if your EMI doesn't go
away as well. MOST EMI comes thru the lower freq. Same / Same with DFX. You can drop the 3Khz
and get the same effect
*Note – It appears that Filters can very much affect correlates function.
Span & Wrap
Fox - These two controls are only operational when the Correlate Mode is active. Correlate
Mode is availabe in both Normal and Salt Compensate frequency modes.
Span Limit sets the range that the VDI signals from different frequencies can be separated.
Beyond the operator selected "Span Limit" the Correlate function will declare the target as
iron.
Higher number settings allow greater differences between a target at the different frequencies
and still be considered a good or valued target signal.
Lower number settings dictate less difference between the target at the different frequencies is
require to be considered a good or valued target as opposed to a trash metal.
Ideal span limit varies with the ground and target corrosion conditions.
Typically a lesser span limit is better suited to lower ground mineralization and/or lesser
target corrosion factors. A higher span limit is better suited to higher ground mineralization
and higher target corrosion factors.
Wrap Limit controls how far VDI signals from different frequencies can be separated for the
condition where the "higher" reading has wrapped to the negative VDI range. When the
operator selected "Wrap Limit" is exceeded, the Correlate function will declare the target as
iron.
When searching in the difficult ground and target corrosion conditions Correlate was
developed to address, it is typical for high range target signals (Quarter through Silver Dollar)
to exceed the top end of the scale (+95) at one or more of the primary operating frequencies.
VDI range from -95-+95 is circular (phase) so targets that exceed +95 re-appear at the <->
end of the scale -90s.
Correlate normally perceives -90s indications combined with +90s indications as hugely
uncorrelated (span the entire scale) so dictates such a target as a trash metal.
Wrap limit allows correlate to disregard normal correlation methods (sequential or linear) and
consider any -90s range signals that also have one or more +90s range target measurements,as
within reasonable correlate parameters. In other words a +95 combined with a -95 = one digit
off (close correlation) rather than when Wrap is OFF = full scale (no reasonable correlation).
By adjusting Wrap Limit, Correlate becomes more effective, indicating difficult targets in
30
difficult ground as good or valued target signals as opposed to immediately dictating such
signals as trash metal. Because in difficult ground and corrosion conditions the target signal at
one or more frequency often wraps around to the <-> end of the scale, wrap limit effectively
captures these target signals as worthy of interest.
In summary, Wrap and Span work together, and again, are only active in the multifrequecy
modes when the Correlate function is selected. Together, Wrap and Span help V3i overcome
the effects of ferrous mineralization and target corrosion.
Fox - "Turning Off" (Rejecting) a VDI won't eliminate wrap. The machine just won't report it. The idea
of Wrap and Span is to allow the machine to recognize what is happening, and to preserve those
targets that meet the parameters that you, the user set, rather then simply reject the target out of
hand. This is especially important because large silver, large quantities of silver can, under the right
conditions wrap into the -95, -94 region, depending on the ground conditions.
A more simplified version of Wrap and Span would only be more confusing and lead to more
questions and extra posts. Been there, done that. Got the T-shirt and post card. This IS the simplified
version. We didn't get into the part where V3i looks at all three frequencies and picks the two that
are hitting the hardest for that particular target, THEN starts the correlate process. With DFX,
Correlate is all "hard wired". The returns from the 3Khz and the 15Khz frequencies are compared to
preset limits. With V3i, you get to set the limits .... V3i still picks the two freqs to use.
Fox to me - Slowing down your physical sweep speed gives the same result as speeding up the
Recovery Delay without the loss of depth and target breakup.
Dropping gain past the point where edge effect is minimalized only costs depth. The coil will see
what's UNDER it.
Running in Correlate Mode with BCR=6 helps a lot with ferrous mineralization. You might try
adjusting Wrap and Span for your area.
Adding the proper Ground Filter for your area is the right move.
Bottlecap Reject controls how your detector responds to ferrous objects .... I'd run it up a tad, but
not too high, as TOO much BCR can cause good targets to break up.
Iron doesn't correlate well with various frequencies. It responds differently to 2.5Khz then it does to
22.5Khz. Correlate mode on V3i looks at the two strongest returns, and then correlates those ....
The 2.5Khz signal generally punches deeper than the 22.5Khz freq, so you'll most likely be correlating
between 2.5Khz and 7.5Khz. If your iron is deep, you'll be seeing some "iffy" VDIs to begin with. You'll
see some smearing as well. You'll also note a drop in the threshold as you pass over a large deep iron
target. That's a "classic" deep iron signature that has been used since TR units have been around.
Use the Ground Filter that works best with the rest of your settings.
Make a good Ground Balance the last thing you do after you've made all your selections.
31
Fox - WRAP controls how far high end signals (+90's) can go from the +95 into the -90's region (wrap
around) and still be considered a good target. If WRAP is set = OFF, any signal that "wraps" into the 90's is immediately disregarded. That's not getting the most out of the correlate feature. Soooo - by
adding a wrap limit of -94, I'm giving something like a silver dollar, in high mineralization or next to a
piece of junk the opportunity to "wrap" all the way to -94 before its kicked out of the pool. For what
its worth, Jack (CyberSage) and I arrived at this setting independently. Range = -95 to -90. The
HIGHER the number, the closer to +95, and the less wrap accepted. -95 IMHO is "too tight" and
anything more is bringing in too much junk, which is counter to the reason we're using Correlate in
the first place .... Good, bad or moderate ground, I don't think I'd go any further then -94 on the
Wrap.
Hope this answers your questions, and hope this is helpful. Let us know how the Correlate program
works out for you and what you did to optimize performance in YOUR ground.
Q - Can you tell me why one would not use the Wrap feature if it helps prevent a possible good
target from being kicked out? And, does it have to be used in conjunction with Correlate?
Yes - Wrap and Span have to be used with Correlate. Correlate doesn't just allow targets to "wrap", it
also says "the data from the two frequencies hitting the hardest agree" (correlate). Ferrous targets
don't usually correlate very well, so Correlate helps with ferrous target rejection.
Some people prefer to see more targets, so they employ BEST DATA, that says "show me the target
info from the frequency that is hitting the best ....
Other Rob - The theory behind correlate is that iron will respond with different phase angles for the
different frequencies whereas coins and such will give the correct response across the frequency
ranges. So, so correlate is one way to discriminate out iron. The drawback is that potentially you
could lose depth because the ground affects how the targets come in so they might appear to have
the phase difference like iron and get discriminated out. EMI noise would theoretically have an
unpredictable response across the frequencies and so EMI might be one way to remove EMI. So, for
those that don't want to hunt the deep targets might get an advantage for skipping over the iron
targets using correlate. But for those that want deeper, I don't think correlate would be a good
option.
I have used correlate for hunting newer and trashier sites with great success. I wonder about deeper
targets in my soil which is in no way sweet like Fox's. I'd like some discussion on deeper targets in soil
with more minerals using correlate.
Cybersage - My deepest finds have been in the correlate mode. I am pulling Indians, Wheats and
Silver Dimes at 8 to 10 inches on a regular basis from the local parks. My mineralization strength is
moderate. A large number of finds contain more than 1 target in the hole, mostly iron nails and rusty
caps. (This is probably why they have been missed in the past). To get those deep targets you need to
open up your discrimination all the way, reject nothing. (set the tones you don't want to hear to "0",
Slow down the recovery to 90 - 110, and slow your swing to a crawl.
32
Fox - Watch the Spectragraph .... You can see which frequency is hittin' the most consistently, and
you can use that information to determine small surface targets like can slaw from a deep nickel.
When you have all three frequency bars lined up, and you have a depth of 3" or more - you need to
think "DIG!" .... If you get just a "chirp" of audio, and see only 22.5Khz hittin' with an consistency,
you'll learn that's a small bit of can slaw on the surface .... There's a lot of info on the Spectragraph
with this setup ... You just have to get used to thinkin' about everything that Spectra is showin' you.
Cyber Sage - Too much RX will cause more problems with deep iron sounding like good targets.
White's Spectra V3 Manual - Page 37
Correlate (ON/OFF, "OFF") - Measures the targets differences between different primary frequencies
and calculates if those differences likely indicate a valued target signal or trash metal.
White's Spectra V3 Manual - Page 38
Span (0 to 189, OFF, "30") - Adjust how different targets can be at the different frequencies and still
be considered a likely valued target signal or trash metal.
- Higher number settings allow greater differences between a target at the different frequencies and
still be considered a good or valued target signal.
- Lower number settings dictate less difference between the target at the different frequencies is
require to be considered a good or valued target
as opposed to a trash metal.
- Ideal span limit varies with the ground and target corrosion conditions. Typically a lesser span limit
is better suited to lower ground mineralization and/or lesser target corrosion factors. A higher span
limit is better suited to higher ground mineralization and higher target corrosion
factors.
- Primarily developed for rejecting difficult iron, Correlate has an advantage over Best Data in difficult
ground and target corrosion applications.
White's Spectra V3 Manual - Page 38
Wrap (OFF, -95 to -90, "-90") - When searching in the difficult ground and target corrosion conditions
Correlate was developed to address, it is typical for high range
target signals (Quarter through Silver Dollar) to exceed the top end of the scale (+95) at one or more
of the primary operating frequencies. VDI range from -95-+95 is circular (phase) so targets that
exceed +95 re-appear at the <-> end of the scale -90s.
- Correlate normally perceives -90s indications combined with +90s indications as hugely
uncorrelated (span the entire scale) so dictates such a target as a trash metal.
- Wrap limit allows correlate to disregard normal correlation methods (sequential or linear) and
consider any -90s range signals that also have one or more +90s range target measurements, as
within reasonable correlate parameters. In other words a +95 combined with a -95 =
one digit off (close correlation) rather than when Wrap is OFF = full scale (no reasonable correlation).
- By adjusting Wrap Limit, Correlate becomes more effective, indicating difficult targets in difficult
ground as good or valued target signals as opposed to immediately dictating such signals as trash
metal. Because in difficult ground and corrosion conditions the target signal at one or more
frequency often wraps around to the <-> end of the scale, wrap limit effectively captures these target
signals as worthy of interest. OFF eliminates (rejects) all target signals that wrap around to the -90s.
- Adjustments from -95 through -90 increases the acceptable range a difficult target can wrap around
to the -90s and still be considered near to (correlate with) the +90s.
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Cybersage - The Correlate mode looks for two frequencies to agree on a response from a target. The
criteria for determining whether two frequencies agree is how close the VDI response matches. This
"how close" condition is determined by the Span Limit The larger the span limit the more accepting
the response trigger is to the VDI response of the target between those two frequencies. The Wrap
Limit allows the Span setting to extend to the negative side. Deep targets can cause the higher two
frequencies to "Wrap" around to the negative side. I have even seen all 3 frequencies wrap in high
EMI scenarios, or improperly nulled coils. These settings are among the most powerful options on
the V3/V3i.
The correlate mode on the V3 compares frequency responses. It looks for at least 2 of the 3
frequencies to agree on the response from the target. The Span setting determines at what level the
frequencies must agree before giving an audible response. Among the benefits of using the Correlate
mode is the quieting effect it has on deep iron. In essence it is another form of discriminating out a
target. Instead of just a simple VDI range you are determining a response by the overall consistency,
and to a lesser degree shape of a target. The span setting is important to have set correctly to get the
full effect of this mode.
Fox - Jack is correct on the quieting effect of Correlate and the help with deep iron. I'd like to
expound on the workin's of the Correlate function a bit if I may .....
The Correlate function looks at all three frequencies first, then determines which two are hitting the
hardest. (That's why the 7.5Khz freq will almost always be in the mix). Spectra then selects the two
hardest hitting frequencies and compares the responses from the two frequencies to see if they fall
within the VDI range set by the SPAN limit.
The WRAP limit determines how far a signal can move across the +95 / -95 boundry and still be
considered a good target. This is a major contributor to the iron rejection capability of the Correlate
function. Even Bottle Cap Reject plays in this feature, since it controls, to a degree, how Spectra deals
with ferrous targets.
Again, Jack correctly noted that the filters will have an effect on the performance of this mode. Hand
in hand will go sweep speed, coil size and configuration and Recovery Delay.
Robert - the salt compensate is smoother than the normal 3 freq program in All Instances by far..(not
some)....also the salt compensate is smoother than the correlate as well...the correlate might see
about 1/2" deeper than the salt compensate...but you'll have more falsing to deal with....then you
gotta factor in that the salt compensate program can run WAY HOTTER than the correlate without all
the falses...so you just gained that 1/2" depth (maybe a tad more) difference back and still having the
smoothest program...I have already tested this to hear the falsing differences of the two programs...I
thought about making a video to show it....and I still may .....don't get me wrong...the correlate
program is good..really good...but...the salt compensate is better.
Jbow - I'd suggest that you experiment with correlate the next time you are in a place with iron. Find
an iffy target and switch to correlate, then start tweaking settings. I set my tracking on 20 all the
time. I set wrap at -94, I use the default setting for the span.
When I experimented with correlate I found that I could get a better hit on an iffy signal but it took
some counter intuative settings. I had to set the filter on 10khz high, recovery on 95 and I had to
34
sweep slow (usually 10khz high is best suited to a faster swing but not in this case). With those
settings the hit was more consistent and the VDI was much improved over both other correlate
settings and over "best data". The target was a minnie I had buried at 8". The VDI should have been
51 but in best data it consistantly read in the 90s. With the correlate settings, recovery=95,
filter=10khz high and a SLOW SWING it was consistantly in the low 60s with the occasional dip into
the low 50s... much better. Why? Beats me.... but it worked, however I will not just go to a site and
use those settings. I use more standard settings unless the hits are iffy and the VDI numbers are off...
I think then is the time start fiddling with correlate.Don't forget to also tweak recovery, filters, and
different swing speeds to see what best works at the site. I would never have guessed that 10khz
high and a slow swing would have worked best but I am sure that the 95 recovery had something to
do with it... but still? There could be different settings that work even better but I stopped when I got
it working that well.
Just don't assume that the manual is always correct. It is correct in certain situations but odd ground
and minerals can change everything. This is the strength of the V3. The E-TRAC does all this
automatically but since the adjustments on the V3 are manual... the more you learn the better you
can adjust it and since there are so many adjustments that you can make manually I am convinced
that you can bring it to a higher level of performance than any other detector at any site. IMO, the
V3 can outperform any VLF detector at any and every site but the user has to put in the hours and
have an understanding of all the possibilities and adjustments. Personally, I am not there yet but I am
continually amazed by the new things I learn about the V3. If you make assumptions about the V3
and don't try to make it do things you don't think it can do... well, it wont do them but you, like me,
may be surprised to find what it will do if you think outside the box and try different things to get a
vetter VDI and tone.
Recovery Delay Potentially Important:
bfodnes
...A smoother start and end to the tone, Less beep like, more food for the ears and
brain in the target tone. Easier to hear a blend of two close targets too
Jack
Using Tone ID in combination with a slow Recovery Delay (90 to 110) you will get this
effect. You must have each VDI assigned with it's own tone and incremented by one. The
Default Coin or Coin and Jewelry is set this way. This is actually how I pick out good deep
targets. Rusty nail tips which can present themselves as a good target at times will sound
different. Typically the high tone will be cut off sharp on a nail tip. The tone will roll
smoothly on a uniform target such as a coin or ring. the ramp up and decay of the tone can tell
you a lot. This requires a steady and slow swing. The slow Recovery Delay will still work
well in heavy iron using Correlate modes. The V3/V3i really shines in this situation, as it
will prioritize it's response based on the dominance of the targets. This usually gives the
coin the advantage without having to rely on separation of targets. It's why we find so
many targets together in the same hole. I hunt old parks and this is very common. Most
detectors will mask in this situation. On a side note I have found many more deep coin spills
as well. Even multiple good targets can appear as trash, as it will confuse the filters of a lot of
detectors. End
35
Chapter 7 - Air Tests by Earthmansurfer
5“ Excelerator
Rx 10 Disc 95, Recovery Delay 23, Filter 7.5 Band (3 frequency and 22.5, Best Data)
Penny - 8" with ID jumping from 77-81. Normal ID of 65 in 3 freq and 83 in 22.5 normalized
Nickel - 8" with ID jumping from 20-30. Normal ID of 21 in 3 and 21 in 22.5
Dime - 8" with ID jumping from 80-89. Normal ID of 75 in 3 and 77 in 22.5
Quarter - 9" with ID jumping from 85-91. Normal ID of 83 in 3 and 85 in 22.5
Rx 8, 80 disc: penny 6", Nickel 7", dime 5", Quarter 6"
6X10 DD – Not Yet
Stock DD
Rx10, Disc 95, Recovery Delay 60, Filter 5 pass, 3 freq. Best Data
Coin(Clad)
Quarter
Dime
Penny
Nickel
VDI
83
78
54
19
Depth
13”
11"
12"
12"
Notes
relatively fast swipe, slower swipe gave me 11"-12"
9" depth when swiped slower
10"-11" when swiped slower
8"-9" when swiped slower
36
Chapter 8 – Analysis
Understanding Some of the Magic of the V3's Analysis Screen
By Jeff Foster
The V3's Analysis Screen is a great feature of the V3. It allows the user to see more of the
details of what the detector's computer sees. Because of this, the user can better understand
the target being detected, before it is dug, and the user can see firsthand situations where the
single frequency modes may be best for certain types of targets. However, some basics of
detector operation need to be reviewed to better understand how these Analysis Screens
should be interpreted.
Fundamental to the V3 (and DFX, MXT, etc.) operation is the VDI scale. While this is
sometimes shown as a straight line, with -95 at one end and +95 at the other, it is really a
wheel, or circle, with -95 and +95 back-to-back, like so:
Because the VDI scale is like a wheel, certain effects that occur near the -95/+95 boundary
tend to spill across the boundary. Of huge importance to V3 users (and DFX users for that
matter) is the influence of the ground-balance, which has effects that wrap across the -95/+95
portion of the wheel.
This notion, that effects of the ground-balance may spill across the part of the VDI wheel,
where -95 and +95 are back-to-back, may sound a little scary to understand, but it's not really.
And the effects can be clearly seen on the V3's Analysis Screen and in day to day V3
operation.
37
First, let me provide a little foreshadowing of what I'll explain. One thing that you'll see is
why it is often said that 2.5kHz is best for "silver" (that is to say U.S. style silver coins with
high-VDI numbers, not antiquated "hammered" silver coins found in Europe with much lower
VDI numbers). The fact is that 22.5kHz and 2.5kHz have roughly the same sensitivity for
silver (i.e. high-VDI targets) in fact 22kHz can be better for high-VDI targets. The principal
that most often gives 2.5kHz the edge on U.S. silver has to do with this crazy VDI wheel,
ground-balance wrap-around stuff. It's not scary to learn. I promise. Relax. And, you'll be able
to make better sense of the Analysis Screen, and Single Frequency operation once you've had
this glimpse under the hood. So, without further ado, here's the inside scoop.
Everything to which a detector responds strongly enough has a VDI number. It's a bit like
seeing in color everything seen in strong enough light has a color. A problem for the detector,
which wants nothing more than to find neat buried jewelry and coins for its user, is that the
ground contains minerals to which the detector also responds. Fortunately though, the ground
also has a VDI number.
The ground-balance system on the V3 is a mechanism that is used to tune-out the effects of
the ground minerals by "tuning in" or balancing to the ground's VDI number. When the
detector is ground-balanced, it makes it so that detector loses sensitivity to anything with the
VDI number of the ground. This allows the detector to ignore the ground, and find the
goodies buried in it. Most often the ground-balance story stops there, but we're going to have
a closer look at it, whether the ground-balance system likes it or not.
Imagine that the ground has a VDI number of, say, -93. This is a common ground VDI
number. When the V3 is ground-balanced to -93, it makes it so that the V3 doesn't respond to
stuff (the ground in this case) that has a VDI number of -93. The V3 shows no sensitivity to 93, but wait, there's more!
With the ground-balance set at -93, the V3 shows almost no sensitivity to -92 and -94 as well.
In fact, the entire region of the VDI wheel (you were wondering when I'd get back to that darn
wheel, weren't you?) where the ground-balance is set, shows diminished sensitivity. In one
direction, -91, -90, -89, 88, etc is affected. In the other direction, -95, and spilling around to
+95, +95, +94, +93, +91, etc., is affected as well. In fact, there is a noticeable impact of
reduced sensitivity, stretching down to VDI numbers in the +70's and beyond!
"Wait just a minute buster," you're probably saying to yourself right now, "are you saying that
when the ground-balance is set to -93, I'm losing sensitivity to targets like silver dollars, half
dollars, quarter, and even mercury dimes?" Well yes, yes I am saying that. But no need to
panic, call 911, or Sweet Home Oregon for that matter, because the V3 has one more trick up
its sleeve I still need to tell you about.
You may recall, or have read something about VDI numbers being skewed a bit for different
frequencies. No matter, because I'm going to tell you about it now.
The trusty VDI scale was created a long time ago on a White's detector that used 6.6kHz as its
frequency. This is fairly close to the V3's 7.5kHz. However, at much higher frequencies, like
the V3's 22.5kHz, VDI numbers tend to shift higher. A quarter that may read at +84 on
7.5kHz, really reads around +91 on 22.5kHz. A dime that may read at +76 on 7.5kHz, really
reads around +89 on 22.5kHz.
38
For lower frequencies, like 2.5kHz, VDI numbers tend to shift lower. A quarter's VDI number
may change from +84 on 7.5kHz to +65 on 2.5kHz. A dime that may read at +76 at 7.5kHz,
might show a "non-normalized" 2.5kHz VDI of +50. At 2.5kHz, VDI numbers of targets
like "silver dollars, half dollars, quarter, and even mercury dimes" shift lower on the
VDI scale away from the naughty effects of the ground-balance, spilling across the 95/+95 boundary of the VDI wheel. This why I assured to you that there was no need to
panic three paragraphs ago. 2.5kHz saves the day!
It is because the raw, non-normalized, VDI numbers of targets in 2.5kHz are skewed away
from the effects of the ground-balance, wrapping around the -95/+95 boundary of the VDI
wheel that makes 2.5kHz (i.e. low frequencies) better for "silver" (high-VDI targets). That's
why. That's the reason why you hear over, and over, and over, and over, again that 2.5kHz is
better for "silver". It's not because 2.5kHz is more sensitive to silver than 22.5kHz on the V3.
In fact, the opposite is true, but when the ground-balance is set near -95, as is so often the
case, 2.5kHz is less affected by the ground-balance wrap-around effects, and provides the
strongest response to silver.
Since this is such a widespread myth, let me repeat: 2.5kHz is not better for silver 2.5kHz is
better for silver when the ground-balance is set near -95.
Again:
2.5kHz is not better for silver
2.5kHz is better for silver when the ground-balance is set near -95
So, the V3's Analysis Screen (you though that I'd completely forgotten). When you're seeing
targets using the V3's analysis screen, you will see the principles I've just described. And now
that you understand these principles, you can use them to your benefit.
For example, if the ground's VDI is near -95, you may want to use 2.5kHz Single Frequency
for hunting high-VDI targets (i.e. U.S. silver coins). You can use the Analysis Screen on a
buried test quarter to see if 2.5kHz is best for that ground, like so:
However, in other ground, where the ground-balance is further away from -95, you may see
that 2.5kHz no longer outshines the other frequencies, like here:
39
The only difference between the two Analysis Screens shown here is the ground-balance
setting! In the top one, the ground-balance is set near -95, its sensitivity reducing effects are
spilling around the -95/+95 part of the VDI wheel, and 2.5kHz shows the best result.
In the lower Analysis Screen, the ground-balance is set away from -95 and it can be seen that
all frequencies respond to the quarter at almost the same strength.
(Remember to ground-balance when doing a test like this!)
And, finally, the grand finale that you've all been waiting for. What would you expect to see
on the Analysis Screen in Three Frequency Salt Mode???
**********************************************************************
Yazoo
What type of effects if any will this have if accepting all VDI #'s ?
None. The effects I describe above happen at the Non-Motion (All-Metal) level. The GroundFiltering system creates the VDI numbers by using the Non-Motion stuff as a basis. Jeff F.
RacerX
If you have time to respond I have a question.......In my test bed I have a silver dime
buried in the 8" range. I played with different frequencies and I can hear it in all
frequencies but I hear it best (by far) in 22.5. I live in CA bay area so my soil if pretty
mineralized...So I guess the question would be, under what conditions would 22.5 let
us hear deep silver better?
The higher the target's VDI number, and the closer the ground's VDI is to -95, the more the
factors that I describe above occur (about the ground-balance effects wrapping around the 95/+95 boundary). So in order of decreasing benefit of 2.5kHz, would be: Silver Dollar, Half,
Quarter, and Dime. The dime has a VDI number that is right on the boundary, and that's why I
suspect you are the observing the results that you are. Try the test with a quarter, and you'll
probably see 2.5kHz be the deepest. The determining factor is how far away the target's raw
VDI number is from the ground-balance point on the VDI wheel. Jeff Foster
40
Aurium
How do you see what the ground balance is set to with the V3 is that somewhere in the
ground probe window?
Not directly. However, when you have a good ground-balance, it will match the ground-VDI
in the Ground-Probe screen. Jeff Foster
Bodhi3
To go straight to the point and imagining what could happen in Salt Compensate mode
(using my imagination and from a theoretical point of view), I suppose the V3 will
show a general effective loss of sensitivity in the 0-+2 VDI area and beside that point
(both in the positive and the negative sides).
That's correct with regard to target sensitivity. This is why targets that have VDI numbers
close to that of salt (0 to +2 region and slightly beyond), like small gold, small gold chains,
etc., do not respond in Salt Mode. Jeff Foster
Bodhi3
This is due to White's Signal Subtraction Technique used to compensate marine salt
mineralization.
I'm getting ahead of myself here, but the Signal Subtraction Technique handles the ferrous
portion of the ground-balance. The V3's analysis screens provide a view into the effects of
this. I will try to cover this in a simplified fashion in my next thread on this topic. I originally
thought I would be able to write that in a few days, but I'm very busy and it will be longer
than I expected before that is completed. Jeff Foster
Bodhi3
Of course 22.5KHz and 7.5KHz graphs should be less effected than 2.5KHz one due
to the natural Up-Shift of gold target's VDI (exspecially thin jewelry) you have by
using higher frequencies.
That is also correct. Jeff Foster
The initial motivation in writing the parent post was to illustrate how 2.5kHz may not
necessarily provide the best high-VDI response in the Analysis Screens. This was illustrated
in this thread and will be more apparent in Salt mode. Without this information on how
detectors operate, it is more difficult to interpret these screens and raises questions as to why
22.5kHz will in many cases show better responses to high-VDI targets than one might expect.
Jeff Foster (End of Jeff Foster Section)
**********************************************************************
41
How to Differentiate between Bottlecaps vs. Quarters with Spectra V3
I just check when I am pin pointing the target.
Rob
Using analyze – trigger forward
Quarter and Bottlecap targets share the same V.D.I. of which fall generally into the 82 to 85 range.
Watch for % of probability of targets in Analyze Mode, generally,
5% to 20% = Bottlecaps
42% to 80% = Quarters TC-NM
42
Chapter 9 Recovery Delay & Sweep Speed
Start Thread – next 8 pages
Estimating Optimum Recovery Delay Settings – by Fox
There has been some discussion on the forum since the release of V3 regarding Recovery
Delay and how to set it .... I have set up a chart showing RD time settings for four (4) coil
sizes - 4", 6", 9.5" and 10", deployed at sweep speeds ranging from .5 ft/sec to 5.0 ft/sec. The
"average detectorist" swings somewhere between 1.5 ft/sec and 2.5 ft/sec. At 2.0 ft/sec it will
take 2 seconds to swing a 4' arc in one direction.
First off, definitions: Recovery Delay settings are just as the name implies - the delay time
that you are imposing on Spectra before it can process a second target after the first target has
been processed. Another term would be Signal Processing Delay, or how long Spectra has to
process the first target, and then be ready to process a second target. When I "explain" this
time, I like to use the analogy that a target is processed in four steps .... (1) It is acquired (2)
target data is calculated (3) target data is displayed (4) target is released and housekeeping
done in preparation for the next target. Steps 1 - 4, added together = Recovery Delay.
Lower numbers = SHORTER delay. Higher numbers = LONGER delay.
Optimized Recovery Delay is a function of Sweep Speed, Ground Filter, Mineralization, Coil
Size and to some degree, RXG and Disc Sensitivities.
The premise that the attached chart is founded upon is that (1) the coil can't see anything
before or after it is over the target (discounting edge effect for purposes of this discussion)
and (2) a full coil width's separation will minimize masking. You may find that you can
actually reduce your delay times a bit from the settings in the table. They are given a 5%
margin to address edge effect. I used the middle of the road 7.5Hz filter.
Faster RDs are best deployed in high trash areas. Slower RDs will provide more depth, up to
the point that the coil is no longer over the target. Increasing / decreasing RD around the
"recommended chart setting" will not add or subtract inches from your target depth, unless of
course you adjust "too far" in one direction or the other. EG: A RD = 0 will make a quarter
"chattery" at about 3", so that's "too short".
Coil size. Just want to touch on this .... A 4" coil (4X6"DD shooter) will pass over a quarter in
less time then a 10" coil (10"DD) if both are moved at the same sweep speed. Thus, it has
been my suggestion that if one is making a significant change in coil size, it may be
worthwhile to adjust the Recovery Delay accordingly.
The chart is purely mathematical. I have sampled the data using all four coil sizes and varying
sweep speeds and the performance matches the numbers. Please note that the sweep speeds
are "Mississippi's", they are not timed with a laser and the coil wasn't moved by a highly
consistent mechanical arm.
The quickest way to arrive at your "optimum" RD (IMHO) would be to place a two coins, one
coil's width apart and swing the coil at your speed until you got two hits from the unit. If you
know your sweep speed (and most people think they are sweeping slower then they really are)
43
then the chart will "get you in the ballpark" and minimize your tweaking time. It will also
provide a "sanity check" for your program settings as you develop them, or perhaps help you
understand other people's program settings.
To estimate your sweep speed, lay off a line 4 feet long. Stand in the middle and sweep your
coil from end to end, counting "Mississippi's". A 2 ft/sec sweep speed should take you 2
seconds to cover that 4 feet in one direction. I have seen many a surprised detectorist when
they discovered that their sweep was closer to 4 ft/sec !!!
44
johno
Just thinking out loud fox,, we say a rd of 120 gives the spectra more time to analyze a
target versus an rd of 45. my question is doesnt the computer do this instantly . i mean
like millisecs.. another words the lower the setting you can use without hinderance
from masking from the next target be the best setting. i guess what im saying is the
machine does it that fast no matter what. we, say lower rd for trashy area when in
actually we should run this whenever theres numerous targets good or bad close
together. what i guess im asking is does the machine itself give you any better info by
givin it more time.. sounds stupid but just wondering
Fox - You are thinkin' good .... And yes, Spectra's processor does do things in milliseconds,
but a millisecond is a long time .... Blink your eyes .... That is roughly 250 milliseconds. One
quarter of a second ....
Giving Spectra "all the time it needs" (but no more) is the right answer to your question
(IMHO). It's like cookin' .... Too long in the oven and its burned. Too little time and its raw ....
To my way of thinkin', "just right" is to give Spectra all the time that the coil is over the
target, plus a little bit for edge effect, and a touch to process the data, display and do
housekeeping.
Now, lets talk about "Time on Target" (ToT) for a second .... (That's 1000 msec btw). A
"normal" rate of coil movement is somewhere in the 2 ft/sec range. That's 24 inches per
second. So, every 1000 milliseconds, your coil moves 24 inches. That equates to about 42
msec per linear inch of motion across a fixed point. (1000 msec / 24 inches = 42 ms/in)
If the coil isn't OVER the target, or "just past it", the coil isn't sending any target data to the
box for processing .... (well, duhhhh ... ). And yes, there may be some edge effect, but
gimme a little slack .... I'm tryin' to keep this on-point and as simple as possible.
So, if it takes a coil 42 msec/in to pass over a target at a swing speed of 2 ft/sec it will take
420 msec for the 10"DD to completely pass over a point. (42 ms/in * 10"). If we give Spectra
a little "extra time" for cleanup (ToT post processing), then we've allowed for all the data to
be gathered, processed, displayed and housekept. Let's say that adds a burden of 5%,
(completely arbitrary), so now we're up to about 440 msec. If we give Spectra much more
than that, we are just in "dead time". It has seen the target, processed it, displayed it, done its
housekeeping, and is ready for the next target. Keepin' the processor tied up for 600, 700, 800
msec doesn't make any sense to me, and I can't see any depth loss if we follow these "rules".
As long as you have given Spectra enough tiime to process all the data available from the coil
AT YOUR COIL SWING RATE, and added a little "Kentucky windage" for housekeeping,
you're there.
And just to be clear - the SLOWER you sweep, the longer your coil is over the target, the
longer Spectra is getting data, the SLOWER your RD (higher number) needs to be. Is there a
"Maximum" delay ? Based on the results of my testing, it appears to be about one (1) second.
That says it could take the 10" coil one second to pass over a target if ALL the RD time was
used. 10" per second is slooooooow. (About .83 ft/sec). With that kind of RD, your target
separation distance would be measured in railroad car lengths .... (It would take almost 5
seconds to make a one-way, 4-foot wide sweep ...).
Without opening another topic, remember that Spectra is a MOTION unit in Disc mode.
There comes a point when "too slow" = "bad signal". Quick test .... Throw down a quarter.
45
Hold Spectra motionless over the quarter. What do you hear? Now, try different swing speeds
and listen to the target response quality .... Enough of that ....
To determine the "optimum" RD in terms of Adjacent Target Processing (masking), lay two
coins, one coil's width apart and pass over the targets at 3 - 4", using your "normal" swing
speed. Set RD so that you get two hits. Now, raise the coil and see if you continue to get two
hits .... This will give you a good idea of where you should be with YOUR coil, in YOUR
soil, with YOUR swing speed, YOUR sensitivity settings, etc, etc. Or, you can start at MAX
RD and work down until you start to LOSE target separation. If your swing and depth are
consistent (good luck unless you have a good mechanical lab setup), you should arrive at just
about the same RD setting.
If you run with TOO LITTLE RD, you can indeed lose some depth. The target will still be
under the coil when the entire target cycle time has been depleted, hence Spectra will try to
"see the same target twice" and will give you a very poor signal. To prove this, set RD=0 and
move a target under the coil. Then, as you increase RD time, note how the target signal
stabilizes, and depth returns. Now, continue to move the target away from the coil - increasing
target to coil distance. Note that as you increase RD, depth does not increase. Sensitivity starts
to weigh more in the equation then RD. (If Spectra can't see the target, it can't process it, so
RD becomes a "non factor").
If you laid ten Spectras side by side, all running the same programs, all using the same size
coil, and ran the above tests on each one, you will find some minor deviation in the unit-tounit results. This is MAINLY due to the variation in coil performance.
Takeaway: Too much RD = Masking. Too little RD = depth loss. Just right RD = happy.
Finally, again .... The chart posted is a GUIDELINE, not "The Gospel". Its a sanity check. A
tool for you to use to get you close. The "optimum setting" for YOUR setup will have to be
determined by YOU, using a process similar to the one above. Hope this is helpful. Da FoX
That's some fancy math you got going on there Fox. Good stuff. I have a question concerning
variations of DD coils verses concentric coils. Given that the DD has a much narrower
footprint at depth wouldn't this actually throw off the above calculations. Even with my
extremely slow RD of 110 I can still pick out a nickel and a quarter sitting 3.5 inches apart at
about 7 inches deep. Even on a surface or air test they are clearly distinguished by the V3. It
would appear that the above chart is geared more for the concentric style coil if I am
understanding it correctly. Thanks for the great chart.
CyberSage
Jack:
Given that the DD has a much narrower footprint at depth wouldn't this actually throw off the
above calculations.
It would appear that the above chart is geared more for the concentric style coil ...
The premise that the attached chart is founded upon is that (1) the coil can't see anything before or
after it is over the target (discounting edge effect for purposes of this discussion) and (2) a full coil
46
width's separation will minimize masking. You may find that you can actually reduce your delay times
a bit from the settings in the table. They are given a 5% margin to address edge effect.
Finally, again .... The chart posted is a GUIDELINE, not "The Gospel". Its a sanity check. A tool for you
to use to get you close. The "optimum setting" for YOUR setup will have to be determined by YOU,
using a process similar to the one above.
And herein lies the problem with producing a "generic" chart. As noted throughout this thread, the
purpose of the chart is to "get you close". I purposely did not address differences in coil
configurations, but opted to use the "edge to edge" approach since that will encompass both DD and
Concentric coils. No matter WHAT configuration coil, it can't see a target if it isn't over it. Conversely,
the coil IS providing target information if the target is in the coil field and the unit is properly tuned.
So - the "window of targeting opportunity" is never much greater or less than the width of the coil.
While we're splitting hairs, we might as well lap and polish them too .... Hopefully the following
explaination will HELP more folks then it confuses or puts to sleep .....
You are partially correct - The pattern from a DD coil is more narrow than the cone shaped pattern of
the concentric. However, as depth increases, the concentric pattern gets MORE narrow then the DD
coil pattern, so there is a point where the DD's "apparent speed" across a point, graphed with that of
a concentric's, will be faster, equal then slower as a function of the decrease in size of the concentric
coil's pattern. These sizes and departure points will vary with coil null, size and gain settings and
make for a pretty chart but not much useful data when it comes to field ops. As an "exercise" you
might want to make a determination of "how wide" a DD pattern is at various sensitivities, and
where the point of the concentric cone is at the same sensitivity, and then calculate the crossover
points (slower / faster / equal). The dilemma starts when you ask .... What % of physical coil width
would you use for the pattern width in the 10"DD? Half? Three quarters? Five-eights? What point
would you consider the "significant narrowing" of the concentric coil to start? 50%? 75% Whatever
you pick can either be "close enough" or "absolutely wrong", depending on the accuracy of the
information that you're trying to extrapolate from the data. My goal for this exercise was "close
enough to be helpful but not harmful". In other words, as you correctly noted, the RD times are a tad
high, especially if you're using a DD coil. And, folks who have a propensity to "run hot and swing fast"
may indeed encounter some adjacent target masking, but there is some "forgiveness" for those folks
built in. Everyone should abide by my continued admonishment to use the chart / process as a
guideline, and to optimize with their OWN setup.
Now, to focus on your DD coil question from another angle. Enough testing on a sufficient universe of
sample items will reveal that identical coils types do not demonstrate identical coil patterns. When
tested on the identical machine, including M6 / DFX / Spectra NONE demonstrate IDENTICAL
performance patterns. Close - absolutely. Within a more than reasonable manufactuing tolerance for
a commercial product - absolutely. I'm talkin' 1 - 3% variance within coil type / size. So, when I put
the chart together, I dusted off some old benchmark and field test data and put a little "Kentucky
windage" in to accommodate those folks who are using non-V coils on their Spectra, and again, those
non-V coils are both concentric and DD configured.
As you hunt along thru life, you may find yourself compelled to take a look a what the effects of
47
aging do to coil performance. Besides being hot, cold, wet, dry and beat on trees, coils "age" daily in
an air conditioned closet. Some epoxy, like concrete, continues to "cure" over time. Solder gets
brittle. Annealing cracks. The combined effects of use and time may cause a coil to "drift", or go out
of null, which changes the performance parameters as well as the coil pattern. It has never been my
experience that coils get "better", so there is a bit of "age bias" added in for those folks who may be
using coils from their DFX days that may be 10+ years old.
If memory serves, your sweep speed with the 10"DD coil is about 1.5 feet per second. "I would say
the arc of my swing is about 4 to 5 feet. It takes me a good 3 seconds in one direction." (4+5)/3 = 1.5
ft/sec
The chart, including the 5% edge effect bias + "stacking error" would suggest that you employ a RD
setting = 123. If we take off the 5% edge effect since we're lookin' at deep targets, that would
indicate a setting of about 116. Your setting is 110. (116 / 123) = 94.8%, which says the "stacking
error" built into my calculations to accommodate coil size, configuration, age, V / non - V rated,
depth performance, gain, pattern size and the other stuff that the "average user doesn't want / need
to think about" equates to just over 5%.
Adding the two "Kentucy windages" yeilds (5% + 5.45%) = 10.45% built in "margin".
If we remove the total margin from the chart's recommended setting of 123 (123 * .8955) = 110.1465
And last but not least, by way of FULL disclosure, all my calculations for this exercise were done using
the ROUNDUP feature so that I continuously "erred on the high side".
Or, if you just look at my chart, and do a rough calculation of 90% of the posted value, you will find
that it is recommending a RD = 110 at your sweep speed with the 10"DD coil. (What RD setting did
you say you were using? ) What your setting reveals is that you have done a process that says,
"this is what works best for me and my style of hunting" and "that is is optimized for my coil size and
sweep speed". A person using all your settings but who sweeps at 2 ft/sec should set RD = 92 by the
chart or 83 for "optimized performance", balancing depth with target separation. You will note that
the 92 setting is better for depth than the factory recommended setting of 80, but detracts
somewhat from target separation. My chart - my choice - I erred on the side of depth, 'cause there's
always a chance that based on sweep width, the target might be picked up "on the way back".
(Explainations are much easier when you don't add all the factors attendant to that return sweep).
Try cranking your RD = 123 and see if your performance suffers greatly .... Your depth won't, but you
may see a slight decrease in target separation. Try cranking in 100 and try the same thing and see
what differences in depth and target separation you encounter. It won't be much, however, if you try
it with several different V and non-V rated coils, it will be different. And yes, it will be "something less
than optimum".
Another "sanity check" would be to look at the factory recommended setting in the Owner's Guide.
Based on a 2 ft/sec sweep speed, most of the programs recommend a RD = 80. The chart indicates
92. Reducing that by 10% reveals a recommended setting of about 83, or within about 4% of the
factory setting.
48
Finally, and not to indicate that I'm any kind of a benchmark, but I have settled on a RD setting of 45
for my style, swing speed, etc, hunting with the 6X10"DD coil. The chart recommends a 49, or about
44 w/o the edge effect and other "Kentucky windages" built in.
My goal was to help those folks who didn't know if 45 or 145 was the right number, based on their
style of hunting, their coil, their settings and their ground. "If you don't know where you are, it
doesn't matter which direction you take ...."
I figured that if I can help get the folks that don't have the benefit of all your experience, knowledge
and wisdom get to within 90% of where they "should be", they wouldn't take a BIG hit on either
depth or target separation. From the 90% point, its just a few swings to check depth and target
separation to reach "optimization".
Hope this clears up any misunderstanding, angst or other misgivings you or other forum members
from newbie to expert may have about the recommended settings.
Good luck and good hunting. Da FoX
Johno - jack im i wrong in thinking at depth the concentric would be narrower( meaning
smaller field of view if you would),, thinking of a cone type signal versus the narrow but
wider front to back of the dd... im old and confused hehe. im still trying to get constant
readings past the 6 inch mark. but i am making some progress thanks to you guys
I'm not Jack, but since I started the tread I'll answer. Please read the above post, and you'll see that
your question was already addressed ....
You are partially correct - The pattern from a DD coil is more narrow than the cone shaped pattern of
the concentric. However, as depth increases, the concentric pattern gets MORE narrow then the DD
coil pattern, so there is a point where the DD's "apparent speed" across a point, graphed with that of
a concentric's, will be faster, equal then slower as a function of the decrease in size of the concentric
coil's pattern. Fox
bobamis
Da Fox,
Three questions:
1. I note you used a 7.5Hz filter. How would a different filter setting change these
calculated figures, if at all?
2. And speaking of filters, has anyone done something like this chart for speed of
swing of coil and filter settings?
3. Also, if I swing relatively fast (like 3 feet/sec), but have relatively low ground
mineralization, what would be a good filter setting?
(I hope I'm not showing too much of my ignorance!)
Using a different filter at any given sweep speed could help or hurt a bit. Slower filters help
slower swings, and faster filters accommodate faster swings. Thats why I "stuck to the
middle".
I don't know of any charts on swing speed vs filter speed, but feel free to put one together !!!
49
At your swing speed, I'd stick with the 10 / 12Hz filters. That's a pretty fast swing. Fox
I've been on RD of 45 almost since I got my V3 way back since March/April 2009...it did not take me
long to find that RD 45 was my sweet spot....and this can be seen in my Old Post where I usually
stated my settings...and yes I too am like Fox I use the 6x10dd v-coil 98% on all hunts with 10.0 &
12.5 filters (can't decide which I like better)...anything much higher than RD 45 is just plain way to
slow for me...I'd be hunting like an old granny with no perspective of time....I just don't ever plan to
hunt that freakin slow.....but...that's just My Style of hunting....that's not to say it's Yours....that's the
beauty of the V3i...you have the option to set it at What You Want for Your style of hunting....so cool.
Robert
Mighty Mace - So what does proper target separation "sound like" ....... I tried setting two
pennies side by side about a coil width apart and when i swing over them I hear a
baaaahhhhhbeeep. Not beep, beep. But almost like the second hit, comes in and interrupts
the first. Is this correct? I will try and tinker with the RD to see how it affects the separation,
but wondered what you considered proper separation.
I did find a penny, about 5 inches to the left of a piece of clothespin yesterday. I would hit the
70's vdi from the penny and then right to the 20's from the clothespin. After removing the
clothespin target the 70's then took over. I can't remember but I think it might have only
been on the one direction of the swing.....penny then pin. From pin to penny, I don't think I
was getting the 70's vdi (wish i would have read this thread before finding it, lol)
You should hear a definite change in tone between to dissimiliar targets. If you put two identical
targets close enough together, you will most likely hear one long tone. I like to use a quarter and a
nickel. That way you'll hear low - high, high - low.
Work with your coil, your swing speed and your settings. It won't take you long to "rock it in" ....
Hope this is helpful. Da FoX
hey mighty....if you wanna hear target separation clearly for two targets relatively close....place two
different coins 3" center to center apart and swing over them with a 6x10dd coil then with the
950...you'll hear the difference really good.. Robert
To determine the "optimum" RD in terms of Adjacent Target Processing (masking), lay two coins, one
coil's width apart and pass over the targets at 3 - 4"........... Fox
End Thread
Im in Europe.
I use the 6x10 nearly all the time. I have my recovery delay at 50 - 60...
Recovery delay isnt everything involved in a fast recoveryspeed. Lets take the XP goldmaxx power as
an example. It is known to have a very fast recovery speed. The disc knob on the GMP stops at coke.
You can only disc out iron and coke...
To obtain the best recoveryspeed possible You can not disc out all the iron and coke.
50
As with the MXT where the disc knob is best set at 1,7-1,9, not any higher.
Or the new goldbug where the iron split tone is best set at below 20 to obtain the best results for
discoveryspeed.
On the V3 I get good recoveryspeed when i open up the disc window from - ( minus ) 30 with the
same tone as all + ( plus ) numbers. It is not annoying at all cause there is not many trash items
hitting solid there anyway. This setting helps the machine to see the low conductors better as the
window from disced out and to the ID of a solid 12 for excample now is 42 and not 12 as it would
have been with all iron disced out.
Its not a secret and most people using the XP use this kind of setting but do not realize why the
machine gets a better recoveryspeed from it.
It is just that way with any machine.... Make the window bigger and your recoveryspeed will be faster
without losing depth. Bfodness
Start New Thread
On the subject of correlate vs. best data the depth should be the same...
...Giving this some thought it would be what I would expect from the V3. However the targets
were would have been dug in either mode and most of them were 6 to 8 inches down. As both
correlate mode and best data look at the VDI /phase of the target and then processes the audio
information according to the setting of the machine such as disc, recovery delay, tones and the
list goes on.
On the subject of recovery delay it does pretty much what you are seeing except as the signal
received from the target decays on its slope if a stronger signal is received before the end of
the original target signal the the stronger signal will take over and sound off. At least this is
the way it should work...
rcsnake
Bob@Whites
What he stated in the last paragraph has got me wondering. Maybe we are not dealing with
separation at all. He talks about a stronger signal becoming dominant and sounding off. It
kind of sounds like the Recovery Delay is actually interrupted before it's prescribed setting
has a chance to finish.
Bob, if you are out there reading this, may be you could elaborate on the definition of
"stronger" in this instance. Is it just a higher conductive target or larger target, or a
combination of both? Thanks in advance. Jack
This would be for all targets irregardless of being a higher conductive target or lower conductor. If
the new target/signal goes above the signal threshold of the older target/signal, then the new one
will respond before the old signal is finished and returns to threshold.
The down side is if then new signal is weaker than the one being processed it will not be heard until
51
the recovery delay is finish or a stronger signal is detected. Hence, as you have seen a slower sweep
(with the dd loops) for moving the loop is very helpful for separating out targets in the ground.
rcsnake
That was a fast reply Bob! Thanks for the clarification on that. Those rusty caps must be the weaker
signal then. What a beautiful thing that is. Maybe I should spend less time trying to understand this,
and more time hunting.
Thanks again. Jack
In my opinion using the above logic you can use the D2 just as effectively in trash. Your not going to
see through a aluminum can, but in the majority of cases I believe the coin will be dominant in it's
response. You are going to dig a few nails, but it won't take long to get the hang of what that coin
sounds like in trash.
Kid, it's nice to see your enthusiasm. Thank you for your input here on the forum. You are motivating
me to get out and hunt more often at the end of the day.
Jack (This last post was from another thread referencing the above thread though.)
Note - Think about what Jack is saying here. Perhaps a smaller (lower) recovery delay on the V3i is
not the only, or even best way, to handle trash/iron. Maybe… EMS
End Thread
Sweep Speed vs Coil Size Considerations - Fox
As I've been working up the Recovery Delay and Filter Selection charts, one thing has come
abundantly clear. "Sweep Speed" is a "relative" term ....
What we need to understand when we're optimizing Spectra is that the coil is collecting data
ONLY when it is over the target. With that understanding, it is then clear that if we hold
physical sweep speed constant, a 10"DD coil being swept at 2 fps will be over a given target
2.5 times longer than a 4X6"DD coil swept at the same 2 fps. If all the settings are optimized
for the 10"DD coil, and later a 4" shooter is hung on the end of the stick, it will appear to
Spectra that the physical sweep speed has increased to 5 fps !!!
A more reasonable case can be made for the swap to a 6"DD coil. Without any changes,
Spectra will "see" target data as if the 10"DD coil was being swept at about 3.3 fps.
So in order to maintain optimized performance, one of two things needs to occur when you
change coils. You must either (1) adjust your physical sweep speed to accommodate the new
coil size, or (2) you must change any "time sensitive" settings.
Two KEY settings that come to mind are a) Recovery Delay and b) Ground Filter (if
mineralization allows).
Going in the other direction, say with settings optimized for the 6"DD and changing to the
9.5" concentric, the detector will "see" the target much longer. This will appear as a
REDUCED physical swing speed, again suggesting an adjustment to RD and GF.
52
For a fixed sweep speed, Recovery Delay should INCREASE as coil size increases, to
accommodate the longer time on top of the target. Ground Filter speed should DECREASE to
accommodate the apparent slow-down in physical sweep speed.
Or, if you want to keep your settings constant .... Sweep Speed should DECREASE as coil
size decreases, and INCREASE as coil size increases, using the coil size with which the the
unit was optimized as the departure point.
This second option is applicable to those folks with any units other then Spectra, DFX and
XLT, which have settings that will accommodate a change in physical sweep speed. In other
words, if you go from the 950 stock coil on your M6 to a 4X6"DD shooter, then you need to
SLOW DOWN your sweep speed.
The attached chart provides the "Time Over Target" times in seconds that you can use as
necessary to adjust settings and / or physical swing speed to accommodate coil changes.
I addressed swing speeds from .5 fps to 4.0 fps, with coil sizes including the 10"DD, 9.5"
concentric, 6" (DD or Concentric) and 4X6"DD. Hope this is helpful. Da FoX
53
Chapter 10 Filter Related
EMS – What I have found regarding Filters on any given day is summed up best by what Rob said. To
quote –
“The charts are great, but I don't even know what my swing speed is. There is no reason for me to
know, because it makes no difference. I swing one speed and Larry swings faster. We both use the
same filter most of the time. As I said all I have to do when I get to a site is bury a coin and swing. I
will hear a signal. Which filter is best, the one that works. So all I have to do is try them all and find
the one most quiet and with the most accurate signal, so much for charts.
Depth has nothing to do with faster or slower filters. The right one for that site will be the deepest.
A lot of fun is knowing your detector. Only so much can be learned from reading.” Rob
If you are interested in knowing more technically about filters, then read on:
A band pass filter will only allow signals within a certain frequency band to go through (harmonics
can also go through though). A high pass filter will allow frequencies at and above the specified
frequency to go through. So, if you have a 10Hz band pass filter, you might see frequencies in the
range of 8 - 12Hz go through (I forget the characteristics of the filters, but there is a "band" of
frequencies that are allowed - the example numbers do not necessarily represent the filter on the
machine, but the 10Hz filter does have 10Hz as the center frequency). A 10Hz high pass filter might
allow frequencies of 8Hz and above to go through (it's not a perfect world...). So if you have high
frequency noise, a high pass filter will also accept that high frequency noise. But, you also get more
signal, so it should go deeper if you don't have high frequency noise issues. Ak_1234
Without getting too techincal ....
A High Pass Filter is designed to eliminate LOW FREQUENCY harmonics from an analog signal. It has a
response from Infinity to a designed cutoff frequency. Generally that frequency is the point at which
the filtered signal reaches 70.7% (.707emax) or approximately 3db down.
A Low Pass Filter is designed to eliminate HIGH FREQUENCY harmonics from an analog signal. It has a
response from DC to a designed cutoff frequency. Generally that frequency is the point at which the
filtered signal reaches 70.7% (.707emax) or approximately 3db down.
Band Pass filters are used for everything from tone detection to passing a narrow to very broad
range of frequencies. Band Reject filters reject a band of frequencies, based on the design of the
filter. Notch filters are generally employed to pass, or eliminate a single frequency. Various filter
types are sometimes employed in sequence ("cascading") to achieve a specific filtering task.
Keep in mind, that the days of the "discrete component filter" are pretty much gone. Talking about 2
/ 3 / 4 filters today just makes no sense. Filter SPEED and Filter TYPE required to achieve the
objective is more accurate.
Hope this is helpful. Da FoX
54
For example:
Low mineralisation with no EMI = 5Hz High pass
Low mineralisation with random EMI = 5Hz Band pass - Fox
Folks have been askin' for some information on selecting Ground Filters. Most are askin' about
Sweep Speed.
The below chart will help you select the best Ground Filter for your sweep speed. If you want to take
into consideration Ground Mineralization and EMI, then the chart will help point you in the right
direction using those factors as well.
How to read the chart ..... Let just take a couple of examples.
Using ONLY Sweep Speed:
.5 to 1.25 fps = 5Hz
1.5 to 1.75 fps = 7.5Hz
2.0 to 2.25 fps = 10Hz
2.5 fps and up = 12.5Hz
A "rule of thumb" to remember is:
Ground Filter = Sweep Speed X 5.
Using ONLY Mineralization:
Very Low Mineralization = 5Hz
Low Mineralization = 7.5Hz
Moderate Mineralization = 10Hz
High Mineralization = 12.5Hz
Using ONLY EMI:
Low = High Pass
Higher EMI = Bandpass
If your sweep speed is 1.65 fps then you would want to use the 7.5Hz filter. (1.65 X 5) = 8.25, which is
closer to 7.5 then it is to 10.
Like my previous Recovery Delay chart, this information is meant ONLY to "get you close". YOU
decide what factors you want to drive the filter selection. Then, optimize your settings in the field.
I will offer one suggestion .... You CAN change your physical sweep speed ....
You CAN'T do anything about Ground Mineralization or EMI. If you find yourself in a HIGH
Mineralization and HIGH EMI environment, then you want the 12.5Hz High Pass filter.
In other words, in priority order, select the best filter considering;
o Mineralization first
o EMI next
o Sweep Speed last
55
Adjust your physical sweep speed a bit for the best target response after selecting the best filter for
the environmental conditions.
Hint: At any level of mineralization, the slowest sweep speed that you are comfortable with will
generally produce the best results. A "good average" sweep speed is 1.50 to 2.25 fps.
Hope this is helpful. Da FoX
56
High Pass - A little more sensitive in areas free of external electrical interference. – manual
Use the higher filters reluctantly, for they will 'in general terms', reduce the apparent detectability
of targets.
There are times when detection depth is limited by 'bad ground'', in which case the main criteria is
'limiting the effective loss.'
In some instances, increasing sweep speed to some optimum value, dependant on depth and
target, will enhances the detection of an object.
In either of these cases, it will be beneficial to employ a 'higher' ground filter to offset the incurred
ground effect.....normally by using 'High pass' ones.
If other factors introduce 'interference' besides the mineralisation effects, then a 'BAND-PASS'
version may offer the better filtration.
The band-pass filter is more selective / restrictive on what signals it 'lets through' compared to the
High Pass.....(Block low...pass all higher frequencies..possibly including 'interference'.)
There are problems incurred with offering 'brief' explanation's on such a complex subject, which
may not carry the message well enough for some folk.
Please comment if a better explanation is required...........TheMarshall
Ground filters help the V3 find deeper targets in areas with high concentrations of ground minerals
by filtering out the minerals. Simply put, the higher the concentration of minerals, the more filters
are needed to compensate. Band filters also help reduce the amount of EMI (Electro-Magnetic
Interference).
Use caution. If you use too much filtering in areas with moderate to low amounts of ground minerals,
it will dramatically decrease depth.
You should also decrease filters in trashy areas.
More filtering requires faster sweep speed, while lower filters allow for a slower sweep speed.
There is much more to it and I am sure more of the guys will chime in soon.
I hope this helps! Neil
I have experimented with the different filters and find that 5 Band gives me the best depth and less
falsing. Surprisingly I can sweep at a good clip probably a complete arch in a little over 1.5 seconds,
plenty fast for my style of hunting. My ground reads -90 my RX is 10, motion sens. 92, non motion
sens.68. Boost off, I can also sweep very slow if I want and continue to git excellent depth.
Jerry Murphy
57
Ground Filters......for advanced users
I have a little time before getting to work so I thought I would tell you about some of the Filter
settings. For the average user, you can use the factory preset and do just fine, but for the tinkerer
you can set the filtering system to squeeze out a little more depth. In older terminology it would be
considered an 8 filter detector, but in today's microprocessor controlled detectors, it is really one
adjustable filter with 8 selections. Two types of filters are used with 4 speeds available for each type
of filter, 5 Hz, 7.5 Hz, 10Hz and 12.5 Hz. You have a Band Pass filter and you also have a High Pass
filter. Within each type of filter you can select the speed which best suits your swing speed habits.
The lower frequency filters tend to favor slower search coil sweep speeds and the higher frequency
selections tend to favor faster sweep speeds. The Band Pass version of each filter speed works better
for lower mineral ground conditions and the High Pass filter for higher ground mineral conditions.
What all of this means is just because you have high, medium or low mineralization does not mean
you set your filters to this or that. Some hunters like to swing slow and other go like the wind. This
filter selection system lets you adjust filtering for each personal preference. An easy way to set up
which filter works best for you is a test coin in the ground, swing your coil the way you normally hunt
and try each of the 8 selections. The best audio and depth is the one you should use. Larry
EMS – I have noticed that I can swing faster (2-3 FPS) or slower (1 FPS) with the 5 band filter and still
get results, but I can’t swing slower with the higher band filters and get results. This is in next to no
mineralized ground but with a -91 VDI (iron mineralization). This is with the 6X10 and a recovery
delay of 42. Actually, the 10 and 12.5 filters won’t usually work at all in my soil.
Chapter 11 Ground Balance
A note on GB by Fox, inspired by Mntnflyr4fun:
Here's the "process" that I use .... Right or wrong - it works for me.
1) Make all the changes you want to make to the program that you're going to run
2) Get a good ground balance
3) Watch the tracking arrows as you hunt
.....a. If they change really fast, and / or you hear "overshoot" you probably have too much offset
cranked in
.....b. If they don't change very much, but you're hearing "drop-out", you probably need a bit more
As you hunt, AutoTrack is continuously updating the Ground Balance that you established at the
outset. The idea is to make the "ground invisible" so that "targets are MORE visible". A POSITIVE
offset sets the units GB a bit BELOW the Ground VDI, and a NEGATIVE offset sets it a bit ABOVE the
Ground VDI.
58
As to adjustment range - keep in mind that "adjustments" comes with "granularity". EG: One "unit" in
one adjustment might be worth 25 "units" in another adjustment. Just like DFX. One unit of "Coarse"
GEB = 255 units of "Fine" GEB. I expect that what you're doing is making "Fine GEB" adjustments with
the OFFSET in V3i.
Just as everyone's ground is different, so then is the "right offset number" for everyone's personal
huntin' patch. What works best for you in one spot might need to be tweaked if you move 200 yards
or 2 miles down the road.
I'll end with this. If you don't use ANY Track offset, you are gonna be mighty close to "really good",
because V3i's tracking is as good as it gets. It employs different tracking algorithms / ranges for
different soil types (Normal / Salt) and if you just let AutoTrack do its job, you'll be well served by V3i
and VX3 as well.
Hope this is helpful ....
59
Appendix
Expert Menu Flowchart
by Scott (Mid-Mich.)
Diagram 1 of 4 – Frequency, Ground Tracking and Filter & Speed
60
Diagram 2 of 4 – Discrimination and Sensitivity
61
Diagram 3 of 4 - Audio
62
Diagram 4 of 4 – Program
63
Pose by Tom Dankowski on V3i
EMS – I found the following words by Tom D. very interesting and worthy of inclusion here as it gave
me a different view of the V3i and perhaps points out its potential strengths and weaknesses. This is
not at all a criticism, but rather of benefit to knowing your machine better. Bolding and underlining
by EMS.
Tom Dankowski - Although you may select/choose to run all 3 freq's on the V3i..............yet; even in
this configuration........ by definition....... it is still a single freq unit. All three freq's are kept separate.
They are also displayed separately. Never once..... do the 3 freq's come together. Unlike a Minelab or
Fisher CZ..... where all of the frequencies are 'merged' in a comparator.
There are advantages/disadvantages to both types of platforms. True multi-freq units handle baddirt/higher-mineralization better than single freq units. In general........ multi-freqs will provide
greater depth in bad dirt...... as compared to their single freq counterpart. BUT...... multi-freq units
will 'false' on iron to a greater extent.
Single freq units handle iron much better......... with substantially less falsing. Single freq units have
less depth performance in bad dirt....... due to it's inability to 'comparator' analyze ""confirmed-dirtmineralization-feedback...vs...actual-deep-target-delta/return"".
((( To contradict myself; the F70/F75/F75 LTD single freq platform seems to handle bad dirt...... to the
capability level of the multi-freq CZ platform. Leave it to Dave Johnson/John Gardiner to partially
defy mother nature ))).
The V3i does conceptually pose a interesting attribute.............. as........ it is 3 single freq detectors in
one unit. In theory...... it should 'resonate' on silver........ 'resonate' on brass........ and 'resonate' on
gold.......(high, medium, low conductors). I often wonder how the V3i platform would respond to a
target that is at fringe depth. A target that is just barely within detectable range of only ONE
frequency; yet, out of range of the other two frequencies.