N ovember 2010

November 2010
6
Can
broadband
HF meters
*accumulate*
practise-signals
correctly ?
2
Content and Colodings
Measuring is knowing
Measuring DECT's
Colofon het bitje
Charles Claessens
Charles Claessens
Charles Claessens
Charles Claessens
Page
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A manufacturer of meters summoned a rectification, and such was done in the Second Edition
of September, as well as in this issue.
But that does not mean, that broad band meters can accumulate correctly. A little bit
they can, but the big question remains if they do that correctly.
I am not capable of switching off- and on of phone masts, but DECT and modem I can.
And they are supposed to being measured by the broad band-meter-manufacturers.
At page 3, a well-known worldwide thousandfold used meter is shown. Strangely, the more
carriers are used, the less this meter indicates.
Furthermore I have accomplished quite different measurements. Not in a laboratory with
unpulsed signals, but with real time practical pulsed signals, which we are confronted with
every day. Practical measurements, which can be easily reproduced by anybody.
At ca. 6 meter distance I have placed two different DECT base stations, and measured them
first separately, and then together.
Thus, those are two similar (frequency-wise seen) signals, which should, if those broad band
meters could really *add up*, show together a higher value, than the separate values alone.
So I have positioned different broad band meters in the same spot on a table, and measured.
I have even tried the outdated HF Detektor II Profi, and the Digitmeter II with AS2002
antenna, but with the same results.
Firstly the Chicago 150 DECT was measured, then the Malibu 100 DECT, and after that
both together. Every time there was a waiting pause till the fluctuations had settled, and then
the highest value was noted. Those DECT phones were sold by dutch KPN as standard.
Although the manufacturers would like to have it otherwise, these practical tests do show
clearly, that these broad band meters cannot *add up* correctly. They measure only one clear
signal. The point here is not the difference in measured values among the different meters,
but about the fact in order to determine if the sum of both the single DECT signals are accumulated correctly indeed.
Normally one would expect that the measured single values of the Chicago and Malibu measured together would register a higher value than the single values .
But that is not the case. The total value is NOT equal to the sum of both the single values.
November 2010
In the last issue September 2010 some faults were later on detected.
The feeded signal peak was first created in one carrier, and then with 10 carrier. The mistake
which happened then was that the total load was carried out over all ten carriers but the total
output was identical to the single carrier. Because of that did the broad band meter rightfully
show the right value. And so a wrong conclusion was drawn. I reflected, that those 10 carrier
had each 0dBm and had expected for that reason a tenfold outcome capacity..
But 1 x 0 dBm = 0 dBm, and 10 x -10 dBm are also 0 dBm.
November 2010
3
November 2010
4
This meter should have shown the same value all the time.
It cannot do that, because it cannot *add up*.
Here both of the DECT base stations.
To the right the Chicago 150, and to the left
the Malibu 100, like they are sold by KPN in
their Primafoon shops in Holland.
They seem to be manufactured by Siemens.
At the top right a Gigahertz Solutions HF35C.
Starting value 1 µW/m²
Here what the Chicago 150 shows.
Because the values do fluctuate, I have registered the highest value.
The unit is µW/m².
Here what the Malibu 100 shows.
And here what the Chicago together with the
Malibu shows.
It is less than the sum of the single values.
November 2010
5
This is a HF59B.
Starting value 0,00 mW/m².
6
Here what the Malibu 100 shows.
And here what the Chicago
together with the Malibu shows.
It is less than the sum of the
single values.
November 2010
Here what the Chicago 150 shows.
Because the values do fluctuate, I have
registered the highest value.
The unit is mW/m², not µW/m².
And here a HF58B.
The starting value.
Here what the Malibu 100 shows.
And here what the Chicago together with the
Malibu shows.
It is less than the sum of the single values.
November 2010
Here what the Chicago 150 shows.
Because the values do fluctuate, I have registered the highest value.
Die einheit ist mW/m².
7
This is the HFR-2 by ROM Elektronik.
It shows the unit values in V/m.
Here in mV/m.
Here what the Malibu 100
shows.
The unit is mV/m, thus
equals 345 µW/m².
And here what the Chicago
together with the Malibu
shows.
It is less than the sum of the
single values.
The unit is mV/m, thus equals
273 µW/m².
November 2010
Here what the Chicago 150 shows.
Because the values do fluctuate, I
have registered the highest value.
The unit is mV/m, thus equals
12,88 µW/m².
8
Here the HFA-3 by ROM-Elektronik.
The HFA-3 is special, because it has built-in
filters.
D-Netz, E-Netz, d-DECT, UMTS and
WLAN.
Now no filter has been chosen, thus it is the
Allpass.
Starting value.
Here what the Malibu
100 shows.
And here what the
Chicago together with
the Malibu shows.
It is less than the sum
of the single values.
November 2010
Here what the Chicago 150 shows.
Because the values do fluctuate, I
have registered the highest value.
The unit is µW/m².
9
Here with the HFA-3 I have chosen the filter for DECT, which can be seen by the small
*d* to the right in the display.
10
Here what the Chicago 150 shows.
Because the values do fluctuate, I
have registered the highest value.
The unit is µW/m².
And here what the Chicago together with the Malibu shows.
It is less than the sum of the
single values.
November 2010
Here what the Malibu 100
shows.
Now a test with a Spectran 6065 X, with Omnilog 90200 antenna, and with LCS 2.0.0.0.
software.
When a different unit as dBm has been chosen, no curves are visible, and all markers are
below at the bottom of the horizontal axis.
The first screen shows the Chicago with 6,377 µW/m².
The second shows the Malibu with 5,540 µW/m².
And both together show 20,91 µW/m².
Measured with RMS, and those values are generally much lower than *Spitzenwert.*
If manually calibrated with 13 dB we will have 519,7 µW/m².
November 2010
11
The difference here is probably caused by measuring inaccuracy.
Because 12 µW/m² to 21 µW/m² are 2,5 dB.
I should have used much more markers here, but the LCS does have only a maximum of 10
Automarkers.
The MCS software (still in BETA) would have been much more precise, because he knows
99 markers, but the function *Marker accumulate* is momentarily not implemented yet.
November 2010
12
Now we have repeated everything, but now with a logger, connected to a HF58B.
The units to the left on the vertical scale are not correct because of the preprogramming of
the logger. But it is clearly recognisable that the two DECT separate signals do NOT lead
to a higher value when accumulated together.
Malibu
13
Chicago
+
Malibu
So, what I have measured so far, and what everybody can replicate in a very simple way, is
the fact, that broad band HF meters cannot accumulate different signals together correctly.
That is not so bad, as long as one is conscious of that fact.
One should control much more often the audio analysis and that way detect more different
signals, and measure them separately. Because the values are given in µW/m², they may be
added up.
(That is NOT allowed with V/m. Here, one has to calculate.)
+Malibu
Modem
+Chicago
This was measured with *Spitzenwert* with a HF58B with Logger connected. A modem
was added. Observe the great fluctuations with the Malibu.
November 2010
Chicago
14
+Malibu
+Chicago
Here *Spitzenwert halten* was chosen. The maximum value was hold in the display.
Notice how long it takes before the maximum value was stabilised with the Malibu.
Modem value: 0,36 mW/m²
Plus Chicago: 0,39-0,36 mW/m²
Plus Malibu climbing to 1,02 mW/m²
Modem
+Chicago
+Malibu
-Modem
-Malibu=
Chicago
Because the HF58B showed many fluctuations, now a HF59B with logger was taken.
After every change, the *Spitzenwert halten* function was switched on, and afterwards
followed by a reset.
The Chicago DECT was placed at two meters close to the meter in order to have more
capacity.
The Modem alone showed 0,83 mW/m².
Added the Chicago DECT 0,70 mW/m², thus Modem +Chicago.
Added the Malibu DECT 1,10 mW/m², thus Modem + Chicago + Malibu
Then the modem switched off: 0,46 mW/m², also Chicago + Malibu.
Then the Malibu off: 0,05 climbing to 0,44 mW/m². That is the Chicago alone.
Apparently the measurements of DECT do raise heavy problems.
It is curious, that the Chicago together with the modem indicates a lower total value.
November 2010
Modem
15
Chicago
Spitzenwert halten
+Modem
HF59B with Logger. The Chicago DECT here at a distance of 2 meter.
First Chicago only *Spitzenwert*; then *Spitzenwert halten*.
Value Chicago alone 1,77 mW/m², and together with Modem 1,76 mW/m².
Thus, Chicago + Modem.
Remarkable how the peaks go up and down.
November 2010
Chicago nur
Spitzenwert
On this and the next pages, several different HF meters are lying on a table and are measuring the same source (a DECT base station).
November 2010
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November 2010
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Tja, here differences in values between meters are shown.
But one should realize that those meters should full fill certain tolerances, and because of that
such differences may occur, as ROM-elektronik has clearly explained in the picture below.
What irritates me personally, is then fact that I cannot measure a value of f.i. ca. 230 µW/m²
with a HF58B or HF59B. In position *mittel* they show a I, saying, the value is bigger than
199 µW/m². When I switch to *grob*, he starts with 160 µW/m².
November 2010
18
With DECT, GSM etc. thus with practical signals, the puls-width is too small, and because
of that, the notification of the meters of the total capacity does not function correctly.
As of any detector, one may receive complete different values (see the test with the different
meters), the measurement values cannot be trusted completely..
So a BIG PROBLEM has been unfolded, which was NOT noticed in such a way with a generator. That happens only with practice signals.
19
I was informed from two different sides, that tests done in laboratories showed that
broad band meters did nicely and correctly *accumulate* signals.
A shame that they did forget, or did not know, that unpulsed signals do react quite differently from pulsed ones, like I did show here clearly with both DECT's.
Factum: With artificial CW-generator-signals (which do not exist in the practice) some meters
are capable in showing a total capacity, if these signals exist FAR FROM EACH OTHER;
the Trifield is not capable for that at all, and that is good! That way it should be, otherwise
one cannot measure a signal ever, because surrounding signals always trouble the outcome of
measurements. A big problem!
The broad band meters of Narda, which are commonly used by the authorities, are also broad
band meters.
In laboratories they may *accumulate* unpulsed signals from CW-generators, but for me the
question remains if they can do that also with pulsed signals, like those we are exposed to
everyday in the open.
This remains a very big question for me.
(Because I do not have at my disposal a Narda NBM550 or a Narda EMR300, I can not
control that, but my doubts remain.)
November 2010
So, tests with signals originated from a signal generator, which are not pulsed, can be *accumulated* to some extent, but pulsed signals, like they exist in the practice exclusively, do show
quite another reality.
Marker summieren or marker accumulate.
20
A measurement in the frequencyband UMTS NL downlink. There is a peak for Vodafone,
KPN and T-Mobile. The value (Standard) is in dBm, and of the strongest signal.
Attention, *Marker summieren* is grey and cannot be activated.
Here a unit in dBuV was chosen.
Here also *Marker summieren* is grey.
November 2010
What is meant is the following:
Below is a spectrumanalysis of UMTS downlink Netherlands.
Three Auto-Markers are chosen.
Now mV/m or V/m is chosen. The highest value is now 6,985 mV/m.
*Marker summieren* is now white and can be activated.
With *Marker summieren* activated, the total value of the three markersis now 11,24 mV/m.
November 2010
21
One can also choose for µW/m². Then the highets value is 129,5 nW/m².
And if *Marker summieren* is activated, with only one mouse click, the total value will be
335.5 nW/m² (= precise 11,24 mV/m).
November 2010
22
This is a spectrum analysis of a random measurement report of Agentschap Telecom, made
with a Spectrum analyser of R&S.
It is clearly visible, that next to marker 1 another peak exists, and precise more peaks next to
marker 3 and 2.
Those are also transmitters who are momentarily sending, and who belong to the what the
Germans call *Wellensalat*.
Let's assume, the authorities say, that the total capacity is 1,47 V/m (or 5732 µW/m²).
If this is the only signal Signal, then these 1,47 V/m are correct as field strength.
But when other signals are present, which is mostly the case, for instance 9 other signals of
f.i. 1,40 V/m (or 5199 µW/m²), together 46.791 µW/m², or 4,2 V/m.
Together with the measured signal the total amount will be 52.523 µW/m², or 4,45 V/m.
It seems to me, that 4,45 V/m is more than the suggested 1,47 V/m.
I have the impression that measurements are not done accurately nor correctly in Belgium
as well in the Netherlands. Not with broad band meters nor with spectrumanalysers.
And that the citizens are presented with much lower values than are present in reality.
November 2010
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24
Eindredactie:
Ontwerp en vormgeving:
Redactie:
Charles Claessens
Charles Claessens
Charles Claessens
[email protected]
tel 0031-76-7518891
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November 2010
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