Part II

Transcription

Part II

How to begin TEM measurements with
FastSnap.
Quick start guide.
Maxim V. Sharlov, [email protected]
Irkutsk, 2015
Introduction
This short guide is intended for the beginner user of FastSnap equipment. It is intended to
enable the user to acquire their first* TEM signals with FastSnap.
The guide consists of two parts:
1) Short review of using software: structure of FastSnap database, Project Manager 3 and
FastEM-registration software;
2) Step-by-step guide for first measurement.
For more details on software or hardware please refer to respective User Guides.
*
First signals can be obtained either “on the table” (just to check proper operation with equipment) or in the field conditions with real survey template, i.e.
transmitter and receiver placed on the ground.
FastSnap quick start guide
2
Part I.
Short overview of database,
Project Manager 3
and
FastEM-registration software
3
Part I. Overview of common architecture of FastSnap database (DB).
Relational database
Projects list Database
The reference DB is for storing
the list of attributes/links to
different Projects (i.e. sounding
DB-s)
D:\SGS\FDB
Soundings Database
File Database
Intended to store information
of each stand-alone field
project in separate DB. Stores
coordinates of survey
templates (Tx-s and Rx-s),
parameters of recording of
EM-signals, links to source
(raw) binary and processed
files.
File database (FDB) is a structure of
directories and files on the local hard disk.
FDB stores information of each stand-alone
field project in a separate folder. Each FDB
Project folder contains source (raw) binary
and processed files, GIS-files and others.
4
Part I. Overview of structure of FastSnap Relational Database.
Structure of FastSnap relational
database:
1) Projects list DB. Contains several
tables for storing of list of Projects
and links to certain sounding DBs.
Projects DB usually located in file
“D:\SGS\Data\adProjects.mdb”.
2) Soundings DB. Contains tables for
storing of coordinates of Tx’s and
Rx’s (tab_MD and tab_PK).
Parameters of recording of EMsignals are stored in prof_PK table.
Parameters of processed signals
are stored in prof_Mod table. DB
located in a
“Data_HDD\FDB_Path\ProjectFold
er\Data\Project_Filename” mdbfile.
5
Part I. Overview of structure of FastSnap File Database (FDB).
Structure of File Database:
Usual place for File DB is
“D:\SGS\FDB” folder (can be
other disk/folder).
Folder “D:\SGS\ADO” contains
installed FastSnap software.
Folder “D:\SGS\Data” contains
“adProjects.mdb” – reference
database for Projects (Projects
list DB) – contains names,
paths and other attributes of
Projects.
File database (FDB) intended to store source and processed TEM/FastSnap data (binary files with EM-signals, final
curves in different transformations and formats, GIS data and so on). For each Project DB (sounding DB) in FDB are stored
the following directories:
AVR – contains files of *.avr format (processed signals and geoelectrical models);
Curves – for *.tqq files - optional;
Data - contain mdb-file of relational Project DB;
GIS – spatial and geo-information data (tracks, rasters, waypoints, shapes) - optional;
POD – contains files in PODBOR format - optional;
RB – source (raw) binary files with EM-signals with arithmetic sampling step;
TMP – temporary files, optional;
TXT – contains *.txt (processed signals with geometric time step).
6
Part I. Overview of Project Manager 3 software.
Project Manager 3 Software is intended to manage the FastSnap database. The main features of
software are as follows:
1) Creating, editing and deleting of sounding databases (Project DBs);
2) Working with DB data in table form (viewing, editing an so on);
3) Special tool for querying and editing data in DBs based on SQL;
4) Importing of DBs from external places and synchronization of existing DBs;
5) Integrated specialized electromagnetic GIS-system (map) supporting of raster and vector data
types for visualization;
6) Coordinate systems and map projections transformation tool;
7) Tool for working with mobile GPS-devices (Garmin GPS devices are supported) –
upload/download tracks and waypoints functions are available;
8) Automated tool for planning of survey templates / designing points of observations for
different observation configurations – planning along line, on defined area and so on. Storing
results of planning in one or several Project DBs;
9) Visual (on the map) or manual (changing coordinates in tables) editing configurations of
transmitters and receivers;
10) Forming of report of field operator in MS Excel format for selected Project DB.
7
Part I. Project Manager 3 software. Main window.
Show dialog for editing of list of FastSnap field operators
Synchronization / Import Dialog
Create New Sounding DB (New Project)
Open Project Dialog (List of Projects window)
DB editing password
Dialog. Default password
– “123”
Close program
8
Part I. Project Manager 3 main menu and Connect DB item.
Duplicate functions of main window Toolbar buttons
Default folders (during software
installation) for FastSnap
database are D:\SGS\Data –
for projects list database and
D:\SGS\FDB – for sounding
databases.
Please check your database
location and change
connection settings with
‘Connect to DB’ dialog if
necessary.
Change connection to Projects list DB.
If several “Projects list DB” is used please select needed /
proper one for using via this Dialog.
Select MS Access option and fill path to Projects list DB
mdb-file (by default - D:\SGS\Data\AdProjectsNew.mdb).
Project Manager software supports work only with one
Projects list DB at time.
9
Part I. Functions of FastEM-registration software.
FastEM application main functions:
- Controlling of hardware parameters of RX and TX units (sampling rate, gain, synchronization, current
mode, damping resistor and others);
- Working with TX&RX unit’s in-built GPS receivers (acquiring of coordinates, showing current sounding
template in GeoMap window in real coordinates, updating coordinates of recorded template, etc.);
- Acquiring and visualization of signals from RX units, showing current value and waveform;
- Express processing of obtained records, calculating of EMF, apparent resistivity and apparent
conductivity transformations;
- Manual or automatic (via presets) recording with one or two channels simultaneously;
- Storing of obtained information in FastSnap database.
10
Part I. Controls of FastEM-registration software.
Main toolbar & menu
Hardware parameters tabs
Visualization & information tabs
List of internal software’s messages (LOG window)
11
Part I. FastEM-registration software. User interface.
Indication of GPS and TX status info
Auto scale function for visualization
Acquire GPS info from TX&RX units
‘Load data’ dialog
‘Save record to DB’ dialog
‘Input current’ dialog
Manual stop of current in TX loop
Manual start of current in TX loop
Terminate / stop current action
Start acquisition. Button is active when parameters were sent and tested.
Test parameters
Send RX&TX parameters
Turn RX units ON/OFF. Button is active when DLA is connected to PC.
Close program
12
Part I. Hardware parameters tab overview. FastEM-registration.
RX units parameters:
- Choice of ADC
(Fast/Std);
- Discretization
(sampling rate);
- Samples count per
one pulse;
- Dynamic range (1V
is default);
- Gain factors and
high impedance
input;
Parameters, stored in
DB:
- Pulses count;
- Shift in ms (see
further);
- MD shunt (i.e.
damping resistor for
TX loop);
- Size and turns of RX
loop;
- Serial number of
loop (if any) and
parallel shunt (if
any);
Synchro parameters:
- Way of RX & TX
synchronization (no,
GPS, wire);
- Period in ms (i.e.
current pulse + no
current pause – for
20 ms period will be
10 ms current + 10
ms pause, next
period will be
different polarity);
- Duty cycle – relation
between length of
current to length of
pause (1:1 – current
length equals to
pause length, 3:1 –
current 3 times
longer then pause);
Parameters of RX units and synchronization
settings on the hardware parameters tabs
13
Part I. ‘State’ tab. FastEM-registration.
Serial number, voltage of connected battery, ADC
LSB value, measured gain – parameters, returned
by each RX unit respectively
TX unit parameters: serial number, voltages,
firmware version
LOG of events inside of software – interchange
with RX and TX units, parameters, etc.
14
Part I. ‘Tx Switch’ tab. FastEM-registration.
Connection to control port (RS232 or
WiFi optional) and management controls
Current and
temperature
values at the
moment; green
‘led’ show running
current, red –
current is stopped;
Real time current diagram
15
Part I. ‘Visualization’ tab. FastEM-registration.
Amplitude (in ADC
quants) axis
Time axis
Signals from RX units (red – first
channel, blue – second channel). Signals
on the screen are updating in real time
during recording.
16
Part I. ‘All pulses’ tab. FastEM-registration.
Selected number of pulses (i.e. all pulses
in record) from two channels showed on
one plot. It lets to examine behavior of
noise during time of acquisition
17
Part I. ‘Spectrum’ tab. FastEM-registration.
Spectrum of signals from both channels
is calculated and showed in real time. X
axis is frequency, Y axis – amplitude.
18
Part I. ‘GPS’ tab. FastEM-registration.
GPS information (coordinates, signal quality,
mode, time, etc.) obtained from RX and TX
units. Information is updated once per second
by special command from main toolbar.
19
Part I. ‘Map’ tab. FastEM-registration.
Tab showing
geometry of survey
template (if there are
coordinates stored in
DB for current
template/station).
Red and gray points
show real position of
RX and TX units. Lines
connecting blue
points – position of
TX loop.
20
Part I. ‘AutoProc’ tab. FastEM-registration.
The records (consist
of number of pulses)
from both channels
averaged and
interpolated to
logarithmic time step.
Transformations of
EMF(t), apparent
resistivity (Rho(t)) and
apparent conductivity
(Stau(Htau)) are
calculated after each
record has been
completed.
21
Part I. ‘Express-processing’ tab. FastEM-registration.
Bad records which
don’t match by
level with all
records can be
turned off.
Difference in the
level of record
usually caused by
error in
synchronization,
gain or current.
All records, obtained
during each work (during
recording of each station),
are stored in this tab (each
record in the list has own
color). It is possible to turn
some records off and
make summation between
all records for obtaining of
final curve. Four
summation algorithms are
available. Records from
each channel are stored in
separate list and
processed independently.
Result of such express
processing can be stored
in DB.
22
Part I. ‘Presets’ tab. FastEM-registration.
Predefined settings (i.e. preset) for sequence of records. Some parameters for each
channel are defined independently (gain, dynamic range), some parameters intended for
both channels (sampling rate, synchro, samples and pulses count, etc.).
Such preset can be run automatically with storing all signals and parameters to DB (after
prepare of station for recording – see Part II). User can define his own preset or use one
available from the list. Completed records are marked with green color, current record –
yellow and the rest of unfinished preset – white lines in the table.
23
Part II.
Step-by-step guide:
How to begin TEM measurements
with FastSnap
24
Part II. Steps to success.
1)
2)
3)
4)
5)
6)
7)
Create the new database for the first (next) project (PM3);
Create appropriate source (transmitter loop) and receiver (receiver loop) in DB (PM3);
Preparing units to turn on. Starting of FastEM-registration application;
Connecting to RX unit(s);
Connecting to TX unit;
Making of first (noise) record;
Creating of ‘station’; (i.e. preparing and filling of DB with parameters for storing of
records for selected receiver and transmitter loops);
8) Controlling of TX unit;
9) Making records in manual mode;
10) Making records automatically via preset;
11) Express-processing of result and saving to DB.
Thus, before acquisition procedure it is necessary to prepare proper database – make
new sounding DB for each new project, create transmitters and receivers and then each
obtained record will belong to certain TX and RX loops. Procedure of creation of TXs and
RXs can be done manually (suits more for small amount of TEM points) or automatically
in GIS window (when cartography is available – GPS tracks, coordinates of lines, etc.)
25
Part II. Create the new project (new sounding DB) – PM3.
1)
2)
3)
4)
5)
6)
7)
Press “New Project”
button in Main window
– Create Project dialog
will appear;
Type name of new
project in “New project
name:” edit field;
Press Create button –
the edit fields for project
parameters will become
available to edit –
usually no need to edit
default values. It’s
important to
check/change FDB folder
path (is it available in
system?);
After everything is ready
to create New Project –
press Apply button.
If selected folder for
storing project is not
exists – PM3 will ask to
create it (and all subdirs)
automatically.
After message about
successful creating of
new project it will
become available in list
of Projects.
Close the dialog.
26
Part II. Open project dialog – PM3.
1)
2)
3)
4)
Press “Open Project”
button in Main window –
Open Project dialog will
appear;
Type name of wanted
Project in special search
field or select Project
from the list with LMB;
Press Edit button – the
edit fields for project
parameters will become
available to edit – paths
to files, name of mdb-file
could be edited. To
confirm changes after
editing please press
Apply button;
Press Delete button if
you want to remove
selected Project from the
list. No actual deleting
will be performed – only
Project name will be
removed from the list. To
delete the Project user
need to remove it
manually from FDB
(delete folders and files
manually).
27
Part II. Create source (define transmitter loop parameters) – PM3.
1)
2)
3)
4)
5)
6)
7)
8)
Select project in Open
project dialog and press
TXs button – dialog for
editing of TX parameters
will appear;
Press New Tx button;
Fill ‘Tx’ field with number
for transmitter loop you
want. Only numbers are
possible as Tx numbers
and all numbers should be
unique;
Fill ‘Size’ and ‘Size 2’ and
other fields with proper
values;
It is possible to leave ‘-1’
as values for coordinates
of corners ABCD and
center of loop Q;
Press Accept changes
button to save parameters
of transmitter loop to
selected project DB;
Press Edit Tx or Delete
current to edit or delete
selected transmitter loop
respectively;
Repeat steps to create
new TX or close dialog
when finished.
28
Part II. Create receiver (define receiver loop parameters) – PM3.
1)
2)
3)
4)
5)
6)
7)
Note! Recording of signals and storing it to DB only possible when transmitter and
receiver loops (receiver points) are defined in project DB. Each transmitter physically
relates to geographic place in area of investigation. Each receiver point should belong to
its transmitter loop. Transmitter loops numbers should be unique among the project. All
receiver point numbers which belong to one transmitter should have unique numbers
but receiver points numbers may repeat among different transmitters.
8)
9)
Select project in Open
project dialog and press
RXs button – dialog for
editing of RX parameters
will appear;
Press New Rx button;
Fill ‘Rx’ field with number
for receiver point you want.
Only numbers are possible
as Rx numbers and all
numbers should be unique;
Select number of related
transmitter loop from the
‘Tx’ list of available TX
loops in project;
Fill ‘Size’ and ‘Offset’ and
other fields with proper
values;
It is possible to leave ‘-1’ as
values for coordinates;
Press Accept changes
button to save parameters
of receiver to selected
project DB;
Press Edit Tx or Delete
current to edit or delete
selected transmitter loop
respectively;
Repeat steps to create new
RX or close dialog when
finished.
29
Part II. Turning ON RX units in FastEM software.
1)
2)
3)
4)
5)
6)
Connect all modules of
FastSnap station with proper
wires (i.e. connect RX unit to
DLA, connect RX loop and so on
as described in FastSnap user
guide) and execute FastEM
software;
If DLA is connected properly
(and proper device driver
installed in system) ON/OFF
button will be enabled
(colored);
To turn RX unit(s) ON press
ON/OFF button;
If everything is connected
properly the information panel
will show RX units details;
To turn RX unit OFF press
ON/OFF button again – don’t
forget to turn off RX units while
not in use, it can help to save
internal battery power;
Always turn OFF RX units in
FastEM software before
disconnecting of DLA or
physical units switch off, in
other case it is possible to get
software error/exception (like
‘USB read error’…)!
30
Part II. Checking parameters of RX units in FastEM software.
1)
2)
3)
4)
5)
6)
7)
8)
To check RX units press Send
parameters and then Test parameters
buttons;
‘Send parameters’ command setup
(upload) selected by user parameters
into RX units;
‘Test parameters’ command perform
testing of some parameters (e.g. real
gain factor will be detected, voltage of
internal battery, value of ADC
quant/ADC LSB in mcV);
If link between PC->DLA->RX units is
stable and everything work properly the information panel fills with
detailed parameters of each connected
RX unit;
In case of any error user can see
appropriate message in LOG-window;
Common settings for all connected RX
units are: ADC input, discretization,
samples and pulses number, way of
synchronization.
Individual settings for RX units:
dynamic range (for Fast ADC input),
gain factor;
After any change of any parameter
necessary to perform Send parameters
command at first and then Test
parameters command (actual
parameters will be updated on the
screen) and only after that it is possible
to start acquisition.
31
Part II. Setup link with TX unit - FastEM software.
1)
2)
3)
4)
5)
6)
DLA contains special noise-immune COM port (TX Control socket) for
managing of TX unit;
Make sure the TX unit is connected to DLA or to other COM port (see
FastSnap UG on this issue) via TX control & synchronization cable;
Select proper COM port number from the dropdown list (if DLA socket is used
it is easy to detect it’s COM port number – to do this*: disconnect DLA from
USB, press Refresh button, look into the list, connect DLA back, again press
Refresh button and look into the list – proper COM port number just
appears);
Press Open port button to open selected port;
FastEM software will remember selected port number and will connect
automatically during next run;
To change COM port press Close port button, select another COM port from
the list and press Open port button again;
*Auto-detection of proper port number is in ‘to-do’ list for future software updates
32
Part II. Managing of TX unit - FastEM software.
1) After the proper COM port is opened it is necessary to
switch TX unit to PC controlled mode (it can be done from
the TX unit Settings menu or from the FastEM software);
2) To toggle PC mode from FastEM software: select ‘New TX
param’ checkbox, ‘FastSnap II options’ dialog appears. This
dialog window can be opened during all work – no need to
close it until closing of FastEM software;
3) Press ‘Switch to PC/Manual mode’ button – in case of
success OLED screen of TX unit shows message about
working in PC controlled mode;
4) Select needed values for parameters of CURRENT VALUE,
TURN OFF SHIFT, DAMPING R, R_Add 0.5 Ohm, GPS Antenna
and press Send TX parameters button (some kind of ‘click’
sound can appear in TX unit);
5) Press ‘Measure PWR voltage’ button to get voltage of
power battery (if connected);
6) Use appropriate buttons on the ‘TX Switch’ page to get
serial number, battery voltage etc. information (some
information about TX unit shows on the ‘State’ page);
7) Use Start / Stop current buttons to manual start and stop
current (usually manual control is used for checking of
correctness of connection etc.). Information about current
updates on the screen in real time;
8) Never change CURRENT VALUE option (i.e. select new value
and press Send TX parameters) while current is injecting
into the load (TX loop). Never give HIGH or Medium current
into the rolled on the handle TX loop due to risk of
damaging of internal electronics!
33
Part II. Algorithm of acquisition - FastEM software.
After the RX and TX units are connected and checked for proper operation it is possible to begin measurement.
Common algorithm of measurements is as follows:
1)
2)
Acquire of ‘noise’ record without current in TX loop with maximum gain factor of RX units and use it to
create the new station (i.e. prepare DB for data saving – select TX and RX numbers, etc.);
Continue to work in manual or automatic mode (with presets);
Usage of GPS synchronization is preferable due to higher accuracy.
For manual recording:
 Change discretization, gain, samples and pulses count for different records if needed (usually fast
discretization is used with low gain and low current etc.);
 Change CURRENT VALUE from low to high and make several records for each current mode (usually 3 modes
of current are enough – Low, one of Medium, High);
 Acquire 100-200 pulses for each record, input current value in appeared dialog and save record to DB;
For automatic recording:
 Create or select/load suitable preset;
 Activate usage of preset and run automatic measurements – RX unit’s parameters will change automatically
for each record in accordance with preset, collected data will store in DB;
 Change CURRENT VALUE during pauses in preset;
Usually 15-20 records consist of 100-200 pulses each is enough to get good quality TEM curve. In case of high
level of EM-noise may be necessary to increment number of records and/or pulses in record. Main idea during
measurement is investigating of early, medium and late times of curve with fast discretization and low current
(early time), medium discretization and medium current (medium time), slow discretization and high current (late
time) respectively;
34
Part II. Make first ‘noise’ record - FastEM software.
+ ADC clipping level
1)
2)
3)
Select 25 ns discretization;
Select 4000 samples, 50-100 pulses;
Uncheck ‘Manage switch’ and ‘Autostart’ checkboxes on the ‘TX Switch’
page;
4) Select maximum gain (‘Channels’ page), send & test parameters, then run
acquisition (Run button);
5) Press ‘Cancel’ button in current dialog after record completed;
6) Open ‘All pulses’ page and examine the signal for ADC clipping effect. Each
discretization has its own level of ADC clipping in +/- samples, for 25 ns it is
the +/- 8192 samples (it is possible to see the clipping level as hint message
during changing of discretization on the ‘Common param.’ page);
7) If noise level is high and there is ADC clipping on the signal, it is necessary to
check lower gain – i.e. select previous gain, send & test & run acquisition
again;
8) Repeat section 7) until signal without clipping is acquired;
It is important to detect maximum possible gain factor without ADC clipping (for
each channel) due to using of improper gain will cause unrecoverable error in
average level of measured signal.
- ADC clipping level
35
Part II. Selecting of Project DB.
1
2
3
4
1) After the maximum gain factor was detected on
previous step, it is necessary to save noise record to
DB – make one more acquisition with detected gain,
and in ‘Input current’ press OK (value will be 1) – see
fig. 1;
2) Program ask to continue with previously selected
project DB (see fig. 2);
3) Press ‘No’ to select another Project DB or ‘Yes’ to
continue with showed in message Project DB;
4) If ‘No’ pressed – Project list dialog will appear (see
fig.3) – check needed Project DB in the list and press
‘Select’ button;
5) In Project list dialog it is possible to open source’s and
receiver’s tables/dialogs for creating or editing
(buttons ‘Tx’s’ and ‘Rx’s’);
6) After the Project DB was selected ‘Profile_picket’
dialog appears (see fig.4);
7) To save first record it is necessary to create the new
station – press respective ‘New station’ button;
36
Part II. Creating of the new station.
1
2
3
1) The ‘Create new station’ dialog shows list
of available transmitters, list of connected
channels (one or two) and list of defined
receivers for selected transmitter number
(see fig.1);
2) To create the new station it is necessary to
select proper transmitter number in the
‘Tx’ list and add receivers to ‘Station list’
accordingly to channel number (double
click on receiver number or select it with
mouse and press ‘-->’ button) – fig.2;
3) Select ‘Operator’ from the dropdown list
(contents of this list can be edited in PM3
– button ‘List of Operators’ in main
window);
4) If needed to edit parameters of receiver
(like size of RX loop) - select receiver
number assigned to defined channel from
the ‘Station’ list and edit available
parameters in the text fields, press ‘Apply’
to accept changes;
5) When all parameters are correct – press
‘Save and exit’ button – new station will be
created and first record of station will be
saved to the Project DB;
6) if same transmitter/receiver numbers
already existing in the DB in different
stations warning will appear (see fig. 3) –
press ‘No’ to change transmitter/receiver
numbers or ‘Yes’ to continue – new station
will be created to keep the new data for
the same TX/RX;
37
Part II. Creating of the new station.
1) After ‘Create station’ dialog closed
program will return to ‘Profile_picket’
dialog;
2) New rows with parameters of ‘noise’
record will appear in the grid;
3) Press ‘OK’ button to save binary file with
signal to DB and close this dialog;
Station created - now you are ready to save
acquiring data to DB which will be stored to
the Project DB with defined Station/TX/RX
numbers!
38
Part II. Controlling of current and other TX parameters.
1) After the station was successfully created
it is necessary to check ‘Manage switch’
and ‘Autostart’ checkboxes;
2) If checkboxes, mentioned above are
checked – program will autimatically start
and stop current while acquisition
procedure, i.e. no need to start or stop the
current manually!
3) Select ‘current diagram’ to see current
waveform updating in real time
(optionally);
4) Select needed values for the CURRENT
VALUE, DAMPING R (i.e. parallel shunt),
R_add and other parameters in ‘FastSnap II
options’
dialog,
press
‘Send
TX
parameters’;
5) If there is current overload (i.e. >20A) in
HIGH current mode can be useful to
activate ‘R_add 0.5 Ohm’ parameter – it
will serially connect additional resistor=0.5
Ohm to TX loop and will decrease current
value;
Change current parameters only when there
is no current in the TX loop!
39
Part II. Acquisition in manual mode – general information.
1) After the ‘noise’ record saved to the DB it is possible to continue acquisition in manual mode – all next records
during acquisition will be saved into the created station (until closing of program or selecting of ‘Clear station’
option from main menu of program);
2) Good practice is to make one-two records without damping resistor (i.e. DAMPING R: OFF in ‘FastSnap II options’
dialog) – to save waveform of oscillations in loops. Preferable parameters for such record: dT 25 ns, gain 1-3 (no
ADC clipping!), samples count 4000-10000, pulses count 50-100, CURRENT VALUE = LOW;
3) Using of damping resistor for the next records is highly recommended! Reference values of damping resistor for
different sizes of TX loop are as follows: 25x25 m – 170-220 Ω, 50x50 m – 270-350 Ω, 100x100 m – 450-650 Ω;
4) For next records change dT, gain, samples and pulses number, period of synchro, current and damping resistor
value for each new record if needed;
5) For the further processing better to make several records (by 100-200 pulses in each) than one big record (10002000 of pulses);
6) Early time of decay usually is measured with fast discretization (25-100 ns) and low gains (1-13). At least 2-3
records should be acquired without ADC clipping effect (if ADC clipping if still happens even with low gain settings
- try to set lower current by decreasing of power voltage or selecting proper current options)! Five-six records
usually are enough to get good quality result on early times;
7) Medium time of decay usually is measured with dT 800 ns, medium gain and medium current. 6-5 records usually
are enough. Early time of decay usually is corrupted with ADC clipping effect but it is normal – our interest is on
the middle part of decay.
8) Late time (deepest part of curve) is measured with dT 800 ns – 6.4 mcs, maximum possible gains (remember
about maximum possible gain detected during ‘noise’ recording) and HIGH current. Strong ADC clipping on
starting part of curve is visible. Number of records depends on the needed length of acquisition by time and on
noise conditions in the place of measuring (6-8 records in normal condition are enough);
Need to remember that length of each record should be enough to ‘stitch’ different records between others by
time!
40
Part II. Acquisition in manual mode – procedure.
2
1
1) Setup all necessary parameters of record like dT, gain, length etc.;
2) Send parameters, Test parameters and Run acquisition;
3) If ‘Manage switch’ and ‘Autostart’ checkboxes are checked and TX COM-port is opened – current will
start and stop automatically;
4) After acquisition of record completed check the current value and press ‘OK’ in the ‘Current value’
dialog (see fig.1);
5) Double press ‘Enter’ key or press with mouse ‘New record’ and ‘OK’ buttons respectively in appeared
‘Profile-picket’ dialog (see fig.2);
6) Obtained record will be saved to the DB - LOG window will show message about file saving;
7) Select next records parameters and continue from the section 2) – all records will save to DB;
41
Part II. Acquisition in automatic mode – general information.
1) If station is created (after ‘noise’ record or after any number of manually saved records) it is possible to continue acquisition in automatic mode
(using presets);
2) User can select one of predefined preset from the ‘Standard presets’ list or load from file, or create new preset using appropriate buttons;
3) Grid shows in each row independent parameters for each record. Each row contains settings for one record (for single or two channels
configuration) ;
4) Each cell of grid can be easily edited by double-clicking on it with mouse and selecting value from dropdown list of typing;
5) Additional rows can be added if needed as easily as deleted from the grid;
6) Preset from the grid can be saved to preset file (*.prs);
7) Preset for two-channels system can be used in single-channel system – program will show message that settings of channel one of preset will
apply;
8) If TX unit is controlled by cable make sure ‘Manage switch’ and ‘Autostart’ checkboxes are checked otherwise uncheck it for manual operations
with TX unit;
42
Part II. Acquisition in automatic mode – procedure.
1) Check ‘Use presets’ checkbox and press Send, Test and Run buttons – program will follow the preset row by row, automatically setup parameters and
save records to DB. Already completed rows show with green color, acquiring row shows with yellow color and rest of rows with white. Also progress on
preset shows in progress bar;
2) PAUSE in preset is intended to suspend program on this row to have possibilities to change current – when program reaches row with PAUSE it shows
message that work is suspended. Until user presses ‘OK’ in this message dialog program won’t do anything. With manual TX unit control mode (without
cable) just select needed CURRENT VALUE in the TX unit and start current again. With automatic TX unit control user should press ‘OK’ and then
terminate acquisition process by pressing ‘Terminate’ button – then change CURRENT VALUE in the ‘FastSnap II options’ dialog, select next after PAUSE
number of row in ‘Start from’ dropdown list and press Send, Test and Run again. Program will continue from selected row with changed current.*
3) After preset completed program shows appropriate message;
4) Recording by preset can be repeated from beginning or from any row – just set number of row in ‘Start from’ dropdown list and start acquisition again –
new records will save to DB;
* Future releases of FastEM software will include automatic management of current options (CURRENT VALUE, DAMPING RESISTOR, etc.) in the preset
43
Part II. Express processing – general information.
1) During process of recording (manual or by preset) all saved to
DB records are appeared on ‘Express-processing’ page;
2) Screen on this page is split to one or two parts accordingly to
connected number of channels in system;
3) Each record is showed with its own color;
4) It is easy to detect the erroneous records on the EMF plot
(such records is distinguishing from others by level);
5) Negative polarity records are drawn with blue bordered
circles while positive records – with black bordered circles;
6) It is possible to flip polarity of record by selecting it in the list
and pressing ‘Enter’ key (or pressing ‘Reflect signal’ button);
7) Record can be deleted from the list (and accordingly - from
the summary result) by selecting and pressing ‘Delete’ key or
pressing ‘Delete record’ button – record will be removed
ONLY from the list and will remain in database for future
processing etc.;
44
Part II. Express processing – parameters of summation.
On the ‘Settings’ page of ‘Express-processing’ window several
options are available:
1) ‘Remove ADC cutting’ (i.e. ADC clipping) – auto-detect and
auto-remove part of records which affected by ADC clipping
effect;
2) ‘ADC cutting, %’ – part of full dynamic range of record which
can be evaluated as clipping;
3) Summation (averaging) algorithm can be selected in
‘Summation’ dropdown list – four choices are available:
regular arithmetic mean ‘SumAvg’, ‘Mediana’ for the median
averaging, ‘WghtSum’ and ‘SigmaSum’ for kind of trimmed
mean. For the draft express processing ‘Mediana’ or
‘WghtSum’ is more suitable;
4) Starting and finishing time of curve can be selected in
respective dropdown lists ‘First T sum’ and ‘Last T sum’ –
this options are only available before averaging procedure;
5) ‘T rot [ms]’ option keeps time of auto-detection of signal
polarity.
45
Part II. Express processing – building a curve.
To build resulting curve from set of acquired records:
a) Delete erroneous records from the list;
b) Make sure all records are in proper polarity;
c) Select summation algorithm and other options on
the ‘Settings’ page;
d) Press summation and transformation buttons to see
the result (summary EMF curve shows with yellow
squares, apparent resistivity and apparent
conductivity curves showing with red circles);
e) Save resulting curve to DB if needed.
46
Congratulations!
If you followed up this guide, you’ve
measured and processed your first TEM
point with FastSnap.
For further details please refer to respective User Guides on FastSnap station and
software or contact with dealer/manufacturer
47

Part II

Transcription

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