Zonge GDP-32II User manual

May 2002
6. RECEIVER SETUP
6.1 CALIBRATION .......................................................................... 2
SPECIAL INSTRUCTIONS FOR MT/AMT ............................................................. 2
INITIALIZING THE CALIBRATION CACHE............................................................. 3
STARTING A CALIBRATION ................................................................................. 5
AUTOMATIC CALIBRATION ................................................................................ 6
STOPPING A CALIBRATION WHILE IN PROGRESS ................................................ 9
SYSTEM CHECK ................................................................................................ 9
QUALITIES OF A GOOD CALIBRATION .............................................................. 11
QUESTIONABLE CALIBRATIONS ....................................................................... 11
6.2 SYNCHRONIZING TIMING CIRCUITS............................. 14
FREQUENCY ADJUST AND SYNCHRONIZING OPERATIONS ................................. 14
SYNCHRONIZING THE TRANSMITTER AND RECEIVER ......................................... 17
MANUALLY TRIM THE XMT............................................................................. 20
LOSING SYNCHRONIZATION............................................................................. 21
SYNCHRONIZING MULTIPLE RECEIVERS WITH THE MULTI/SY-16 SYNC. BOX:23
SYNCHRONIZING MULTIPLE RECEIVERS WITH THE MULT/SY-32 SYNC. BOX:.25
SYNCHRONIZING AN ADDITIONAL XMT-32 (MULTI/SY-16)............................ 26
6.3 MEASURING CONTACT RESISTANCE ............................ 27
6.4 SETTING THE POWERLINE NOTCH FILTER................ 28
6.5 GAINS ........................................................................................ 29
HOW GAINS ARE DEFINED .............................................................................. 29
GAIN-SETTING STRATEGY ............................................................................... 29
SETTING GAINS .............................................................................................. 30
OPTION 1 – FULLY AUTOMATIC GAIN-SETTING ............................................ 33
OPTION 2 – AUTOMATIC GAIN SETTING........................................................ 34
OPTION 3 – MANUAL GAIN SETTING ............................................................ 34
OPTION 4 – CLEARING GAINS AND SP.......................................................... 36
OPTION 5 – ADJUSTING SP OFFSET............................................................. 36
OPTION 6 – NOISY/STANDARD GAIN MODE .................................................. 36
OPTION 7 – SET NUMBER OF REPEATS .......................................................... 37
OPTION 8 – TURN ON G0 GAIN CALCULATION............................................... 37
6.6 BITS OF RESOLUTION ......................................................... 38

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 2
6.1 CALIBRATION
Calibration routines are generic for all Field Survey Programs. Calibrations are initiated from
each Survey Program’s Data Acquisition Screen. Calibration data are stored in the survey
program’s calibration cache and automatically applied to all acquired survey data.
Calibrations are made for two reasons:
 To remove amplitude change and phase shift from the measured results due to anti-alias
and powerline notch filters.
 To correct for gain differences between channels.
With frequency domain signals, amplitude and phase variations due to filters are removed by
dividing field voltages by the normalized calibration magnitude then subtracting calibration
phase from measured field phase. This is done on a frequency-by-frequency basis.
For time domain signals, only the amplitudes are corrected for filtering distortion.
In the field, calibration should be done at the operator’s convenience; one calibration every few
days is usually sufficient, with daily system checks over the frequency range of interest. An
average calibration takes about 15 minutes.
When in doubt, recalibrate, except when having problems with the receiver. Recalibrating a
malfunctioning analog card may tend to compensate for some problems and make it difficult to
diagnose the problem in the field.
NOTE: A single calibration for each Field Survey Program (e.g. RPIP) is stored in memory at
any one time. When performing a calibration, the calibration data is automatically stored in
memory. This overwrites all previous calibration data for that Field Survey Program and any
other Survey calibrations stored in the same calibration cache.
If the data are not to be corrected for calibration, the Calibration Cache must be initialized. For
instructions on initializing see below.
SPECIAL INSTRUCTIONS FOR MT/AMT
Calibrations for the present version of the MT/AMT program require the following:
The hard disk must be turned off. This is done in the initial program screen for the MT/AMT
program.
For a full frequency calibrate (low band to very high band) start the calibration at the 5th level of
decimation in the low band (0.1875-4Hz).
These conditions must be set up before the calibration routine is entered.

RECEIVER SETUP
Section 6, Page 3 May 2002
INITIALIZING THE CALIBRATION CACHE
It is good field practice to initialize the Survey Program Calibration Cache before performing a
calibration. This avoids confusion about the most recent calibration.
For example:
 Yesterday, a calibration was run from 0.125 to 8192 Hz.
 Today, a calibration was run from 1 to 8192 Hz.
 Today’s calibration from 1 to 8192 Hz data is current (since the most previous calibration
data will overwrite previous values at those frequencies); however, the old 0.125 to 0.5
Hz calibration data remains in the cache. This problem can be avoided by performing
each calibration over the same frequency range.
To initialize the Calibration Cache:
1. Press to enter Data Mode.
2. Press Escape to bring up the Field Data Menu.
3. Press Escape a second time to bring up the Cache Utilities Menu.
4. Press , “Initialize Cache”.
VER 320 Main Menu
Current:Field Data Remaining:3388KB
Parallel Port Disabled
1) Access Cache
2) Initialize Cache
3) Configure Serial Port
4) Set Parallel Port Mode
5) Memory Diagnostics
6) Rebuild Cache Index
(Press 1 – 6, ESCAPE):

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 4
5. Select the survey program calibration cache to be initialized.
6. The following warning appears:
7. Press Enter .
8. The survey program calibration cache is now empty. Press Enter
VER 320
Current:Field Data Remaining:3388KB
WARNING: The contents of this calibrate
Cache will be INITIALIZED
To proceed, press Continue
To abort, press Escape

RECEIVER SETUP
Section 6, Page 5 May 2002
STARTING A CALIBRATION
NOTE: A summary of the Calibration procedure is located in the Section 4 - Quick Start.
From the Program Menu, select the Survey Program to calibrate. Proceed to the Data
Acquisition Screen. Select the lowest frequency, cycles and the notch filter.
NOTE: The notch filter to be used for the survey must be selected before starting the calibration.
Perform the calibration using that filter setting, and then acquire the field data with the same
filter setting. If a different setting is required, either recalibrate at the new filter setting, or input
new calibrations into the GDP-32II using a calibration data set stored previously on a field
computer.
Press to enter Calibration mode. The following message appears:
Only the first option performs an automatic calibration and loads the results into the Calibration
and Field Data caches. The second and third options are system checks, useful for checking
calibrations and general machine operation. Data from system checks are automatically stored in
the Field Data cache.
0151 RPIP0613 11.7 26 Jan 00 20:31:58
Survey D-D
Tx 1Rx 700N 60, 5
1 Hz 16 Cycles Tx Curr 8
1) Create new calibrate records
2) System check
3) Auto system check
4) Set calibrate voltage
(Press 1 – 4, ESCAPE):

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 6
AUTOMATIC CALIBRATION
Ensure that the starting frequency is set at
the desired values for the calibration. The
calibration can be started at any frequency.
Zonge recommends beginning the
calibration at the lowest survey frequency
to be used. The purpose of the calibration
is to remove the effects of filtering, stray
capacitance and inductance in the system.
Press to begin automatic
calibration. Below the Data Acquisition
Screen the following warning is displayed:
This warning underscores the fact that
previous calibration data will be
overwritten. Press Escape to return to the
Data Acquisition Screen.
Press Enter to complete the calibration.
The following message appears:
These options select how to route the
calibration signal to the analog boards.
The INTERNAL option routes the signal
from the Calibration Board to the analog
boards via internal wiring. The
EXTERNAL option routes a calibration
signal of known voltage amplitude to the
output jacks of the Analog I/O Panel.
Jumper wires are required to patch the
signal from these jacks to the signal input
jacks located on the Analog I/O Panel, the
Patch Panel, (See Figure 6.1) and any
amplifiers or other external devices in the
signal stream.
0151 RPIP0613 11.7 26 Jan 00 20:32:16
Survey D-D
Tx 1Rx 700N 60, 5
1 Hz 16 Cycles Tx Curr 8
This will destroy previous calibrates.
CONTINUE to proceed, ESCAPE to abort.
0151 RPIP0613 11.7 26 Jan 00 20:32:46
Survey D-D
Tx 1Rx 700N 60, 5
1 Hz 16 Cycles Tx Curr 8
1) Internal
2) External
(Press 1 – 2, ESCAPE):

RECEIVER SETUP
Section 6, Page 7 May 2002
Figure 6.1 - Wiring for an external calibration – large case with Patch Panel using an isolation
amplifier on the reference channel.
Use an internal calibration for standard operations. Use an external calibration if there are active
auxiliary electronics such as preamplifiers or isolation amplifiers whose effects must be included
in the calibration, or if the analog input section needs to be checked.
After selecting an internal or external signal source, the cursor goes to the end of the third line on
the display, where the display reads:
ICal = 1v
This is the “calibration signal voltage” (i.e. the amplitude of the voltage signal that is supplied by
the Calibration Board for calibration.) The default selection amplitude is 1 volt. Generally
speaking, there will be no need to change it. The Instruction line displays:
Change Calibration voltage or press
CONTINUE to proceed, ESCAPE to abort.
Escape exits the calibration mode and returns to the Data Acquisition Screen.
Enter begins an automatic calibration. Press Enter . The Instruction Line reads:
CONT when gains are set, ESCAPE to exit.
1 2 3 4 5 6 7 8
PATCH PANEL
ANALOG I/O PANEL
GND CASE
INPUT
CHANNELS 1-6
ANALOG I/O
ISO/I Isolation
Amplifier
CALIBRATOR
CAL+ CAL- COM CASE
GND
CH1
++++ +
CH2 CH3 CH4
-
+
-
+
-
--- -
CH5 CH6
-

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 8
The program pauses here to permit the operator to manually set the gains, if desired. Press
Enter to use the default gains, or change gains (see Section 6.5 below) and then press
Enter .
The GDP-32II begins the calibration at the starting frequency specified in the Data Acquisition
Screen. The message:
Taking Data
is displayed at the bottom of the screen. When the first stack is complete, the message:
Processing
appears and the screen displays the un-normalized results. However, these results are quickly
erased. Review the data in Data Mode after the calibration. The internal beeper sounds an alert
at the completion of the calibration of the first frequency. The receiver then:
 Increments the frequency by a factor of two
 Increments the cycles by a factor of two
 Performs a calibration at the new frequency
 Displays the results
This process is repeated until the maximum frequency has been calibrated. The program then
returns to the starting frequency and exits the automatic calibration mode.
Zonge recommends immediately performing a system check (see Section 6, page 10) at any
frequency to spot-check the automatic calibration.

RECEIVER SETUP
Section 6, Page 9 May 2002
STOPPING A CALIBRATION WHILE IN PROGRESS
NOTE: To avoid confusion, Zonge strongly recommends that the entire calibration be
performed in one continuous sequence, rather than in segments. If a problem arises that
requires the calibration to be prematurely aborted, it is recommended that the entire sequence
be repeated after resolving the issue.
At times it may be necessary to stop the calibration process (i.e. to change the number of cycles).
To stop the calibration process, press Escape . The Instruction Line now displays:
Exit autocal mode? (1 - yes,2-no)
Press to exit. Press to change parameters. Upon pressing the
Instruction Line displays:
Press CONTINUE when values are correct
The cursor appears in the “cycles” field of the Data Acquisition Screen. After changing
parameters, press Enter to resume the calibration.
To view calibrates, see section 7.3 for instructions about how to access board calibrate caches.
Calibrations are written to the Field Data cache as well as the Calibration cache so that there is a
permanent record of the calibration values. Access the Calibration cache of interest and you will
notice that the date, time and condition of the power line notch filter at the time of the calibration
are all recorded in the Calibration header.
SYSTEM CHECK
NOTE: A summary of the System Check procedure is located in the Quick Start Section.
Perform a system check to check the quality of a calibration. This process is similar to a system
calibration except that the results are NOT stored in a Calibration buffer, only in the Field Data
buffer. Calibration corrections are applied to the results, which are then displayed to the screen.
Hence, the system check is a good way to look at the quality of a calibration. The ideal result in
phase should be zero milliradians.
Following is a typical reason for using the system check utility:
Assume that three-frequency RPIP data are being acquired, and late in the day you discover that
the phase data all decrease suspiciously at the high frequency. A bad calibration or a receiver
problem is possible and can be quickly confirmed or rejected by doing a system check at the
suspect frequencies. If the phase differences in the decalibrated system check display are zero or
nearly zero, the present calibration is the same as the earlier one. So long as the calibration
procedure is correct and the calibration agrees with earlier calibrations, the explanation for the
problem must be found elsewhere (i.e. faulty analog card, field wire problem, etc.).
1. Set the frequency value to check (e.g. 0.125 Hz)
2. From a survey program’s Data Acquisition screen, press . Select the Calibrate or
the System Check Mode.

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 10
3. To check the calibration for a single
frequency, select , “System
check” from the Calibration Screen.
The system check is performed one
frequency at a time. After each
check, the operator has the option
of continuing or exiting. Before
continuing, the frequency must be
incremented manually.
NOTE: When checking multiple
frequencies select option
,“Auto System Check”.
4. Press for “Internal” voltage
source.
5. Press Enter to set the default
calibration voltage (ISys=1v.)
6. Press Enter to begin data acquisition. If this is the first time data have been acquired at
this frequency, the automatic gain adjust program takes over. Watch the screen to see
how it adjusts the gains. The program goes directly from automatic gain setting to data
acquisition.
7. The GDP-32II receiver:
 Stacks and averages the calibration signal
 Calculates a standard error of the mean (SEM) on the real- time parameter displayed
 Calculates the resistivity and IP parameters, displays them, and asks if you want to
save or discard your data.
8. Press Enter to store the data in the Field Data cache, or press to discard the
data.
9. Press or Enter to stay in the System Check mode, or press to exit.
0151 RPIP0613 11.7 26 Jan 00 20:31:50
Survey D-D
Tx 1Rx 700N 60, 5
1 Hz 16 Cycles Tx Curr 8
1) Create new calibrate records
2) System check
3) Auto system check
4) Set calibrate voltage
(Press 1 – 4, ESCAPE):