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):

RECEIVER SETUP
Section 6, Page 11 May 2002
QUALITIES OF A GOOD CALIBRATION
Since all data will be normalized by the system calibration, it is important to ensure that the
calibration is reasonable immediately after it is acquired. (All calibrations are written to
memory. If the operator does not verify the calibrations, a bad calibration can be replaced later
during data processing; but it's always better to catch the problem in the field.)
Table 6.1 (below) lists values from a typical RPIP calibration. Remember calibrations
incorporate the electronic characteristics of each individual receiver, so the numbers may vary
depending upon the filters and other components in a particular receiver.
The magnitudes in the Calibration Cache will differ from the magnitudes shown on the display
while the calibration is in progress. This is because the initial magnitudes are raw values, while
the values stored in the caches have been normalized to the calibration voltage and have been
corrected for any gain differences in the individual channels.
QUESTIONABLE CALIBRATIONS
If a calibration differs significantly from a known, correct value for a particular instrument, and
that difference cannot be due to recent hardware modifications, there may be a system problem.
Consult Section 15 - Maintenance for trouble-shooting. Otherwise, an error may have been
made in the calibration set-up. Re-check the set-up procedure. Common errors include:
 Incorrect wiring to the input channels for an external calibration.
 Checking the calibrations using a notch filter setting different from the calibration setting.
If a bad calibration is discovered before any data is taken, simply re-run the calibration. This
replaces the old values with the new ones. Either erase (initialize) the old calibration first or run
the new calibration at the same frequencies. This avoids the problem of combining old
calibration data with new.
If an invalid calibration is discovered after taking data, the data can be saved.
1. Dump the bad calibration file into a file on a personal computer (See Section 7.6).
2. Recalibrate the receiver, and dump this file to the personal computer (See Sections 6.1,
7.6).
3. Process the data through the Zonge SHRED program, and provide both the good and bad
calibration files. SHRED will remove the bad calibration and renormalize the data with
the good calibration.

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 12
Table 6.1 - Examples of Good RPIP Calibration Values
Note: Values vary from board to board, depending upon components and filters. Magnitudes
are normalized to the magnitude at the lowest calibration frequency; phases are in milliradians.
NOTCH FILTER SELECTION
Frequency None 60/180 Hz 50/150 Hz 50/60 Hz
(Hz) Mag Phase Mag Phase Mag Phase Mag Phase
8192 .14 1370 .14 1347 .14 1347 .14 1322
4096 .40 2792 .40 2789 .40 2787 .40 2783
2048 .59 -2597 .59 -2581 .60 -2585 .60 -2570
1024 .60 -2469 .59 -2426 .60 -2434 .60 -2392
512 .82 -1557 .81 -1460 .82 -1479 .82 -1381
256 .83 -1536 .78 -1229 .81 -1327 .78 -1019
128 .86 -1389 .81 -1551 .72 -1862 .68 -2024
64 .86 -1384 .46 -508 .79 -1114 .45 -239
32 .97 -697 .95 -878 .94 -954 .93 -1136
16 1.00 -349 .99 -423 .99 -451 .99 -515
8 1.00 -174 1.00 -210 1.00 -218 1.00 -254
4 1.00 -174 1.00 -192 1.00 -196 1.00 -213
2 1.00 -181 1.00 -190 1.00 -192 1.00 -201
1 1.00 -181 1.00 -184 1.00 -186 1.00 -190
.5 1.00 -90 1.00 -92 1.00 -93 1.00 -95
.25 1.00 -90 1.00 -91 1.00 -92 1.00 -93
.125 1.00 -90 1.00 -91 1.00 -92 1.00 -92

RECEIVER SETUP
Section 6, Page 13 May 2002
Figure 6.2 - Pictorial description of the Frequency Adjustment and Synchronizing operations.
a)
fRX
fTX
ff
RX TX c)
fRX
fTX b)
fRX fTX
0
Initial State:
signal frequency from
receiver and controller
crystals are different
After Triming Oscillator:
signal frequencies are
now the same but are
out of Phase by
After Pressing RESET
on XMT:
receiver and controller divider
chains are now at same
frequency and in phase
synchronization
XMT
Transmitter
Controller
Receiver

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 14
6.2 SYNCHRONIZING TIMING CIRCUITS
FREQUENCY ADJUST AND SYNCHRONIZING OPERATIONS
The timing circuits of the XMT-32 and the GDP-32II are comprised of an ultra-stabilized
4.980736 MHz oscillator and a digital counter chain providing a binary sequence of frequency
divisions. Frequencies on the XMT-32 Transmitter Controller are selectable from a push-button
panel switch. Frequencies on the GDP are selectable from a menu screen under the control of
the on-board computer.
To ensure that the timing edge of the transmitter controller (i.e. the transmitter output) and the
receiver waveforms coincide exactly throughout the day, two adjustments must be made:
 First, the two 4.980736 MHz crystals must be adjusted to EXACTLY the same frequency
to prevent the phase drift.
 Second, the counter chains in the XMT-32 and GDP-32II must be reset so that the
switching edges of both occur simultaneously (i.e. the waveforms are synchronized.)
The GDP uses the counter waveform to determine the polarity of the transmitted waveform and
the on/off cycle in the case of time domain. Both of these adjustments require that the
synchronization cable be connected between the XMT-32 and GDP-32II.
The synchronization cable connects the GDP-32II’s 4.980736 MHz oscillator output to the XMT-
32 phase detector. The detector displays the frequency difference between the two oscillators on
the XMT-32 phase meter. Each complete swing of the meter represents one cycle of 4.980736
MHz or 0.2 microseconds (µsec) of time shift.
The following table shows the phase shift in milliradians (mr) per meter swing that occur at
various frequencies, where:
Period = 1/Frequency
Period/mr = Period/(6.283*1000)
Freq Period Period/mr mr/swing
8192 Hz 122.0µ
µµ
µsec 0.019µ
µµ
µsec/mr 10.5mr/swing
512 1953.0 0.31 0.62
64 15.6msec 2.5 0.08
8 125.0 19.9 0.01
1 1.0sec 159.0 0.00125
0.125 8.0 1.3 msec/mr 0.00016
The above list shows the importance of accurate frequency adjustments for the acquisition of
accurate high frequency phase measurements. The frequency match is obtained by performing a
Frequency Adjustment as outlined in the section below. Typically, the frequency should be
adjusted so that meter drift is less than one division over a 30 second interval. Drift rates of this
magnitude yield phase drifts of less than one hundredth of the above values.
The synchronization cable also connects and enables the counter chain reset circuitry in both the
GDP-32II and XMT-32.
Refer to Figure 6.3 and 6.4a,b for a pictorial description of the frequency adjust and
synchronization operations.

RECEIVER SETUP
Section 6, Page 15 May 2002
Figure 6.3 – Connecting the GDP-32II Receiver and XMT-32 Transmitter Controller for
synchronization.
DOWN
XMT-32
TRANSMITTERCONTROLLER
BATT
PHASE
100%
RESET
TIMES
SERIES
MANUAL
MODEUPDOWN
OFF
ON
OSC
TRIM
BATT
50%
250mV
2.5V
25mV
CAL
I/O

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 16
Figure 6.4(a) - Wiring for verifying synchronization to a small case GDP-32II.
Figure 6.4(b) - Wiring for verifying synchronization to a large case GDP-32II.
+
ANALOG I/O PANEL
TRANSMITTER CONTROLLER
CAL
INPUT
CHANNELS 1-6
ANALOG I/O
CALIBRATOR
CAL+ CAL- COM
CASE
GND
CH1
++++ +
CH2 CH3 CH4
-
+
-
+
-
--- -
CH5 CH6
-+
+
CH 3
+
CH 1
CAL+ CAL- COM GND
CASE
+
CH 2
+
CH 4
INPUT
CHANNELS 9-16
INPUT
CHANNELS 1-8
CALIBRATOR
ANALOG I/O
CAL
TRANSMITTER CONTROLLER

RECEIVER SETUP
Section 6, Page 17 May 2002
SYNCHRONIZING THE TRANSMITTER AND RECEIVER
The GDP-32II receiver and XMT-32 Transmitter Controller have identical crystal oscillators and
circuitry for dividing the crystal frequency into a set of precise, selectable, operational
frequencies. For synchronous operation, the two oscillators must be equal in frequency to
provide an absolute phase reference.
NOTE: For surveys such as complex resistivity (CR), roll-along IP, and NanoTEM where the
receiver is linked to the transmitter directly, synchronization is not required. The receiver clock
controls both the transmitter and the receiver.
At least one hour prior to adjusting the frequency:
1. Press the Power On/Off Button on left side panel of the GDP-32II to apply power to the
crystal oscillator. Make sure that the red LED marked CRYSTAL ON is illuminated.
2. Turn the XMT-32 Power Switch to ON.
NOTE: During continuous field operations, power to either the GDP-32II or the XMT-32
crystals should rarely be turned off. Crystals can remain on during charging. This practice
eliminates the wait for the crystal ovens to warm.
NOTE: Before using the “Synchronize to XMT” routine or the manual synchronization routine,
make sure you have a good calibration for the RPIP exists (FDCALS in the CALIBRATION
cache) as that program is used in the synchronization routine.
After the crystal ovens have heated for at least 60 minutes:
1. Disconnect the Battery Charger.
2. Connect the synchronization cable between the I/O port on the XMT-32 Transmitter
Controller and the TRANSMITTER I/O port on the Control I/O panel of the GDP-32II
receiver (Figure 6.3.)
3. Switch the PHASE/BATT switch to the BATT position to check the transmitter
controller battery voltage. The voltage should read at least 12.5 volts. If lower, there is
either a poorly charged battery or a problem with the power system (see Section 15 -
Maintenance.)
4. Switch the PHASE/BATT switch to the PHASE position. Observe the needle on the
PHASE/BATT analog meter. Any needle movement indicates that some frequency
difference exists between the GDP-32II and the XMT-32 oscillators.
The faster the needle is swinging, the greater the frequency difference. If there is
absolutely no swinging over a period of a minute, the oscillators are either adjusted to the
exact same frequency (skip to step 10), or the oscillators are very different in frequency
and the resultant beat frequency is beyond the response of the meter (see Section 6 to
manually trim the XMT-32).
Frequency adjustment and synchronization are accomplished with the GDP-32II by
executing the “Synchronize to XMT” function (Utilities Menu - Option 4.)
5. Follow the directions given on the screen:

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 18
6. Press Enter .
7. Continue to follow screen
instructions for external
connections: (see Figure 6.4)
8. Press Enter when the connections
have been completed.
ZONGE ENGINEERING 11.8 04 Jan 18 16:38:23
GDP32II320
Turn on XMT and GDP. Then wait 1 hour.
Set XMT to 1 Hz
and 100% DUTY CYCLE.
ZONGE ENGINEERING 11.0 04 Jan 18 16:38:37
GDP32II320
Connect sync cable between XMT and GDP.
Connect calibrate output of XMT to CH 2
(RED to RED, BLACK to BLACK)
Connect CAL output of GDP to CH 1
(Cal+ to RED, Cal- to BLACK)
Set meter switches in lid of GDP to
Monitor Channels 1 and 2.
CONTINUE: Next menu, ESCAPE: Prev. menu

RECEIVER SETUP
Section 6, Page 19 May 2002
0575 SYNC0537 11.7 04 Jan 18 16:39:06
Tx 2 Rx 3 N OUT Esys 0.35 v
1 Hz 00008 Cycles Tx Curr 1
Adjust crystal using SELECT UP/SELECT
DOWN for coarse, UP/DOWN ARROW for
medium, and PREV/NEXT FIELD for fine
adjust until phase meter needle stops
completely. Then press RESET on XMT.
Both meters should deflect to right.
CONTINUE to acquire phase data
ESCAPE to exit
CONT-Take data, ESC-Prev Menu
9. To electronically adjust the crystal frequency of the GDP-32II to match that of the XMT-
32 use the cursor control keys and follow the instructions on the display:
While adjusting the frequency of
either instrument, the XMT-32
phase meter needle should come to
rest near the center of the meter,
where it is most sensitive to
movement. Use the cursor control
keys to adjust the frequency up or
down slightly until the needle
roughly stabilizes near the center of
the scale.
10. Press RESET on the XMT-32 to
synchronize the counter chains of
the two instruments. RESET places
the counters in both instruments in
the reset mode with the needles on
the analog meters steady and
deflected towards the right. When
RESET is released, both counters
simultaneously start to count,
thereby providing synchronized
frequency waveforms that can be
selected from the GDP-32II and
XMT-32.
11. Press Enter . The GDP-32II automatically measures the phase difference between the
external calibration signal generated by the GDP-32II and the corresponding signal
generated by the XMT-32. If the two instruments have been properly synchronized, the
measured phase difference is close to 0.0 mr.
12. Repeat step 11 several times to check the synchronization. The measured phase
difference should remain close to 0.0 mr.
13. Ensure that synchronization can be maintained without the synchronization cable. First,
disconnect the cable from the XMT-32, then from the GDP-32II, then repeating the phase
measurement.

GDP-32II INSTRUCTION MANUAL
May 2002 Section 6, Page 20
MANUALLY TRIM THE XMT
In extreme cases, the frequency difference between the two oscillators is too large to adjust out
electronically. In this case, manually trim the oscillator on the XMT-32 using a plastic trimming
tool or a small, insulated, flat-bladed screwdriver.
NOTE: The GDP-32II crystal adjustment potentiometer is not externally accessible. It is
unlikely that a customer would need to trim both oscillators.
There are approximately 70 coarse divisions for crystal adjustment of the GDP-32II. Before
adjusting the trim pot in the XMT-32, set the coarse adjustment on the GDP-32II to mid-range
using the following procedure:
Set the Crystal adjustment on the GDP-32II to Mid-Range:
1. Hold down one of the coarse adjustment keys ( Home
SELECT UP
or
SELECT DN
End ) until a rapid beep is
heard.
2. Press the opposite button ( Home
SELECT UP
or
SELECT DN
End ) 35 times (35 beeps) to set the coarse
adjustment to mid-range.
Manually trim the oscillator in the XMT-32:
1. Locate the OSC TRIM potentiometer adjustment screw on the panel of the XMT-32
(Figure 6.3.)
2. Make sure the meter function switch is in the PHASE position.
3. Using a plastic adjustment tool, turn the trim pot screw slowly in one direction and
observe the response on the XMT-32 meter.
4. If the needle motion slows down, the screw is being turned in the correct direction. If it
speeds up, turn it the other direction. Keep turning the screw until the needle movement
comes to a stop near the center of the meter.
5. Use the cursor control keys to adjust the frequency up or down slightly until the needle
roughly stabilizes near the center of the scale.
6. Using the fine adjustments on the GDP-32II, trim the frequency until the meter movement
halts. The oscillator is properly adjusted if the needle drifts less than the distance
between two meter marks over a 30 second interval.
7. If the PHASE needle does not stop after setting the crystal adjustment on the GDP-32II to
mid-range and manually trimming the XMT-32 oscillator, it is necessary to adjust the
crystals in either the GDP-32II or XMT-32. Consult Zonge Engineering before
attempting this procedure.