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GDP-3224 October 2014
9. TIME DOMAIN INDUCED POLARIZATION
PROGRAM (TDIP)
9.1 INTRODUCTION .................................................................... 3
9.2 FIXED FUNCTION KEYS ...................................................... 4
9.3 TDIP PROGRAM OPERATION ........................................... 5
MAIN DISPLAY: ................................................................................................5
HEADER ......................................................................................................7
FOOTER ......................................................................................................8
LINE SETUP ................................................................................................8
ACQUISITION CONFIGURATION ..........................................................10
CHANNEL TABLE ...........................................................................................12
SOFT FUNCTION KEYS .................................................................................13
ARCHIVE SUBMENU ............................................................................14
SCREEN: CHANNEL TABLE DISPLAY SCREENS ...............................15
SCREEN: SETUP .......................................................................................15
SCREEN: GAIN/CRES ...............................................................................17
SCREEN: RESULTS ..................................................................................18
SCREEN: STACKS .....................................................................................19
SCREEN: XYZ EDIT ..................................................................................20
JOB_INFO SUBMENU ..........................................................................22
RESET FUNCTIONS ..............................................................................23
SCOPE FUNCTION ...............................................................................25
9.4 BOARD CALIBRATION SUBMENU ................................. 26
9.5 GATHERING DATA ............................................................. 31
PROGRAM START UP ....................................................................................31
DATA ACQUISITION ......................................................................................31
STOP ACQUISITION.......................................................................................32
ACQUISITION ERRORS .................................................................................32
9.6 VIEWING DATA ................................................................... 32
9.7 CACHE FILE ......................................................................... 38
9.8 A NOTE ON AUTOMATIC LOCATION UPDATES ........ 40
RST_OFSET EXAMPLE ..................................................................................42
RST_N-SPC EXAMPLE ...................................................................................47
9.9 A NOTE ON SCALING ......................................................... 54
9.10 ALGORITHMS ...................................................................... 55
TIME DOMAIN WINDOW TIMING INFORMATION ...............................56
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 2 October 2014
9.11 SAMPLE MENUS FOR "LABROX" ARRAY ................... 57
9.12 NOTES ON FIELD CONFIGURATIONS .......................... 58
9.13 FIELD CONFIGURATIONS ................................................ 59
GDP AS TRANSMITTER CONTROLLER WITH REFERENCE RECORDING ...................59
GDP SETUP FOR RESISTIVITY, TDIP, RPIP, NRCR .............................................62
GDP SETUP WITH ROLL-ALONG CABLE: RESISTIVITY, TDIP, RPIP, NRCR ..........63
TRANSMITTER SETUP: TDIP, RPIP, NRCR..........................................................64
TRANSMITTER SETUP WITH CURRENT REFERENCE ..............................................65
RECEIVER SETUP WITH CURRENT REFERENCE ....................................................66
LABORATORY ROCK MEASUREMENT SETUP .........................................................67
ALTERNATE LABORATORY ROCK MEASUREMENT SETUP .......................................68
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 3 GDP-3224
9.1 INTRODUCTION
This Time Domain Induced Polarization (TDIP) program uses standard phase-lock stacking and
averaging for field and laboratory multifrequency IP measurements. This is an enhanced
program using synchronous stacking and averaging to improve the signal to noise ratio.
The frequency range of the TDIP program is from 0.015625 to 32 Hz. TDIP measurements are
commonly made using the fundamental frequencies of 0.125, 1.0, and 8 Hz.
Available channel designations include: Ex, Ey, Ez, and Ref (for current referenced TDIP).
New to the GDP-3224
, the electrode locations can now be described in 3 dimensions, simplifying
the description of special case field conditions, and improving the calculation of apparent
resistivity for those conditions.
X Station distance along line.
Y Station distance across line.
Z Station distance below surface.
Apparent Resistivity (Rho) calculations, both in the GDP and in Post Processing, use a general
equation based on the transmitter and receiver electrode locations, and are no longer based on
N-values. This general equation for Rho is used for all ARRAY types except for laboratory rock
measurements. N-values are used only to help operators accustomed to the GDP-32II, in entering
and verifying the values that describe the actual survey setup. Electrode Offset distance from the
receiver, new to the CR and TDIP programs for the GDP-3224
, can also be used to describe the
survey setup. Use of Offset can simplify data entry when moving transmitter electrodes or the
receiver, especially for operators new to geophysical surveying.
The standard board calibrate buffer is saved as 24BOARD.CAL on the GDP C:\ drive. Board
calibration data can be viewed in the Calibration submenu of the TDIP program. If no calibrate
files are found, empty files are created and factors of 1.0 mag and 0.0 phase are assumed.
All selectable fields can be modified using and . Numeric fields can be
incremented or decremented using the same keys. Some numeric fields, such as Gain/Atn can
only be modified to allowable values by using these keys.
Pressing quickly moves the cursor around the various areas of interest for the main menu
screen and some submenus in all programs.
Section 6 describes calibration, synchronization and generic program operation.
At the end of this TDIP program manual are several setup diagrams for field measurements.
Note: Some numeric or alphanumeric values are not registered in the GDP memory until you
exit the parameter field by pressing , , or . Exceptions are the frequency
and the powerline notch filters. Whenever the frequency is changed, the sample rate is
automatically changed through the timing card, but the anti-alias filter is not changed until just
prior to data acquisition. Pressing to gather data, the receiver will automatically set the
anti-alias filter as defined by internal look-up tables.
Home
SELECT UP SELECT DN
End
Pg Up
PREV FIELD
Pg Dn
NEXT FIELD
Enter
Enter
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 4 October 2014
9.2 FIXED FUNCTION KEYS
Six fixed function keys are located below the six soft function keys ( through ) at
the bottom edge of the LCD.
Enter the cache viewer. Data can be viewed as time-series or apparent resistivity
plots vs. frequency.
Exits the TDIP program and return to the main menu for selection of other data
acquisition programs. The key can also be used to exit submenus of the program.
Enter the calibrate and system checking submenu. See the Calibrate section of
this manual as well as GDP Section 6.1, Calibration for more details.
Perform a one-time gaining of the channels that are currently On and for the
current selected frequency (FREQ). (This key has no function in older versions of
this program.)
Perform a one-time buck out of any self-potential (SP) or amplifier offset, for all
the channels that are currently On. (This key has no function in older versions of
this program.)
Measure the contact resistance or coil output resistance.
See GDP Section 6.3, Measuring Contact Resistance for more details.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 5 GDP-3224
9.3 TDIP PROGRAM OPERATION
One of the differences between the GDP-3224
and its predecessor the GDP-32II is that there is no
longer a menu structure at the start of each acquisition program. Each program will now start in
the main user interface menu. There are submenus that the operator may use to enter program
specific entries. These submenus vary between the different programs. Instead of cumbersome
menu levels which force a sequence of data entry, the operator can use the following guideline:
1. Start by filling in the parameters in the JOB_INFO submenu.
2. Back on the Main Menu, set ARRAY type, A-SPACE, S_SPACE and other Line Setup
parameters. Press , RST_TX, to initialize default values based on these settings.
3. Configure the channels in the Channel Table using , RST_OFSET or RST_N-
SPC, to configure automatic location updates for the survey.
4. Set Acquisition Configuration parameters.
5. Acquire data.
6. Review the data, and finally,
7. Archive the data cache file.
These steps are all accessed from the Main Menu, and its various screens and submenus, as
described in this manual.
Note: The order of these steps is not required, however due to some features of the program,
changing some fields can cause other fields to be updated. This can cause some values,
particularly in the Channel Table, to be modified after the user has already set them.
MAIN DISPLAY:
The screen provides 80 characters on 30 lines. The entire screen is visible on the Color display.
However, 60 characters on 20 lines are visible on the Monochrome display. Use the key
and one of the quadrant keys to shift the display to another area:
+
For example, shift the display down by using , and back up with .
Only the first diagram below shows the entire screen. MOST OF THE OTHER SCREENS IN
THIS MANUAL DISPLAY ONLY 60 characters BY 20 lines.
The TDIP Main Menu has three areas for data entry: Line Setup, Acquisition Configuration, and
the Channel Table. A Header line shows current conditions and a Footer area shows status and
messages. Below this, the lower left screen shift area holds historical Error and Warning
Home
SELECT UP
Pg Up
PREV FIELD
SELECT DN
End Pg Dn
NEXT FIELD
SELECT DN
End Home
SELECT UP
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 6 October 2014
messages. These are generally common with all the GDP programs. The key moves the
cursor directly to some of the main input areas of the display.
<0903a_24TDIP_MainAreas>
Full display screen showing defined areas.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 7 GDP-3224
<0903a_24TDIP_MainAreas>
Display showing 60 characters and 20 lines. (the colors are for this illustration only)
AREAS COMMON TO ALL PROGRAMS
HEADER
The Header line contains the following information:
0 Block number.
TDIP_1.37j Program name and version.
BAT 14.3 Battery Level in Volts.
Sats 0 Number of GPS satellites (when GPS sync option is available).
21 Jul 2014 Date.
14:28:46 Time (Hours Minutes, Seconds).
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 8 October 2014
FOOTER
The Footer area contains several lines of information: The STATUS: line Indicates the general
status of the program or progress during data acquisition. Below this is a Help line that displays
warnings, acquisition progress steps, and requests operator confirmation or input. The third line
acts as labels for the soft function keys. These labels change depending on the SCREEN and
field that the cursor is in.
The last ten lines of the display are a history of messages, not generally visible in the small LCD
screens unless it is shifted by pressing . These historical messages are cleared at
the start of each new acquisition period.
LINE SETUP
The Line Setup area of the screen should be filled in before setting parameters in the Channel
Table. The information in this part of the screen can have an affect on how changes to other
fields are automatically updated, especially in the Channel Table. Many of these input fields are
seldom changed after a survey has started, therefore they are located in the lower half of the
screen. Though there is no required sequence for editing the input fields, it is suggested that
these fields be entered first. The following list of input fields is in the suggested order of data
entry.
TIME SERIES This setting determines if all the raw A-D readings should be written to
the cache as a time series, Yes or No. Writing the time series to the cache
significantly increases the size of the cache file. This option is set to No. for
normal operation. It is set to Yes for enhanced Post Processing, for analyzing
input signals or other diagnostic purposes.
Note: The GDP always collects the “time series”, a continuous stream of A-D readings for all
of the cycles, into a memory buffer for processing, regardless of this setting.
ARRAY Seven types of arrays are selectable with the or keys:
D-D Dipole-Dipole
P-D Pole-Dipole
P-P Pole-Pole
Sch Schlumberger
Grd Gradient
D-H Downhole
LAB Core Sample
Note: Different ARRAY types can require different Line Setup information, therefore as the
ARRAY type is changed, the input fields will change according to the type selected.
TX STN Informational, transmitter location identifier.
A-SPACE E-field dipole size in meters or feet (a-spacing). Notice that entering a value
in this field causes all the values in the Length column of Channel Table,
to be modified to match. Variable a-spacing can later be configured by
SELECT DN
End
Home
SELECT UP SELECT DN
End
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 9 GDP-3224
modifying values in the Length column of the Channel Table as discussed
later in this manual.
Ft / M Specifies units of length, Feet or Meters, for all length and space entries.
S-SPACE Station number space, or S-space (stn#), is a “unit dipole length” in whatever
units are to be used for TX and RX locations. This allows correct calculation
of apparent resistivity, Rho, when station numbers are not scaled to feet or
meters. A dipole's length can be calculated by the formula:
Length = (RX2 – RX1) * Aspace / Sspace
Note: ALL electrode locations for the transmitter TX, and receiver RX, must be entered in S-
space units. The Length displayed in the Channel Table will be in feet or meters for verification.
LINE Informative user defined alphanumeric identification that may be used in post
processing.
Direction Informative selection for line direction. Selections are: N, NE, E, SE, S, SW,
W, NW, DH (drill hole), SET (any user defined set).
X-AZ Informative azimuth of the X direction of the line (0 to +/-360).
SPREAD Informative 2-character user defined identification.
TX: AX Location, along line (X) of the lowest numbered electrode of the transmitter
dipole. The field for AX designation is NNNNNNN with a floating decimal
point.
TX: AY Location, grid line or across line distance (Y) of the lowest numbered
electrode of the transmitter dipole. The field for AY designation is
NNNNNNN with a floating decimal point.
TX: AZ Depth below surface (Z) of the lowest numbered electrode of the transmitter
dipole. The field for AZ designation is NNNNNNN with a floating decimal
point.
Note: The AZ field is only visible in the XYZ EDIT screen, but is always used in Rho
calculations.
TX: BX Location, along line (X) of the highest numbered electrode of the transmitter
dipole. The field for BX designation is NNNNNNN with a floating decimal
point.
TX: BY Location, grid line or across line distance (Y) of the highest numbered
electrode of the transmitter dipole. The field for BY designation is
NNNNNNN with a floating decimal point.
TX: BZ Depth below surface (Z) of the highest numbered electrode of the transmitter
dipole. The field for BZ designation is NNNNNNN with a floating decimal
point.
Note: The BZ field is only visible in the XYZ EDIT screen, but is always used in Rho
calculations.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 10 October 2014
RX0: RX Reference location, along line (X) of the receiver. The field for RX
designation is NNNNNNN with a floating decimal point.
Note: Positive channel electrode locations, RX1, are calculated as: RX1 = RX0:RX + Offset.
RX0: RY Reference location, grid line or across line distance (Y) of the receiver. The
field for RY designation is NNNNNNN with a floating decimal point.
RX0: RZ Reference depth below surface (Z) of the highest numbered electrode of the
transmitter dipole. The field for RZ designation is NNNNNNN with a
floating decimal point.
Note: The RZ field is only visible in the XYZ EDIT screen.
Note: The TX: AX, AY, AZ, BX, BY, and BZ ,locations are always used in Rho calculations.
They are also used to calculate RX1 and RX2 locations from N values, or the reverse. RX0: RX,
RY and RZ, are not use in Rho calculations. They are used to calculate RX1 and RX2 locations
from Offsets, or the reverse.
Note: Changes to any of the TX: and RX0 fields will cause RX1, RY1, RZ1, RX2, RY2 and RZ2
values in the Channel Table to be automatically updated. This feature is explained in more
detail later in this manual.
SAMPLE ID Informative field used for Lab Rocks testing (ARRAY Lab).
SAMPLE LEN The axial length of a rock specimen, in centimeters, for calculating
resistivity, used for Lab Rocks testing (ARRAY Lab).
SAMPLE AREA The cross sectional area of a rock specimen, in centimeters squared, for
calculating resistivity, used for Lab Rocks testing (ARRAY Lab) .
The fields visible in the Line Setup area of the screen change in response to the ARRAY type
selection.
ACQUISITION CONFIGURATION
The Acquisition Configuration area of the screen contains the following fields:
FREQ This selects the frequency to analyze. The selections increment in binary
steps from 0.016 to 32 Hz. When the CYCL count is a binary value,
adjusting the FREQ field up or down causes the cycles to automatically
change by the same factor. When CYCL is set to a non-binary value it
remains constant while the frequency is changed.
CYCL This field specifies the number of cycles to average. All data points will be
read in a continuous series without breaks. This value can be modified
directly to any value, or the and keys can be used to select
values from 1 up 16,384 in binary steps.
Note: While making selections to the FREQ, and CYCL, settings, the GDP will evaluate the
memory and flash disk space required, based on those settings, and number of on channels. If
the selected or entered values would cause the collected data to exceed available memory, based
on these settings the CYCL value will be reduced to a value that will allow maximum memory
Home
SELECT UP SELECT DN
End
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 11 GDP-3224
utilization. An audible warning will be given and the STATUS will indicate: “Cycles
Reduced, Not To Exceed Memory Limit”.
Note: This feature can be used to maximize the data collection capability of the GDP. The
operator can enter a CYCL value of 99999, and it will be adjusted to the maximum cycles that
can be collected in memory.
STACKS The total number of time series records specified to be acquired and processed.
Each STACK will be recorded in individual blocks in the cache file.
Note: If the entered value would cause acquisition memory or flash disk space to be exceeded,
the value will be adjusted down in order to have successful data acquisition. The STATUS:
field will show a message “INSUFFICIENT DISK SPACE for ACQUISITION” or
“INSUFFICIENT MEMORY for ACQUISITION”.
GAIN Selector for setting the method the GDP-3224
will use for setting gain. Options
are
ALWAYS Automatic gaining, with SP bucking, will occur before each stack.
ONCE Automatic gaining, with SP bucking, will occur only for the first stack.
After the first stack, this option will change to DONE.
DONE No gaining will occur on subsequent stacks. Changes to some fields will
cause this selection to revert back to ONCE.
SPONLY SP bucking will be performed for all stacks. The gain values currently set
in the Channel Table will not be altered.
MAN The gain and SP values currently set in the Channel Table will not be
altered.
Note: On older versions of the Field Survey Program, the Automatic Gain algorithm does not
apply an Attenuator setting. It assumes that the operator has set the transmitter to a level that
will not require attenuation, relying instead on the increased dynamic range of the 24-bit analog
converter. If the incoming signal does however require Attenuation, the MAN or SPONLY
modes should be selected for GAIN. The SCOPE function can be used to inspect the incoming
signal while making adjustments to the Transmitter Output.
NOTCH Powerline notch filter switch. There are several possible selections here,
depending upon the hardware configuration of the receiver.
OUT All notch filters bypassed.
60-3 60 and 180 Hz notch filters enabled.
60-359 60, 180, 300 and 540 Hz notch filters enabled.
60-59 60, 300 and 540 Hz notch filters enabled.
Other standard selections are:
50-3 50 and 150 Hz notch filters enabled.
50-359 50, 150, 250 and 450 Hz notch filters enabled.
50/60 50, 150, 60 and 180 Hz notch filters enabled.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 12 October 2014
Note: Powerline notch filters inject some noise into the system, and should only be used when
absolutely necessary. More information on Notch Filter design can be found in Chapter 16.
SENSE When using the Ref channel, enter the value of the current sense resistor for
calculation of the transmitter output current. Values of current sense (shunt)
resistors for standard GGT-series transmitters and the laboratory setup are as
follows (all values in ohms):
0.100 or 100m GGT-2.5, GGT-3
0.100 or 100m GGT-5, GGT-6, GGT-10
0.050 or 50m GGT-20, GGT-25, GGT-30
0.100 or 100m ZT-30 / ZT-20
1.00 NT-20
1m to 1000K LABROX
Note: The SENSE field is not displayed if no Ref component type is defined.
Note: If more than one Ref channel is defined, the lowest numbered Ref channel will be used.
There is no requirement as to which channel is used.
TXCR The Transmitter Current, in amperes. This current is the square-wave equivalent
current or what the operator would read off of the transmitter current display.
Note: If a Ref component type is defined, the value for this field will be calculated based on the
magnitude of the Ref signal and the SENSE resistor value.
TIME Informational display of the total time required to collect, process and write all
of the STACKS to the cache.
MEM(mb) Informational display of the memory required to collect all the cycles for one
stack.
CHANNEL TABLE
The channel table refers to a separate section of the main menu where settings pertaining to a
specific channel are made and results for that channel are displayed. The table is a distinct
grouping of fields which can be accessed by pressing .
There are four SCREEN: selections that configure the Channel Table. Pressing cycles
through: SETUP, GAIN/CRES, RESULTS, and STACKS. A fifth screen, XYZ EDIT, can be
activated when the cursor is in the Channel Table and the operator presses . See the
section on SOFT FUNCTION KEYS for more information.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 13 GDP-3224
SOFT FUNCTION KEYS
The function keys through are considered “soft function keys” because they may
perform different functions not only in different programs, but their functionality can change
within a program depending on the menu, input field, or Channel Table column the cursor is in.
Each key's functionality is identified by its label on the bottom line of the display screen.
While the Main Menu is displayed, the keys perform the following functions:
ARCHIVE: Start the Archive submenu used to rename the current cache
file and initialize a new file. The Archive submenu is described below.
SCREEN: Cycle through the Channel Table display screens.
JOB_INFO: Job Information submenu used to enter survey job information.
Multiple function key based on the current SCREEN and cursor location. For
more information, see the section on RESET FUNCTIONS, below.
CH_OFF/ON: Toggle channels Off or On. This function is available
while the cursor is in the Cmp Typ column of the Channel Table.
RST_TX: Reset transmitter and receiver locations. Initialize some
features of the CR program based on Line Setup settings. The operator
should press this key when finished setting the fields ARRAY, A-SPACE,
S-SPACE, TX:AX, TX:AY, RX0:RX and RX0:RY. This function is
available in the SETUP screen, and the cursor is not in the Channel Table.
RST_OFSET: Re-sequence the Offset for channels above and below
the channel row that the cursor is on. This also places the program into
the Offset mode for automatically updating electrode locations when RX0
or TX locations are modified. This function is available while the cursor
is in the Offset column of the Channel Table.
RST_N-SPC: Re-sequence the N-values for channels above and
below the channel row that the cursor is on. This also places the program
into the N-space mode for automatically updating electrode locations
when RX0 or TX locations are modified. This function is available while
the cursor is in the N-column of the Channel Table.
SCOPE: Real time scope display of a channel's input signal. It functions
only when the cursor is in the Channel Table and in the row of a channel that is
currently On.
Multiple function key based on the current SCREEN and cursor location.
EDIT_XYZ: When the cursor is in the Channel Table, this key will
enable the XYZ EDIT screen.
XYZ_EXIT: When in the XYZ EDIT screen, this will return to the
SETUP screen.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 14 October 2014
ARCHIVE SUBMENU
The Archive submenu, accessed with , allows the user to rename the current cache data
file and initialize a new empty file. The renamed cache file is archived to the C:\DATA
directory. The screen displays the number of blocks in the current cache file. Only the 8-
character file name can be changed. The default name will start with the prefix “TDI”, followed
by 2-character day of the month, then 2-character hour. The last character is sequenced to ensure
that a unique name is used. The file extension is always .CAC.
<0903c_24TDIP_Archive>
If the cache archive name is acceptable, press . If there is a name conflict, and error will
occur and allow the name to be changed. When successful, the archive name will be displayed
to the operator. When finished, press any key to return to the Main Menu. To abandon
archiving the cache file, press .
The name of the current cache file to which data is written is always 24TDIP.CAC. A new,
empty file is initialized when the old cache data have been archived and the stack/block number
has been reset.
Enter
Escape
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 15 GDP-3224
SCREEN: CHANNEL TABLE DISPLAY SCREENS
Cycle through the Channel Table screens by using .
SCREEN: SETUP
The SETUP screen is the initial Channel Table configuration displayed after starting the
program. It can also be viewed by pressing and cycling through the screens.
<0903d_24TDIP_Setup>
In the SETUP screen, the column entry fields are: Ch, Calibration Found, Cmp Typ, Saturated
Reading, Offset (RX1-RX0), N, Length (Ft/M), RX1 and RX2. Non editing fields are: Ch,
Calibration Found, Saturated Reading, and Length.
Ch The channel and card cage slot number for the A-D Card.
Calibrate If proper board calibration records are not found in the calibration caches,
the TDIP program will display a large exclamation point (!) next to the channel
number in the Channel Table. Data acquisition can be completed without the proper
calibration record loaded into the cache, but the data displayed on the GDP screen
will assume calibration values of 1.0 mag, and 0.0 phase, and thus will not accurately
represent the actual earth response. Calibration caches are ASCII files.
Cmp Typ Channel component type selection. Any selection other than OFF will
turn the channel ON. While the cursor is on a channel, the key is used to
turn a channel Off or On. This key is the only way an operator can turn off a channel.
Refer to the CH_OFF/ON function key described later. An Off channel can also
be turned On by selecting a component type.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 16 October 2014
Ex, Ey, Ez Electric field designators
Ref Designates the transmitter current reference input channel for CR
measurements.
Note: This field also indicates empty slots and cards not directly supported by the AMT
program, such as NanoTEM cards.
Saturate When the inputs to the channel, after applying the gain and attenuate,
saturate the A-D converter, this field will indicate “▲”. Data acquisition can be
completed, but the data acquired by the GDP will not accurately represent the actual
earth response. Saturation is detected while gaining, and in real time during data
acquisition.
Offset Station distance along line, between the receiver reference location, RX0,
and the positive electrode of the channel's dipole, RX1. It is used to calculate RX1
whenever the operator changes RX0. It is automatically adjusted whenever the
operator changes RX1, or N.
Offset = RX1 – RX0
Note: Offset is the distance between the receiver reference location and a channel's positive
electrode, not the distance to the center of a channel's dipole.
N N-spacing (includes fractionals) for a channel designated as Ex, Ey, or
Ez.
Length Informative field showing the true distance (XYZ) between the
channel electrodes.
RX1 The location, along line, of the positive electrode, in S-space units.
This value is automatically set by changes to RX0:RX , Offset, and N.
It can also be set manually to match field conditions. See SCREEEN:
XYZ EDIT for additional information.
RX2 The location, along line, of the negative electrode, in S-space units.
This value is automatically set by changes to Offset, N, and RX0:RX.
It can also be set manually to match field conditions. See SCREEEN:
XYZ EDIT for additional information.
Note: Resistivity is calculated based on transmitter and receiver electrode locations, TX, RX1
and RX2 locations, not RX0, offset or N-values. The operator should always inspect the RX1 and
RX2 values, after automatic update, to make sure they reflect the actual electrode locations in
the field.
Note: See the section covering SOFT FUNCTION KEYS for how configures the
automatic update of RX1 and RX2 locations, based on TX and RX0 changes.
Note: The X and Y locations for receiver and transmitter electrodes, or stations, may also be
used as indexes into post processing station files. These files will then provide actual locations
for post processing calculations. More information about this feature is available in the various
post processing software manuals.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 17 GDP-3224
SCREEN: GAIN/CRES
The GAIN/CRES screen can be viewed by pressing and cycling through the screens.
<0903e_24TDIP_GainCRES>
In the GAIN/CRES screen, the column entry fields are: Ch, Calibration Found, Cmp Typ,
Saturated Reading, Offset (RX1-RX0), Gain, SPmv, and CRES. Non editing fields are: Ch,
Calibration Found, Saturated Reading, and CRES.
Gain Gain settings for stages 0 and 1 (in powers of 2). The attenuator settings are
separated by a dash from the gain settings. More information about the gain
stages can be found in chapter 16 of this manual.
SPmv Self Potential or offset in millivolts. Initially set to 0.00.
CRES Contact Resistance, measured in Ohms and is obtained by pressing .
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 18 October 2014
SCREEN: RESULTS
The RESULTS screen can be viewed by pressing and cycling through the screens.
<0903f_24TDIP_Results>
In the RESULTS screen, the column entry fields are: Ch, Calibration Found, Typ, Saturated
Reading, Vp, M, Rho, SEM, Win1, Win2, Win3, Win4 and Win5. Only the Comp Type is
editable. The Win3, Win4 and Win5 are not normally visible on the smaller LCD screen unless
the view is shifted using .
Vp Primary (ON) voltage, with magnitude calibration removed (which is the
magnitude of the fundamental board calibrate, stored in the 24BOARD.CAL
file). See the section towards the end of this manual on SCALING for more
information.
M Average chargeability in millivolt-seconds per volt or milliseconds. Chargeability
is determined by integrating from 0.45 to 1.1 seconds for both positive and
negative polarities using an 8 second period. Data for other periods or
frequencies are normalized to this standard.
Rho Apparent resistivity in ohm-meters.
SEM Standard error of the mean chargeability, in milliseconds, calculated for each
cycle for frequencies of 1Hz and lower, or the average of 2 sec, for frequencies of
2Hz and above.
Win1 to Win5 Time Domain normalized decay point value windows 1 through 5.
The smaller LDC screen must be shifted in order to view the last 3 columns.
Pg Up
PREV FIELD
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 19 GDP-3224
SCREEN: STACKS
The STACKS screen can be reached by cycling . This screen displays the selected results
for the last 5 Stacks of data, as each stack is acquired. When this screen is displayed, the cursor
is moved to the results selector field. The selections are: Vp, M, Rho, SEM, SEMR, and Win1
through Win13. The SEM values are identical to those displayed in the RESULTS Screen. The
SEMR value is accumulated over all the repeating stacks of an acquisition, where SEM
represents the standard error for each individual screen. Note that while data are being collected,
this selection cannot be changed. When data acquisition has finished, cycling this field will
update the Channel Table display with the selected results for the last 5 stacks. The STACKS
Channel Table is cleared at the start of an acquisition.
<0903g_24TDIP_Stacks>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 20 October 2014
SCREEN: XYZ EDIT
The XYZ EDIT screen can be reached by pressing , EDIT_EYZ, while the cursor is in
the Channel Table. This screen allows full X, Y and Z location editing of the Transmitter,
Receiver reference and all channel electrode locations. By recording X,Y,Z values for each
electrode, the GDP can accommodate unorthodox resistivity/IP survey configurations which do
not conform to a standard survey like in-line dipole-dipole or pole-dipole. X is distance parallel
to line, Y is distance perpendicular to the survey line, and Z is depth below the surface. For a
generic in-line dipole-dipole survey, all of the electrodes are on the survey line, so X = distance
along line, Y is a constant value (line number by default) and Z is 0 for surface electrodes.
X,Y,Z values represent distance in station number units, which are not required to be scaled to
feet or meters. The GDP compares the unit dipole length in station numbers, S-space, with the
unit dipole length in length units, A-space, to get the relationship of X,Y,Z coordinates to length
units. If station numbers are in meters, then both S-space and A-space specify the unit dipole
length in meters and have the same value. If station numbers are not scaled to meters or feet,
then S-space and A-space will have different values and the GDP will use the ratio A-space/S-
space to get a length_unit/station_number scaling factor. The use of line and station numbers
scaled to length units simplifies record keeping, especially for 3D surveys that use off-line
electrodes.
<0903h_24TDIP_XYZ_Edit>
The Channel Table columns displayed are, Ch, Cmp Typ, Length, RX1, RY1, RZ1, RX2, RY2,
and RZ2. There is one row in the channel table for each input channel.
Ch Input channel index
Cmp Type Measurement type, Ex, Ey, Ez, or Ref
Length Receiver E component dipole length in station numbers.
RX1 Receiver electrode 1 X location (distance parallel to line in station number
units).
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 21 GDP-3224
RY1 Receiver electrode 1 Y location (distance perpendicular to line in station
number units).
RZ1 Receiver electrode 1 Z location (depth below surface in station number units).
RX2 Receiver electrode 2 X location (distance parallel to line in station numbers).
RY2 Receiver electrode 2 Y location (distance perpendicular to line in station
number units).
RZ2 Receiver electrode 2 Z location (depth below surface in station number units).
Just below the Channel Table are fields for specifying the transmitter (TX) electrode locations.
AX Transmitter electrode 1 (distance parallel to line in station numbers).
AY Transmitter electrode 1 (distance perpendicular to line in station number
units).
AZ Transmitter electrode 1 (distance depth below surface station number units).
BX Transmitter electrode 2 (distance parallel to line in station numbers).
BY Transmitter electrode 2 (distance perpendicular to line in station number
units).
BZ Transmitter electrode 2 (distance depth below surface station number units).
Receiver reference location (RX0) is used to expedite the calculation of default electrode
locations for standard survey arrays. The XYZ EDIT screen includes the fields for RX0 X,Y,Z
at the bottom of the screen.
In the screen shot example above, the Line value is 1, based on the TX: AY, BY and RX0: RY,
locations. This indicates that this particular line's Y grid coordinate is 1 S-space unit.
The Z locations all represent depth below the surface, in S-space units.
Below are diagrams showing the relationship between Line and Station numbers, and X and Y
coordinates of electrode locations. These also show the way S-Space and A-Space factor into
that relation. On the left, we see a plan view of several survey lines and their stations. The S-
Space has a value of 1, indicating that the station space numbering increments by the value of 1
for every A-Space distance. In this case the Station numbers match the X values of transmitter
(TX;AX, BX), and receiver (RX0:RX, RX1, RX2) electrode locations. The Line numbers match
the Y values of transmitter (TX:AY, BY) , and receiver (RX0:RY, RY1, RY2) electrode
locations. Z values, indicating depth below surface, would also be in the same units. The A-
Space can be of any value.
The plan view on the
right depicts a similar
layout, but in this
case the S-Space is
equal to the A-Space.
The X, Y and Z
values are all in the
same units as the A-
Space, either feet or
meters.
<0903i_
TDIP_waveform>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 22 October 2014
JOB_INFO SUBMENU
The Job Information submenu can be accessed by pressing from the main menu. Entries
in this menu are saved as metadata in the data cache and in the 24COMMON.INI file so that
users do not have to re-enter these fields every time any of the acquisition programs are started.
Entries in these fields carry into Zonge data processing programs as well.
<0903j_24CR_JobInfo>
GDP OPERATOR User defined identification. Alphanumerics permitted.
JOB NAME User defined identification. Alphanumerics permitted.
JOB FOR User defined identification. Alphanumerics permitted.
JOB BY User defined identification. Alphanumerics permitted.
JOB NUMBER User defined identification. Alphanumerics permitted.
TX SN User defined identification. Alphanumerics permitted.
The GRIDS area of the Job Info screen can be used to aid in post processing of the data. The
information in these fields is stored in the cache, but is not used by the GDP or directly by any of
the current post-processing software.
OffSet This field can provide post processors with information about abbreviated
location information, if used by the operator. The field provides a reference
Label, as well as Survey X and Y offsets. In the event that electrode survey
locations require many digits, these values could be used to minimize data entry.
For example, if a survey was conducted in an area whose electrode locations had
X values above 490000, and Y values above 3680000, a location such as TX:AX
of 490862, and AY of 3687927, could be entered as TX:AX 862, and AY 7927.
Ref1, Ref2, Calc These can be used as reference and a calculator to transform
mapping Easting and Northing coordinates to Survey X and Y coordinates, or
reverse. To use the calculator, the coordinates of two reference points must be
known in both the Survey and Mapping coordinate systems.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 23 GDP-3224
For example, locations tx1, and tx2, are known. The Survey location of
tx1 is 0X, and 0Y. The mapping coordinate of tx1 is 490862 East and
3687927 North. The Survey location of tx2 is 3388X and 1017Y. The
mapping coordinate of tx2 is 494250 East and 3688944 North. After entering
these values in the Ref1 and Ref2 fields, points can be calculated in either of
the two coordinate systems by entering the coordinates of the known location in
the Calc field. Entering a SurveyX value of 750, and a SurveyY value
of 893 will result in calculated values of 491612 East and 3688820 North.
Entering values in the East and North columns will result in calculated
SurveyX and SurveyY values.
RESET FUNCTIONS
is a multifunction key whose functions configure the automatic location update features
of the TDIP program. These are designed to reduce the number of data entries that need to be
made as a survey progresses. The reset functions are: RST_TX, RST_OFSET, and RST_N-SPC.
RST_TX should always be used at the start of a survey. Either RST_OFSET or RST_N-SPC,
should be use during initial channel spread configuration, and in some cases, when the Receiver
reference location, RX0:, is moved above or below the Transmitter location TX.
There are two methods by which the TDIP program automatically updates channel locations
whenever the transmitter or receiver electrodes are moved. The Offset method is based on the
location of electrodes with respect to the receiver itself. The N-space method is similar to the
methods used by the GDP-32II. Modifying the Transmitter electrode location and/or the
Receiver reference location during the progress of a survey will cause the automatic update of
channel electrode locations RX1 and RX2. With both methods, channels whose electrodes are in
conflict with Transmitter electrodes should be turned off manually.
The operator should decide which method to use before configuring the channels, then use the
RST_OFSET or RST_N-SPC function to perform channel configuration.
See the section “A NOTE ON AUTOMATIC LOCATION UPDATES” for more information
and some examples.
Note: Not using the Reset Functions, and not understanding the automatic location update
features, can make the Survey Setup procedure seem difficult. Use of these features can simplify
data entry and reduce errors.
Note: also functions to turn channels Off or On while the cursor is in the Cmp Typ
column of the Channel Table.
RST_TX This function resets transmitter BX, BY and BZ locations, based on the ARRAY
type, S-SPACE and the transmitter AX, AY and AZ, locations. It also initializes
some features of the TDIP program based on various Line Setup fields of the
Main Menu.
The operator should press this key while initially setting up for a survey, after
setting the fields ARRAY, A_SPACE, S_SPACE, TX:AX, TX:AY, RX0:RX or
RX0:RY. This function is available while in the SETUP screen, and the cursor is
not in the Channel Table.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 24 October 2014
RST_OFSET This function will re-sequence the Offset for channels above and below
the channel row that the cursor is on. Pressing repeatedly will toggle
between channel Offsets increasing or decreasing, effectively shifting a spread
pattern above or below a transmitter location. The Offsets will increment or
decrement by the S-SPACE value. The RX1 and RX2 values for all channels will
be reset based on their Offset and the RX0 location. The N values for all channels
will be reset based on their distance from the transmitter electrodes. This also
places the program into the Offset mode for automatically updating electrode
locations when RX0 or TX locations are modified. This function is available
while the cursor is in the Offset column of the Channel Table.
RST_N-SPC This function will re-sequence the N values for channels above and below
the channel row that the cursor is on. Pressing repeatedly will toggle
between channel N values increasing or decreasing, effectively shifting a spread
pattern above or below a transmitter location. The N-values will increment or
decrement by 1. The RX1 and RX2 values for all the channels will be reset based
on their N-value and the TX location. The Offset values for all the channels will
be reset based on their RX1 and RX0 locations. This also places the program into
the N-space mode for automatically updating electrode locations when RX0 or
TX locations are modified. This function is available while the cursor is in the N
column of the Channel Table.
This method of setup is similar to the methods used for the GDP-32II.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 25 GDP-3224
SCOPE FUNCTION
The Scope function allows the operator to see a real time graphical representation of the input
signals to individual channels. When the cursor is in the Channel Table and in the row of an On
channel, pressing the key will bring up a Scope display of the input signal to that
channel. Moving the cursor to the row of another On channel will cause the Scope to display
that input signal. Moving out of the Channel Table or to the row of an Off channel, will not
affect the Scope. Pressing again, pressing , or starting data acquisition will clear
the Scope display.
<0903k_24TDIP_Scope>
The Scope display can be used to evaluate the input signal to a channel, as well as to evaluate the
gain, attenuate and SP settings. The Scope's response time is faster than the analog panel
displays, and will provide a better evaluation of the magnitude of higher frequency signals.
While on the SETUP Screen, the operator can manually adjust the gain, attenuate and SP values,
and evaluate their effect on the signal. If the trace of the signal reaches the top or bottom frame
of the Scope it will be saturating the A-D converter, affecting measurements and interpretation of
actual earth response.
Note: On older versions of the Field Survey Program, the Automatic Gain algorithm does not
apply an Attenuator setting. It assumes that the operator has set the transmitter to a level that
will not require attenuation, relying instead on the increased dynamic range of the 24-bit analog
converter. If the incoming signal does however require Attenuation, the MAN or SPONLY
modes should be selected for GAIN. The SCOPE function can be used to inspect the incoming
signal while making adjustments to the Transmitter Output.
Escape
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 26 October 2014
9.4 BOARD CALIBRATION SUBMENU
The calibration data for the TDIP program is shared with several other GDP-3224
programs:
CSAMT, CR, TEM SYSCHK and SYNC_CHK. The standard board calibrate buffer is saved as
24BOARD.CAL on the C:\ drive of the GDP. Board calibration data can be obtained and
viewed in the Calibration submenu of the TDIP program. TDIP calibration data contains the 1st,
3rd
, 5th
, 7th
and 9th
harmonics magnitude and phase values.
The Calibration submenu is brought up by pressing from the main menu. Only the
channels that are On in the Channel Table are included for calibration and viewing in this
submenu. Below is a sample of the calibration submenu display.
The Board Calibration values stored in 24BOARD.CAL are obtained by measuring each board's
response to a 1.0v, 100% duty, square wave. The FFT results of these measurements are then
divided by the FFT results of an ideal square wave. This results in a Board Calibrate factor. The
magnitude of the Board Calibrate for the fundamental frequency of investigation is used to
decalibrate the time domain readings used in the TDIP program.
<0904a_24TDIP_CalCal>
The Channel Table for the calibration submenu contains the following fields:
BOARD Analog board serial number(s), in channel order. This display only includes
channels that were On when the submenu was activated. Calibration values are
associated with board serial numbers as opposed to channels, since the operator
may exchange cards between channels within the GDP case.
Gain These settings can be made by the operator in order to obtain calibration sets at
different gain and attenuation values. The gaining and attenuation circuitry on the
analog boards can have a minor effect on the overall measurement of the
incoming signal. If a high degree of accuracy is required, calibrations can be
performed at specific gain settings. Calibration sets for different gain settings are
all maintained within the same calibration file. Whenever readings are
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 27 GDP-3224
decalibrated, and a calibration for a specific gain setting is not available, the
program uses the calibration values for the 00-0 gain. The AUTOCAL METHOD
described below will not automatically cycle through all the possible gain setting
variations. The operator must perform an AUTOCAL calibration for each
variation of gain setting. Thus, a calibration value for a gain of 11-0, cannot be
obtained by perform calibrations for a 10-0 setting and a second calibration for a
01-0 setting.
Board Cal This displays the magnitude and phase values for the board calibration
value just written to, or recalled from, the calibration file. The column label for
the values displayed during either a AUTO_CK or 1SHOT_CK is changed to
“Cal File” for clarity and comparison to the values obtained and displayed in
the Check columns described below.
System Cal This displays the magnitude and phase of the raw values just obtained
during a calibration. If no calibration was just performed, these display default
values. These values are not recorded or maintained in memory. The system
calibrate values represent the response of the system to the calibration signal input
to the cards. Because the calibration signal is an ideal square wave, the FFT
values of an ideal square wave are factored out of the readings in order to obtain a
general board response, the Board Cal. The Board Cal values are those which are
actually recorded in the cal file and used to decalibrate readings during data
acquisition.
Check These are board response values obtained during either the AUTO_CK or
1SHOT_CK procedures as described below. These provide the operator a visual
confirmation of calibration and board quality made during the check procedures.
These values are not maintained in a file or in memory, and will display default
values if a check reading has not just been performed. How closely these values
match to those in the Cal File columns is an indication of data quality.
The calibration and viewing parameters are set in the following fields:
FREQ The calibration frequency setting which ranges from 0.016 to 8192 Hz. The
calibration values for the fundamental frequency, from the calibrate file, will be
displayed as frequencies are selected.
CYCL The setting for the number of cycles to take when taking the calibration readings.
NOTCH The Notch filter setting for the calibration set. This setting must be made
manually and is not automatically changed during the AUTOCAL METHOD of
calibration.
METHOD The operation method for the calibration. The selected calibration METHOD will
be performed when the operator presses the key.
AUTOCAL Perform calibration starting at the selected FREQ, and automatically
sequencing up to the highest frequency of 8192 Hz. This will
automatically select sample rates, and high pass filter settings for each
frequency of the calibration set. Calibration sets include the magnitude
and phase for the 1st, 3
rd, 5
th, 7
th, and 9
th harmonics, which are written to
Enter
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 28 October 2014
the calibration file. This automatic calibration does not cycle through the
possible NOTCH or gain values. Calibration sets for specific NOTCH and
gain settings can be included in the calibration file, but calibrations must
be made for each selection combination.
AUTO_CK This selection will perform calibration in exactly the same manner as the
AUTOCAL method described above, however rather than writing the
results to the calibration file, it compares the resulting values to those
already in the file. The automatic sequencing through the various
frequencies progresses automatically up through the highest frequency,
displaying the difference for each setting. If the difference between the
resulting value and the value in the cache exceeds the delta phase percent
limit set in the dθ% LIM field described below, the program will issue an
audible alarm and pause for an operator response. The operator may press
to cancel the check, or any other key to continue.
<0904b_24TDIP_CalCheck>
Note: One method of verifying both the calibration file and the operation of the TDIP program
is to perform calibration with the TDIP program. Then exit TDIP and start one of the other
programs that share the 24BOARD.CAL file, CR, or CSAMT. From the Calibrate submenu in
that program, perform the AUTO_CK procedure.
1SHOTCAL Perform calibration for one FREQ setting. It will cycle through the
harmonics, sample rates, and high pass filter settings for that frequency.
The results are written to the calibration file.
1SHOT_CK Perform a calibration in exactly the same manner as the 1SHOTCAL
method and compare the resulting values to those already in the cache. If
the difference exceeds the delta phase percent limit set by dθ% LIM, the
program will issue an audible alarm.
Escape
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 29 GDP-3224
SYS_CK This system check selection will cause a calibration signal to be enabled
during data acquisition. The MODE selection will control how the signal
is routed. The CAL V setting will set the reference voltage. Pressing
the key while this method is set will have no effect. To enable this
method the operator must press the key to return to the Main
Menu, and then perform the system check readings by pressing . If
the MODE is set to INTERNAL, the signal will only be routed to those
channels that were On when the Calibration submenu was activated.
For the EXTERNAL MODE, the operator must route the signals
externally. No automatic checks are performed when the readings are
made. The Main Menu will display a message below the date and time,
indicating that the system check is enabled, as in the sample screen display
below.
<0904c_24TDIP_SysCheck.png>
MODE The selections are INTERNAL and EXTERNAL. INTERNAL will connect the
calibration reference signal through internal circuits of the GDP, directly to the
channel inputs for calibration. EXTERNAL will connect the calibration signal to
the CAL+ and the CAL- terminal on the outside of the GDP case. The operator
must then route the signal from these outputs through the desired channel
components, and to the channel input terminals for calibration.
Note: The calibration file does not maintain separate data sets for INTERNAL and EXTERNAL
calibrations. The operator must decide which type of calibration is required and perform a full
calibration for the desired MODE.
Enter
Escape
Enter
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 30 October 2014
CAL V Set the calibration signal voltage, and can only be made by the operator when the
METHOD selection is SYS_CK and performing a system check. During the
calibration and cal check METHODS, the value of the cal voltage is automatically
adjusted when gain or attenuate settings are adjusted. The voltage is adjusted so
that the signal to the A-D converter is 1.0 volts, after being modified by the gain
and attenuate circuits. All calibration values are based on a 1.0 volt signal being
read by the A-D converters.
dθ% LIM Set a stop limit while performing an AUTO_CK or 1SHOT_CK check of
the calibration data in the calibration file and calibration readings made during the
check. The delta phase percentage is calculated as the difference between the
calibration phase just measured and the phase recorded in the file, divided by the
phase recorded in the file, represented as a percent.
Note: The limit is normally set to 1% for running the AUTO_CK procedure, and can detect
basic system or card errors. Generally the measured phase difference is well below this. Higher
frequencies, which have calibrates with a greater number of cycles, can be expected to have
phase differences of less than 0.05%. Lower frequencies, particularly the lowest frequency of a
sample rate 0.016Hz, 0.063Hz, and 2Hz, can have higher differences around 0.2 %. When the
NOTCH filter is set in, the differences near the harmonics of the NOTCH, can have significantly
higher values, and may exceed the 1% limit. This does not indicate a hardware problem.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 31 GDP-3224
9.5 GATHERING DATA
PROGRAM START UP
During start up, the TDIP program will perform various system checks. It will search and
identify all cards installed in the GDP. It will open and index the calibration file. The input
parameters from the last TDIP session will be loaded into the display. When complete, the
STATUS line will indicate Ready, and the message “Press CONTINUE to take
data” will be displayed.
If the GDP detects that the version of the board calibration file is incompatible with the version
of the TDIP program, the old calibrate file will be renamed to BOARDTD.CAL and a new,
empty 24BOARD.CAL will be created. An audible warning will be made and the GDP will
display a message to the operator that a new calibration must be performed. The GDP will wait
for a key press in response before the startup process continues.
If no calibrate files are found, the GDP will make an audible warning, inform the operator of the
problem, and wait for a key press in response before the startup process continues. The required
board calibration file is 24BOARD.CAL. A new empty file will be initialized. The GDP will
not inform the operator if the files do exist, but are empty. The No Cal Found symbol, '!', in the
Channel Table will be the only indicator of missing calibrates. The GDP must perform the board
calibrates.
DATA ACQUISITION
When the STATUS is Ready, the operator can proceed to set the various parameters required
for the data acquisition. After filling in the parameters for Job Information, Line Setup,
Acquisition Configuration and setting up the Channel Table, the operator should confirm that
calibrates are found and input signals are good. Use of the SCOPE can detect channel saturation,
poor connections, and excessive powerline noise. Pressing will start the data acquisition
sequence.
Immediately after pressing , the GDP will set gains. When the selected gain method has
completed, the GDP acquisition will synchronize with the timing card and indicate that it is
taking data. At frequencies of 2 Hz and above, no other indication of collecting data will be
observed, as the GDP is using its full resources to read the A-D cards and store the raw data into
the computer memory. For 1 Hz and below, a progress bar will be displayed showing the time
left for taking data. When data has been acquired, the results will be calculated and displayed.
When acquiring a single stack of data, the GDP will display the message
“Press ESCAPE to discard, CONTINUE to save – Hit Key”,
make an audible signal, and then pause for the operator's response. The operator must then
respond. The data will be written to the flash card or discarded, based on their review of the
results. After responding, the GDP will write the data, make an audible signal, and be Ready for
further acquisitions.
Enter
Enter
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 32 October 2014
STOP ACQUISITION
If the operator wishes to cancel the acquisition of data at any time before normal completion of a
stack, or to terminate acquisition of a large number of stacks, pressing the key will stop
the process. Depending on sample rate and the various stages of data acquisition, the GDP may
stop immediately, or it may take a few moments to finish before it is ready.
ACQUISITION ERRORS
If there are any processing errors due to hardware or other acquisition issues, the GDP will make
an audible signal, display a message to the operator, and wait for a response before going to the
Ready state.
A history of error and warning messages is displayed below the Main Menu, in an area not
normally visible on the smaller LCD screen. These messages can be useful to monitor progress
and to review any messages associated with an error.
9.6 VIEWING DATA
After stacks of data have been acquired and saved to the cache file, the data can be reviewed by
pressing to start the Cache Viewer. The initial display will display zero values in the
table. The operator can make selections for SET (or BLOCK), PLOT type, CH (channel), and
CYCLE. The SET value identifies a group of stacks, with the same frequency, and channel
configuration (spread). Sets are numbered sequentially as they are identified when the cache is
initially scanned. The FREQ field displays the frequency of a Set or Block.
Press to scan the cache and present the data. The display is not immediately updated
upon making any of the selections in order not to scan the cache with each key press, thus
slowing down response.
The PLOT types for TDIP are: Window, Rho_N, M_N, Stack, and TimeSr. The Window plots
present the data for Sets. The Rho_N, and M_N, plots present a pseudosection of all the blocks
in the cache. The Stack and TimeSr, plot data for individual blocks.
The operator can toggle between a GRAPH or TABLE view of the data by pressing .
When in the TABLE view, pressing will shift the columns to other channels if there are
more channels to view.
Escape
Enter
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 33 GDP-3224
The Window Plot presents the averaged results for a Set of blocks. The Time is in
microseconds. The window value is the normalized decay point in 10's of milliunits.
<0906a_24TDIP_CacVu_Win_Tabl>
<0906b_24TDIP_CacVu_Win_Graph>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 34 October 2014
The Rho_N Plot presents the resistivity vs N-values for all the blocks on the cache, represented
as a Pseudosection.
<0906c_24TDIP_CacVu_RhoN_Tabl>
<0906d_24TDIP_CacVu_RhoN_Graph>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 35 GDP-3224
The M_N Plot presents the Chargeability vs N-values for all the blocks on the cache, represented
as a Pseudosection.
<0906e_24TDIP_CacVu_MN_Tabl>
<0906f_24TDIP_CacVu_MN_Graph>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 36 October 2014
The Stack Plot presents the Mag vs time values, averaged over the entire acquisition period, for a
single block. When in the TABLE view, the and keys scroll up or down the
table, increasing or decreasing the cycle time. When viewing the GRAPH these keys have no
function.
<0906g_24TDIP_CacVu_Stack_Tabl>
<0906h_24TDIP_CacVu_MN_Graph>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 37 GDP-3224
The TimeSr Plot presents the voltage vs time values for a single cycle of the acquisition period,
for a single block. When viewing the time series, each CYCLE can be selected by pressing
. In TABLE view, the and keys scroll up or down the table, increasing or
decreasing the cycle time. In GRAPH view, the and keys increase or decrease
the cycle being displayed. The key will have no function.
<0906i_24TDIP_CacVu_Time_Tabl.png>
<0906j_24TDIP_CacVu_Time_Graph.png>
SELECT DN
End
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 38 October 2014
9.7 CACHE FILE
The TDIP data cache is much like that of other GDP-3224
programs. It contains binary data
blocks with ASCII metadata descriptors. See chapter 7, DATA, FILE AND PROGRAM
TRANSFER for more detailed information.
Note: Though the cache file can be viewed and partially read with simple text editing programs,
doing so can irrevocably destroy the navigation pointers within the file, or the data itself,
resulting in total loss of data.
The TDIP cache contains the following records for every stack recorded:
Header ASCII record contains survey data including: job descriptors, locations,
channel component types, GPS timing, and other data required for post
processing. This portion of the cache can be edited with the CACEDIT
program.
Cal ASCII record containing calibration factors for all channels.
WinDefs Begin and end point count and times for the chargeability and decay windows.
Time Series An optional binary data record containing all the raw A-D data readings
for all channels.
Stack Data A binary data record containing an average of the time series, stacked into
a single cycle.
Windows A binary data record of the Vp, chargeability and the decay windows, for each
channel.
Summary A binary data record containing IPSEM, Vp, IPM, and ARes, for each
channel.
Quality ASCII record of the internal temperature, humidity and battery voltage at the
end of acquisition.
The following is an example of the Header metadata for a CR cache. HEADER.TYPE,Survey
DATA.VERSION,1.00
DATA.BLOCK,1
DATA.SKIP,0
DATA.STACKCTDN,2
GDP.DATE,07/22/2014
GDP.TIME,10:13:50.125000
SURVEY.TYPE,TDIP
SURVEY.ACQMETHOD,stack
SURVEY.ARRAY,D-D
LINE.NAME,0
LINE.NUMBER,1.000000
LINE.DIRECTION,N
LINE.SPREAD,88
JOB.NAME,Quality Assurance
JOB.FOR,Customer
JOB.BY,Engineering
JOB.NUMBER,123-456-JOB
GDP.OPERATOR,Zonge Field Crew
GDP.TYPE,GDP32-24
GDP.PROGVER,TDIP_1.37j
GDP.SIGSOURCE,ESys
GDP.CALVOLTS,1.000000
GDP.SYNC,Manual
GDP.GAINMETHOD,Once
GDP.GAINMODE,Noisy
GDP.FPSN,328
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 39 GDP-3224
GDP.SN,3252
GDP.TCARDSN,336
GDP.NUMCARD,8
GDP.ADCARDSN,C83C,C87E,C8DA,C880,C83D,C8FF,C875,E8D2
GDP.ADCARDSND,60,126,218,128,61,255,117,210
GDP.CARDTYPE,ANA24CARD,ANA24CARD,ANA24CARD,ANA24CARD,ANA24CARD,ANA24CARD,ANA24CARD,ANA24CARD
GDP.ADCARDVER,09,8B,0B,89,09,0B,0B,09
GDP.ADCARDFEAT,05,07,07,07,05,07,07,07
GDP.BAT,12.7046871
GDP.TEMP,31.666666
GDP.HUMID,26.0273972
GRID.XYOFFSET,490000:3680000,"TEST"
GRID.REF1,0:0,490862:3687927,"tx1"
GRID.REF2,3388:1017,494250:3688944,"tx2"
GRID.CALC,750:893,491612:3688820,""
TX.STN,100
TX.XYZ1,4:1:0
TX.XYZ2,5:1:0
TX.SN,123
TX.FREQ,8
TX.DUTY,0.5
TX.AMP,1.00263786
TX.SENSE,1
TS.ADFREQ,32768
TS.NCYCLE,16
TS.NWAVEFORM,4096
TS.DECFAC,1
TS.NPNT,65536
RX.STN,8
RX.AZIMUTH,88
RX.ASPACE,100
RX.SSPACE,1
RX.XYZ0,8:1:0
RX.XYZ1,10:1:0,9:1:0,8:1:0,7:1:0,6:1:0
RX.XYZ2,11:1:0,10:1:0,9:1:0,8:1:0,7:1:0
RX.LENGTH,100,100,100,100,100
RX.ADDELAY,81
LAB.ID,
LAB.AREA,100
LAB.LENGTH,1
UNIT.LENGTH,m
CH.NUMON,5
CH.ADCARDSN,C83C,C87E,C8DA,C880,C83D
CH.GDPSLOT,1,2,3,4,5
CH.FACTOR,2.98023224e-007,2.98023224e-007,2.98023224e-007,2.98023224e-007,2.98023224e-007
CH.GAINFACTOR,1,1,1,1,1
CH.GAIN,00-0,00-0,00-0,00-0,00-0
CH.NUMBER,2,1,0,-1,-2
CH.NOTCH,NONE,NONE,NONE,NONE,NONE
CH.HIGHPASS,NONE,NONE,NONE,NONE,NONE
CH.LOWPASS,14000,14000,14000,14000,14000
CH.CRES,0,0,0,0,0
CH.CMP,ex,ex,ex,ex,ex
CH.STATUS,0000,0000,0000,0000,0000
CH.SP,-3,0,0,0,-1
<0906i_24TDIP_CacHeader.txt>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 40 October 2014
9.8 A NOTE ON AUTOMATIC LOCATION UPDATES
The automatic location update features of the TDIP program are designed to reduce the number
of data entries required as a survey progresses. The reset functions configure these update
features and are accessed through . The context of the cursor on screen controls the
functionality of . The functions are labeled: RST_TX, RST_OFSET, and RST_N-SPC.
RST_TX should always be used at the start of a survey. Either RST_OFSET or RST_N-SPC,
should be use during initial channel spread configuration, and whenever the Receiver reference
location, RX0:, is moved above or below the Transmitter location TX:
There are two methods by which the TDIP program automatically updates channel locations
whenever the transmitter or receiver electrodes are moved. The Offset method is based on the
location of electrodes with respect to the receiver itself. The N-space method is similar to the
methods used by the GDP-32II. Modifying the Transmitter electrode location and/or the
Receiver reference location during the progress of a survey will cause the automatic update of
channel electrode locations RX1 and RX2.
The operator should decide which method to use before configuring the channels, then use the
RST_OFSET or RST_N-SPC function to perform channel configuration.
Note: Not using the Reset Functions, and not understanding the automatic location update
features, can make the Survey Setup procedure seem difficult. Use of these features can simplify
data entry and reduce errors.
Note: also functions to turn channels Off or On while the cursor is in the Cmp Typ
column of the Channel Table.
RST_TX Reset transmitter BX, BY and BZ locations, based on the ARRAY type, S-
SPACE and the transmitter AX, AY and AZ, locations. This function also
initializes some features of the TDIP program based on various Line Setup fields
of the Main Menu.
The operator should press this key after setting the fields ARRAY, A-SPACE,
S-SPACE, TX:AX, TX:AY, RX0:RX or RX0:RY. This function is available
while in the SETUP screen, and the cursor is not in the Channel Table.
RST_OFSET Re-sequence the Offset for channels above and below the channel row that
the cursor is on. Pressing repeatedly will toggle between channel Offsets
increasing or decreasing, effectively shifting a spread pattern above or below a
transmitter location. The Offsets will increment or decrement by the S-SPACE
value. The RX1 and RX2 values for all the channels will be reset based on their
Offset and the RX0 location. The N-values for all channels will be reset based on
their distance from the transmitter electrodes. This also places the program into
the Offset mode for automatically updating electrode locations when RX0 or TX
locations are modified. This function is available while the cursor is in the Offset
column of the Channel Table.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 41 GDP-3224
Note: N-values are equivalent to the distance between the closest electrodes of the channel and
transmitter, and related to the depth of investigation.
The Offset method that the TDIP program uses to update locations as the survey
progresses, is based on the RX0 reference being the actual location of the
receiver, not the location of an electrode nearest the transmitter. The channel
offset values represent the physical distance between the RX1 electrode and the
actual receiver.
For standard surveys the pattern, or spread, of electrodes does not change as the
survey progresses. Channels may be turned On or Off, but unless the receiver
itself moves, the electrodes do not, and when the receiver does move, the pattern
in which the electrodes are laid remains essentially the same.
The operator should first set the ARRAY type, A-space, S-space and TX
locations, then press , RST_TX.
After spreading out the electrodes, the operator should identify the station whose
positive electrode is nearest the receiver. This station number should be entered
as the RX0:RX location. The cursor should then be moved to the Offset column
of the Channel Table, and to the row for that nearest channel. The offset should
be set to 0, and while the cursor is still on that field, RST_OFSET, should
be pressed. The Offset and RX1 locations for all ON channels will then be
reset. If the layout of the channels is reversed, press again to reverse the
order.
Note: Pressing will only affect channels that are ON therefore any channels that are
OFF will not have correct Offset values. Pressing at a later time, while the cursor is
again on the channel with the nearest electrode, will fix the situation. It is best to have all
channels ON.
RST_N-SPC This function will re-sequence the N values for channels above and below
the channel row that the cursor is on. Pressing repeatedly will toggle
between channel N-values increasing or decreasing, effectively shifting a spread
pattern above or below a transmitter location. The N-values will increment or
decrement by 1. The RX1 and RX2 values for all the channels will be reset based
on their N-value and the TX location. The Offset values for all the channels will
be reset based on their RX1 and RX0 locations. This also places the program into
the N-space mode for automatically updating electrode locations when RX0 or
TX locations are modified. This function is available while the cursor is in the
N-column of the Channel Table.
This method of setup is similar to the practice used for the GDP-32II.
The N-space method that the TDIP program uses to update locations is based on
the RX0: RX reference being the lowest numbered electrode for the dipole closest
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 42 October 2014
to the transmitting dipole (or pole). The channel N-values are the depth of
investigation for the channel which is equivalent to the distance between the
closest electrodes of the channel and transmitter.
For standard surveys, the pattern, or spread, of electrodes out from the receiver
does not change as the survey progresses. Channels may be turned on or off, but
unless the receiver itself moves, the electrodes do not, and when the receiver does
move, the pattern in which the electrodes are spread out remains essentially the
same. When the receiver moves to the opposite side of a transmitter, the lower
numbered channels must be arranged to be closer to the transmitter. The
transmitter electrode polarity must be changed.
The operator should first set the ARRAY type, S-space and TX locations, then
press RST_TX.
The RX0:RX location should be set to the lowest numbered electrode for the
dipole closest to the transmitting dipole (or pole). The cursor should then be
moved to the N-column of the Channel Table, and to the row for that channel
nearest the transmitter. The N-values should be set appropriately, and while the
cursor is still on that field, RST_N-SPC, should be pressed. The N-values
and RX1 locations for all ON channels will then be reset. If the layout of the
channels is reversed, press again to reverse the order.
Note: Pressing will only affect channels that are On, therefore any channels that are Off
when it is pressed will not have correct N-values. Pressing at a later time, while the
cursor is again on the channel nearest the transmitter, will fix the situation. It is best to have all
channels ON.
RST_OFSET EXAMPLE
To setup the TDIP program for the example spread below, the following steps can be followed:
Set ARRAY to D-D.
Set A-SPACE and Ft/M as required.
Set S-SPACE to 1.
Set TX: AX to 4, Set AY as required.
Press .
Set RX0:RX to 0.
Set Cmp Typ for Channels 1-6, to Ex.
Set Offset for Channel 3, to 0. DO NOT MOVE THE CURSOR.
Press . If the sequence of Offsets for the other channels are reversed, or the
RX1 values are reversed, press again. In this example the lower numbered
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 43 GDP-3224
channels are connected to higher numbered electrodes nearest the transmitter, but this
is not required.
<0909a_24TDIP_Setup_Spread_1_1>
<0909b_24TDIP_Setup_1_1>
After setting the other acquisition parameters, the GDP will be ready to acquire data.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 44 October 2014
When the transmitter electrodes are to be moved, use the following sequence of steps:
Set TX: AX to 3.
Note: The N-value for channel 1 has changed to 0, indicating that the channel is in conflict with
a transmitter electrode, and should be turned Off. The channel is not automatically turned off,
however an Error will be issued if an attempt is made to acquire data while the channel is on.
Turn off channel 1.
<0909c_24TDIP_Setup_Spread_1_2>
<0909d_24TDIP_Setup_1_2>
The GDP will be ready to acquire data.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 45 GDP-3224
When the receiver moves to stations “above” the transmitter, the operator could follow past
procedures, and turn around the receiver so that the lower numbered channels are still towards
the transmitter and reverse the transmitter polarity. For this example we will leave the channel
spread the same, the lower numbered channels will still be connected to higher numbered
electrodes. Channel and transmitter polarities do not need to change. Use the following steps:
Turn on channel 1.
Set RX0:RX to 8, because the receiver moved to that location.
<0909e_24TDIP_Setup_Spread_1_3>
<0909f_24TDIP_Setup_1_3>
The GDP will be ready to acquire data.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 46 October 2014
When the transmitter electrodes are to be moved, use the following sequence of steps:
Set TX: AX to 4.
Note: The N-value for channel 6 has changed to 0, this indicates that the channel should be
turned OFF. The channel is not automatically turned OFF however an Error will be issued if an
attempt is made to acquire data while the channel is ON.
Turn off channel 6.
<0909g_24TDIP_Setup_Spread_1_4>
<0909h_24TDIP_Setup_1_4>
The GDP will be ready to acquire data.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 47 GDP-3224
Note: An advantage to this method is that two receivers with similar spreads and setups, can
acquire data simultaneously on opposite sides of the transmitter without changing transmitter or
channel polarities.
The basic rules to remember are:
RX0 is the actual location of the receiver.
Offset is the distance between the receiver, RX0, and a channel's positive electrode,
not the distance to the center of the channel's dipole.
The channel whose positive electrode is at or nearest to the receiver, has the offset of
0, and RST_OFSET, is pressed while the cursor is on that channel, and in the
Offset column.
The positive electrode of a channel, is nearest the positive electrode of the transmitter.
When on the opposite side of the transmitter, the negative electrode of a channel, is
nearest the negative electrode of the transmitter.
The RX1 and RX2 electrode locations must be verified, as these values are used in
processing. These locations may be set directly, for special circumstances, after TX
and RX0 locations have been set.
RST_N-SPC EXAMPLE
To setup the TDIP program for the example spread below, the following sequence of steps
can be followed:
Set ARRAY to D-D.
Set A-SPACE and Ft/M as required.
Set S-SPACE to 1.
Set TX: AX to 4, Set AY as required.
Press .
Set RX0:RX to 1.
Set Cmp Typ for Channels 1-6, to Ex.
Set N for Channel 1, to 1. DO NOT MOVE THE CURSOR.
Press . If the sequence of N's for the other channels are reversed, or the RX1
values are reversed, press again.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 48 October 2014
<0909i_24TDIP_Setup_Spread_2_1>
<0909j_24TDIP_Setup_2_1>
After setting the other acquisition parameters, the GDP will be ready to acquire data.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 49 GDP-3224
When the transmitter electrodes are to be moved, use the following sequence of steps:
Set TX: AX to 3.
Set RX0:RX to 2.
Note: Changing RX0:RX at this point is not strictly required to obtain correct RX1 and RX2
locations, but will match the procedures of the GDP-32II.
Note: The N-value for channel 1 has changed to 0, indicating that the channel is in conflict with
a transmitter electrode and should be turned OFF. The channel is not automatically turned OFF
however an Error will be issued if an attempt is made to acquire data while the channel is ON.
Turn off channel 1.
<0909k_24TDIP_Setup_Spread_2_2>
<0909l_24TDIP_Setup_2_2>
The GDP will be ready to acquire data.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 50 October 2014
When the receiver moves to stations above the transmitter, the operator should follow past
procedures, connecting the channels to the receiver so that the lower numbered channels are still
towards the transmitter. The transmitter polarity should be reversed. Use the following steps:
Turn on channel 1.
Set RX0:RX to 5
Set N for Channel 1, to 1. DO NOT MOVE THE CURSOR.
Press because the channel sequence has been changed. If the sequence of N's
for the other channels are reversed, or the RX1 values are reversed, press
again.
Change the polarity of the transmitter electrodes.
<0909m_24TDIP_Setup_Spread_2_3>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 51 GDP-3224
<0909n_24TDIP_Setup_2_3>
The GDP will be ready to acquire data.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 52 October 2014
When the transmitter electrodes are to be moved, as in the next example, use the following steps:
Set TX: AX to 4.
Set RX0:RX to 6
Note: Changing RX0:RX, at this point, is not strictly required to obtain correct RX1 and RX2
locations, but will match the procedures of the GDP-32II.
Note: The N-value for channel 1 has changed to 0, this indicates that the channel should be
turned off. The channel is not automatically turned off, however an Error will be issued if an
attempt is made to acquire data while the channel is on.
Turn off channel 1.
<0909o_24TDIP_Setup_Spread_4_1>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 53 GDP-3224
<0909p_24TDIP_Setup_4_1>
The GDP will be ready to acquire data.
Note: As with the GDP-32II, the procedures can be altered so that two receivers can acquire
data simultaneously, on opposite sides of the transmitter, without changing transmitter or
channel polarities
The basic rules to remember are:
RX0 is the lowest numbered electrode for the dipole closest to the transmitting dipole
(or pole).
N-values are the depth of investigation for the channel which is equivalent to the
distance between the closest electrodes of the channel and transmitter.
The N-value for channel closest to the transmitter should be set as appropriate, and
, RST_N_SPC, is pressed while the cursor is on that channel, and in the N-
column.
The negative electrode of a channel, is nearest the negative electrode of the
transmitter. This may require reversing the polarity of the transmitter electrodes.
With special setups the positive electrode of a channel is nearest the positive
electrode of the transmitter.
The RX1 and RX2 electrode locations must be verified, as these values are used in
processing. These locations may be set directly for special circumstances, after TX
and RX0 locations have been set.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 54 October 2014
9.9 A NOTE ON SCALING
The following convention is used for all measured and calculated parameters:
Voltage (magnitudes) displayed in volts.
Current displayed in amperes.
Phase displayed in milliradians.
Apparent resistivity displayed in ohm-meters.
Dipole spacings displayed in meters.
SP displayed in millivolts
SEM displayed in milliradians
If scaling is necessary on these values, the following labels are appended to the end of the
number string:
M - Mega units
K - Kilo units
m - milli units
u - micro units
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 55 GDP-3224
9.10 ALGORITHMS
The equation used for calculating the time domain (see below) is the equation used in Swift
(1973). By inverting the negative half-cycle, chargeabilities are averaged over each cycle for the
specified number of cycles. The output will be in milliseconds or millivolt-seconds per volt.
This equation was originally given to Zonge by Newmont as the "Newmont Standard"
chargeability. Since that time it has been determined that this is not really the Newmont
standard, but it can be obtained by multiplying this "Zonge Standard" by 1.53. In order to reduce
confusion, we have retained the original chargeability definition, and convert to the Newmont
Standard (if desired) in our data processing programs.
For the "Zonge" standard at 0.125 Hz (8 second perod): 𝑀 =𝑇
8192∗1.87
𝑉𝑝∗ ∫𝑉𝑠
Where T is the cycle period of 8 seconds, 8192 is the number of points per cycle, and the integral
of the secondary (Vs) or off-time voltage is from 0.45 sec to 1.1 sec.
With 8192 points sampled per cycle, Vs is summed over 666 counts out of 2048 per quarter-
cycle. The 13 windows defining the off-time decay waveform are obtained on 148 ms intervals
at 0.125 Hz. The closest combination of windows to get an approximation of the chargeability is
a sum of windows 4, 5, 6, and 7. At 0.125 Hz this effectively integrates from 500 to 1100 ms,
which is 50 ms shorter than the standard window, so this approximation will always be slightly
lower than the Zonge Standard chargeability. The table below shows the following values for
the frequencies available in TDIP.
Freq SR NPts VpPnts MStrt MPts WStrt WPts
32 32768 1024 64 61 83 8 19
16 32768 2048 128 118 167 16 38
8 32768 4096 256 234 332 32 76
4 32768 8192 512 464 666 64 152
2 32768 16384 1024 925 1331 128 304
1 1024 1024 64 61 83 8 19
0.5 1024 2048 128 118 167 16 38
0.25 1024 4096 256 234 332 32 76
0.125 1024 8192 512 464 666 64 152
0.063 1024 16384 1024 925 1331 128 304
0.031 32 1024 64 61 83 8 19
0.016 32 2048 128 118 167 16 38
<0910a_24TDIP_WinPoints.txt>
SR A-D sampling rate, samples per second.
Npts Number points per cycle.
VpPnts Number points averaged for Vp.
Mstrt Starting point for summing Vs, for M.
Mpts Number of points to be summed for M.
Wstrt Starting point for first decay window, W).
Wpts Number of points to be summed for each decay window.
With Wi = Normalized decay point value in 10's of milliunits
= (Sum of Vs over the window interval Wpts)/(Vp x WPts)
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 56 October 2014
The chargeability, M = T/NPts x 1.87 / Vp x ΣVs / 10
where: T/NPts is , the digitization interval
1.87 is the Swift constant
Vp is the measured on-time voltage.
ΣVs is the summation of off-time voltages, MPts, from point Mstrt.
Reference: Swift, C.M., Jr, 1973, The L/M parameter of time domain IP measurements --- a
computational analysis, Geophysics, v 38, p 61-67.
TIME DOMAIN WINDOW TIMING INFORMATION
<0910b_TDIP_waveform>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 57 GDP-3224
9.11 SAMPLE MENUS FOR "LABROX" ARRAY
Selecting the ARRAY type, Lab, causes the fields in the Line Setup are of the Main Menu to
change. The TX and RX0 locations are replaces with SAMPLE ID, SAMPLE LEN and
SAMPLE AREA.
<0911a_24TDIP_Results_LabRox>
Channels 1 and 2 are customarily set as shown. Channel 1 (Ex) is the voltage across the rock
sample, Channel 2 (Ref) is the voltage across the decade resistance box or sense resistor.
Here the length, SAMPLE LEN, and cross-sectional area of the rock sample, SAMPLE AREA,
are input to the system for calculation of the resistivity of the sample. The SENSE is set to the
value of the current measuring resistor (typically a decade resistance box) that is set equal to the
resistance of the rock sample. SAMPLE ID is an informative alphanumeric field. S-space is not
used.
Use the CRES function key to get an approximate value for the rock resistance for setting the
shunt resistor.
The RESULTS screen displays the resistivity of the sample, in place of the Rho column, and the
channel Gain settings are also accessible for convenience.
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 58 October 2014
9.12 NOTES ON FIELD CONFIGURATIONS
When running multiple channel receiver systems, you must be very careful to avoid common
mode problems. Common mode effects are caused by lack of a reference voltage or level
(floating ground), or a reference level that exceeds common mode limits of the input amplifiers.
Common mode levels for the standard configuration of the GDP-3224
are 10 volts. With
isolation amplifiers, this level can be extended to several thousand volts, but in exchange one has
to contend with higher noise and a lower overall frequency response.
The best configuration that we have found is to install a REFERENCE ELECTRODE
(standard copper/copper-sulfate electrode or equivalent), connected to analog ground (COM on
the analog side-panel) and the case ground (CASE GND on the side panel), positioned next to
the receiver and at least one meter distant from the nearest receiving electrode. This also
provides maximum protection from static discharge and nearby lightning strikes.
Additional protection in lightning-prone areas can be afforded by using a galvanized iron plate
(or equivalent) as a REFERENCE ELECTRODE. This plate should be buried close to the
receiver in a hole that has been well watered and the soil mixed to make good mud contact with
the plate. Typical size for the plate would be 30 by 30 cm.
The following figures provide examples of receiver connections using the REFERENCE
ELECTRODE or REFERENCE POT connected to both analog ground (COM) and case
ground (CASE GND).
We have found that for most environments, the best noise rejection is obtained by connecting the
analog ground (COM) to the case ground (CASE GND) on the analog I/O side panel.
Note: The GDP-32II receiver has a captive jumper between COM and CASE GND for the
standard configuration.
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 59 GDP-3224
9.13 FIELD CONFIGURATIONS
GDP as Transmitter Controller with Reference Recording
In this application a GDP is used in place of an XMT to control the frequency of the transmitter.
At the same time, it is set up with one channel as the reference channel to record the transmitter’s
current waveform as a time series.
The reference GDP will continuously record the current reference while the receiving GDPs will
record whatever number of stacks are necessary to acquire good data.
All of the stacks are given a time stamp that records the time of the first sample in the time
series. When the data caches are processed, the time series segments from the receiving GDPs
can be lined up with the long TX reference time series.
Note: The GDPs must be synchronized either with GPS, or manually with a MULT/SY-32 SYNC
BOX in order to obtain an accurate time stamp in the cache. Refer to Section 6.2,
Synchronizing Timing Circuits.
In this way it doesn’t matter when the receiving GDPs are started and stopped, as long as the TX
reference GDP is also recording during this time.
WARNING: never connect the reference output of a transmitter directly to a GDP. An ISO Amp
must be used to avoid burning out the front end of the GDP analog circuitry.
<0913a_CR_TXREF_max_cycs>
Make sure Time Series is Yes.
Set up one of the channels as the Ref channel.
Turn all other channels OFF.
Set STACKS to 1.
Set SENSE resistor value. (Current will be calculated once first stack is taken)
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 60 October 2014
Set GAIN to MAN
Manually set the gain to 00-0.
Set the frequency.
Before transmitting, take one stack with a few cycles to allow GPS sync to occur.
Now you can get the transmitter transmitting and adjusted.
Take one stack with a few cycles so the reference current will be calculated.
Verify the magnitude is not saturating (around 2V). If it is, put in a -1 or a -2
attenuation to bring it below 2V.
Use the Scope view to verify the magnitude and that the SP Offset is centered. Manually
adjust the SP as needed.
Move to Cycles field. Press until the maximum number of cycles is reached.
<0913b_CR_TXREF_Scope_SP>
Note: Press to activate and de-activate the Scope while the cursor is on the channel to
be viewed.
Note: The TIME field displays the maximum amount of time the reference waveform can be
recorded for each stack.
WARNING: Whenever the frequency has changed it is best to take one stack with a small
number or cycles without the Transmitter transmitting. Whenever the frequency has changed,
the first stack will do a GPS sync. During the GPS syncing process, the TX frequencies will
change abruptly.
At this point, the GDP is ready to acquire the TX current reference waveform time series. The
GDP gain and SP has been set up. Once a receiving GDP is ready, the Transmitter should be
Home
SELECT UP
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 61 GDP-3224
running with the same settings used during setup. The current shown on the GDP should be
close to the TX reading, but does not need to be exact. That is why the Current Reference
waveform is being recorded. You should start collecting data with this TX reference GDP first,
before the receiving GDP. This GDP should be continuously recording the entire time a
receiving GDP is collecting stacks. It should only be stopped when the receiving operator is
ready to change frequencies.
NOTE: It is best to Archive the cache before taking each long time series.
Press to start recording the TX Reference Time Series.
<0913c_CR_TXREF_ProgBar>
Notice the Progress Bar. It indicates how much longer the GDP can collect the continuous time
series. In this case, there are about 29 minutes remaining. If the receiving GDP cannot finish its
stacks in this time, it is best to stop this time series, archive the cache, and start again.
Press to stop recording the TX Reference Time Series.
Press to save the data in the cache file.
Enter
Escape
Enter
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 62 October 2014
GDP Setup for Resistivity, TDIP, RPIP, nrCR
<0913d_Setup_IP_GDP_nr>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 63 GDP-3224
GDP Setup with Roll-Along Cable: Resistivity, TDIP, RPIP, nrCR
<0913e_Setup_IP_GDP_ra>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 64 October 2014
Transmitter Setup: TDIP, RPIP, nrCR
<0913f_Setup_IP_Tx_set>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 65 GDP-3224
Transmitter Setup With Current Reference
<0913g_Setup_IP_Tx_REF>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 66 October 2014
Receiver Setup With Current Reference
<0913h_Setup_IP_GDP_ref>
TIME DOMAIN INDUCED POLARIZATION PROGRAM
October 2014 Section 9, Page 67 GDP-3224
Laboratory Rock Measurement Setup
<0913i_Setup_Lab>
GDP-3224 INSTRUCTION MANUAL
GDP-3224 Section 9, Page 68 October 2014
Alternate Laboratory Rock Measurement Setup
<0913j_Setup_Lab_alt>