Guideline Geo ABEM Terrameter LS 2 User manual

ABEM Terrameter LS 2
ELECTRICAL RESISTIVITY
Quick guide for 4-cable 48 & 64 electrode systems
For more detailed and in-depth instructions regarding proper usage of the instrument, please consult the ABEM Terrameter LS 2 User Manual .
The current and voltage transmitted can be life threatening. The emergency button must
be engaged while working with connected cables and electrodes. Before starting ANY
measurements, ensure survey cables and electrodes are not being handled or touched.
Keep connectors dry and clean. Poor connector handling and maintenance are the
main causes of cable failure. Always interconnect dust caps to keep them clean and
dry during measurements (right).
LAYOUT PROCEDURE
A. Setting-up for survey
- Measure a straight line along the ground. Profile length
= (no. of electrodes – 1) * electrode spacing.
- Hammer electrodes vertically into the ground along
survey line (depth < 1/10 of the electrode spacing).
- Place Take-out 1 of Cable 1 adjacent to the first
electrode in the spread. Walk cable reel 1 along the
survey line until all take-outs on the cable are aligned
with an electrode.
- Next, place Take-out 1 of Cable 2 at the next available
electrode. Walk cable reel 2 along survey line until all
cable take-outs are aligned with an electrode.
- Repeat with Cables 3 & 4. The last take-out (highest
number) on Cable 4 should coincide with last electrode.
- NOTE: If the electrode spacing
is much smaller than the cable
take-out spacing, avoid
coiling and excessive
overlapping of spare cable
between the take-outs (right).
- Take-out numbers should always increase along profile.
- TIP: To avoid confusion when processing results, profiles
should run in southerly-to-northerly or westerly-to-easterly
direction.
- Finally, place the ABEM Terrameter LS 2 instrument and
external battery in the middle of the survey line (between
Cable 2 and Cable 3).
B. Connecting and powering the system
-Press the emergency stop button in; this should be
the case whenever handling the cables / electrodes.
-Use cable joints to connect Cable 1 & 2 and Cable 3
& 4. Important: cable joints are directional. Ridges
on the cable joints should be towards the instrument.
-Connect jumper wires between cable take-outs and
electrodes (preferably connected to upright section).
-Put Cable 2 into Connector 1, and Cable 3 into Connector 2
on the instrument end panel.
-Using the external power cable, connect the instrument to
an external 12V car battery.
-Press the power button on the instrument to start.
Clicking noises will be audible during this start-up as
the instrument exercises the relay matrix.

USER INTERFACE AND KEYBOARD FUNCTIONS
A. Welcome View & Screen Features
B. Keypad Functions
-An external keyboard can be attached to the USB
port on the end panel of the Terrameter, however
full operation can be achieved very easily using just
the front panel keypad.
-When using an external keyboard, the following
relationship between external keys and keypad
functions can be used:
F10 = Play/Pause
F11 = OPT
F12 = Power button
ALT = Menu
TAB = Browse
ESC = Clear
ENT = OK
PROJECT AND SETTINGS
A. Create Project & Task
-From the ‘Welcome’ view, use the Browse key to navigate to the
‘Project List’ view (one tab to the right).
-Select < Create New Project >. The ‘Task List’ automatically
displays.
-Select < Create New Task >. A pop-out window will prompt
selections for task settings.
-Use the Up/Down arrow keys to navigate to each option within
the screen and Left/Right arrows to select the spread and
protocol.
-Spread: Select 4x12 (48 electrode system) or 4x16 (64
electrode system).
-Protocol: Choose electrode array.
-Next, input Minimum Electrode Spacing X [m] by highlighting
the option and pressing the OK key. The virtual keyboard will
open. Enter the correct electrode spacing and press the OK key
to exit. (It does not matter what values are in the Y and Z
electrode spacing for these 2D measurements).
-Select < OK > to exit pop-out window and automatically move to
settings.

B. Receiver & Transmitter Settings
-Settings are most often dictated by geologic/field conditions, instrument capabilities, and personal preference.
-To use pre-loaded instrument settings, navigate one tab to the left (‘Load/Save Settings’ view). This tab will allow you to load
and view recommended ‘starting’ settings for various types of surveys.
Receiver Settings
oMeasure mode: Select desired measurement mode:
“Res” = resistivity measurements
“Res, IP” = resistivity and traditional 50% duty cycle IP measurements
“IP 100%” = resistivity and novel 100% duty cycle IP measurements.
oStacking & Error limit:For “Res” or “Res,IP” mode this is number of
repetitions to improve data quality; maximum will be either the chosen
value or when the resistivity error drops below the percentage limit. For
“IP100%” mode, the maximum category defines how many current
polarity ‘switch-overs’ there will be (this is when the IP effect is recorded),
it always does that many switch-overs regardless of resistivity data quality.
oDelay & Acq. Time:defines total ‘current on’ time, a longer delay will avoid
IP effects, longer acquisition times average out noise better.
oIP Windows:Rely on pre-loaded settings for IP parameters.
oFull Wave Form:In addition to the single averaged data values measured at each location, choose this option to map the
full output and input current and voltage patterns during the measurement cycle. Does not increase measurement time
but creates bigger project files.
oPower line frequency:Select the power line frequency, based on region/location of survey (either 50Hz or 60Hz).
oSample rate:Define how often the output current/voltage and input voltages are recorded for creating the full wave form.
Transmitter Settings
oMinimum & Maximum settings: Maximum values will limit the instrument
output; minimum values do not force that amount for current / voltage /
power to be used (actual values are based on ground conditions) but
instead they provide a warning if the values fall below this threshold.
oElectrode Test: Choose ‘Focus One’, this allows the instrument to test the
contact resistance and connection of each electrode on the survey line.
oBad & Fail electrode: Select threshold for classifying each electrode
during the electrode test. Values below “bad”, count as a pass (low
contact resistance).
oElectrode test current:Do not change.
oLoad variation margin:Defines how much the instrument can vary the
settings during measurement to maintain constant current – set to 10%.
MEASUREMENTS
A. Measurement Configuration
-Navigate to the ‘Progress’ view.
-< SAFETY SWITCH STOP > indicates emergency stop button is in use.
-Select < Create New Station (Roll Along) >. A pop-out window will open.
-Station position is location of first electrode – this is displayed in electrode position rather than distance; this means the
Station Positions. (In electrode positions not distance); check spread extent reflects the correct length of survey line.
-Select ‘4 cables no move’ and exit pop-out window by selecting < OK >.
-Caution:Before beginning measurements, check the survey line and ensure the area is clear.
-Turn the emergency stop button until it pops out. Then, select the < Start Measuring > message.
-A warning message will appear. Select <OK> to accept and continue.

B. Electrode Contact Test
-The instrument will begin the electrode contact test prior to taking any measurements and will only test the electrodes
required to complete the next phase of measurement.
-Electrode Test Pass:If all electrodes pass, the instrument will begin survey measurements automatically.
-Electrode Test Fail:If the electrode test fails, the instrument will wait for further user instruction. The ‘Progress’ view will
display a message, “Electrode test FAIL (OK: XX, Bad: XX, Fail: XX)”, indicating how many electrodes were good, bad, or
failed based on the threshold settings.
-Push emergency stop button prior to handling cables/electrodes.
-Navigate to the ‘Electrode’ view. This tab displays a table detailing the
results of the electrode contact test.
-Pay attention to columns ‘S’ (special instructions given to a cable or
electrode), ‘Takeout’ (which indicates cable # - takeout #), and ‘Ohm’
(measured contact resistance and a corresponding notification).
-Identify all electrodes that have a ‘Bad’, ‘Fail’, or ‘No Contact’
notification in the ‘Ohm’ column (consider increasing the threshold if
most electrodes are ‘Bad’, with similar contact resistance values).
-Locate the problem electrodes on the survey line.
-First, check jumper wires are firmly connected to the electrode and
take-out. Next ensure that electrodes are well grounded (hammer
deeper, reposition slightly, add water, double-up electrodes etc.).
-Release the stop button and restart measurement (either from
Progress tab or by pressing the Play/Pause button). This will automatically retest all the ‘Bad’, ‘Fail’, or ‘No Contact’
electrodes. This will NOT retest electrodes that have already passed.
-After retesting, the instrument will either begin the survey or produce another failed message.
-In case of another fail, repeat the process of locating poor electrodes and attempting to improve their grounding.
-Retest the electrodes after each improvement. Repeat the process, until the electrode contact test passes.
-Note In some cases, it may be necessary to exclude or force the use of individual electrodes which can be done manually
or by choosing an automatic option such as excluding all ‘Bad’ electrodes from the popup menu (accessed by pressing the
OPT key). It is also possible to exclude a whole cable through the pop-up menu. Any excluded electrodes will have an “X”
next to them in first column; those which are forced to be used despite failing the electrode test will have a “U” adjacent to
them.
-When deciding to exclude electrodes, use the Status column to see the impact it will have on the final dataset; the “AB”
count is how many times that electrode will be used for current injection, the “MN” count is how many times it will measure
voltage.
C. Measurement Progress
-Navigate to the ‘Resistivity Results’ view to monitor real-time measurements.
-The table displays channel number, electrode pairings used for measurement (cable#- electrode#), measured quantity
(voltage or current), normalized standard deviation (variation coefficient), resistance, apparent resistivity and, if applicable,
chargeability (IP) from the first-time window (as this is the one at risk of spiking from the current switch-off). The bottom
row reports the final transmitter output voltage and current.
-Watch for high standard deviations, excessive negative IP values and/or error messages that may appear during survey.
-The measurement progress is shown on the left side of the status bar (described by how many measurements are
complete out of the total number of station measurements). Compare this with the “Cables in use” notation on the
‘Progress’ tab, which will tell you if any of the 4 cables are no longer needed.
-When measuring is complete, a ‘Measuring Done’ message will appear in both the ‘Progress’ view and the status bar.
FILE MANAGEMENT
-The most effective way to download data is through the PC companion software ABEM Terrameter LS Toolbox, via ethernet
or Wi-Fi connection. Refer to the ABEM Terrameter LS Toolbox user manual for more information.
-To download data using a USB storage device, insert the device into the USB port on the end panel of the instrument and
wait a few seconds for USB device to be recognized and read.
-Note You cannot download data (projects or tasks) that are open to USB. The currently active project and task is shown in
the upper-right corner of the screen. To change active projects/tasks, open a different pre-existing project/task or create a
new project/task.
-USB Project Download: Navigate to the ‘Project List’ view.
oHighlight the project and press the OPT key. A smaller pop-out menu screen will appear. Select “Export Project” (if
grayed out, ensure the project is inactive and the USB device is in the USB port).
oSelect < Yes > when prompted to export the project to the USB. Note The project database file is required for
opening data in ABEM Terrameter LS Toolbox and undertaking quality assurance procedures and filtering.
-USB Task Download:Navigate to the ‘Project List’ view and open the project containing the task(s). Ensure the task is
inactive.
oHighlight the task and press the OPT key. Select the file format preference, then select < Yes > to export.
oWhen data are downloaded, take out the USB memory device from the USB port.