Geometrics MetalMapper 2x2 User manual

MetalMapper 2x2
Operations Manual
Revision 2.1
P/N 0071740-01
GEOMETRICS, INC.
2190 Fortune Drive
San Jose, CA 95131 USA
Phone: [phone]
Fax: [phone]

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Table of Contents
BATTERY SAFETY ............................................................................................................................. 3
1. Introduction .............................................................................................................................. 4
2. System Overview......................................................................................................................... 5
2.1 Data Acquisition Electronics and Software ....................................................................... 6
3. System Setup............................................................................................................................... 7
3.1 Cart Assembly .................................................................................................................... 7
3.2 GPS/IMU Tower ................................................................................................................. 9
3.3 Data Acquisition Electronics Backpack ............................................................................ 11
3.4 Cable connections............................................................................................................ 12
3.5 Batteries........................................................................................................................... 14
3.6 Skid steer mode ............................................................................................................... 15
4. Quick Start Guide ...................................................................................................................... 17
4.1 System connection .......................................................................................................... 17
4.2 System Configuration ...................................................................................................... 19
4.3 Parameter Setup.............................................................................................................. 20
4.4 QC Settings....................................................................................................................... 22
4.5 Survey Window................................................................................................................ 22
4.6 Measurement Types........................................................................................................ 25
4.7 Sample Project File .......................................................................................................... 25
5. Sensor QC Features................................................................................................................... 27
5.1 Static Function Test (SFT) ................................................................................................ 27
5.2 Dynamic Function Test .................................................................................................... 30
5.3 Reference SBG ................................................................................................................. 30
6. Static and Dynamic Measurements .......................................................................................... 32
6.1 Static Measurements....................................................................................................... 32
6.2 In-Field Inversion ............................................................................................................. 33

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6.2 Dynamic Measurements.................................................................................................. 36
7. Instrument Settings................................................................................................................... 37
7.1 Application.properties file............................................................................................... 37
7.2 IMU Overview.................................................................................................................. 39
7.2 Calibrating the IMU ......................................................................................................... 39
7.3 GPS Configuration............................................................................................................ 39
7.4 Using a Robotic Total Station (RTS) or other external device ......................................... 40
8. Data File Format........................................................................................................................ 41
8.1 HDF5 files and export ...................................................................................................... 41
9. System Diagnostics and Troubleshooting................................................................................. 52
10. Storage and Maintenance....................................................................................................... 54
10.1 Lithium Ion Battery Shipping Guidelines for Customers ............................................... 54
10.2 Packing the Shipping Crate ............................................................................................ 55
Appendix I: Standard Inventory List.............................................................................................. 60
Appendix II: Theory of Operation ................................................................................................. 61
Appendix III: Application.properties file ....................................................................................... 63
Appendix IV: Importance of Valid Background Measurements ................................................... 65

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BATTERY SAFETY
WARNING- Do not damage the rechargeable Lithium Iron Phosphate batteries. A damaged
battery can cause an explosion or fire, and can result in injury or property damage.
Do not use or charge the batteries if they appear to be damaged. Signs of damage may
include punctures, leaks, or warping.
Do not expose batteries to fire or prolonged high temperatures.
Do not immerse the batteries in water.
Do not drop or puncture the batteries.
Do not open the batteries or short-circuit the contacts.
Discontinue using or charging the batteries if they give off strong odor or extreme heat.
Charge the batteries only with approved chargers.
See Chapter 10 of this manual for Shipping Information.

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1. Introduction
This manual is a User’s Guide for the Geometrics MetalMapper 2x2 geophysical instrument
used for the detection and characterization of Unexploded Ordnance (UXO). This instrument is
based on the Naval Research Laboratory TEMTADS MP 2x2 Cart system developed over the past
several years.
The system uses time domain electromagnetic (TDEM) principles to induce electrical currents in
buried metallic objects and then measures the effects of those currents in receivers on the
surface. It has four (4) co-planar transmitter coils placed in a 2 by 2 square. Each transmitter
coil is approximately 35 cm x 35 cm in size. Located in the center of each transmitter coil is a 10
cm x 10 cm x 10 cm receiver cube, each one containing three (3) orthogonal coils to measure
the fields resulting in 12 different receiver coils. The receiver coils are oriented in 3-dimensions.
The transmitter coils are powered using a bi-polar half duty cycle and the time decay of the
subsurface currents (transients) are measured during time off of the transmitter coils.
The MetalMapper 2x2 can be used in two collection modes, dynamic or static. Dynamic mode
is collected by pushing the cart over targets in a series of closely spaced parallel lines.
Navigation features in the software direct the user to stay on the correct path. Static mode is
collected by moving the instrument over predefined targets from an anomaly list. This
anomaly list can be derived from the results of a dynamic survey, or from another previous
geophysical survey (EM61-MK2 for example).
Data is collected and stored in a HDF5 file format. This format is self-describing and easy to
read and edit with many available free software packages. This manual does not cover any
post-processing of the HDF5 files to invert the data and identify the buried metallic objects.

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2. System Overview
The MetalMapper 2x2 is comprised of four transmitter coils approximately 35 cm x 35 cm in
size. Located in the center of each transmitter coil is a 10 cm x 10 cm x 10 cm receiver cube,
each one containing three (3) orthogonal coils to measure the fields resulting in 12 different
receiver coils. The receiver coils are oriented in 3-dimensions. The center-to-center distance of
each receiver cube is approximately 40 cm. The sensors are mounted on a platform that is
typically 26 cm above the ground surface. A GPS and IMU (inertial measurement unit) are
mounted on a tower centered above the sensor platform. The transmitter electronics and
batteries are mounted on a backpack carried by the operator. The system is operated from a
tablet computer running the MetalMapper software.
Figure 2.1: Cart layout showing naming convention of A, B, C, D transmitter coils and receiver
cubes. X, Y, and Z coordinates are positive in the directions shown.

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Figure 2.2: Sensor platform with top cover removed. Sensor platform fully assembled.
2.1 Data Acquisition Electronics and Software
The data acquisition electronics and batteries are mounted on a backpack worn by one of the
operators. The electronics are connected to the cart by 3 cables: Tx Cable, Rx Cable, and
GPS/IMU Cable. The second operator controls the system from a tablet computer running the
MetalMapper software and connected to the electronics via an Ethernet cable. Navigation is
directed by the software.

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3. System Setup
The MetalMapper 2x2 system is packed and shipped in a collapsible plastic crate (P/N MM2x2
Crate) secured with banding. The crate dimensions are 48 in x 44 in x 36 in with a packed
weight of approx. 350 lbs. (shipping weights and dimensions may vary). Foam inserts are cut to
protect and secure the instrument during shipment. See Chapter 10 for more information on
packing and unpacking the system from the shipping crate.
3.1 Cart Assembly
The 4 transmitter coils (Tx) and 4 receiver cubes (Rx) are attached to the sensor platform with
plastic bolts. These items should not be removed or replaced unless instructed to do so by the
project geophysicist. The Rx cubes and Tx coils are covered by a piece of plastic attached to the
sensor platform. The cover should remain attached under most conditions. There is a cable
connection facing the rear of the sensor platform. The sensor platform cover should not be
removed without consulting Geometrics for instructions on how to remove it without damaging
the cable connection.
The axles are attached to the sensor platform with the axle mounting brackets. Slide the axles
through the brackets. Attach the wheels and spacers to the axles as shown below. There are 3
plastic spacers and 1 washer placed on the axle between the wheel and the hub. The wheel can
be secured to the axle on the outside with the small nut and bolt included, or with an optional
zip-tie.

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Figure 3.1: Axles with wheels and spacers installed. Note optional zip ties to secure wheels.
Take care to avoid getting debris inside the wheel hubs and axles. Wheels and axles should be
periodically checked for debris and cleaned to prolong the life. The wheels do not need
lubrication during normal operation.
The cart handle will ship preassembled and only needs to be attached to the cart. The
mounting brackets have different mounting holes depending on the desired height of the
handle
.
Figure 3.2: Handle attachment

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3.2 GPS/IMU Tower
The GPS and IMU are installed on a 4-legged tower which is centered above the middle of the
sensor platform. Assemble each leg of the tower as shown below:
Figure 3.3: GPS tower legs
The GPS sits on the mounting bolt which is standard 5/8”-11 threaded nylon rod. The numbers
on the GPS tower legs must be installed so the number is right-side up. The legs are
interchangeable so the number positions do not matter. The height of the GPS above the
sensors is set using the GPS thread sheath attachment as shown below. It is helpful to use 2
nuts on the underside of the GPS tower rod and sheath to prevent the tower from loosening
during operation. The default height is set in the applications.property file. If this height is
changed from factory default see Chapter 7 on how to adjust the applications.properties file.

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Figure 3.4: GPS Platform Installed. Note the tapered corners point in the direction of travel.
The IMU is mounted in a weather-resistant housing. It sits on the underside of the platform
below the GPS and is centered above the sensor cart. The IMU is designed to only be installed
with the correct orientation. The 3 bolts are in a triangular arrangement which secures the IMU
to the platform ensure that the IMU is oriented correctly. The IMU box is secured to the shelf
with small plastic nuts that screw into the permanent bolts on the IMU box. The tapered edge
of the GPS platform must face in the direction of travel.

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Figure 3.5: IMU Installation. The IMU is mounted on the underside of the GPS platform.
3.3 Data Acquisition Electronics Backpack
The electronics which control the data acquisition are housed in a weather-resistant orange
Pelican case. The electronics housing box has 5 external connections- Rx cable, Tx cable,
GPS/IMU cable, power, and Ethernet. The housing and cable connectors are designed to be
water resistant. The electronics are cooled by the external heat sink fins. This heat sink needs
to be exposed to the air and not covered by clothing or other equipment.
Figure 3.6: Backpack with Electronics and Batteries Mounted

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Figure 3.7: Electronics box mounting brackets
3.4 Cable connections
The MetalMapper 2x2 is typically supplied with 2 complete sets of different length cables. The
shorter (9 foot) set is used with the system in walking mode, while the longer set (20 foot) is
used with the instrument in skid-steer mode and as spares. The Tx and Rx cables connect to the
cable junction housing on the rear of the cart. The cables are not reversible. Ensure that the
notches on the connectors are aligned before trying to tighten the connections.
Figure 3.8: Transmitter Tx and Receiver Rx Cable Connections
The electronics box is mounted to the backpack
with top and bottom mounting brackets. The
brackets are designed to hold the box so the
handle is down and heat sinks are facing both
up and outwards. These brackets can be left
on for storage and shipment, but if the box
needs to be removed see below:

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The GPS serial output connects to the IMU box. Use the GPS system’s own serial cable to
connect the GPS to the DB-9 serial port on the IMU box. On the other side of the IMU box,
connect the IMU cable to the round connector. The IMU cable is reversible so it does not
matter which side is connected to the electronics box and which side is connected to the IMU
box. The dust cap is used to protect the connectors during shipment and storage, but please
remove these and place them away from the sensors during operation.
Figure 3.9: GPS cables input on IMU box. IMU cable output on opposite side.
The electronics box is connected to the field tablet computer via the ruggedized Ethernet cable.
The Ethernet cable plugs into the top of the field tablet and the side of the electronics box. In
the event the cable is damaged, any Cat 6A or Cat 7 Ethernet cable with RJ45 connectors can be
used as a replacement. Note that Cat5e or lower will not work with the instrument as the
throughput is not high enough.
Figure 3.10: Side of electronics box showing Battery cable, Ethernet cable and GPS/IMU cable

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3.5 Batteries
The system is powered by an assembly of two Li-FePO (Lithium-Iron Phosphate) batteries. The
batteries are connected in via a custom cable which allows for easy swapping and charging of
the batteries. The system is available with a large battery pack (22Ah) or an optional small
battery pack (10Ah).
Battery
Rate of Discharge (hours)
# of static
measurements
Battery pack dimensions
Dynamic
Static
Weight
LxWxH
Small (10Ah)
3.0
6.0
175
6.0 lbs.
6.3”x5.3”x4.5”
Large (22Ah)
7.5
12.5
360
16.0 lbs.
8.5”x7.0”x8.5”
The battery pack is housed in the pouch on the backpack. The battery cable connects to the
electronics box via the power cable. The fuses are standard 20A automotive fuses. If the
batteries will not charge or will not power the electronics box, check for blown fuses. Fuses are
20A automotive fuses. In the case that fuses continue to be burned out repeatedly please
discontinue use of the battery pack and contact the factory for further instructions. For
shipping instructions please refer to Chapter 10. For battery MSDS please see the appendix.
Figure 3.11: Battery pack and cable

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To charge the batteries please use the charger supplied. It will need 2 power outlets as each
battery is charged separately. Total charging time is approx. 4 hours. See instructions on
charger for indicator lights explanation.
Figure 3.12: Battery Chargers
3.6 Skid steer mode
The MetalMapper 2x2 can also be deployed via a vehicle-mounted skid-steer. Customers will
need to design or build their own skid steer as Geometrics no longer offers this option To use
the MetalMapper 2x2 with the skid-steer attachment, remove the wheels and axles from the
sensor platform. Foam may need to be added to the instrument bucket to achieve a ~ 20 cm
sensor height off the ground.

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Figure 3.13: Example Skid Steer Attachment

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4. Quick Start Guide
Assemble the sensor cart, electronics box, and GPS/IMU as described in Chapter 3. The
electronics box will start-up upon connecting the power. Connect the field tablet computer via
the Ethernet and launch the MetalMapper 2x2 software. The software is on the desktop as
MetalMapper with a Geometrics logo icon. Launch by double clicking the icon. The software
will prompt the user to accept the EULA and confirm the Instrument Serial Number. Note that
many of the settings can only be changed by editing the application.properties file. More
information on that is given in Chapter 7.
4.1 System connection
The software will connect to the electronics via Ethernet in about 45 seconds. During this time
the software will display “Waiting” in the status window in pink. There will be no position
indicated nor coils displayed in the other status windows.
Once the hardware and software are successfully communicating, the status window will
display “Ready” in blue.

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The status window is always shown in the software. From left to right it indicates: date and
time from the computer’s clock, event log, GPS fix quality indicator, and position and IMU
information.
GPS fix information is parsed out of the NMEA string. The first number displayed is the GPS
quality. Status of 2 indicates GPS position without RTK correction. Status of 4 indicates GPS
position with RTK correction. When GPS status 4 (RTK) is being collected a picture of a satellite
will appear. The second number is the number of satellites used. Clicking on the GPS status
window will display the entire NMEA string that is being read by the software.
(Example of GPS information with no RTK information.)

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YPR indicates Yaw (magnetic heading), Pitch, and Roll, in degrees, from the IMU. The Yaw is
corrected for magnetic declination. The magnetic declination is automatically calculated once
the GPS is connected to the software through a magnetic declination look-up table.
4.2 System Configuration
When the software is successfully communicating with the electronics, navigate to the Project
Settings tab in the Control window.
Host Software: Displays the acquisition software version.
Ambient AC Frequency: Select Powerline Frequency for noise cancellation (60 Hz in US or 50 Hz
in Europe and China).
Swath width:Width of dynamic swath displayed on the navigation window display.
Data directory: Indicates where the collected data will be stored on the computer. Note that
each Project will create a new directory under the main directory, and each GeoID will have its
own directory within the project directory. This default data directory can be edited in the
application.properties file.
GPS: Ensure the GPS string type and baud rate is correct in the application.properties file.
GPGGA is the default.