MALA MIRA User manual

MALÅ MIRA System
Operating Manual v. 1.1
19-001034

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Table of Contents
___________________________________________________________________
Table of Contents 2
1 Introduction 3
1.1 Unpacking and Inspection 4
1.2 Repacking and Shipping 4
1.3 MALÅ Geoscience Indemnity Clause 4
1.4 Important information regarding the use of this GPR unit 4
2 System components 5
2.1 The ProEx control unit 6
2.2 The MIRA option 6
2.3 Antennas 8
2.4 Positioning systems 9
2.5 Accessories 11
3 System set up 14
3.1 Antenna array 14
3.2 ProEx control unit and MIRA option 15
3.3 Antennas 16
3.4 Power 17
3.5 Computer 18
3.6 Positioning system 18
3.6 Remote Control 19
3.7 Others 21
4 Data acquisition 24
4.1 Planning the survey 24
4.2 Data collection 26

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1 Introduction
___________________________________________________________________
Thank you for purchasing the MALÅ Imaging Radar Array, the MIRA System. The MIRA system
enables any combination between the individual receiver and transmitter antennas used in the array.
The separate transmitter and receiver antennas can be combined into one single antenna array unit
tracked and positioned by a total station or RTK GPS for precise positioning. Operated in default
mode, this will give parallel swaths of dense and exactly positioned GPR data, which may be
seamlessly loaded into the processing software. The results, produced by the rSlicer software, are
seamless 3D pictures of the subsurface, with a high-resolution of subsurface features both in
horizontal and vertical direction.
The MIRA systems are designed with new technology and protected by new patent applications,
meaning that the compatibility with old array systems have been taken away, both for hardware and
software.
We at MALÅ Geoscience welcome comments from you concerning your experiences in using this
equipment, as well as your impressions of this manual. Please take the time to read through the
instructions carefully and address any questions or suggestions to the following:
Main Office:
MALÅ Geoscience AB
Skolgatan 11
S-930 70 Malå
Sweden
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
Technical support issues can be sent to: [e-mail]
Information about the products from MALÅ Geoscience is also available on Internet:
http://www.malags.com

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1.1 Unpacking and Inspection
Great care should be taken when unpacking the equipment. Be sure to verify the contents shown on
the packing list and inspect the equipment for any loose parts or other damage. All packing material
should be preserved in the event that any damage occurred during shipping. Any claims for shipping
damage should be filed to the carrier. Any claims for missing equipment or parts should be filed with
MALÅ Geoscience.
1.2 Repacking and Shipping
If original packing materials are unavailable, the equipment should be packed with at least 80 mm of
absorbing material. Do not use shredded fibres, paper wood, or wool, as these materials tend to get
compacted during shipment and permit the instruments to move around inside the package.
1.3 MALÅ Geoscience Indemnity Clause
Operators of MALÅ MIRA system or other GPR systems shall hold harmless, defend, and indemnify
MALÅ Geoscience from and against any and all losses, liabilities, damages, injuries, claims, demands,
costs and expenses or claims including claims by third parties arising out of the use or possession of
the MALÅ MIRA GPR system.
1.4 Important information regarding the use of this GPR unit
According to the regulations stated in ETSI EN 302 066-1 (European Telecommunication Standards
Institute): - The control unit should not be left ON when leaving the system unintended. It
should always be turned OFF when not in use.
- The antennas should point towards the ground, walls etc. during measurement
and not towards the air.
- The antennas should be kept in close proximity to the media under
investigation.

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2 System components
___________________________________________________________________
In short the MIRA system comprises the following parts (see Figure 2.1):
- Antennas, separate transmitters and receivers antennas with the centre frequencies of
200MHz, 400MHz or 1.3GHz.
- The antennas are preferably placed in a special antenna box for deployment of the system.
- The MIRA option. The standard configuration is equipped with 16 channels but can be
customized for any number of channels up to 31.
- A modified ProEx control unit.
- A positioning system, Total station (ATS type) or RTK GPS.
- A Windows based computer to collect, save and process data, with data acquisition
(MIRASoft) and processing (rSlicer) software
- Suitable vehicle or arrangement (with antenna array on wheels for moving).
- Power supply for the ProEx control unit and the antenna array, 12V.
These different parts are explained in more detail below.
Fig. 2.1 The MIRA system, with the antenna array on a vehicle (A) and the positioning system (self-
tracking Total station) (B).
The following definitions are used:
Trace= The recorded radar signal from one channel at one point. An envelope built up by a certain
number of samples.
Point distance = Distance between each trace collected for all individual channels.
Sample= Instant, digital value of recorded radar signal at one specific time.
Stacks= Number of averages for each trace
Swath= One complete profile line including all channels in the array. The coverage for every swath
depends on the individual channel spacing times the number of channels.
A
B

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2.1 The ProEx control unit
The ProExTM control unit (Fig. 2.2) is a general tool for controlling data acquisition with various GPR
systems. In its basic configuration it operates all kinds of antennas, shielded, unshielded, borehole etc.
More on this can be read in the ProEx operating manual.
The ProEx main unit communicates via a fast Ethernet link with a PC. In the MIRA system the ProEx
control unit will operate more or less as a slave. Its main task is to keep track of the position along the
profile and collect data at equidistant points.
Fig. 2.2 The ProEx control unit.
The leading thought behind the design of this unit is modularity and data throughput, the latter being
very important in conjunction with the array option. In order to handle the data stream, each data
channel has its own processor taking care of the reading, stacking, buffering and transfer of data. This
will ensure undisturbed data throughput, regardless of the number of channels used. Internally this is
implemented via a distributed design with multiple controllers, each taking care of its own data stream
and communicating with the master controller via dual port memories.
In this design, the master controller is mainly managing the flow of data to/from the distributed
controllers. The design also lends itself to expansion to any number of data channels, a fact used in
the array option design.
ProEx standard units are not configured for the array option, if not asked for at time of purchase. In
order to be able to control an array option/module the base unit must be equipped with connectors on
the back side, see Figure 2.3 below.
Fig. 2.3 The back-side of a ProEx unit configured for array-use.
2.2 The MIRA option
The design supports arrays of up to 31 receivers and transmitters, making it the most versatile array
option on the market.

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The array option connects to the main ProEx unit by means of two 25-DSUB connectors, see Figure
2.4 below. It is powered from the main unit and has no external power connector.
Fig. 2.4 Connectors for attaching the MIRA option to the main ProEx unit.
One side of the array option has coaxial connectors for the receiver and transmitter trig lines. The
number of lines is dependent on how the system was ordered. The MIRA option in Fig. 2.5 is for
maximum 10 receivers and transmitters. The standard array option is equipped to handle 16 channels.
Fig. 2.5. On one side of the array option, the receive and transmit trig signals cables are connected
(left) and on the other side connectors for the digital data lines from the receiver antennas are found
(right).
The array option is fastened to the main unit with help of screws and small metal plates. See Fig.2.6.

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Fig. 2.6. The MIRA option connected to the ProEx control unit. The metal plate and place for securing
screws are marked.
2.3 Antennas
The MIRA system is designed to handle shielded separable antennas only, no other antennas can be
used with the MIRA system. The MALÅ separable antennas are designed to show as similar response
(signature) as possible and each data channel in the array is tested individually with regard to this
parameter.
The MALÅ shielded separable antennas are available with the centre frequencies of 200MHz, 400MHz
or 1.3GHz. These frequencies will cover investigations ranges from 0 to approximately 6 m depth in
non-conductive ground.
These antennas have one power connector and one trig connector. The receiver antennas are also
equipped with a connector for the digital data.
For each trig line there’s a LED on the antenna. This LED, when blinking, tells that the trig signals are
received by the electronics inside the receiver and transmitter antennas. Similarly there is a LED
telling that digital data is leaving the receiver antenna, when blinking.
The antennas contain all electronics for generating the impulse, sampling the incoming signals and
digitise it to 16-bit. The raw 16-bit data is transferred to the array-option where it’s buffered for later
transport to the PC for final storage and display. In Fig. 2.7 below available MIRA antennas is shown.

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Fig 2.7. 200 MHz, 400MHz and 1.3 GHz antennas. Lengths are 455, 230 and 90 mm respectively.
Several separate transmitter and receiver antennas are combined into one single antenna array unit
mounted in a box suitable for field surveys. 200 and 400MHz boxes are designed to include also the
control unit.
2.4 Positioning systems
The antenna array must be positioned with a high level of accuracy through out the survey. A precise
control of the geometry is an absolute prerequisite to make the resulting 3D radar picture correct and
reliable. Centimetre accuracy is needed over the whole investigation site. The MIRA system can be
positioned by using a RTK GPS system or a self-tracking laser theodolite, a so called total station. A
prism or a GPS rover antenna is attached to the array box, and a radio link transfers the positioning
data from the GPS base station or Total station back to the acquisition laptop. See Fig. 2.8.
Fig 2.8 Principal layout of the positioning system.
With the layout in Figure 2.8 the operator of the carrier vehicle will be able to control/monitor both the
operation of the radar system as well as the positioning system while steering the carrier vehicle.

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The positioning system used needs to communicate the positioning data in XYZ- format for Total
Station and in NMEA 0183 GGA for GPS, so that the data acquisition software MIRASoft can read it
and connect it correctly to the measured GPR swaths.
Total station: A self-tracking total station is locked on and follows a prism mounted on the antenna
array when the MIRA system moves in the investigation area and a radio link communicates the data
from the Total station to the MIRASoft. See Fig. 2.9. The Total station should be of ATS type.
Fig. 2.9. A self-tracking Total station is used to position the MIRA array.
RTK GPS: A base station is established in the investigation area, while the rover antenna is mounted
on the antenna array. A radio link communicates the positioning data to MIRASoft. An example base
station is shown in Figure 2.10.

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Fig 2.10. The RTK GPS base station.
Depending on the conditions on the investigation site the best method is used. Some points to
consider:
If working in an environment with a number of trees, high buildings or others that might disturb
the communication with GPS satellites a Total station is preferred. In these types of
environments it can also be hard to define lines and point features with the GPS.
However, on open ground with lower vegetation or obstacles, the RTK GPS solution most
often is a faster and easier way of positioning.
The Total Station needs line of sight, and by that one extra operator for the Total station if the
tracking fails.
If the investigation area is large, the Total Station needs to be moved and new Total Station
positions need to be defined, which can be more time consuming. However every type of
investigation area can be covered by a Total Station, which is not the case with a GPS.
It should also finally be mentioned, that temporary loss of tracking will not cause the data to be
useless, as long as start and end points of each swath are well defined.
Note! A GPS is very effective when it works! In order to be 100% sure that you can perform the
investigation a Total station is needed, though.
2.5 Accessories
The target applications for the MIRA systems are radar surveys over large areas and, practically, it’s
not feasible to move the array manually over thousands of square meters. Some kind of motorized
carrying system is usually necessary. It’s possible to ship the radar parts and accessories and attach
the system to any carrier, but this requires a case by case handling and cannot be described precisely.
For example lawn-mower types of vehicles are very suitable for carrying the MIRA arrays and in
Figure 2.11 below a carrier, including the antenna array box, are shown. This type of arrangement is
highly recommended by MALÅ Geoscience on surfaces like grass and high vegetation. For small size
scanning on concrete and asphalt the antenna box can be attached to a special design of our
standard RTC cart, see example in Figure 2.12.

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Fig. 2.11. A suitable mounting of the array system on a lawn-mower type of vehicle. The antenna box
contains a 400 MHz 16 channel array.
Fig. 2.12. A 12 channel MIRA 400 MHz antenna array mounted on a small cart.
Whatever vehicle chosen to carrying the MIRA, some adoption for the radar system has to be done,
these include:
- Fastening arrangement for the array box.
- Power supply, typically the generator has to be exchanged to one with higher current
specifications. Cables, fuses, and switches have to be installed.
- Attatchment of marking system and laptop mounting.
If the carrier is part of the purchase, these details will be taken care of by MALÅ Geoscience.
However, the client may find it more suitable to supply the vehicle locally, in which case he has to
arrange the mounting details by himself. It is most highly recommended to use the power from the

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carrier as the antenna array box has quite high power consumption. The vehicle must be able to
support 12V@22Amps.
In order to perform effective surveys the following tools and accessories are needed:
-Marking system for plotting the array paths on ground. This is necessary in order for the
operator to ensure proper coverage of the area. It’s simply a spray-bottle with remote control,
attached to the array and aligned with the centre line of the outmost channel.
-Measuring wheel for control of the data acquisition. Usually this is mounted on one of the
wheels of the carrying vehicle, but other designs are possible.
-Power supply. Preferably a connection to the generator of the carrying vehicle is used, if this is
not an option, arrangements with portable power sources may be considered. Operation from
batteries is possible but will require exchanges during a working day.
Other accessories may be necessary in the specific case/application, which can be discussed with the
MALÅ Geoscience Head Office. The contact information is found in Chapter 1 Introduction.

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3 System set up
___________________________________________________________________
In this chapter all connections to make prior operation of the MIRA system is explained. The MIRA
system is developed to be rough and stand heavy weather conditions. However, it is advisable to
make all connections within the antenna box in dry conditions, to prevent water in the electrical outlets.
An overview on the main connectors on the MALÅ standard antenna boxes is shown in Fig. 3.1.
1. Power supply from the battery box. 12V DC
2. Connector for the Spray paint system.
3. Connector for the remote control for the
Spray paint system.
4. Connectors for power (12V DC) of extra
equipment as radio link and prism for
positioning system.
5. Connector for data communication, Ethernet
cable. Note! This should be crossed to the
control unit and straight from the antenna box
to the computer.
6. Connector for encoder wheel cable.
Fig. 3.1. The main connectors on the MALÅ standard antenna box.
3.1 Antenna array
The separate receiver and transmitter antennas are placed in the antenna box, according to the
configuration chosen. See Fig. 3.2. To each antenna the antenna cables are connected, three to the
receiver (power, trig and data) and two to the transmitter (power and trig) antennas. The standard
configuration of a 16-channel set up is shown in Fig. 3.3.
Fig. 3.2. Examples of antennas in the antenna box and the connection to the coaxial cables and
power supply. The receiver antennas are seen at the bottom and transmitter antennas, at top. In this
example 400 MHz antennas are seen.
Receiver:
Data cable
Rx trig cable
Power cable
Transmitter:
Tx trig cable
Power cable
1
2
3
4
5
6

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Fig. 3.3. The standard bi-static fixed offset 16 channel array, with 9 transmitter and 8 receiver
antennas. Each receiver is synchronized against two transmitters in order to make the physical
channel spacing as small as possible.
3.2 ProEx control unit and MIRA option
The ProEx control unit is mounted to the MIRA option, with the two 25-DSUB connectors, and secured
by two screws on each side. See Fig. 3.4.
Fig. 3.4. Connection of the ProEx unit to the MIRA option.
IMPORTANT NOTE! The interface between the main ProEx unit and the array option is not protected
against over voltage. Therefore the units must be powered off before connection/de-connection.
Connect the Ethernet cable from the ProEx unit and further on to the main connector (Fig.3.1) and the
power cable from the power box to the ProEx unit. Note! The power box is equipped with fuses for
each source.

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Fig. 3.5. Ethernet cable and power connection to the ProEx unit.
3.3 Antennas
The MIRA option is connected to the antennas by means of coaxial lines, carrying control signals and
digitized data. Deployed for data acquisition, numerous cables will be connected to the option and,
therefore, it is recommended to be mounted as a fixed installation, whatever the carrying system may
be. Care should also be taken for minimizing the environmental stress on the option, such as rain,
temperature variations etc. However, when a standardized package is purchased, these kinds of
practical issues will be taken care of by MALÅ Geoscience.
The cables between the antennas and the MIRA option are connected according to Fig. 3.6 below.
Note! In order for the MIRASoft data acquisition software to work, the numbering of the connectors
must follow the antennas.
Fig 3.6 The cables from the antennas are connected to the MIRA option. Observe that the connectors
are marked both on the antennas and on the MIRA option, with T (Transmitter), R (Receiver) and D
(Data). The T and R are found on one side and D on the other.
Ethernet cable connection
Power cable
connections

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3.4 Power
Depending on your system the power supply is customized. One example on how to power the
antennas and the control unit is shown in Fig. 3.7.
Fig. 3.7. The red/blue power cable supplies the power box directly from the carrier battery or en
external battery (connected via the main connector shown in Fig. 3.1) and the black cables are
connected to each antenna element and to the ProEx control unit. In this power supply box, fuses for
each connector are also found.
The ProEx control unit, together with the attached MIRA option and the antenna array are powered
externally.
The main power for the whole set up is turned ON or OFF by switching the key on the external battery
box, shown in Figure 3.9. This will turn off the power to the antennas, the ProEx control Unit, the Spray
paint marker, the radio link and prisms.
IMPORTANT NOTE! It is important to turn off the power when the antenna array is not in use,
otherwise it will drain the power supply.
The MIRA system operates at 10-14V and to supply the system from a car battery is most convenient.
MALÅ Geoscience provides suitable cables and boxes for this. See Fig. 3.8. However it is
recommended to power the system directly from the carrier used, as an ordinary car battery will last
for approximately 4-5h. MALÅ Geoscience provides suitable solutions for this.
Fig. 3.8. The main power switch on the external battery box.

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3.5 Computer
The computer used for measurements are placed as convenient as possible for the operator carrying
out the measurements. The Ethernet cable is used to transfer the measured data from the control unit
to the computer for storage, display and processing. Fig. 3.9
Fig. 3.9. Connection of the Ethernet cable between the antenna box (left) and the computer (right).
3.6 Positioning system
The used positioning system is initialised according to the equipments operating manual. Make sure
that the communication settings match the settings made in MIRASoft (see operating manual
MIRASoft).
Total Station
The total station needs to send out data in XYZ-format.
Place the Total Station so a good coverage of the investigation is reached.
Properly mark tie-in-points outside the investigation area (use the prism) (see operating
manual MIRASoft) and position these. Note! If the Total Station needs to be moved the same
tie-in-points needs to be seen from the new location.
Place the prism on the antenna array, in one of the spray mark holder (with the 5-8 UNC
thread, see Fig. 3.15). Preferably in line with the encoder wheel.
Connect the external radio link to the Total station and on the antenna array carrier. The radio-
link antenna is connected to the computer to gather the positioning data from the Total station.
Note! In some areas the radio link needs to be elevated for best possible transferring. Although the
radio modems provided by MALÅ Geoscience is of high quality, with checksum handling and quite
high power ratings, they may be disturbed by ongoing radio traffic. In such case a different frequency
should be chosen, manuals for the modems are provided separately.
Examples of Total station and radio link arrangements are seen in Fig. 3.10.
.
Ethernet connections for
communication between the MIRA
option and computer.
The computer communicates
between the GPS or Total
Station on the serial COM-port
or by a USB to COM port
converter.

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Fig. 3.10.Left: Radio link on carrier and a prism on antenna array box. Right: Robotic total station and
radio link.
GPS
The GPS needs to send out data in NMEA 0183 GGA format. However this is saved in a local
coordinate system, related to the centre of the local coordinate system set in MIRA Soft.
Place the GPS base antenna outside the investigation area. Note! Sometimes the distance
between the base and the rover needs to be several hundred meters during initialization.
Make all connections between the base antenna and the GPS base receiver.
Place the GPS rover antenna on the antenna box, in one of the spray mark holders (with 5-8
UNC thread, see Fig. 3.15), preferably left side in-line with the first channel and make all
connection between the rover antenna and the receiver antenna and the computer.
Examples of GPS arrangements are seen in Fig. 3.11.
Fig. 3.11.RTK GPS set up.
3.7 Remote Control
Radio links
Base station
Rover antenna
Prism

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The MIRA system can also be used together with a remote control for an even easier operation of the
measurement system, see Figure 3.12. Instructions in eight simple steps are found below.
Fig. 3.11. The MIRA remote control, with three function buttons (Stop, New and Marker) and 4 LED
indicators. The two LED´s (1 and 2) indicates ongoing survey (measurement) with steady green light
and when blinking ready or stopped. The LED´s (3 and 4) indicates no connection or error with steady
or blinking red light..
Note!The remote control should be connected prior the power of the MIRA antenna box is turned ON.
Note!Whenever a button is pressed on the remote control, a beeping sound is heard.
1. Connect the remote control to the 15-pin DSUB connector on the outside of the MIRA
antenna box, see Figure 3.12.
Fig. 3.12.Connection of the MIRA remote control to the MIRA antenna box.
2. Connect the remote control cable between the ProEx AUX1 connector and the internal 15-
pin DSUB connector of the MIRA box. See Figure 3.13.
1
2
3
4