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.