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GeoScope
TM
User’s Manual
© 2013 3d-Radar AS
Page 3
Revision 2.0
Date: 02/07/2013
time per frequency as well as the start and stop frequencies as shown in
Figure 2. The GeoScope sequentially transmits one complete waveform on
each transmitting antenna while receiving on the corresponding receiving
antenna. The transmission of one complete waveform on one transmitting
element is called as scan. The recorded frequency domain data contain one
complex value for each frequency in the waveform.
The radar system performs real-time time domain conversion through Fast
Fourier Transform allowing the user to view radargrams from the antenna
array. These data can be imported into either
3dR Examiner
software, or
RoadDoctor
TM
from Roadscanners OY.
Figure 2 - Step-frequency waveform.
The radar is controlled from a laptop computer through an Ethernet cable.
The system can also be configured with GPS/Total Station interface (option)
to allow recording of position data through the serial port (RS-232).
1.2
Collect up to 41 survey lines simultaneously
The GeoScope
TM
GPR is designed to operate with an electronically scanned
antenna array with up to 41 antennas. The antennas are scanned
sequentially by the radar. The unique antenna system consists of air-coupled
bow-tie monopole pairs as shown in Figure 3. This gives a quasi-monostatic
antenna configuration with practically zero-offset distance. The air-coupled
antenna array can be operated at elevations up to 50cm off the ground
allowing high-speed surveys.
Figure 1 shows the spatial sampling grid for a typical 3D radar survey. The
Distance Measurement Instrument (DMI) outputs a trigger signal to the
system every time the array has moved the specified interval along the x-
axis. The horizontal sampling interval determines the
∆
x in the sampling grid.
The array is aligned along the y-axis. The spacing between the antenna
elements in the array gives the
∆
y in the sampling grid.
time
N frequencies
frequency
Frequency step
Dwell Time
Scan Time (for one single antenna element)
3.0 GHz
140 MHz
