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Design and simulation of a coded sequence ground penetrating radar

University of British Columbia

In the context of climate change, ground water monitoring has become an important task for which Ground Penetrating Radar (GPR) has been ideally suited. However, the limited depth of investigation has prevented GPR’s use in situations with deep water tables. In order to meet these new depth objectives, a novel Radar has been designed. This new radar, marries modern digital coding techniques and the ever improving field of digital electronics with that of a prototypical GPR. The sequences chosen for investigation include Golay-codes and M-sequences. This new GPR uses off the shelf digital equipment to meet these demands and does so in a more cost effective manner than conventional GPR. The design and implementation of this radar is covered. Simulations of theoretical performance are included for both code types and include factors for both white noise and digitizer quantization. Preliminary results demonstrate that the use of digital codes allow for greater dynamic range above and beyond that afforded by an impulse radar. Specifically, we show that when used with pre-existing dynamic range Golay-codes can add an additional 50 dB of dynamic range. Contrarily, we show that M-sequences can provide a similar dynamic range but this is total and not in addition to receiver sensitivity. In both cases, however, we achieve total dynamic ranges greater than that of an impulse radar. According to the simulation, the increase in dynamic range from the sequences, combined with a lower frequency of radar (25 MHz), allow us to achieve previously unseen depths of investigation (180 m). This depth is under a presumed attenuation of 1 dB m −¹ . As an additional benefit of using these codes, we can exploit the use of commercial FPGAs for code generation and processing. This substantially reduces the cost and opens up the radar for the intended application of remote monitoring. This lower frequency has the adverse effect of lowering the radar’s resolution. Moreover, the use of long codes increases the device’s acquisition time. However, these limitations do not unduly impact its intended use.

Text

2015-12-03

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/55659

Electrical and Computer Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/