USRP based through wall radar

Abstract

Radar systems for detecting the humans present behind the wall are powerful tools for law enforcement, military and elderly care. Walls are complex propagation mediums that introduce attenuation, refraction and multipath to the radar signals. These radar waveforms provide significant attenuation to the signal (from 0 dB to 20 dB one way path loss). Hence, a radar platform that is reconfigurable in terms of carrier frequency, transmitted waveform etc. may be especially useful for test and measurement purposes in a variety of through-wall scenarios. In this work, we have used a software defined radio platform using universal software radio peripheral and Labview to implement a through-wall radar system. We have implemented two waveforms - a continuous wave (CW) signal and an orthogonal frequency division multiplexing (OFDM) signal at a carrier frequency of 3 GHz. A CW radar provides micro-Doppler signatures of humans. An OFDM radar additionally provides range information but due to system constraints, the realized range resolution is poor. Both the radar configurations have been tested in free space and through-wall conditions to detect the presence of one or more humans.