Detection of People Trapped under the Ruins Using Dual-frequency IR-UWB Radar

Detection of people hidden by obstacles using impulse radio ultra wideband radar has become a keen research nowadays. According to theories of the UWB radar, the lower center frequency is, the better penetrability radar has. And the larger bandwidth is, the higher radar range resolution becomes. In order to detect survivors trapped under the ruins of collapsed buildings, researches commonly focus on the radar with center frequency below 500 MHz. However, the radar with low center frequency always has small bandwidth, so it is relatively insensitive to the weak signal of the survivor. And this may lead to miss detection in search and rescue missions. Therefore, a novel dual-frequency IR-UWB radar system is developed in this paper. It can works alternately at each waveform with two center frequencies, which are 270 MHz and 400MHz. And the equivalent bandwidth of the system is relatively extended to enhance the sensitivity to weak vital signals. Moreover, cross-correlation technique is applied to the processed data of the two channels to improve the detected signal to noise ratio (SNR). The experimental results show that this system can both meet the need of low center frequency and large bandwidth in life detection and the detected SNR of the system is much higher than that of the single-frequency IR-UWB radar. So this system can work more reliably and effectively in the detection of people trapped under the ruins.