In this paper, a self-adaption matched filter (SMF) and bi-directional difference techniques are proposed to detect a small moving target in urban environments. Firstly, the SMF technique is proposed to improve the signal-to-interference-noise ratio (SINR) by using the power factor. The properties of the transmitting signal, the target echoes and the interference and noise are considered during the power factor generation. The amplitude coherent accumulation technique that extracts the coherent amplitude information of echoes after being processed by the SMF, is used to improve the SINR based on multiple measurements. Finally, the bi-directional difference technique is proposed to distinguish the target echoes and the interference/noise. Simulations and experiments are conducted to validate and demonstrate that small moving targets can be detected with high probability using the proposed method in urban environments, even with just one measurement.
Orthogonal frequency division multiplexing (OFDM)-based ground penetrating radar (GPR) has been proved to have a number of advantages. To improve the performance of a GPR system, time domain non-periodic autocorrelation (AC) of the transmitted OFDM signal should be designed to have similar shape to an ideal pulse. Challenge in OFDM signal design for GPR is that there is little pertinent literature and the design should be different from that in communication and air radar fields. In this paper, we propose a design scheme of OFDM signal with good AC for GPR. We divide the AC into main lobe and side lobe with proving that the main lobe is dominated with the functionality of the modulating amplitudes while the side lobe’s main function is modulating phases. Thus, modulating amplitudes and phases can be designed, respectively. Performance of this proposed approach is demonstrated by numerical examples. The results show that the designed OFDM signal yields a better AC and fewer false alarms for GPR systems.
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