On Time Compression Overlap-Add Technique in Linear Frequency Modulation Pulse Compression Radar Systems: Design and Performance Evaluation

This paper introduces a novel approach to incorporate the time compression overlap-add (TC-OLA) technique used in communication systems into linear frequency modulation pulse compression (LFM-PC) radar systems. This technique significantly boosts the signal-to-noise ratio (SNR) and provides a robust processing gain compared with the traditional radar LFM-PC systems. In addition, TC-OLA provides a better immunity against powerful jamming techniques. At the transmitter side, we divide a digitized LFM chirp signal into a controlled number of overlapping segments. We then speed up each segment by increasing the sampling rate to account for the segment overlap. At the receiver side, we apply OLA to reconstruct the signal with a much higher gain. To simulate and evaluate the performance of the new system, we extend the conventional LFM-PC radar model, which includes matched filter (MF) processor, moving target detector (MTD), and two common constant false alarm rate (CFAR) algorithms, by suitably adding TC and OLA blocks at the transmitter and receiver, respectively. Using the TC-OLA-based LFM radar system, we have control over the SNR level and the spectrum spread while preserving the same Doppler shift and target time delay as the conventional LFM radar system. Furthermore, we transform LFM chirp signal into a novel TC signal that inherits LFM properties while possessing better immunity to jamming. Moreover, the proposed radar model relies on high sample rates only when needed and, therefore, does not require changing MF, MTD, and CFAR as is the case for a wideband LFM radar with the same processing gain. Detailed comparisons between the conventional LFM and the wideband LFM radars against the proposed model are also presented.