Multi-Sub-Chirp Signal Synthesis for Millimeter-Wave Radar Based on Dechirp Processing

Due to the limitation of hardware, the transmission bandwidth of the miniature millimeter-wave (mmW) radar is restricted. This paper considers a signal composed of multiple sub-chirps to synthesize wide-bandwidth chirp signals based on dechirp processing. However, dechirp operation results in undesirably high sidelobe peaks and sidelobe shape distortion due to the discontinuities caused by chirp interference between the simultaneous presence of multiple sub-chirps. In the short-time Fourier transform (STFT) domain, we utilize an autoregressive (AR) model to reconstruct the interference regions between the sub-chirps by linear prediction (LP), to reduce the influence after dechirp processing. The proposed method is robust to low SNR and large gap width, and does not need to know the target number in advance. Further, by adjusting the chirp rate of each sub-chirp of the transmitted waveforms, it can be further applied to mmW multiple-input multiple-output (MIMO) radars. The simulation results verify the effectiveness of the method in this paper.