A Signal Coherence Recovery Method for Dechirp Sampling Radar

Due to the range gate hopping and Doppler frequency modulation, the coherence of the high-speed targets radar echoes received via dechirp sampling is disrupted, leading to a significant decrease in the accuracy and robustness of radar imaging. To address this issue, a new method for echo coherence recovery in dechirp sampling radars is proposed. Assuming the range gate hops with a fixed step size, the radar’s reference range can be accurately estimated by combining range alignment (RA) and range unwrapping technique. Simultaneously, the target’s range and velocity can also be estimated by using polynomial smoothing. By deriving and analyzing the accurate dechip signal model, the coherence of the echo is restored by compensating for high-speed Doppler modulation, residual video phase (RVP) terms, and residual motion errors through the construction of corresponding functions. Finally, the effectiveness of this method is validated by simulation experiments.