An Efficient Coherent Integration Method for Non-Uniform Pulse Repetition Interval Radar

Long-time coherent integration is an effective method to enhance the signal-to-noise ratio (SNR) of radar echoes. However, non-uniform Pulse Repetition Interval (PRI) radar faces the challenge of Doppler spectrum distortion besides the range migration during long-time coherent integration. This paper proposes a new algorithm to correct non-uniform spectrum and range migration in a single processing step. The proposed method, implemented using a DFT-based approach, achieves a good balance between compensation performance and computational load compared with existing methods, such as correcting spectral distortion using NUDFT followed by range migration correction using KT, or implementing non-uniform KT via sinc interpolation principle. The simulation results demonstrate that the proposed method achieves an improvement in integration gain of 4.9 dB and 2.2 dB compared to the above two methods when the target velocity is near the boundary. The real-measured data analysis further indicate that the proposed method reduces the runtime by 37% compared to the NUDFT method under the condition of comparable integration gain. And the proposed method achieves an improvement in integration gain of 1.7 dB compared to the sinc interpolation method under the condition of comparable runtime. The results validate the effectiveness of the proposed method.