Long-time integration by short-time cross-correlation and two-step Doppler processing for Passive Bistatic Radar

PBR (Passive Bistatic Radar) exploits existing transmitters for sources of illumination. In general, PBR requires long-time coherent integration for improvement of SNR (Signal-to-Noise Ratio), because PBR cannot control transmitter related to the gain. For long-time coherent integration of signals, range cell migration caused by the target movement should be compensated. A conventional algorithm expands range cell migration by polynomial, and searches for coefficients of the polynomial sequentially with stretch-processing; however, this algorithm takes a long-time for the compensation. In addition, most conventional algorithm should remove guard-interval to suppress the ambiguity. To overcome this problem, this paper proposes a modified long-time coherent integration algorithm for PBR that considers the relationship between 1st order of range cell migration and Doppler frequency by using Doppler filtering processing based on short-time cross-correlation. This two-step Doppler processing does not require to remove guard-interval because effective symbol-time of ISDB-T satisfies PRI (Pulse Repetition Interval) of this analysis. Furthermore, the proposed algorithm compensates 2nd and higher order of range cell migration after performing 1st order of that for fast processing. The experimental results show the effectiveness of the proposed algorithm.