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 1^st 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 2^nd and higher order of range cell migration after performing 1^st order of that for fast processing. The experimental results show the effectiveness of the proposed algorithm.