Time-Varying Clutter Suppression in CP-OFDM Based Passive Radar for Slowly Moving Targets Detection

Time-varying clutter suppression is challenging in passive radar. Although some existed methods are robust against the time-varying clutter, they bear heavy computational burden and memory load. In this study, we propose two advanced versions of the average channel response filter on subcarrier (ACRF-C) for time-varying clutter suppression. The methods take advantage of the orthogonal frequency division multiplex (OFDM) modulation with cyclic prefix (CP-OFDM) of the third-party radio sources, and are implemented in the subcarrier domain. The proposed batch version of ACRF-C (ACRF-CB) can effectively suppress time-varying clutter but modulates targets with small Doppler frequency. To detect slowly moving targets, a sliding version of ACRF-C (ACRF-CS) is presented to partially overlap the channel frequency response for filter coefficients estimation. The ACRF-CS yields a good trade-off between time-varying clutter suppression and slowly moving targets detection. Simulation and experimental results following the theoretical analysis validate that the proposed methods can obtain comparable performance to that of the existed methods but possess remarkable computational and memory advantages.