A simple clutter suppression approach for OFDM-based passive radar exploiting reciprocal filter

This paper proposes a simple non-adaptive approach for the suppression of direct signal and clutter contributions in a passive radar system based on OFDM transmissions, exploiting the properties of a reciprocal filter (RF). The use of a RF allows to circumvent the limits posed by the waveform ambiguity function, producing a data-independent time-invariant response to a point-like target echo at the output of the range compression stage. This feature enables simple clutter cancellation strategies, based on the subtraction of delayed portions of the surveillance signal, according to the conventional moving target indication (MTI) methodologies. The proposed processing scheme consists of a range compression stage based on a RF, followed by a Single Canceller (SC). Its performance is investigated against a simulated data set, for the case of a DVB-T-based passive radar scenario, and compared to an alternative scheme based on a conventional matched filter (MF), and an adaptive cancellation technique. The proposed approach is shown to yield a perfect cancellation of the clutter returns from a stationary scene under ideal conditions. Moreover, it proves to be robust to real-world conditions, despite its considerably limited computational load.