A Design of the Matched Filter for the Passive Radar Sensor

This paper discusses a method of designing a matched filter for a passive microwave sensor. This sensor receives pulse signals transmitted by a target active radar. Received signals can be categorized into two types due to either the pulse signals or noise. The method first estimates an autocorrelation function of the received signals. The autocorrelation of the pulse signals is then extracted from the autocorrelation of the received signals by exploiting the difference between the statistics of the pulse signals and the noise. A power spectrum of the pulse signals is obtained by taking discrete Fourier-transform of its autocorrelation. The matched filter is designed from the knowledge of this power spectrum. The spectrum of the matched filter is identical to the spectrum of the pulse signals transmitted by the radar, and then signal-to-noise ratio (SNR) is improved by matching the filter with the pulse signals. Performance of the proposed method is theoretically analyzed in term of SNR. Moreover, simulations verified that the proposed method correctly designs the matched filter and achieves expected performance. Key-Words: signal estimation, stochastic process, pulse signal, matched filter, signal-to-noise ratio, passive sensor