LPI waveform shaping by modified chirp filter

Abstract

A computer simulation has shown that a modified chirp filter with odd phase symmetry can suppress the line spectrum produced by a binary phase shift keying (BPSK) signal at the output of a squaring circuit (SC) by destroying the cyclostationarity of the signal. Unlike LPI waveform shaping by heavy filtering, the modified chirp filter converts the line spectrum to the self-noise spectrum. This line spectrum can be restored using a matched filter. However, the advantage of using the modified chirp filter over an ordinary chirp filter is the difficulty of figuring out its matched filter even if the chirp duration and frequency slope are known to the interceptor.<>