The symmetry in a chirp filter and its application to LPI communication

The even phase symmetry property of a chirp filter is discussed. It is known that significant spectral lines are produced at the output when a binary phase-shift keyed (BPSK) signal is applied to a squaring circuit (SC) or a delay and multiply circuit. These spectral lines can be suppressed by using an even phase symmetric filter. One application of a chirp filter is to transform a conventional direct sequence spread spectrum (DS-SS) low probability of intercept (LPI) signal into a form that is more difficult to detect. Computer simulation results are presented to show the effectiveness of the proposed technique.<
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