Multi-parameter local optimization for the design of superior matched filter polyphase pulse compression codes

Abstract

Polyphase codes, such as the Kretschmer-Lewis palindromic P4 code, and the nonlinear FM P(n,k) code, have been used in radar systems to provide low sidelobe autocorrelation properties and superior Doppler performance. A disadvantage in using these codes, is that they are susceptible to defeat, when a repeat jammer is present. In this paper, we use a multi-parameter optimization algorithm to find sets of quasi-orthogonal polyphase codes that retain most of the superior matched filter qualities of polyphase codes. This is done so that the radar designer can alternate quasi-orthogonal polyphase coded versions of the same waveform sequence length, for pulse-to-pulse, or dwell-to-dwell, ECM robustness. All or any subset of a set of parameters of these matched filter code sets (peak sidelobes, integrated sidelobes, Doppler tolerance, and level of orthogonality) can be optimized simultaneously according to a predetermined weighting priority.