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Methods for optimization of phase coded waveforms often entail a nearest-neighbor search used in reducing autocorrelation or crosscorrelation sidelobes. Computing the energy gradient -the change in sidelobe energy that results from single -element modifications to the sequence -is a computationally expensive component of the nearest-neighbor search. A recent paper showed that the autocorrelation sidelobe energy gradient for binary sequences could be computed with O(N log N ) operations in initialization and O(N ) operations in iteration, substantially faster than previous methods which required O(N 2 ) operations both initially and in iteration. In this paper the same approach is extended to additional sequence optimizations -polyphase sequences, biphase cross-correlations, and biphase sequence filtering. It is shown that similarly efficient equations are available for those gradient calculations.

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