Second- and higher-order cyclostationary processing using acousto-optics

In this paper we consider cyclostationary signal processing techniques implemented via acousto-optics (AO). Cyclic processing methods are reviewed and motivated, including the cyclic correlation and the cyclic spectrum. We show how a 1D AO spectrum analyzer can be used to detect the presence, and estimate the value, of cycle frequencies. The cyclic correlation can then be computed at cycle frequencies of interest using a 1D time-integrating correlator. Next we consider the problem of computing the (2D) cyclic correlation for all cycle frequencies and lags simultaneously. This is accomplished via an AO triple-product processor, configured in a manner similar to that used for ambiguity function generation. The cyclic spectrum can be obtained in a post-processing step by Fourier transforming the cyclic correlation in one dimension. We then consider higher order extensions of the cyclic correlation and show how a 2D slice of the 3D cyclic triple-correlation can be computed using an AO four-product processor.