Walsh spectrum measurement in natural, dyadic, and sequency ordering

An improved processor design to provide Walsh spectra in either natural, dyadic, or sequency ordering is described. Incoming data are stored in a permuted sequence in an auxiliary memory and then sent sequentially to a Hadamard processor. The permutation operation for sequency ordering is that of Gray-to-binary code conversion, followed by bit reversal; for dyadic ordering, the operation is only bit reversal. The hardware required to implement this process is minimal, and the Hadamard processor can operate at speeds greater than that described by Geadah and Corinthios (1977) by a factor of 3m/2(m + 1), where m = log2N. This speed advantage approaches 3/2 for large m. The system can also be used as a pipeline processor using identical modules. Using a similar structure in each stage of the pipeline helps keep the chip count in LSI implementation to a minimum.