Walsh Spectrum Measurement in Natural, Dyadic, and Sequency Ordering

Walsh spectra may have natural, dyadic, or sequency ordering. This paper describes an improved processor design to provide spectra in any selected ordering. The incoming data are stored either directly or in a permuted sequence, and then are followed by a fast Walsh-Hadamard transform. For sequency ordering, the permutation operation is that of a Gray-to- binary code conversion, followed by bit reversal. For dyadic ordering, the operation is only a bit reversal. First a Hadamard processor that uses long shift registers is described. It is adapted to yield coefficients in either of the other two orderings by way of the permuting module (PM).