Comments on "About the enumeration of best biphase codes"

A paper by Fourdan (IEEE Trans. Signal Processing, vol.39, p.1427-8, 1991) discussed a sensible way to classify the catalog of biphase codes with minimum peak sidelobe level. Unfortunately, the properties of the group of invariant transformations mentioned are invalid for sequences of even length. Consequently some of the best biphase codes may not be generated from their independent roots. The purpose of the present comment is to fix the problem by presenting the correct group structure of the invariant transformations.<>