2-VALUED SEQUENCES WITH PERFECT PERIODIC AUTOCORRELATION

Periodic two-valued signals which exhibit two-level autocorrelation can, in many cases, be made to yield an out-of-phase autocorrelation value identically equal to zero. This can be achieved by replacing the two values of the sequence (normally +1 and -1) with the two values +1 and e(i-phi), or with +1 and beta (beta-real). Simple expressions for phi and beta are given, based on the parameters of the difference set to which such signals correspond. Another strategy is to transmit a sequence of +1s and -1s, but to correlate it against a reference version consisting of +1s and bs (b real and negative). An expression for b is also obtained.