New results on minimum-PSL binary codes

Cohen et al., (1990), found the lowest-PSL (peak sidelobe level) codes for N⩽48 using a search algorithm that exploits two PSL-preserving operations. This note explains how to exploit a third PSL-preserving operation in combination with the first two in a single exhaustive search routine. There is a two-fold payoff: a factor-of-two search speedup and a more efficient representation of the set of optimal codes for a given code length. In addition, the list of minimum PSL values is extended to N⩽69. This is achieved by providing examples of PSL=4 codes for each code length N between 49 and 69. It has already been established by exhaustive search that for these code lengths, with the exception of N=51, there are no PSL=3 codes