Extended sonar sequences

Sonar as well as other related sequences were introduced by Golomb and Taylor (1982). Following a similar approach, we introduce the concept of an extended sonar sequence. It is similar to that of a sonar sequence but blank columns are permitted. Several constructions of extended sonars are given. Our constructions are very close to ordinary sonar sequences. However they provide good improvements to the list of the best known constructions for sonar sequences up to 100 symbols given previously (Moreno et al., 1992).