Multibeam imaging using spatially variant insonification

Summary form only given, as follows. The design, fabrication, and preliminary results from a sonar system that projects different orthogonal waveforms in different directions are considered. It is demonstrated that this design criterion is identical to that encountered in multiaccess, spread-spectrum communication systems. The time-bandwidth properties of the system therefore limit the simultaneous requirement of decorrelatable beams and good range resolution. As a specific implementation of the technique a frequency-hopping code is presented. The performance of this code is examined, and it is demonstrated that this code is nearly optimal with respect to the above criterion. Design techniques for frequency-hop codes are presented for both coherent and incoherent processing algorithms. The spatial part of the problem is also addressed. Various configurations of transducers that specifically exploit the properties of spatially variant insonification are considered. The principles of multibeam sonar imaging systems using variant insonification are illustrated by constructing several examples of active sonar systems whose performance is superior to that of traditional designs