A kind of synthetic aperture sonar using multidimensional waveform encoding

To increase the area mapping rate,two kinds of high resolution wide swath SAS(Synthetic Aperture Sonar) using multidimensional waveform encoding are introduced.One uses the techniques of MIMO(Multiple Input Multiple Output) with transmit diversity,and the other applies multidimensional waveform encoding in azimuth.The corresponding signal processing steps are both described.Then a kind of dual-transmitter multiple-receiver SAS with different carrier wave frequencies is designed,which can double the area mapping rate and accommodates itself to higher platform velocity,relative to that of the single-transmitter multiple-receiver SAS.Considering the random motion of the sonar platform as well as acoustic pathlength variations caused by medium induced turbulence,some work has been done to validate the feasibility of multidimensional waveform encoding techniques in the sonar field utilizing the existing experimental data of single-transmitter multiple-receiver SAS.The imaging result shows that the spacial coherence of adjacent frequency band of the backscattered underwater acoustic signals can meet the imaging needs of dual-transmitter multiple-receiver SAS system.