多维波形编码合成孔径声呐技术研究

为了提高测绘效率,提出了两种基于多维波形编码技术的高分辨率宽测绘带合成孔径成像声呐体制,包括使用多发射阵的频分多输入多输出成像方式和方位向波形编码序列的成像方式,并论述了相应的成像处理流程。最后根据高速平台下的成像需求,设计了一种频分双发多收的合成孔径声呐系统,它可以将原有的单发多收系统的测绘效率提高一倍。考虑到水声信号的随机起伏性,利用已有的单发多收系统的实测数据,对多维波形编码技术在水声领域的可行性进行了实际验证。成像结果表明,经水底散射后的相邻频带的回波信号的空间相关性可以满足双发多收体制的合成孔径声呐的成像要求。 

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.