Improving Mapping Efficiency Using a Coprime Dual-Frequency Method for Synthetic Aperture Sonars

Active synthetic aperture sonar (SAS) is a sonar producing a high-resolution, optical-like “image” of the seafloor. However, mapping efficiency has always restricted the further development of SAS. In response to this problem, this article proposes a method for high-resolution image restoration under under-sampling, called the coprime dual-frequency method. This method takes advantage of the different characteristics of the grating lobe caused by coprime dual-frequency in the case of under-sampling to suppress the ghost image of the point target. Simulation shows that our proposed method can effectively eliminate the ambiguity of point targets under under-sampling, which is beneficial to the recognition and resolution of point targets.