Wide-band synthetic aperture sonar data processing and image reconstruction with back projection algorithm

Imaging by high-resolution synthetic aperture sonar (SAS) is studied to detect buried targets. Based on characteristics of sound propagation in water and sediment, a SAS data processing and image reconstruction technique using a back projection (BP) algorithm with a low frequency and wideband signal is analyzed in this paper. In this algorithm, in order to make full use of the energy received at the synthetic aperture elements, all the sonar echoes with respect to every element in the synthetic aperture array are coherently summed. Since shadowing and tail phenomena occur due to the 1/r-tail effect during the implementation of BP, image processing is performed using a ramp filter resulting in a clear reduction of the tail and shadowing effect and improvement in the azimuth resolution. Computer simulation is presented to verify the effectiveness of the data processing and image reconstruction approach for a 15kHz-SAS imaging system with a 20kHz bandwidth.