A novel method to improve the spatial sample rate of synthetic aperture sonar.

摘要

The along-track resolution of a sonar system is proportional to the aperture length in the along-track direction. Synthetic aperture sonar (SAS) coherently sum samples from multiple physical locations to form a synthesized aperture which exceeds practical physical aperture dimensions, offering improved resolution over physical aperture sonars of equivalent size. To avoid spatial under-sampling, single-transmitter SAS can move no more than one half of the along-track physical aperture length between transmit pulses. This requirement creates a SAS "speed limit" which limits the area coverage rate of SAS.;A method is introduced to increase the area coverage rate of SAS through the use of additional transmitters to form a multiple-input -- multiple-output synthetic aperture sonar (MIMOSAS). By placing N transmitters spaced in the along-track direction and simultaneously transmitting non-correlating signals, the effective spatial sampling rate of SAS is increased and the SAS "speed limit" is increased by a factor of N. Finally, a novel spatial coding method is presented which reduces the self-noise created by multiple transmitters and improves the image quality in MIMOSAS systems.