High resolution side scan sonar for underwater mine surveys using a UUV platform

There are many requirements for a seafloor imaging system which has high resolution capability in both cross track and along track directions. Current technology provides for side looking sonar coross track resolution of a few centimeters, however, along track resolution is limited because of transducer radiation pattern and repetition rate. We propose in phase I to verify feasiblity of a concept for implementation of a high repetition rate side looking sonar which would operate with multiple pings in th water simultaneously, allowing for greatly enhanced resolution. The approach is based on binary PSK encoding of successive transmit pings such that echo data, being received simultaneously from several transmit pings, can be decoded and processed with correct alignment of data associated with each ping. Such a technique will allow a combination of faster survey speeds and greatly improved resolution, an important advance for application in underwater mine location surveys. Use of a Chirp swept FM transmit waveform with associated matched filter DSP receive processing will result in longer ranges achieved with high resolution. The system concept also includes a digital multiplexor which allows control of all side scan functions, and transmission of acquired data through an RS-232 serial port, for interfacing with an external processor. Use of a single wire I/O will allow for flexible expansion in the form of additional sensors which could include acoustic transmission of seafloor image data or perhaps processed target location data to the sea surface by acoustic telemetry.