L-3 Communications Klein Associates, Inc. has recently completed the design and development of a Model 3900 Side Scan Sonar. The system is an extremely high resolution digital side scan sonar for use in search and recovery missions which require a portable side scan system. The model has a dual frequency capability with 445 kHz, offering excellent range and resolution; and 900 kHz which offers higher resolution of identified items of interest. The system is configured to operate by one man from a small boat in shallow water. The standard system configuration comes complete with a splash proof Transceiver Processing Unit (TPU), custom configured laptop and 50m of lightweight tow cable. Model 3900 Towfish electronics are housed in a stainless steel body with a phosphorescent finish for easy underwater identification.