Francis J. Higgins - Panama City FL
Chester D. Loggins - Panama City FL
James T. Christoff - Panama City FL
The United States of America as represented by the Secretary of the Navy - Washington DC
A dual frequency, synthetic aperture, sonar system includes a transmitter r projecting insonifying pings alternatively at first and second frequencies and a linear receiving array carried by a vehicle so as to receive returns from said pings. The first and second frequency returns are separated and subjected to processing in parallel channels where they are resolved into in-phase and quadrature components for subsequent phase-error correction, coherent addition, and synthetic aperture beamforming.