An experiment has been performed to determine the applicability of coherent signal processing techniques to a long-range low-frequency side-looking bathymetric survey system. A linear FM sweep of 280-Hz center frequency, 10-Hz bandwidth, and 20-s duration was produced by a source at depths between 120 and 150 m towed parallel to the Blake escarpment at a range of about 250 km. Reflected signals were received by a line array towed at depths ranging from 765 to 825 m. The received signals were passed through a digital pulse compressor and averaged. Groups of the received signals were easily identified as reflections from the Blake escarpment. The experiment has shown that coherent signal processing techniques are applicable to low-frequency side-looking bathymetric survey systems.