SONAR HEAVE COMPENSATION SYSTEM

A ship-borne sonar heave compensation system measures the heave at time of transmit and at the expected time of receive of a bottom-echo which is approximated by the previous depth determination corrected for heave. Using these values of heave, the depth of the detected bottom-echo is corrected to provide the true depth corrected for heave. A chart recorder reads out from memory the sonar return signals, including the bottom-echo, corrected for these heave values to present a true picture of the bottom contour.