Abstract: A method of correcting errors in in inertial navigation system, without imposing restrictions on the ships course, utilizing bathymetric data collected during the Ocean Survey Program (OSP). As the ship is in transit in or crosses an OSP swath, sonar transmissions commence and continue only to acquire bottom data within data areas of predetermined dimensions. Depth gates and transmission power levels are established in accordance with OSP provided bottom data and depth is determined by an autocorrelation process. A virtual linear map is established with the OSP data in the predicted locations of data collection areas. The collected data is then compared to corresponding OSP data to determine inertial navigation system corrections.

Abstract: A simulator of bottom return signals for a sonar system on a moving ship generates pulsed frequency modulated signals to simulate ocean bottom returns. Signals from the sonar transmitter are stretched in accordance with a postulated bottom configuration and applied to the frequency modulators to provide frequency modulated signals for the duration of the stretched pulses. Noise is simulated with the addition of an appropriate sinusoidal signal to each pulsed frequency modulated signal.