Abstract: A temporal correlation SONAR calculates the velocity and position of a water navigable craft. A first pulse and a second set of pulses are transmitted towards an ocean bottom. A tetrad of hydrophones on the craft receives echoes of the pulses. A correlation between the first pulse received on one hydrophone with the second pulses received on another hydrophone produces correlation points, for which a correlogram is generated. The distance between the hydrophones is divided by twice the time value at the peak of the correlation to calculate the velocity of the vessel. Another correlation is generated for hydrophones pairs that are positioned diagonally from one another, and maximum correlation values, along with hydrophone angles, are used to calculate athwart-ship velocity.

Abstract: The present invention is a system that mathematically simulates acoustic waves that are reflected off an ocean floor from a SONAR transducer mounted on a ship, submarine, or other water navigable craft. By varying the number of mathematical equations, the form of the equations, and the parameters of the equations, many different conditions may be simulated in the laboratory before testing and implementing a SONAR system at sea. The system can simulate either a spatial hydrophone SONAR system or a temporal hydrophone SONAR system for all ship speeds (i.e. all velocity components). The novel equations used in the system are based on the physics of correlation SONAR, and are applied in real time simulation environments to provide for accurate SONAR simulation of a ship's velocity.

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.