Bi-directional temporal correlation sonar

A process to determine a velocity of a water navigable vessel, comprising the steps of:

• detecting a first sonic pulse on a first hydrophone;
• detecting a set of second sonic pulses on a second hydrophone;
• correlating said first pulse with several of said second pulses, said correlation producing correlation values, wherein each said correlation value is associated with a time value, said time value representing an interval between said first pulse and pulses of said second set, said time values and said correlation values forming a set of first correlation points;
• inputting said correlation points into a curve fitting algorithm, said curve fitting algorithm producing a curve with a peak amplitude, said peak amplitude corresponding to a peak time differential between said first pulse and said set of second pulses;
• and
• calculating a first velocity by dividing a distance between said first hydrophone and said second hydrophone by twice said peak time differential.

A computer readable storage medium, said medium comprising instructions to:

• transmit a first sonic pulse towards an ocean bottom;
• transmit a set of second sonic pulses towards said ocean bottom;
• detect an echo of said first pulse on a first hydrophone;
• detect echoes of said second pulses on a second hydrophone;
• correlate said first pulse with several of said second pulses, said correlation producing a set of first correlation values, wherein each said first correlation value is associated with a time value, said time value representing an interval between said first pulse and pulses of said second set, said time values and said first correlation values forming a set of first correlation points;
• plot said first correlation points on a first correlogram, said first correlogram comprising said time differential on an abscissa and said first correlation values on an ordinate;
• determine a peak value of said first correlogram, and further determine a corresponding time value on said abscissa of said first correlogram;
• and
• calculate a first velocity of a vessel by dividing a distance between said first hydrophone and said second hydrophone by twice said time value.

A temporal correlation SONAR for a water navigable vessel comprising:

• means to transmit a first sonic pulse;
• means to transmit a set of second sonic pulses;
• a first means to detect an echo of said first sonic pulse;
• a second means to detect echoes of said second sonic pulses;
• means to correlate said first pulse with said second pulses, said correlation producing a set of first correlation values, wherein each said first correlation value is associated with a time value, said time value representing an interval between said first pulse and pulses of said second set, said time values and said first correlation values forming a set of first correlation points;
• means of generating a first correlogram from said first correlation points;
• means of searching said first correlogram for a peak amplitude, said peak amplitude associated with a first peak time differential between said first pulse and said set of second pulses;
• and
• means to calculate a first velocity of said vessel by dividing a distance between said first means and said second means by twice said first peak time differential.