System and method for underwater distance determination

A method for underwater distance determination, the method comprising:

• sending a first sensor-to-hydrophone data signal from a first sensor module of a pair of sensor modules to a hydrophone unit located at a reference point, the pair of sensor modules and hydrophone unit located underwater, the hydrophone unit including at least two hydrophones;
• sending a first sensor-to-hydrophone synchronization signal from the first sensor module to the hydrophone unit located at the reference point;
• sending a first inter-sensor synchronization signal from the first sensor module to a second sensor module of the pair of sensor modules;
• sending a second sensor-to-hydrophone synchronization signal from the second sensor module to the hydrophone unit responsive to receipt of the first inter-sensor synchronization signal from the first sensor module;
• sending a second inter-sensor synchronization signal from the second sensor module to the first sensor module responsive to receipt of the first inter-sensor synchronization signal from the first sensor module;
• sending a second sensor-to-hydrophone data signal from the second sensor module to the hydrophone unit;
• employing the at least two hydrophones to measure a first bearing angle and a second bearing angle of the first sensor module and second sensor module, respectively, the first bearing angle and second bearing angle relative to the reference point;
• and
• at the first sensor module:
• (i) measuring a time value T22 representing a total travel time of the first inter-sensor synchronization signal from the first sensor module and second inter-sensor synchronization signal from the second sensor module;
• and
• (ii) calculating a distance between the first sensor module and second sensor module based on the time value T22 measured.