Patent ID: 7630447

Claim:
A system of digital communication between submarine devices, including at least one submarine sender ( 100 ), at least one submarine receiver ( 200 ), and a common clock, wherein the at least one sender ( 100 ) and the at least one submarine receiver ( 200 ) are synchronized with the common clock, wherein the at least one submarine sender ( 100 ) has means of sending an acoustic signal having a binary sequence of bits in a modulated form, the at least one submarine receiver comprising: a demodulator ( 240 ) for detecting and demodulating each bit of the signal arriving at the at least one submarine receiver ( 200 ) is provided in the at least one submarine receiver ( 200 ), a time-stamping means ( 250 ), by which a time-stamping of each bit of the signal detected on the demodulator ( 240 ) is performed independently with reference to the clock, is provided in the at least one submarine receiver ( 200 ), estimating means for estimating the propagation time of the signal from said at least one submarine sender ( 100 ) to said at least one submarine receiver ( 200 ) based on said time-stampings is provided in the at least one submarine receiver ( 200 ), and a means for applying a quality criterion to the bits from the demodulator ( 240 ), wherein said propagation time is computed by said means for estimating the propagation time taking into account only those bits satisfying the quality criterion.