Patent ID: 6532192
Filing Date: 2003-03-11
Classification: G01S

Abstract:
A positioning system for use in underwater/subsea hydrographic surveying applications which system comprises a submersible having a transponder means formed and arranged for communication with a remote receiver means, said transponder means and said remote receiver means being provided with clock means, both said clock means being in substantial synchronisation; said remote receiver means being provided with processing means for determining the position of said submersible by calculating the time taken for a signal to be transmitted by said transponder means to be received by said remote receiver means utilising the clock time of transmittal with respect of; the clock time of reception at the said remote receiver means, and wherein said transponder means is formed and arranged to transmit a continuous water propagatable data signal, which signal includes a binary signal sequence, which signal sequence has a length at least equal to the propagation time of the signal over a desired given measuring range such that said signal sequence does not repeat itself.