Patent ID: 8509030

Claim:
A positioning system ( 30 ) of at least one underwater apparatus ( 2 ), said underwater apparatus ( 2 ) comprising: an acoustic receiver ( 4 ) comprising a hydrophone, and a computer ( 6 ), said system comprising : a base station ( 8 ) placed in the sea environment, comprising at least two acoustic transmitters ( 10 ) forming an antenna ( 11 ), wherein the distances between the acoustic transmitters ( 10 ) of the antenna ( 11 ) are known and said transmitters are synchronized to each other, wherein said base station transmits through each of its transmitters ( 10 ) an acoustic signal that is received by the acoustic receiver ( 4 ), wherein, the acoustic receiver ( 4 ) comprises signal processing means for detecting the difference between the arrival times of the signals respectively transmitted by the transmitters ( 10 ), taken by pairs, and to attribute to each pair of transmitters ( 10 ) a corresponding arrival time difference; and said signal processing means being adapted for measuring the phase differences, at the time of their arrival on the acoustic receiver ( 4 ), between the signals respectively transmitted by each pair of transmitters ( 10 ), and the computer ( 6 ) comprises means configured for calculating, from the arrival time differences and phase differences of acoustic signals coming from the transmitters of the base station ( 8 ), the precise time differences of the signals transmitted for each pair of transmitters ( 10 ) and received by the acoustic receiver ( 4 ) and means for calculating, from the precise time differences of the signals transmitted by each of the transmitters ( 10 ) and received by the acoustic receiver ( 4 ), the possible geometric loci ( 14 ) of the relative position of the apparatus ( 2 ) with respect to said base station ( 8 ) and to the orientation thereof, and the position ( 17 ) of the underwater apparatus is determined based on these possible geometric loci ( 14 ).