Patent ID: 9645223
Date: 2017-05-09
CPC Classifications: G01S,H04B

Claim:
1. An underwater receiver for determining underwater locations of at least two divers, the underwater receiver comprising: a hydrophone configured to receive an acoustic transmission from one or more acoustic transmitters of a plurality acoustic transmitters, the plurality of acoustic transmitters forming an array having a rigid structure and configured to be suspended underwater, wherein a baseline of the array is less than and including approximately 2 meters, and wherein the one or more acoustic transmissions comprise position information of the array, attitude data of the array, and timing information; computer hardware configured to determine, based at least in part on an absolute-time reference and the timing information, an arrival time of each of the one or more acoustic transmissions, and to use a statistical fit algorithm to determine position data of a first diver in array-fixed coordinates based at least in part on the arrival times, the position data in array-fixed coordinates determining a distance of the first diver from the array; the computer hardware further configured to transform the position data of the first diver from the array-fixed coordinates to geodetic coordinates based at least in part on the position information of the array and the attitude data of the array; the computer hardware further configured to determine a location of a second diver based at least in part on receipt of acoustic signals that are different from the acoustic transmissions from the one or more acoustic transmitters; and a display to display the position data of the first diver and the location of the second diver.