Patent ID: 8009516

Claim:
A system for determining the position of an underwater device to locate, comprising: a plurality of station keeping devices on or below the surface of the water, each station keeping device having: a means for determining its position, a means for keeping time, a means for generating acoustic signals in the water, a memory for storing an acoustic signal schedule, and a processor in communication with the memory and the means for generating acoustic signals in the water according to the acoustic signal schedule; at least one device to locate, the device to locate having a means for keeping time, a memory for storing the acoustic signal schedule and a known position for each station keeping device, an acoustic transducer for receiving acoustic signals sent by the station keeping devices, and a processor configured to calculate the position of the device to locate underneath the water based upon the difference between the arrival time of the acoustic signals and the scheduled time for sending the acoustic signals; wherein each means for keeping time is synchronized, and each memory stores the same acoustic signal schedule.