UNDERWATER ACOUSTIC NAVIGATION SYSTEMS AND METHODS

• US 20140126334A1
• Filed: 01/15/2014
• Published: 05/08/2014
• Est. Priority Date: 12/16/2009
• Status: Active Grant

• Current Assignee: Shb Instruments, Inc.
• Original Assignee: Shb Instruments, Inc.
• Inventors: Megdal, Barry, Scholze, Hans
• Granted Patent: US 9,645,223 B2
• Time in Patent Office: Days
• US Class Current: 367/117
• CPC Class Codes: G01S 11/14 using ultrasonic, sonic, or infrasonic waves
• CPC Class Codes: G01S 3/8083 determining direction of source
• CPC Class Codes: G01S 5/0045 Transmission from base station to mobile station G01S5/009 takes precedence
• CPC Class Codes: G01S 5/30 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves

Abstract

An acoustic underwater navigation system is disclosed. For instance, an underwater receiver determines its position using signals broadcast from an array of acoustic transmitters located near the surface. The position of the array is measured using global positioning system (GPS) technology and the transmitters collectively produce an acoustic signal in which the position and attitude of the array and the GPS time of transmission are encoded. An underwater receiver which is synchronized with the GPS time uses the transmitted position and attitude of the array and the transmission time information to calculate its position.

Claims

1. A receiver for use in an underwater navigation system, the receiver comprising:

a hydrophone configured to receive an acoustic transmission from each of a plurality acoustic transmitters, the plurality of acoustic transmitters forming an array, wherein timing information of the acoustic transmissions is based at least in part on a time-base; and

computer hardware configured to determine a time delay between the transmission and receipt of the acoustic transmission from each acoustic transmitter and to calculate an absolute position of the receiver based at least in part on the time delays, the timing information, and position information and attitude data of the array.

2. The receiver of claim 1 wherein the acoustic transmissions comprise the position information and the attitude data of the array.

3. The receiver of claim 2 further comprising a decoder configured to recover at least one of the position information, the attitude data, and the timing information of the array from the acoustic transmissions.

4. The receiver of claim 1 further comprising an oscillator configured to receive a signal associated with the time-base prior to the hydrophone receiving the acoustic transmissions to provide a source of the timing information.

5. The receiver of claim 4 wherein no signals are sent from the receiver to establish the timing information.

6. The receiver of claim 1 wherein the array has a rigid structure.

7. The receiver of claim 1 wherein a ratio of a distance between the array and the hydrophone to a greatest distance between any two acoustic transmitters of the plurality of acoustic transmitters in the array is greater than 10:

1.

8. The receiver of claim 1 wherein the attitude data comprises at least one of angular magnitude and direction of acceleration of the array, an angular rate of the array, magnitude and direction of the Earth'"'"'s magnetic field near the array, ambient temperature of water surrounding the array, and depth of the array.

9. The receiver of claim 1 wherein the computer hardware is further configured to calculate azimuth, elevation, and range relative to the array based at least in part on the time delays to determine a relative position to the array.

10. The receiver of claim 9 wherein the computer hardware is further configured to determine the absolute position based at least in part on the relative position, the attitude data, and the position information.

11. A method comprising:

receiving underwater at a receiver an acoustic transmission from each of a plurality acoustic transmitters, the plurality of acoustic transmitters forming an array, wherein timing information of the acoustic transmissions is based at least in part on a time-base;

determining a time delay between the transmission and receipt of the acoustic transmission from each acoustic transmitter; and

calculating an absolute position of a receiver based at least in part on the time delays, the timing information, and position information and attitude data of the array.

12. The method of claim 11 wherein the acoustic transmissions comprise the position information and the attitude data of the array.

13. The method of claim 12 further comprising recovering at least one of the position information, the attitude data, and the timing information of the array from the acoustic transmissions.

14. The method of claim 11 further comprising receiving a signal associated with the time-base prior to the hydrophone receiving the acoustic transmissions to provide a source of the timing information.

15. The method of claim 14 wherein no signals are sent from the receiver to establish the timing information.

16. The method of claim 11 wherein the array has a rigid structure.

17. The method of claim 11 wherein a ratio of a distance between the array and the hydrophone to a greatest distance between any two acoustic transmitters of the plurality of acoustic transmitters in the array is greater than 10:

1.

18. The method of claim 11 wherein the attitude data comprises at least one of angular magnitude and direction of acceleration of the array, an angular rate of the array, magnitude and direction of the Earth'"'"'s magnetic field near the array, ambient temperature of water surrounding the array, and depth of the array.

19. The method of claim 11 further comprising calculating azimuth, elevation, and range relative to the array based at least in part on the time delays to determine a relative position to the array.

20. The method of claim 18 further comprising determining the absolute position based at least in part on the relative position, the attitude data, and the position information.