System and method for determining wave characteristics from a moving platform

• US 8,654,607 B2
• Filed: 05/26/2010
• Issued: 02/18/2014
• Est. Priority Date: 05/27/2009
• Status: Active Grant

• Current Assignee: Teledyne Instruments Incorporated (Teledyne Technologies Incorporated)
• Original Assignee: Teledyne Industries Incorporated (Teledyne Technologies Incorporated)
• Inventors: Strong, Brandon S.
• Primary Examiner(s): Alsomiri, Isam
• Assistant Examiner(s): HULKA, JAMES R
• Application Number:
  US12/788,155
• Publication Number:
  US 20100302908A1
• Time in Patent Office: 1,364 Days
• Field of Search: 367/90
• US Class Current: 367/90
• CPC Class Codes: G01C 13/002 Measuring the movement of open water
• CPC Class Codes: G01S 15/02 using reflection of acoustic waves G01S15/66 takes precedence
• CPC Class Codes: G01S 15/58 Velocity or trajectory determination systems; Sense-of-movement determination systems velocity measurement in imaging systems G01S15/8979
• CPC Class Codes: G01S 15/582 using transmission of interrupted pulse-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 15/62 Sense-of-movement determination G01S15/588 takes precedence
• CPC Class Codes: G01S 15/88 Sonar systems specially adapted for specific applications seismic or acoustic prospecting or detecting G01V1/00

Abstract

A system and a method for determining one or more wave characteristics from a moving platform are disclosed. A sonar system, such as an Acoustic Doppler Current Profiler, can profile the water motion relative to the platform, and an earth reference can determine a measure of the platform motion relative to a fixed earth reference. Both water profile and earth reference measurements can be synergistically employed to compensate for motion of the platform. Directional wave spectra and non-directional wave spectrum can be computed and translated via linear wave theory to surface height spectra and used to calculate characteristics, such as significant wave height, peak period, and peak direction.

Claims

1. A system for determining at least one wave characteristic, the system comprising:

a sonar system configured to obtain data indicative of motion of water relative to a platform;

an earth reference sensor configured to obtain data indicative of motion of the platform relative to a fixed reference frame; and

a processor configured to determine at least one wave characteristic by combining the data indicative of motion of the water relative to the platform and the data indicative of motion of the platform to the fixed reference frame, so as to mathematically compensate for the motion of the platform relative to the fixed reference frame.

2. The system of claim 1, wherein the sonar system comprises an acoustic Doppler current profiler.

3. The system of claim 1, further comprising a display configured to output the at least one wave characteristic.

4. The system of claim 1, wherein the at least one wave characteristic comprises height, period, or direction of a wave.

5. The system of claim 1, wherein the data indicative of motion of water relative to the platform comprises one of following:

inertial data, bottom track data, or surface track data.

6. The system of claim 1, wherein the data indicative of motion of the platform relative to a fixed reference frame comprises velocity and orientation data.

7. The system of claim 1, wherein the processor is further configured to perform one or more coordinate transformations in the time domain to bring at least a portion of the data indicative of motion of water relative to the platform and the data indicative of motion of the platform relative to the fixed reference frame into the same coordinate system.

8. A method of determining at least one wave characteristic, the method comprising:

receiving data indicative of motion of water relative to a platform from an acoustic Doppler current profiler (ADCP);

receiving data indicative of motion of the platform relative to a fixed reference frame from a reference sensor; and

determining, using a processor in communication with the ADCP and the reference sensor, at least one wave characteristic by combining the received data to mathematically compensate for the motion of the platform relative to the fixed reference frame.

9. The method of claim 8, further comprising synchronizing the data indicative of motion of water relative to the platform and the data indicative of motion of the platform relative to a fixed reference frame.

10. The method of claim 8, further comprising isolating, in the time domain, platform, water, and earth reference frames from the data indicative of motion of water relative to a platform and the data indicative of motion of the platform relative to a fixed reference frame.

11. The method of claim 8, further comprising performing one or more coordinate transformations in the time domain to bring at least a portion of the data indicative of motion of water relative to a platform and the data indicative of motion of the platform relative to a fixed reference frame into the same coordinate system.

12. The method of claim 8, wherein determining the at least one wave characteristic comprises overlap-add spectral processing.

13. The method of claim 12, wherein:

overlap-add spectral processing comprises computing segment specific statistics, and

determining the at least one wave characteristic comprises averaging segment specific statistics for two or more segments.

14. The method of claim 12, wherein determining the at least one wave characteristic comprises remapping the frequency space for a segment to determine coefficients of a wave spectrum for a wave frequency in a water reference frame.

15. The method of claim 8, wherein determining the at least one wave characteristic comprises triplet processing.

16. The method of claim 8, wherein determining the at least one wave characteristic comprises determining a directional wave spectrum.

17. The method of claim 8, wherein determining the at least one wave characteristic comprises determining a non-directional wave spectrum.

18. The method of claim 8, wherein determining the at least one wave characteristic comprises correcting for platform motion on a short time scale.

19. A method of determining at least one wave characteristic on an electronic device, the method comprising:

receiving acoustic derived data indicative of motion of water relative to a platform and data indicative of motion of the platform relative to a fixed reference frame;

transforming at least a portion of the received data into data indicative of motion of water relative to the fixed reference frame;

determining a directional wave spectrum based at least in part on the transformed data;

determining a non-directional wave spectrum based at least in part on the directional wave spectrum; and

deriving at least one wave characteristic based at least in part on at least one of the directional wave spectrum and the non-directional wave spectrum.

20. The method of claim 19, further comprising synchronizing the data indicative of motion of water relative to the platform and the data indicative of motion of the platform relative to a fixed reference frame.

21. The method of claim 19, wherein determining the directional wave spectrum includes dividing at least a portion of the received data into overlapping segments.

22. The method of claim 21, wherein determining the directional wave spectrum includes calculating a segment specific cutoff frequency.

23. The method of claim 19, wherein determining the non-directional wave spectrum includes a weighted accumulation based on data summed over sensors and segments.

24. The method of claim 19, wherein determining the non-directional spectrum comprises segment specific remapping a power for an observed frequency to a power for a wave frequency in a water reference frame.

25. The method of claim 19, further comprising resealing the directional wave spectrum based at least in part on the non-directional wave spectrum, wherein deriving the at least one wave characteristic is based at least in part on a resealed directional wave spectrum.

26. The method of claim 19, wherein determining the directional wave spectrum includes deriving the directional wave spectrum from a relatively short time series of the transformed data, and decreasing the frequency resolution of the transformed data.

27. A non-transitory computer-readable storage medium comprising instructions that when executed perform a method, the method comprising:

receiving data indicative of motion of water relative to a platform from an acoustic Doppler current profiler (ADCP);

receiving data indicative of motion of the platform relative to a fixed reference frame from a reference sensor; and

determining, using a processor in communication with the ADCP and the reference sensor, at least one wave characteristic by combining the received data to compensate for the motion of the platform relative to the fixed reference frame via synchronizing and collocating the data indicative of motion of water relative to the platform and the data indicative of motion of the platform relative to the fixed reference frame.

28. A non-transitory computer-readable storage medium comprising instructions that when executed perform a method, the method comprising:

receiving acoustic derived data indicative of motion of water relative to a platform and data indicative of motion of the platform relative to a fixed reference frame;

transforming at least a portion of the received data into data indicative of motion of water relative to the fixed reference frame;

determining a directional wave spectrum based at least in part on the transformed data;

determining a non-directional wave spectrum based at least in part on the directional wave spectrum; and

deriving at least one wave characteristic based at least in part on at least one of the directional wave spectrum and the non-directional wave spectrum.