Acoustic under sea position measurement system

• US 4,229,809 A
• Filed: 01/29/1979
• Issued: 10/21/1980
• Est. Priority Date: 01/29/1979
• Status: Expired due to Term

• Current Assignee: Sperry Corporation (Unisys Corporation)
• Original Assignee: Sperry Corporation (Unisys Corporation)
• Inventors: Schwalbe, Julian H.
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US06/007,001
• Time in Patent Office: 631 Days
• Field of Search: 367/2, 367/6, 367/106 (U.S. only), 367/127 (U.S. only)
• US Class Current: 367/6
• CPC Class Codes: G01S 15/74 Systems using reradiation of acoustic waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 15/874 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S15/872 takes precedence
• CPC Class Codes: G01S 7/52004 Means for monitoring or calibrating short-range imaging G01S7/5205

Abstract

The invention concerns acoustic under-water measurement apparatus for determining the location with respect to a surface vessel of objects such as submersible vessels, pipe-riders, mining apparatus, or the like, including tethered submersible vessels. A receiver hydrophone set located on the tethered vehicle receives acoustic reply pulses from sea bottom transponders, telemetering the times of reception to a surface support ship via conductors in the tether cable. Signals obtained at the surface ship directly from the transponders and indirectly via the tether cable conductors are combined aboard the surface ship for computing the positions of both vessels with respect to a base line established by the sea bottom transponders. The system is self-calibrating, so that an expensive survey to determine the actual locations of the bottom transponders is no longer required.

Claims

1. In a machine method of establishing positional data with respect to a base line disposed at a marine bottom, the steps of:

providing first and second acoustic pulse transponder means one each at the respective ends of said base line,

providing third acoustic pulse transponder means at support means disposed intermediate said marine bottom and a location at the associated marine surface,

providing pulse interrogator-receiver means at said location for cooperative communication with said first, second, and third acoustic pulse transponder means by providing respective first, second and third pulse responses thereto at said interrogator-receiver means,

providing hydrophone means at said support means responsive to said first and second acoustic pulse transponder means for providing respective fourth and fifth pulse responses at said interrogator-receiver means,

utilizing said first, second, and third pulse responses at said location for computing the respective magnitudes of the distance vector R_SA from said location to said first acoustic pulse transponder means, of the distance vector R_SB from said location to said second acoustic pulse transponder means, and of the distance vector R_SC from said location to said third acoustic pulse transponder means,

utilizing said first and fourth pulse responses at said location for computing the magnitude of the distance vector R_AC between said first and third acoustic pulse transponder means, and

utilizing said second and fifth pulse responses at said location for computing the magnitude of the distance vector R_BC between said second and third pulse transponder means.

2. The machine method described in claim 1 including the additional step of utilizing the magnitude of said distance vector R_SA and the depth of said first acoustic pulse transponder means for computing the horizontal distance component SA with respect to said location and said first acoustic pulse transponder means.

3. The machine method described in claim 2 including the additional step of utilizing the magnitude of said distance vector R_SB and the depth of said second acoustic pulse transponder means for computing the horizontal distance component SB with respect to said location and said second acoustic pulse transponder means.

4. The machine method described in claim 3 including the additional step of utilizing the magnitude of said distance vector R_SC and the depth of said third acoustic pulse transponder means for computing the horizontal distance component distance SC with respect to said location and said third acoustic pulse transponder means.

5. The machine method described in claim 4 including the additional step of utilizing the magnitude of said distance vector R_AC and the depths of said first and third acoustic pulse transponder means for computing the horizontal distance component AC with respect to said first and third acoustic transponder means.

6. The machine method described in claim 5 including the additional step of utilizing the magnitude of said distance vector R_BC and the depths of said second and third acoustic pulse transponder means for computing the horizontal distance component BC with respect to said second and third pulse acoustic transponder means.

7. The machine method described in claim 6 including the step of providing means for substantially instantaneous transmission of said fourth and fifth responses from said hydrophone means to said location.

8. The machine method described in claim 7 including the step of utilizing said horizontal distance components SA, SC, and AC for computing the angle ACS between said horizontal distance components AC and SC.

9. The machine method described in claim 8 including the step of utilizing said horizontal distance components SC, BC and SB for computing the angle SCB between said horizontal distance components SC and BC.

10. The machine method described in claim 9 including the steps of utilizing said angles ACS and SCB to provide a measure of angle ACB between said horizontal distance components AC and BC and therefrom computing the sine and cosine of angle ACB.

11. The machine method described in claim 10 including the additional steps whereby the rectangular x_C, y_C horizontal coordinates of said support means with respect to said base line are computed, said additional steps including utilizing said horizontal distance components AC and BC and said sine and cosine of angle ACB and for additionally generating the sine and cosine of the angle CAB between horizontal distance components AC and AB for the purpose.

12. The machine method described in claim 10 including the additional steps whereby the rectangular x_S, y_S horizontal coordinates of said location with respect to said base line are computed, said additional steps including utilizing said horizontal distance components SC and SA and said sine of the angle ACS, the angles CAB and SAC, and the sine and cosine of angle SAB.

13. The machine method described in claim 10 including the additional steps whereby the rectangular x_S, y_S horizontal coordinates of said location with respect to said base line are computed, said additional steps including utilizing said horizontal distance components SC and SA and said cosines of the angles ACS and CAB for the purpose.

14. The machine method described in claim 1 wherein the computing of the respective magnitudes of the distance vectors R_SA, R_SB, and R_SC includes the sub-steps of:

generating at said location respective first, second and third measures of the times of propagation of said first, second, and third pulse responses to said interrogator-receiver means from said respective first, second, and third acoustic pulse transponder means, and

multiplying said first, second, and third time measures by an adjusted propagation velocity according to the corresponding velocity-depth marine profile for computing said respective distance vectors R_SA, R_SB, and R_SC.

15. The machine method described in claim 1 wherein the computing of the magnitude of the distance vector R_AC includes the sub-steps of:

generating at said location respective first and second measures of the times of propagation of said first and fourth pulse responses to said interrogator-receiver means from said respective first and third acoustic pulse transponder means,

determining the difference between said first and second measures, and

multiplying said difference by substantially the propagation velocity of said acoustic pulses at said marine bottom.

16. The machine method described in claim 1 wherein the computing of the magnitude of the distance vector R_BC includes the sub-steps of:

generating at said location respective first and second measures of the times of propagation of said second and fifth pulse responses to said interrogator-receiver means from said respective second and third pulse transponder means,

determining the difference between said first and second measures, and

multiplying said difference by substantially the propagation velocity of said acoustic pulses at said marine bottom.

17. The machine method described in claim 2 wherein the computing of the horizontal distance component SA includes the sub-steps of:

generating the square of the distance vector R_SA,

generating the square of the depth D_A of said first acoustic pulse transponder,

obtaining the difference between said squares, and

obtaining the real square root of said difference.

18. The machine method described in claim 3 wherein the computing of the horizontal distance component SB includes the sub-steps of:

generating the square of the distance vector R_SB,

generating the square of the depth D_B of said second acoustic pulse transponder,

obtaining the difference between said squares, and

obtaining the real square root of said difference.

19. The machine method described in claim 4 wherein the computing of the horizontal distance component SC includes the sub-steps of:

generating the square of the distance vector R_SC,

generating the square of the depth D_C of said third acoustic pulse transponder,

obtaining the difference between said squares, and

obtaining the real square root of said difference.

20. The machine method described in claim 5 wherein the computing of the horizontal distance component AC includes the sub-steps of:

obtaining the difference between the depths D_A and D_C of said first and third acoustic pulse transponders,

obtaining the square of said difference,

obtaining the square of the magnitude of said vector R_AC,

obtaining the difference between said squares, and

obtaining the real square root of said difference between said squares.

21. The machine method described in claim 6 wherein the computing of the horizontal distance component BC includes the sub-steps of:

obtaining the difference between the depths D_B and D_C of said second and third acoustic pulse transponders,

obtaining the square of said difference,

obtaining the square of the magnitude of said vector R_BC,

obtaining the difference between said squares, and

obtaining the real square root of said difference between said squares.

22. The machine method described in claim 8 wherein the step of computing the angle ACS includes the sub-steps of:

squaring the magnitudes of each of said horizontal distance components SC, AC, and SA,

obtaining the sum of said squares of the magnitudes of the horizontal distance components SC and AC,

obtaining the difference between said sum and said square of the horizontal component SA,

obtaining twice the product of said horizontal components AC and SC,

obtaining the ratio of said difference and twice said product for generating an output representative of cos ACS, and

converting said output to the angle ACS.

23. The machine method described in claim 9 wherein the step of computing the angle SCB includes the sub-steps of:

squaring the magnitudes of each of said horizontal distance components SC, BC, and SB,

obtaining the sum of said squares of the magnitudes of said horizontal distance components SC and BC,

obtaining the difference between said sum and said square of the horizontal components SB,

obtaining twice the product of said horizontal components SC and BC,

obtaining the ratio of said difference and twice said product for generating an output representative of cos SCB, and

converting said output to the angle SCB.

24. The machine method described in claim 11 wherein the step of computing the rectangular X_C, Y_C horizontal coordinates of said support means with respect to said base line includes the sub-steps of:

obtaining the sum of the squares of said horizontal components AC and BC,

obtaining twice the product of said horizontal components AC and BC further multiplied by said cos ACB in he form 2 AC BC cos ACB,

obtaining the difference between said sum and 2 AC BC cos ACB,

obtaining the real square root of said difference,

obtaining the further product of said horizontal component BC and said sine of the angle ACB,

obtaining the ratio of said further product and said real square root,

obtaining from said ratio the sine and cosine of the angle CAB, and

multiplying said respective sine and cosine terms by said horizontal component AC.

25. The machine method described in claim 13 wherein the step of computing the rectangular x_S and y_S horizontal coordinates of said location with respect to said base line includes the sub-steps of:

obtaining the product of said horizontal distance component SC and the sine of said angle ACS,

dividing said product by said horizontal distance component SA to obtain a first output,

converting said first output to the angle SAC,

adding said angle SAC to said angle CAB for obtaining as a sum output the angle SAB,

converting said sum output to the sine and cosine of angle SAB, and

multiplying said respective sine and cosine of angle SAB by said horizontal distance component SA.

26. Apparatus for establishing positional data with respect to a base line disposed at a marine bottom, said apparatus comprising:

first and second acoustic pulse transponder means one each at the respective ends of said base line,

third acoustic pulse transponder means at support means disposed intermediate said marine bottom and a location at the associated marine surface,

pulse interrogator-receiver means at said location for cooperative communication with said first, second, and third acoustic pulse transponder means for providing respective first, second, and third pulse responses at said interrogator-receiver means,

hydrophone means at said support means responsive to said first and second acoustic pulse transponder means for providing respective fourth and fifth pulse responses at said interrogator-receiver means,

first slant range computing means utilizing said first, second, and third pulse responses at said location for computing the respective magnitudes of the distance vector R_SA from said location to said first acoustic transponder means, of the distance vector R_SB from said location to said second acoustic pulse transponder means, and of the distance vector R_SC from said location to said third acoustic pulse transponder means,

second slant range computing means utilizing said first and fourth pulse responses at said location for computing the magnitude of the distance vector R_AC between said first and third acoustic pulse transponder means, and

third slant range computing means utilizing said second and fifth pulse responses at said location for computing the magnitude of the distance vector R_BC between said second and third pulse transponder means.

27. The apparatus described in claim 26 additionally including means for substantially instantaneous transmission of said fourth and fifth responses from said hydrophone means to said location.

28. The apparatus described in claim 27 additionally including first horizontal distance component computer means responsive to the magnitude of said vector R_SA and the depth of said first acoustic pulse transponder for computing the horizontal distance component SA with respect to said location and said first acoustic pulse transponder.

29. The apparatus described in claim 28 additionally including second horizontal distance component computer means responsive to the magnitude of said vector R_SB and the dpeth of said second acoustic pulse transponder for computing the horizontal distance component SB with respect to said location and said second acoustic pulse transponder.

30. The apparatus described in claim 29 additionally including third horizontal distance component computer means responsive to the magnitude of said vector R_SC and the depth of said third acoustic pulse transponder for computing the horizontal distance component distance SC with respect to said location and said third acoustic pulse transponder means.

31. The apparatus described in claim 30 additionally including fourth horizontal distance component computer means responsive to the magnitude of said vector R_AC and the depths of said first and third acoustic pulse transponder means for computing the horizontal distance component AC with respect to said first and third acoustic transponder means.

32. The apparatus described in claim 31 additionally including fifth horizontal distance component computer means responsive to said vector R_BC and the depths of said second and third acoustic pulse transponder means for computing the horizontal distance component BC with respect to said second and third pulse acoustic transponder means.

33. Apparatus as described in claim 32 including first angle computer means responsive to said horizontal distance components SA, SC, and AC for computing the angle ACS between said horizontal distance components AC and SC.

34. Apparatus as described in claim 33 including second angle computer means responsive to said horizontal distance components SC, BC, and SB for computing the angle SCB between said horizontal distance components SC and BC.

35. Apparatus as described in claim 34 including third angle computer means responsive to the magnitudes of said angles ACS and SCB to provide the magnitude of the angle ACB between said horizontal distance components AC and BC and therefrom computing the sine and cosine of angle ACB.

36. Apparatus as described in claim 35 including first rectangular coordinate computer means responsive to said horizontal distance components AC and BC and said sine and cosine of angle ACB for generating the rectangular x_C, y_C horizontal coordinates of said support means with respect to said base line.

37. Apparatus as described in claim 36 wherein said first rectangular coordinate computer means is additionally responsive to said horizontal distance components AC and BC and said sine and cosine of angle ACB for generating the sine and cosine of the angle CAB between horizontal distance components CA and AB.

38. Apparatus as described in claim 37 including second rectangular coordinate computer means responsive to said horizontal distance components SC and SA and said cosines of the angles ACS and CAB for generating the rectangular x_S, y_S horizontal coordinates of said location with respect to said base line.