Method for Determining the Direction of a Source of Waterborne Sound, a Computer Program Product, a Computer or Sonar, and a Watercraft

Abstract

The invention relates to a method for determining the direction of a source of waterborne sound that emits a waterborne acoustic signal, by means of a hydrophone arrangement which forms a linear antenna or a virtual linear antenna, as well as to a computer program product, a computer, a sonar, and a watercraft.

Claims

1. A method for determining the direction of a source of waterborne sound that emits a waterborne acoustic signal by means of a hydrophone arrangement which forms a linear antenna or a virtual linear antenna, wherein the method comprises the following steps: determining the waterborne acoustic signal incoming at the hydrophone arrangement at a first measurement time t1, performing an electronic antenna swing analysis which determines a sum signal S of the linear antenna or of the virtual signal antenna at every rotation angle n=0n, where 0 is the starting angle, is the step-width angle, and n=0, 1, 2, 3, 4 . . . , such that a measurement series S() is created, determining a maximum sum signal Smax(max), where max represents the maximum rotation angle of the measurement series S(), determining a fit measurement series SFit(), which includes the maximum sum signal Smax(max) and at least two more sum signals S(n)m, with the sum number m=2, 3, 4 . . . , determining a mathematical fit function fFit(Fit) for the fit measurement series SFit() by means of a mathematical equalization calculation, and determining a fit function maximum fFit,Max(Fit,Max) of the mathematical fit function fFit(Fit), wherein the direction of the waterborne sound source can be determined by means of Fit,Max.

2. Method according to claim 1, wherein the procedure or sub-steps of the procedure can be carried out at a second measurement time t2, at a third measurement time t3, at a fourth measurement time t4, and/or at further times t, wherein the corresponding measurement series S()t or the determined directions of the waterborne sound source are averaged.

3. Method according to claim 2, wherein the remaining steps of the procedure are carried out according to claim 1.

4. Method according to claim 1, wherein the additional sum signals are sum signals adjacent to the maximum sum signal Smax(max).

5. Method according to claim 1 wherein the mathematical fit function is a polynomial function, a Gaussian function, a Lorentz function, or a Voigt function.

6. An invention selected from the group consisting of: (a) a computer program product which is set up so that the method according to claim 1 can be implemented with a computer or a sonar; (b) a computer configured for carrying out a method according to claim 1; (c) a sonar system for determining a direction of a source of a waterborne sound, the system comprising: an antenna, wherein the antenna includes a plurality of piezoceramic elements, wherein the piezoceramic elements are configured to: detect the waterborne acoustic sound; and generate, based on the waterborne acoustic sound, a voltage; a control circuit communicatively coupled to the plurality of piezoceramic elements, wherein the control circuit is configured to: receive, from the plurality of piezoceramic elements at multiple points in time, the voltage; perform an electronic swing analysis at a plurality of rotation angles at the multiple points in time; determine, based on the electronic swing analysis, a maximum sum signal; determine a fit measurement series, wherein the fit measurement series includes the maximum sum signal and at least two additional sum signals; determine, based on a mathematical equalization calculation and the fit measurement series, a mathematical fit function; and determine, based on the mathematical fit function, the direction of the source of the waterborne sound; and (d) a sonar system configured for carrying out a method according to claim 1.

7. An invention according to claim 6, wherein the invention is (a) a computer configured for carrying out a method according to claim 1.

8. An invention according to claim 6, wherein the invention is (d) a sonar configured for carrying out a method according to claim 1.

9. A watercraft which includes a sonar according to claim 8.

10. An invention according to claim 6, wherein the invention is (c) a sonar system for determining a direction of a source of a waterborne sound, the system comprising: an antenna, wherein the antenna includes a plurality of piezoceramic elements, wherein the piezoceramic elements are configured to: detect the waterborne acoustic sound; and generate, based on the waterborne acoustic sound, a voltage; a control circuit communicatively coupled to the plurality of piezoceramic elements, wherein the control circuit is configured to: receive, from the plurality of piezoceramic elements at multiple points in time, the voltage; perform an electronic swing analysis at a plurality of rotation angles at the multiple points in time; determine, based on the electronic swing analysis, a maximum sum signal; determine a fit measurement series, wherein the fit measurement series includes the maximum sum signal and at least two additional sum signals; determine, based on a mathematical equalization calculation and the fit measurement series, a mathematical fit function; and determine, based on the mathematical fit function, the direction of the source of the waterborne sound.

11. An invention according to claim 10, wherein in (c) the at least two additional sum signals are adjacent to the maximum sum signal.

12. An invention according to claim 11, wherein in (c) the at least two additional sum signals are symmetric about the maximum sum signal.

13. An invention according to claim 6, wherein in (c) the mathematical fit function is one of a polynomial function, a Gaussian function, a Lorentz function, and a Voigt function.

14. An invention according to claim 6, wherein in (c) the plurality of piezoceramic elements includes between 50 and 200 piezoceramic units.

15. An invention according to claim 6, wherein in (c) the plurality of piezoceramic elements form a side-scan sonar antenna.

16. An invention according to claim 15, wherein the side-scan sonar antenna is one of a linear antenna and a virtual linear antenna.

17. An invention according to claim 6, wherein in (c) there is a common step width between each of the plurality of rotation angles.

18. An invention according to claim 17, wherein in (c) the common step width is approximately two degrees.

19. An invention according to claim 6, wherein in (c) a total rotation for the plurality of rotation angles is one hundred eighty degrees.

Description

[0047] A side-scan sonar antenna 101 is arranged on a submarine 111. The side-scan sonar antenna 101 includes individual hydrophones 103, which have a piezoceramic element. The pressure differences impressed on the piezoceramic elements by the waterborne acoustic signal generate a voltage, which is metrologically processed and evaluated. This processing and evaluation takes place almost continuously. This results over time in an almost continuous signal voltage curve at a hydrophone. These voltage curves are convoluted with a temporal window filter, so that a measurement interval results.

[0048] The individual hydrophone signals are evaluated in each case at different times within the temporal filter window, so that what is effectively a computational rotation of the side-scan sonar antenna 101 results.

[0049] In the present case, the step width for rotation is =2. In addition, a cumulated sum signal covering all hydrophones 103 is formed for each angle formed thereby. The rotation is in the direction of rotation 225. Here, the rotation is about the pivot point 227, which in the present case is the center of the hydrophonesin this case, the central hydrophone with the number 76. As soon as the (rotated) side-scan sonar antenna 223 is rotated (.sub.max), such that it essentially emits in parallel to the propagation waves 231 of the propeller signal 229, the maximum sum signal S.sub.max is obtained.

[0050] The direct sum signals around the maximum sum signal S.sub.max at the rotation angle .sub.max are extracted and fitted mathematically by means of a second-degree polynomial.

[0051] FIG. 3 shows not only the extracted measured values 333 with the corresponding rotation angles , but also a graphical representation of the determined fit function 341.

[0052] Here, the rotation angle is shown in the graph on the independent axis, and the sum signal S on the dependent axis.

[0053] The maximum .sub.fit,max is identified for the determined mathematical fit function 341. This differs somewhat from the value (.sub.max) determined by the rotation of the side-scan sonar. The maximum value .sub.fit,max thus obtained is a marked improvement upon the angular value .sub.max and gives the direction from the pivot point 227 to the point location of the sound source 229, thereby providing a bearing.

LIST OF REFERENCE SYMBOLS

[0054] 101 Side-scan sonar antenna

[0055] 103 Hydrophones

[0056] 111 Submarine

[0057] 221/223 Antenna pivoted electronically to antenna 101

[0058] 225 Direction of rotation

[0059] 227 Pivot point

[0060] 229 Underwater sound sources

[0061] 231 Underwater sound waves

[0062] 333 Measured values

[0063] 341 Graph of a fit function