Producing amplitude values for controlling pixel illumination on a sonar display

• US 7,212,466 B2
• Filed: 07/15/2004
• Issued: 05/01/2007
• Est. Priority Date: 07/15/2004
• Status: Active Grant

• Current Assignee: Imagenex Technology Corp.
• Original Assignee: Imagenex Technology Corp.
• Inventors: Wilson, Douglas James
• Primary Examiner(s): Lobo; Ian J.
• Application Number:
  US10/891,655
• Publication Number:
  US 20060013068A1
• Time in Patent Office: 1,020 Days
• Field of Search: 367/7, 367/68, 367/111
• US Class Current: 367/68
• CPC Class Codes: G01S 15/89 for mapping or imaging
• CPC Class Codes: G01S 15/96 for locating fish
• CPC Class Codes: G01S 7/53 Means for transforming coordinates or for evaluating data, e.g. using computers
• CPC Class Codes: G01S 7/56 Display arrangements short-range imaging G01S7/52053

Abstract

A method and apparatus for producing an amplitude value for use in controlling illumination of a pixel on a display, in response to a sampled sonar signal produced by an element of a sonar array. A pixel time associated with the pixel is found, the pixel time representing a time required for sound to travel a distance represented by the pixel, according to a range of distance to be viewed on the display. A sample point of the sampled sonar signal is then found, the sample point having a sample time nearest the pixel time. A delay value associated with the pixel is then found, the delay value including an array element delay value. A representation of a synthesized waveform is then produced, in response to the sonar signal, the representation comprising a plurality of sample points coinciding in time with the sample points of the sonar signal. An amplitude value representing an amplitude of the synthesized waveform at a time corresponding to the pixel time is then produced by finding an amplitude value of the waveform at a time value corresponding to the sum of the sample time and the delay value. The amplitude value is then made available for use in illuminating the pixel.

Claims

1. A method of producing an amplitude value for use in controlling illumination of a pixel on a display, in response to a sampled sonar signal produced by an element of a sonar array, the method comprising:

finding a pixel time associated with said pixel, said pixel time representing a time required for sound to travel a distance represented by said pixel, according to a range of distance to be viewed on said display;

finding a sample point of the sampled sonar signal, having a sample time nearest said pixel time;

finding a delay value associated with said pixel, said delay value including an array element delay value;

producing a representation of a synthesized waveform, in response to said sonar signal, said representation comprising a plurality of sample points coinciding in time with the sample points of said sonar signal;

producing an amplitude value representing an amplitude of said synthesized waveform at a time corresponding to said pixel time by finding an amplitude value of said waveform at a time value corresponding to the sum of said sample time and said delay value; and

making said amplitude value available for use in illuminating said pixel.

2. The method of claim 1 wherein producing a representation of said synthesized waveform comprises producing a plurality of cosine and sine values representing real and imaginary portions of said synthesized waveform at respective sample points in time.

3. The method of claim 2 wherein finding a sample point comprises finding the cosine and sine values for a sample point having a sample time nearest said pixel time.

4. The method of claim 3 wherein finding a delay value comprises finding cosine and sine amplitude values for said delay value.

5. The method of claim 4 wherein producing an amplitude value comprises adding the product of said cosine values for said sample point having a sample time nearest said pixel time and said delay value respectively to the product of said sine values for said sample point having a sample time nearest said pixel time and said delay value respectively.

6. The method of claim 5 wherein producing an amplitude value comprises adding the product of the sine value for said sample point having a sample time nearest said pixel time and the cosine of the delay value respectively to the product of the cosine value for said sample point having a sample time nearest said pixel time and the sine of said delay value respectively.

7. The method of claim 4 wherein producing an amplitude value comprises adding the product of the sine value for said sample point having a sample time nearest said pixel time and the cosine of the delay value respectively to the product of the cosine value for said sample point having a sample time nearest said pixel time and the sine of said delay value respectively.

8. The method of claim 1 wherein said delay value is pre-calculated, before said representation of said synthesized waveform is produced.

9. The method of claim 1 wherein producing said representation of said waveform comprises producing frequency domain sample values in response to time domain sample values of the sonar signal.

10. The method of claim 9 wherein producing said series of frequency domain sample values comprises performing a Fourier Transform on said time domain sample values.

11. The method of claim 10 further comprising performing an inverse Fourier Transform on said frequency domain sample values.

12. The method of claim 11 wherein said Fourier Transform and said inverse Fourier Transform are performed by a processor programmed to execute a Fourier Transform and an inverse Fourier Transform.

13. The method of claim 12 wherein said processor produces a plurality of cosine and sine values representing real and imaginary portions of said synthesized waveform at respective sample points in time.

14. The method of claim 1 wherein finding a delay value comprises locating a pre-stored delay value in memory.

15. The method of claim 14 wherein said pre-stored delay value is stored in said memory before said representation of said synthesized waveform is produced.

16. The method of claim 14 further comprising calculating said pre-stored delay value as a function of said array element delay value and a difference delay value representing a difference in time between said sample time and said pixel time.

17. The method of claim 1 wherein finding said delay value comprises calculating said array element delay value by calculating array-dependent delay values for a plurality of beam angles within a field of view of the array.

18. The method of claim 17 wherein said array-dependent delay values are calculated as function of array element separation distance, sampling rate of the sonar signal, beam angle and speed of sound.

19. The method of claim 18 wherein said array-dependent delay values associated with respective beam angles are stored in association with identifications of pixels on the display that are associated with the same beam angle.

20. The method of claim 16 further comprising calculating said difference delay value by calculating a fractional value representing said difference in time between said sample time and said pixel time as a fraction of a sample period between two sample times nearest said pixel time.

21. The method of claim 20 wherein calculating said fractional value comprises finding a ratio of the difference between a sample-defined distance and a pixel-defined distance to a sample distance on said synthesized waveform.

22. The method of claim 21 wherein calculating said difference delay value comprises multiplying said fractional value by the number of radians per sample at an acoustic frequency of said sonar signal.

23. The method of claim 22 further comprising for each pixel associated with a distance within said field of view of said array, adding an associated array dependent delay value to an associated difference delay value to produce said delay value and finding cosine and sine values for said delay value.

24. The method of claim 23 further comprising storing said cosine and sine values for said delay value in association with an identification of a pixel with which said delay value is associated.

25. The method of claim 1 further comprising repeating the method of claim 1 for each element in said sonar array until amplitude values, for each element in said array are available for said pixel.

26. The method of claim 25 further comprising summing said amplitude values for each element in said array to produce an illumination value for said pixel.

27. The method of claim 26 further comprising using said illumination value to control illumination of said pixel.

28. The method of claim 9 further comprising repeating the method of claim 9 for the sonar signal from each respective receive element to produce real and imaginary component values for the synthesized waveforms associated with respective array elements.

29. The method of claim 28 further comprising producing modified amplitude values for the real and imaginary component values for each synthesized waveform according to the relations:

For Z=A to P;

Z_R=sign(R_Z)√

{square root over (abs(R_Z))}

Z_I=sign(I_Z)√

{square root over (abs(I_Z))}.

30. The method of claim 29 further comprising producing real and imaginary quadrature multiplication values for each of all unique possible combinations of array elements, in response to said modified amplitude values.

31. The method of claim 30 wherein said real quadrature components are produced according to the relations:

$\begin{array}{c}{M}_{\mathrm{RAB}}=\left(A_R<br><br>B_R-A_I<br><br>B_I\right);<br><br>\\ M_{\mathrm{RAC}}=\left(A_R<br><br>C_R-A_I<br><br>C_I\right);<br><br>\\ <br><br>\mathrm{⋮<br><br>}\\ M_{\mathrm{RYZ}}=\left(Y_R<br><br>Z_R-Y_I<br><br>Z_I\right)\end{array}\hspace{1em}<br><br>$

and wherein said imaginary quadrature components are produced according to the relations;

$\begin{array}{c}{M}_{\mathrm{IAB}}=\left(A_R<br><br>B_I+A_I<br><br>B_R\right);<br><br>\\ M_{\mathrm{IAC}}=\left(A_R<br><br>C_I+A_I<br><br>C_R\right);<br><br>\\ \mathrm{⋮<br><br>}\\ M_{\mathrm{IYZ}}=\left(Y_R<br><br>Z_I+Y_I<br><br>Z_R\right)\end{array}\hspace{1em}<br><br>$

where A–

Z denote any elements and can denote any number of a plurality of array elements.

32. The method of claim 31 further comprising summing said real quadrature components to produce a real magnitude value M_R and summing said imaginary quadrature components to produce an imaginary magnitude value M_I.

33. The method of claim 32 further comprising summing said real and imaginary magnitude values M_R and M_I to produce a single value according to the relation:

M=√

{square root over (M_R²+M_I²)}.

34. The method of claim 33 further comprising scaling said single value to produce an illumination value.

35. The method of claim 34 further comprising using said illumination value to control illumination of said pixel.

70. A computer readable medium encoded with codes for directing a processor to execute the method of claim 1.

71. A computer readable signal encoded with codes for directing a processor to execute the method of claim 1.

36. An apparatus for producing an amplitude value for use in controlling illumination of a pixel on a display, in response to a sampled sonar signal produced by an element of a sonar array, the apparatus comprising:

a component operable to find a pixel time associated with said pixel, said pixel time representing a time required for sound to travel a distance represented by said pixel, according to a range of distance to be viewed on said display;

a component operable to find a sample point of the sampled sonar signal, having a sample time nearest said pixel time;

a component operable to find a delay value associated with said pixel, said delay value including an array element delay value;

a component operable to produce a representation of a synthesized waveform, in response to said sonar signal, said representation comprising a plurality of sample points coinciding in time with the sample points of said sonar signal;

a component operable to produce an amplitude value representing an amplitude of said synthesized waveform at a time corresponding to said pixel time by finding an amplitude value of said waveform at a time value corresponding to the sum of said sample time and said delay value; and

a component operable to make said amplitude value available for use in illuminating said pixel.

37. The apparatus of claim 36 wherein said component operable to produce a representation of said synthesized waveform comprises a processor configured to produce a plurality of cosine and sine values representing real and imaginary portions of said synthesized waveform at respective sample points in time.

38. The apparatus of claim 37 wherein said component operable to find a sample point comprises a processor configured to find cosine and sine values for a sample point having a sample time nearest said pixel time.

39. The apparatus of claim 38 wherein said component operable to find a delay value comprises a processor configured to find cosine and sine amplitude values for said delay value.

40. The apparatus of claim 39 wherein said component operable to produce an amplitude value comprises a processor configured to add the product of said cosine values for said sample point having a sample time nearest said pixel time and said delay value respectively to the product of said sine values for said sample point having a sample time nearest said pixel time and said delay value respectively.

41. The apparatus of claim 40 wherein said component operable to produce an amplitude value comprises a processor configured to add the product of the sine value for said sample point having a sample time nearest said pixel time and the cosine of the delay value respectively to the product of the cosine value for said sample point having a sample time nearest said pixel time and the sine of said delay value respectively.

42. The apparatus of claim 39 wherein said component operable to produce an amplitude value comprises a processor configured to add the product of the sine value for said sample point having a sample time nearest said pixel time and the cosine of the delay value respectively to the product of the cosine value for said sample point having a sample time nearest said pixel time and the sine of said delay value respectively.

43. The apparatus of claim 36 wherein said component operable to find said delay value includes a processor configured to pre-calculate said delay value, before said representation of said synthesized waveform is produced.

44. The apparatus of claim 36 wherein said component operable to produce said representation of said waveform comprises a processor configured to produce frequency domain sample values in response to time domain sample values of the sonar signal.

45. The apparatus of claim 44 wherein said processor is configured to perform a Fourier Transform on said time domain sample values.

46. The apparatus of claim 45 wherein said processor is configured to perform an Inverse Fourier Transform on said frequency domain sample values.

47. The apparatus of claim 46 wherein said processor is configured to produce a plurality of cosine and sine values representing real and imaginary portions of said synthesized waveform at respective sample points in time as a result of said Inverse Fourier Transform.

48. The apparatus of claim 36 wherein said component operable to find a delay value includes a memory for storing a pre-stored delay value and a processor configured to locate said pre-stored delay value in memory.

49. The apparatus of claim 48 wherein said processor is configured to pre-store said pre-stored delay value in said memory before said representation of said synthesized waveform is produced.

50. The apparatus of claim 48 wherein said processor is configured to calculate said pre-stored delay value as a function of said array element delay value and a difference delay value representing a difference in time between said sample time and said pixel time.

51. The apparatus of claim 36 wherein said processor is configured to find said array element delay value by calculating array-dependent delay values for a plurality of beam angles within a field of view of the array.

52. The apparatus of claim 51 wherein said processor is configured to calculate said array-dependent delay values as function of array element separation distance, sampling rate of the sonar signal, beam angle and speed of sound.

53. The apparatus of claim 52 wherein said processor is configured to store said array-dependent delay values associated with respective beam angles in association with identifications of pixels on the display, that are associated with the same beam angle.

54. The apparatus of claim 50 wherein said processor is configured to calculate said difference delay value by calculating a fractional value representing said difference in time between said sample time and said pixel time as a fraction of a sample period between two sample times nearest said pixel time.

55. The apparatus of claim 54 wherein said processor is configured to calculate said fractional value by finding a ratio of the difference between a sample-defined distance and a pixel-defined distance to a sample distance on said synthesized waveform.

56. The apparatus of claim 55 wherein said processor is configured to calculate said difference delay value by multiplying said fractional value by the number of radians per sample at an acoustic frequency of said sonar signal.

57. The apparatus of claim 56 wherein said processor is configured to add an associated array dependent delay value to an associated difference delay value to produce said delay value and find cosine and sine values for said delay value, for each pixel associated with a distance within said field of view of said array.

58. The apparatus of claim 57 further comprising memory and wherein said processor is configured to store said cosine and sine values for said delay value in association with an identification of a pixel with which said delay value is associated.

59. The apparatus of claim 36 wherein each of said components listed in claim is implemented by the same processor and wherein said processor is configured to produce amplitude values for each element in said array for a given pixel.

60. The apparatus of claim 59 wherein said processor is configured to sum said amplitude values for each element in said array to produce an illumination value for said pixel.

61. The apparatus of claim 60 wherein said processor is configured to use said illumination value to control illumination of said pixel.

62. The apparatus of claim 44 wherein said processor is configured to produce real and imaginary component values for synthesized waveforms associated with respective array elements.

63. The apparatus of claim 62 wherein said processor is configured to produce modified amplitude values for said real and imaginary component values for each synthesized waveform according to the relation:

For Z=A to P;

Z_R=sign(R_Z)√

{square root over (abs(R_Z))}

Z_I=sign(I_Z)√

{square root over (abs(I_Z))}.

64. The apparatus of claim 63 wherein said processor is configured to produce real and imaginary quadrature multiplication values for each of all unique possible combinations of array elements, in response to said modified amplitude values.

65. The apparatus of claim 64 wherein said processor is configured to produce said real quadrature multiplication components according to the relations:

$\begin{array}{c}{M}_{\mathrm{RAB}}=\left(A_R<br><br>B_R-A_I<br><br>B_I\right);<br><br>\\ M_{\mathrm{RAC}}=\left(A_R<br><br>C_R-A_I<br><br>C_I\right);<br><br>\\ <br><br>\mathrm{⋮<br><br>}\\ M_{\mathrm{RYZ}}=\left(Y_R<br><br>Z_R-Y_I<br><br>Z_I\right)\end{array}\hspace{1em}<br><br>$

and wherein said imaginary quadrature components are produced according to the relations;

$\begin{array}{c}{M}_{\mathrm{IAB}}=\left(A_R<br><br>B_I+A_I<br><br>B_R\right);<br><br>\\ M_{\mathrm{IAC}}=\left(A_R<br><br>C_I+A_I<br><br>C_R\right);<br><br>\\ \mathrm{⋮<br><br>}\\ M_{\mathrm{IYZ}}=\left(Y_R<br><br>Z_I+Y_I<br><br>Z_R\right)\end{array}$

where A–

Z denote any elements and can denote any number of a plurality of array elements.

66. The apparatus of claim 65 wherein said processor is configured to sum said real quadrature components to produce a real magnitude value M_R and to sum said imaginary quadrature components to produce a quadrature magnitude value M_I.

67. The apparatus of claim 66 wherein said processor is configured to sum said real and imaginary magnitude values M_R and M_I to produce a single value M according to the relation:

M=√

{square root over (M_R²+M_I²)}.

68. The apparatus of claim 67 wherein said processor is configured to scale said single value to produce an illumination value.

69. The apparatus of claim 68 wherein said processor is configured to use said illumination value to control illumination of said pixel.

72. An apparatus for producing an amplitude value for use in controlling illumination of a pixel on a display, in response to a sampled sonar signal produced by an element of a sonar array, the apparatus comprising:

means for finding a pixel time associated with said pixel, said pixel time representing a time required for sound to travel a distance represented by said pixel, according to a range of distance to be viewed on said display;

means for finding a sample point of the sampled sonar signal, having a sample time nearest said pixel time;

means for finding a delay value associated with said pixel, said delay value including an array element delay value;

means for producing a representation of a synthesized waveform, in response to said sonar signal, said representation comprising a plurality of sample points coinciding in time with the sample points of said sonar signal;

means for producing an amplitude value representing an amplitude of said synthesized waveform at a time corresponding to said pixel time by finding an amplitude value of said waveform at a time value corresponding to the sum of said sample time and said delay value; and

means for making said amplitude value available for use in illuminating said pixel.