System for measurement of selected performance characteristics of microwave components

• US 6,484,124 B1
• Filed: 05/22/2000
• Issued: 11/19/2002
• Est. Priority Date: 05/22/2000
• Status: Expired due to Fees

• Current Assignee: Technology Service Corporation
• Original Assignee: Technology Service Corporation
• Inventors: MacMullen, Alexander
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Raymond, Edward
• Application Number:
  US09/576,318
• Time in Patent Office: 911 Days
• Field of Search: 324/612, 324/615, 324/618, 324/619, 324/707, 324/76.12, 324/76.19, 324/76.22, 324/76.23, 324/76.24, 455/205, 455/226.7, 455/309, 702/57, 702/60, 702/65, 702/66-68, 702/71, 702/72, 702/75, 702/81, 702/108, 702/117, 702/121, 702/190
• US Class Current: 702/182
• CPC Class Codes: G01R 29/26 Measuring noise figure; Measuring signal-to-noise ratio
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters

Abstract

An improved process and apparatus for measuring performance characteristics of microwave power components. The invention involves the use of a rotating phase reference technique to improve measurement. The process and apparatus result in fast, accurate, reproducible determination of the desired properties. In addition, the apparatus of the present invention is lightweight, compact, and portable.

Claims

1. A method for the measurement of selected fundamental performance parameters of a test unit, comprising the steps of:

a. generating a first reference signal;

b. generating a second reference signal, that is rotated in phase relative to said first reference signal;

c. supplying said first reference signal to the test unit;

d. supplying the output of the test unit to vector demodulator means, wherein the test unit output comprises an rf signal;

e. supplying said second reference signal to vector demodulator means, wherein the vector demodulator means comprises first vector demodulator means for receiving said rf signal from the test unit and second vector demodulator means for receiving said second signal;

f. generating a signal from vector modulator means; and

g. processing said signal from said vector demodulator means to determine the selected fundamental performance parameters of the test unit.

2. The method of claim 1, wherein said processing said signals from said vector demodulator means further comprise

a. said signal being I and Q signals,

b. digitizing said I and Q signals, and

c. supplying said digitized signals to computer means for determining the fundamental performance parameters of the test unit.

3. The method of claim 1 wherein said fundamental performance parameter comprises signal-to-noise ratio.

4. The method of claim 1 wherein said fundamental performance parameter comprises moving target indicator.

5. The method of claim 1 wherein said fundamental performance parameter comprises clutter attenuation.

6. The method of claim 1 wherein the fundamental performance parameter comprises phase gain.

7. The method of claim 1 wherein the fundamental performance parameter comprises phase insertion.

8. The method of claim 1 wherein the selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

0.2 dB.

9. The method of claim 1 wherein the selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

1.5 dB, in less than about 3 seconds.

10. The method of claim 1 wherein the selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

1.5 dB, through the use of a light weight, portable apparatus.

11. The method of claim 1 wherein the selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

0.1 dB, in less than or equal to about 3 seconds.

12. A method for measurement of selected fundamental performance parameters of a test unit, comprising the steps of:

a. generating a first reference signal;

b. generating a second reference signal, that is rotated in phase relative to said first reference signal;

c. supplying said first reference signal to the test unit;

d. supplying the output of the test unit to vector demodulator means, wherein the test unit output comprises an rf signal;

e. supplying said second reference signal to vector demodulator means, wherein the vector demodulator means comprises first vector demodulator means for receiving said rf signal from the test unit and second vector demodulator means for receiving said second signal;

f. generating I and Q signals from vector modulator means;

g. digitizing said I and Q signals from said vector demodulator means;

h. coordinating said digitizing with said first reference signal generator through clock means; and

i. processing said coordinated digitized I and Q signals to determine the selected fundamental performance parameters of the test unit.

13. The method of claim 12, wherein said processing said digitized I and Q signals further comprises supplying said digitized signals to specialized computer means for determining the fundamental performance parameters of the test unit.

14. The method of claim 12 wherein the fundamental performance parameter comprises signal-to-noise ratio.

15. The method of claim 12 wherein the fundamental performance parameter comprises moving target indicator.

16. The method of claim 12 wherein the fundamental performance parameter comprises clutter attenuation.

17. The method of claim 12 wherein the fundamental performance parameter comprises phase gain.

18. The method of claim 12 wherein the fundamental performance parameter comprises phase insertion.

19. The method of claim 12 wherein said selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than about ±

1.5 dB, in less than about 3 seconds.

20. The method of claim 12 wherein said selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ration to an accuracy of less than or equal to about ±

1.5 dB, through the use of apparatus weighings less than about 50 pounds.

21. The method of claim 12 wherein said selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

0.2 dB , in less than or equal to about 3 seconds, through the use of an apparatus weighing less than about 50 pounds.

22. The method of claim 12 wherein said selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

0.2 dB, in less than or equal to about 3 seconds.

23. The method of claim 12, wherein said method determines the fundamental performance parameter to an accuracy of less than or equal to about ±

0.1 dB, in less than or equal to about 3 seconds.

24. A method for improving the accuracy of measurement of the performance of selected fundamental parameters of a test unit, comprising:

a. generating a first reference signal;

b. generating a second reference signal, that is rotated in phase relative to said first reference signal;

c. supplying said first reference signal to the test unit;

d. supplying the output of the test unit to vector demodulator means;

e. supplying said second reference signal to vector demodulator means;

f. generating I and Q signals from vector modulator means;

g. digitizing said I and Q signals from said vector demodulator means;

h. coordinating said digitizing with said first reference signal generator through clock means;

i. sampling said I and Q signals from vector demodulator means;

j. reducing the data set of said measured said I and Q signals, by averaging over M samples, where M is greater than or equal to 30;

k. estimating average I and Q values, by averaging said reduced data set; and

l. calculating the selected performance parameter.

25. The method of claim 24 wherein the selected performance comprises VDM Correction and the method further comprises:

a. estimating average I and Q values for a selected data collection window;

b. determining phase rotation settings of said second signal for last four pulses;

c. calculating VDM correction parameters;

d. assessing gain imbalance, quadrature error, I and Q DC offsets;

e. determining phase rotation settings of said second signal for pulses 1, 2, and 3;

f. calculating VDM correction constants for pulses 1, 2, and 3;

g. determining data for pulses 1, 2, and 3, and said reduced data for pulses 1, 2, and 3;

h. supplying phase rotation settings of said second signal for pulses 1, 2, and 3;

i. applying VDM corrections to pulses 1, 2, and 3; and

j. calculating corrected values of I and Q for pulses 1, 2, and 3.

26. The method of claim 25, wherein the selected performance parameter comprises MTI, and the method further comprises:

a. averaging said corrected values of I and Q for pulses 1, 2, and 3 over the top of the pulse;

b. supplying said averaged corrected values of I and Q, along with said corrected values of I and Q; and

c. calculating MTI.

27. The method of claim 26, wherein the selected performance parameter comprises signal-to-noise ratio, and the method further comprises:

a. supplying said corrected values of I and Q for pulse 2;

b. supplying said averaged corrected values of I and Q for pulse 2;

c. calculating the variance;

d. calculating signal-to-noise ratio from said variance;

e. estimating signal-to-noise ratio; and

f. estimating signal.

28. The method of claim 27, wherein the selected performance parameter comprises MTI SNR, and the method further comprises:

a. supplying corrected values of I and Q for pulse 2;

b. supplying said averaged corrected values of I and Q for pulse 2;

c. supplying a signal estimate;

d. estimating MTI SNR from said corrected values, said average corrected values and said signal estimate to estimate MTI SNR.

29. The method of claim 28, wherein the selected performance parameter comprises clutter attenuation, and the method further comprises:

a. supplying corrected values of I and Q;

b. supplying said averaged corrected values of I and Q for pulse 2;

c. supplying a signal estimate;

d. estimating Clutter Attenuation from said corrected values, said average corrected values and said signal estimate to estimate clutter attenuation.

30. The method of claim 28, wherein the selected performance parameter comprises phase estimation, the method further comprises:

a. determining the phase shifter setting for pulse 2;

b. supplying said phase shifter setting;

c. and estimating phase from said phase shifter setting and said corrected values of I and Q for pulse 2.

31. The method of claim 24, wherein the selected performance parameter comprises signal-to-noise ratio, moving target indicator, moving target indicator signal-to-noise ratio, clutter attenuation, and phase estimates, and the method further comprises:

a. calculating the mean signal-to-noise ratio estimate;

b. calculating the mean MTI SNR estimate;

c. calculating the mean clutter attenuation estimate; and

d. calculating the mean phase estimate.

32. The method of claim 24, wherein said processing said digitized I and Q signals further comprises supplying said digitizing signals to specialized computer means for determining the fundamental performance parameters of the test unit.

33. The method of claim 24 wherein the fundamental performance parameter comprises signal-to-noise ratio.

34. The method of claim 24 wherein the fundamental performance parameter comprises moving target indicator.

35. The method of claim 24 wherein the fundamental performance parameter comprises clutter attenuation.

36. The method of claim 24 wherein the fundamental performance parameter comprises phase gain.

37. The method of claim 24 wherein the fundamental performance parameter comprises phase insertion.

38. The method of claim 24 wherein said selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than about ±

1.5 dB, in less than about 3 seconds.

39. The method of claim 24 wherein said selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

0.1 dB, in less than or equal to about 3 seconds.

40. The method of claim 24 wherein said selected performance parameter comprises signal-to-noise ratio and the method determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

1.5 dB, in less than or equal to about 3 seconds, through an apparatus weighing less than about 50 pounds.

41. An apparatus for the measurement of fundamental parameters of a test unit, comprising:

a. a first signal generator means, for generating a first signal having first phase;

b. phase shifter means, cooperating with said first signal generator means, for rotating the phase of said first signal to produce a second signal having a second phase, wherein said second signal is shifted in phase relative to said first signal;

c. test unit input means, for supplying said first signal to said test unit input means;

d. demodulator means, comprising first vector demodulator means for receiving said rf signal from the test unit and second vector demodulator means for receiving said second signal;

e. means for supplying said second signal to said demodulator means; and

f. data processing means for computing the fundamental parameter of the test unit from the output of said digitizer.

42. The apparatus of claim 41, further comprising digitizer means for digitizing the output of said demodulator means.

43. The apparatus of claim 41, further comprising digitizer means for digitizing the output of said demodulator means and clock means cooperating with said signal generator means and said digitizer means.

44. The apparatus of claim 41 wherein the fundamental performance parameter comprises signal-to-noise ratio.

45. The apparatus of claim 41 wherein the fundamental performance parameter comprises moving target indicator.

46. The apparatus of claim 41 wherein the fundamental performance parameter comprises clutter attenuation.

47. The apparatus of claim 41 wherein the fundamental performance parameter comprises phase gain.

48. The apparatus of claim 41 wherein the fundamental performance parameter comprises phase insertion.

49. The apparatus of claim 41 wherein said selected performance parameter comprises signal-to-noise ratio and the apparatus determines said signal-to-noise ratio to an accuracy of less than about ±

1.5 dB, in less than about 3 seconds.

50. The apparatus of claim 41 wherein said selected performance parameter comprises signal-to-noise ratio, the apparatus determines said signal-to-noise ratio to an accuracy of less than about ±

1.5 dB, and the apparatus weighs less than about 50 pounds.

51. The apparatus of claim 41 wherein said selected performance parameter comprises signal-to-noise ratio, the apparatus determines said signal-to-noise ratio to an accuracy of less than about ±

1.5 dB, in less than about 3 seconds, and the apparatus weighs less than about 50 pounds.

52. The apparatus of claim 41 wherein said selected performance parameter comprises signal-to-noise ratio and the apparatus determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

0.2 dB, in less than or equal to about 3 seconds.

53. An apparatus for the measurement of fundamental parameters of a test unit, comprising:

a. signal generator means, for generating a first signal having first phase;

b. phase shifter means, cooperating with said first signal generator means, for rotating the phase of said first signal to produce a second signal having a second phase, wherein said second signal is shifted in phase relative to said first signal;

c. test unit input means, for supplying said first signal to said test unit input means;

d. vector demodulator means, for generating demodulator output signals, said vector demodulator means comprising first vector demodulator means for receiving said rf signal from the test unit and second vector demodulator means for receiving said second signal;

e. digitizer means for digitizing demodulator output signals;

f. clock means, cooperating with said signal generator means and said digitizer, for coordinating said digitizer; and

g. data processing means for computing the fundamental parameter of the test unit from the output of said digitizer.

54. The apparatus of claim 53 wherein the fundamental performance parameter comprises signal-to-noise ratio.

55. The apparatus of claim 53 wherein the fundamental performance parameter comprises moving target indicator.

56. The apparatus of claim 53 wherein the fundamental performance parameter comprises clutter attenuation.

57. The apparatus of claim 53 wherein the fundamental performance parameter comprises phase gain.

58. The apparatus of claim 53 wherein the fundamental performance parameter comprises phase insertion.

59. The apparatus of claim 53 wherein said selected performance parameter comprises signal-to-noise ratio and the apparatus determines said signal-to-noise ratio to an accuracy of less than about ±

1.5 , in less than about 3 seconds.

60. The apparatus of claim 53 wherein said selected performance parameter comprises signal-to-noise ratio, the apparatus determines said signal-to-noise ration to an accuracy of less than or equal to about ±

1.5 dB, and the apparatus weighs less than about 50 pounds.

61. The apparatus of claim 53 wherein said selected performance parameter comprises signal-to-noise ratio, the apparatus determines said signal-to-noise ratio to an accuracy of less than or equal to about ±

1.5 dB, in less than or equal to about 3 seconds, and the apparatus weights less than about 50 pounds.

62. The apparatus of claim 53 wherein said selected performance parameter comprises signal-to-noise ratio and the apparatus determines said signal-to-noise ratio to an accuracy or less than or equal to about ±

0.2 dB, in less than or equal to about 3 seconds.

63. The apparatus of claim 53, wherein the apparatus weighs less than or equal to about 200 pounds.

64. The apparatus of claim 53, wherein the apparatus is less than about 4,000 cubic inches in volume.