Phase measurement ranging

• US 4,788,548 A
• Filed: 09/08/1987
• Issued: 11/29/1988
• Est. Priority Date: 09/08/1987
• Status: Expired due to Term

• Current Assignee: ITT Corporation (ITT, Inc.)
• Original Assignee: ITT Gilfillan
• Inventors: Hammerquist, Earl L.
• Primary Examiner(s): Blum, Theodore M.
• Assistant Examiner(s): Sotomayor, John B.
• Application Number:
  US07/095,365
• Time in Patent Office: 448 Days
• Field of Search: 342/458, 342/442, 342/407, 342/411, 342/417
• US Class Current: 342/458
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence

Abstract

A passive radar ranging system having an antenna system for receiving radiated electromagnetic energy emanating from an emitter source, plus a translation resolution system and a digital computation system for making phase measurements of the received electromagnetic energy with the translated and resolved energy signals being operated upon by a plurality of system spacing parameters, the radiated energy being modulated in a particular pattern, randomly modulated or unmodulated and with the emitter source being fixed or moving while the phase measurements are made from a single measurement platform which may also be fixed or moving with respect to the emitter source, the phase measurements being employed for determining the instantaneous range from the emitter source to the measurement platform.

Claims

1. A passive radar ranging apparatus for determining the instantaneous range to an emitter source comprising, in combination:

receiving means for receiving a plurality of radiated electromagnetic energy, said received electromagnetic energy having a non-cooperative waveform and an unspecified frequency;

translating means in communication with said receiving means for translating a first parameter of said received electromagnetic energy for detection and phase measurement;

first resolving means in communication with said translating means for providing a plurality of distance oriented digital phase measurements, said phase measurements being determined directly from said received electromagnetic energy;

second resolving means in communication with said translating means for resolving said first parameter and for providing said resolved first parameter to said first resolving means for utilization in providing said phase measurements;

computing means connected to said first resolving means for receiving and manipulating said plurality of distance oriented digital phase measurements and for determining said instantaneous range to said emitter source of said radiated electromagnetic energy, and further including means for resolving phase ambiguities of said received electromagnetic energy wherein said phase measurements are available only from said emitter source and knowledge of relative motion between said emitter source and said receiving means is unknown; and

displaying means for displaying said instantaneous range to said emitter source wherein said displayed instantaneous range is equivalent to R=[bc(c-b)(a² -φ

₁²)/2a² (bφ

₃ -cφ

₂)].

2. The radar ranging apparatus of claim 1 wherein said receiving means is comprised of a plurality of reception elements.

3. The radar ranging apparatus of claim 2 wherein said plurality of reception elements are aligned in a linear fashion, each reception element being spaced from an adjacent element by a spacing parameter.

4. The radar ranging apparatus of claim 1 wherein said receiving means is comprised of a plurality of antenna elements.

5. The radar ranging apparatus of claim 4 wherein each of said antenna elements is aligned in a straight line.

6. The radar ranging apparatus of claim 4 wherein each of said antenna elements is spaced from each adjacent element by a fixed spacing parameter.

7. The radar ranging apparatus of claim 1 wherein said plurality of radiated electromagnetic energy is received by said receiving means in a plurality of phase fronts.

8. The radar ranging apparatus of claim 7 wherein each of said plurality of phase fronts is located along a locus of points passing through one of a plurality of reception elements comprising said receiving means.

9. The radar ranging apparatus of claim 1 wherein said translating means comprises a plurality of frequency translators.

10. The radar ranging apparatus of claim 1 wherein said first resolving means comprises a plurality of phase resolvers.

11. The radar ranging apparatus of claim 1 wherein said second resolving means comprises a frequency resolver.

12. The radar ranging apparatus of claim 1 wherein said computing means comprises a digital computation system.

13. The radar ranging apparatus of claim 1 wherein each of said plurality of distance oriented digital phase measurements are transmitted to one of a plurality of primary adder circuits in said computing means.

14. The radar ranging apparatus of claim 13 wherein each of said primary adder circuits provides a sum of one of said distance oriented digital phase measurements and a corresponding phase correction value.

15. The radar ranging apparatus of claim 14 wherein each of said sums comprises a corrected phase signal.

16. The radar ranging apparatus of claim 1 wherein each of said distance oriented digital phase measurements is summed to a corresponding phase correction value for providing a plurality of corrected phase signals, each of said corrected phase signals being transmitted to one of a plurality of multiplier circuits.

17. The radar ranging apparatus of claim 16 wherein each of said corrected phase signals is multiplied by a plurality of apparatus spacing parameters stored in said multiplier circuits.

18. The radar ranging apparatus of claim 17 wherein each of said parameter corrected phase signals is transmitted from said multiplier circuits to one of a plurality of secondary adder circuits for adding a plurality of output signals of said multiplier circuits.

19. The radar ranging apparatus of claim 1 wherein said computing means further includes a divider circuit for receiving a pair of parameter corrected phase signals from a plurality of adders and multipliers located within said computing means.

20. The radar ranging apparatus of claim 19 wherein said divider circuit provides a fractional output signal, said fractional output signal being said instantaneous range to said emitter source.

21. The radar ranging apparatus of claim 1 wherein said computing means determines said instantaneous range to said emitter source providing an output signal, said output signal being transmitted to said displaying means for providing communication of said determined instantaneous range.

22. The radar apparatus of claim 1 wherein said computing means further includes a calibration means.

23. The radar ranging apparatus of claim 22 wherein said calibration means provides a phase correction value, said phase correction value being transmitted to each of a plurality of primary adder circuits.

24. The radar ranging apparatus of claim 1 further including a calibration signal generator in electrical communication with a calibrating means, said calibration signal generator for providing a correction signal.

25. The radar ranging apparatus of claim 24 wherein said correction signal provided by said calibration signal generator is transmitted to each of a plurality of receiving elements of said reception means.

26. The radar ranging apparatus of claim 1 wherein said displaying means is in electrical communication with a calibrating means, said displaying means for transmitting a plurality of parameters to said calibrating means.

27. The radar ranging apparatus of claim 26 wherein said transmitted plurality of parameters includes said instantaneous range to said emitter source.

28. A passive radar ranging system for determining the instantaneous range to an emitter source comprising, in combination:

an antenna system for receiving a plurality of radiated electromagnetic energy, said received electromagnetic energy having a non-cooperative waveform and an unspecified frequency;

a plurality of frequency translators in communication with said antenna system for translating a frequency parameter of said received electromagnetic energy for detection and phase measurement;

a plurality of phase resolvers in communication with said plurality of frequency translators for providing a plurality of distance oriented digital phase measurements, said phase measurements being determined directly from said received electromagnetic energy;

a frequency resolver in communication with one of said plurality of frequency translators for resolving said frequency parameter and for providing said resolved frequency parameter to each of said plurality of phase resolvers for utilization in providing said phase measurements;

a computing system connected to said plurality of phase resolvers for receiving and manipulating said plurality of distance oriented digital phase measurements and for determining said instantaneous range to said emitter source of said radiated electromagnetic energy, and further including means for resolving phase ambiguities of said received electromagnetic energy wherein said phase measurements are available only from said emitter source and knowledge of relative motion between said emitter source and said receiving means is unknown; and

a display device for displaying said instantaneous range to said emitter source wherein said displayed instantaneous range is equivalent to R=[bc(c-b)(a² -φ

₁²)/2a² (bφ

₃ -cφ

₂)].

29. The passive radar ranging system of claim 28 wherein said antenna system is comprised of a plurality of antenna elements.

30. The passive radar ranging system of claim 29 wherein said plurality of antenna elements are aligned in a linear fashion, each antenna element being spaced from an adjacent element by a fixed spacing parameter.

31. The passive radar ranging system of claim 28 wherein said plurality of radiated electromagnetic energy is received by said antenna system in a plurality of phase fronts.

32. The passive radar ranging system of claim 31 wherein each of said plurality of phase fronts is located along a locus of points passing through one of a plurality of antenna elements comprising said antenna system.

33. The passive radar ranging system of claim 28 wherein each of said plurality of distance oriented digital phase measurements are transmitted to one of a plurality of primary adder circuits in said computing system.

34. The passive radar ranging system of claim 33 wherein each of said primary adder circuits provides a sum of one of said distance oriented digital phase measurements and a corresponding phase correction value.

35. The passive radar ranging system of claim 34 wherein each of said sums comprises a corrected phase signal.

36. The passive radar ranging system of claim 28 wherein each of said distance oriented digital phase measurements is summed to a corresponding phase correction value for providing a plurality of corrected phase signals, each of said corrected phase signals being transmitted to one of a plurality of multiplier circuits.

37. The passive radar ranging system of claim 36 wherein each of said corrected phase signals is multiplied by a plurality of apparatus spacing parameters stored in said plurality of multiplier circuits.

38. The passive radar ranging system of claim 37 wherein each of said parameter corrected phase signals is transmitted from said multiplier circuits to one of a plurality of secondary adder circuits for adding a plurality of output signals of said plurality of multiplier circuits.

39. The passive radar ranging system of claim 28 wherein said computing system further includes a divider circuit for receiving a pair of parameter corrected phase signals from a plurality of adders and multipliers located within said computing system.

40. The passive radar ranging system of claim 39 wherein said divider circuit provides a fractional output signal, said fractional output signal being said instantaneous range to said emitter source.

41. The passive radar ranging system of claim 28 wherein said computing system determines said instantaneous range to said emitter source providing an output signal, said output signal being transmitted to said display device for providing communication of said determined instantaneous range.

42. The passive radar ranging system of claim 28 wherein said computing system further includes a calibrating means.

43. The passive radar ranging system of claim 42 wherein said calibrating means provides a phase correction value, said phase correction value being transmitted to each of a plurality of primary adder circuits.

44. The passive radar ranging system of claim 28 further including a calibration signal generator in electrical communication with a calibrating means, said calibration signal generator for providing a correction signal.

45. The passive radar ranging system of claim 44 wherein said correction signal provided by said calibration signal generator is transmitted to each of a plurality of antenna elements of said antenna system.

46. The passive radar ranging system of claim 28 wherein said display device is in electrical communication with a calibrating means, said display device for transmitting a plurality of parameters to said calibrating means.

47. The passive radar ranging system of claim 46 wherein said transmitted plurality of parameters includes said instantaneous range to said emitter source.

48. A method for determining the instantaneous range to an emitter source, said method comprising the steps of:

receiving a plurality of radiated electromagnetic energy with an antenna system, said received electromagnetic energy having a non-cooperative waveform and an unspecified frequency;

translating a frequency parameter of said received electromagnetic energy with a plurality of frequency translators for detection and phase measurement;

providing a plurality of distance oriented digital phase measurements from said frequency parameter within a plurality of phase resolvers, said phase measurements being determined directly from said received electromagnetic energy;

resolving said frequency parameter and providing said resolved frequency parameter to each of said plurality of phase resolvers for utilization in providing said phase measurements;

resolving phase ambiguities of said received electromagnetic energy for identifying which of a plurality of wavefronts of said non-cooperative waveform is being intercepted by said antenna system;

manipulating said plurality of distance oriented digital phase measurements for determining said instantaneous range to said emitter source of said radiated electromagnetic energy wherein said phase measurements are available only from said emitter source and knowledge of relative motion between said emitter source and said antenna system is unknown; and

displaying said instantaneous range to said emitter source wherein said displayed instantaneous range is equivalent to R=[bc(c-b)(a² -φ

₁²)/2a² (bφ

₃ -cφ

₂)].