Method of and system for locating a position

• US 3,916,410 A
• Filed: 03/08/1974
• Issued: 10/28/1975
• Est. Priority Date: 06/16/1969
• Status: Expired due to Term

• Current Assignee: Albert A. Elwood
• Original Assignee: Albert A. Elwood
• Inventors: Elwood, Albert A.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Blum, T. M.
• Application Number:
  US05/449,452
• Time in Patent Office: 599 Days
• Field of Search: 343/112D,112C,102 235/150.27
• US Class Current: 342/458
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A method of and system for locating a position in which a plurality of frequency standard devices (atomic clocks) are synchronized or phase compared at the same initial location. Two of three frequency standard devices are placed at transmitting stations on a known baseline. The third device is at a third station which receives signals from the two transmitting stations. The radio frequency carrier signal produced at each transmitting station is modulated with a single, low frequency signal produced under the control of the same frequency standard device which controls the means which produce the radio frequency carrier. At the receiving station, means are provided for producing a reference signal, corresponding, in frequency, to the low frequency modulating signal and two local radio frequency signals corresponding, in frequency, to the radio frequency carrier signals transmitted. The phase of the reference signal is compared, at the receiving station, with the phase of the modulating signals recovered from the radio frequency carriers to determine respective phase differences, the differences representing coarse position data from which the total number of phase rotations (full lanes) the receiving station is from each of the transmitting stations are determined. The phase relationships between each of the received radio frequency carrier signals and the respective one of the two radio frequency signals produced at the receiving station are determined, the relationships representing fine position data which are measurements of the receiving station position within a given phase rotation (lane).

Claims

1. A position locating system comprising, in combination:

a. a first frequency standard source of a signal of given frequency and given phase;

b. a second frequency standard source of a signal of said given frequency and a predetermined phase relationship with said given phase;

c. a third frequency standard source of a signal of said given frequency and a predetermined phase relationship with said given phase;

d. means controlled by said first source for transmitting a first radio signal from a first point including first modulating means controlled by said first source for modulating said first radio signal with at least one first, single frequency signal;

e. means controlled by said second source for transmitting a second radio signal from a second point including second modulating means controlled by said second source for modulating said second radio signal with at least one second, single frequency signal;

f. means controlled by said third source for generating a signal having a frequency related to that of said first radio signal and a signal having a frequency related to that of said second radio signal at a third point;

g. means controlled by said third source for producing respective at least one first reference signal and at least one second reference signal having respective frequencies related to those of said at least one first, single frequency signal and to said at least one second, single frequency signal;

h. means for receiving said first radio signal and said second radio signal at said third point which develop therefrom respective signals respectively identical in frequency to those signals produced at said third point related respectively to said first radio signal and to said second radio frequency signal;

i. first phase comparing means at said third point for comparing the phase of the signal developed which relates to said first radio signal with that of said signal generated at said third point having a frequency identical thereto;

j. second phase comparing means at said third point for comparing the phase of the signal developed which relates to said second radio signal with that of said signal generated at said third point having a frequency identical thereto;

k. means at said third point for demodulating signals to recover respectively signals corresponding to said at least one first, single frequency signal and said at least one second, single frequency signal and having respective frequencies identical to those of said at least one first reference signal and said at least one second reference signal;

l. and means for comparing respectively the phase of the recovered signals corresponding to said at least one first, single frequency signal and said at least one second, single frequency signal with the respective phases of said at least one first and said at least one second reference signals.

2. A position locating system according to claim 1 wherein said first frequency standard source, said second frequency standard source and said third frequency standard source are respectively first, second and third atomic clocks.

3. A position locating system as claimed in claim 1 including computer means receiving output signals from said first phase comparing means, from said second phase comparing means and from said means for comparing respectively the phase of the recovered signal corresponding to said first single frequency signal and the recovered signal corresponding to said second single frequency signal with the respective phases of said first and second reference signals for providing output signal data representative of the distance the third point is from the first and second points.

4. A position locating system as claimed in claim 3 including means controlled by said computer means for storing and displaying said output signal data.

5. A position locating system according to claim 1 wherein said first modulating means is a first amplitude modulating means for amplitude modulating said first radio signal with said first single frequency signal, said second modulating means is a second amplitude modulating means for amplitude modulating said second radio signal with said second single frequency signal, and said means at said third point for demodulating are means for detecting amplitude modulation to recover signals corresponding to said first single frequency signal and said second single frequency signal.

6. A position locating system according to claim 1 wherein said first modulating means is a first frequency modulating means for frequency modulating said first radio signal with said first single frequency signal, said second modulating means is a second frequency modulating means for frequency modulating said second radio signal with said second single frequency signal, and said means at said third point for demodulating are frequency demodulating means for detecting frequency modulation to recover signals corresponding to said first single frequency signal and said second single frequency signal.

7. A position locating system according to claim 1 wherein said first modulating means is a first phase modulating means for phase modulating said first radio signal with said first single frequency signal, said second modulating means is a second phase modulating means for phase modulating said second radio signal with said second single frequency signal, and said means at said third point for demodulating are means for detecting phase modulations to recover signals corresponding to said first single frequency signal and said second single frequency signal.

8. A position locating system according to claim 1 comprising a fourth frequency standard source of signal of said given frequency and a predetermined phase relationship with said given phase, means controlled by said fourth source for transmitting a third radio signal from a fourth point including third modulating means controlled by said fourth source for modulating said third radio signal with a third single frequency signal, means for receiving said third radio signal at said third point, means controlled by said third source fOr generating a third reference signal having a frequency related to that of said third single frequency signal, means controlled by said third source for generating a signal having a frequency related to that of said third radio signal, means for receiving the third radio signal at said third point which develops a signal identical in frequency to that of the signal generated at said third point related to the third radio signal, third phase comparing means at said third point for comparing the phase of the signal developed which relates to said third radio signal with that of said signal generated at said third point having a frequency identical thereto, means at said third point for demodulating to recover a signal corresponding to said third single frequency signal and having a frequency identical to that of said third reference signal, and means for comparing the phase of said signal corresponding to said third single frequency signal with the phase of said third reference signal.

9. A position locating system according to claim 8 wherein said third modulating means is a third modulating means for amplitude modulating said third radio signal with said third single frequency signal, said means at said third point for demodulating to recover said signal corresponding to said third single frequency signal is a means for detecting amplitude modulation, said first modulating means is a first modulating means for amplitude modulating said first radio signal with said first single frequency signal, and said second modulating means is a second modulating means for amplitude modulating said second radio signal with said second single frequency signal, and said means at said third point for demodulating to recover signals corresponding to said first single frequency signal and said second single frequency signal are means for detecting amplitude modulation.

10. A position locating system according to claim 8 wherein said third modulating means is a third modulating means for frequency modulating said third radio signal with said third single frequency signal, said means at said third point for demodulating to recover a signal corresponding to said third single frequency signal is a means for detecting frequency modulation, said first modulating means is a first frequency modulating means for frequency modulating said first radio signal with said first single frequency signal, said second modulating means is a second modulating means for frequency modulating said second radio signal with said second single frequency signal, and said means at said third point for demodulating to recover signals corresponding to said first single frequency signal and said second single frequency signal are means for detecting frequency modulation.

11. A position locating system according to claim 8 wherein said third modulating means is a third modulating means for phase modulating said third radio signal with said third single frequency signal, said means at said third point for demodulating to recover a signal corresponding to said third single frequency signal is a means for detecting phase modulation, said first modulating means is a first modulating means for phase modulating said first radio signal with said first single frequency signal, said second modulating means is a second modulating means for phase modulating said second radio signal with said second single frequency signal, and said means at said third point for demodulating to recover signals corresponding to said first single frequency signal and said second single frequency signal are means for detecting phase modulation.

12. A position locating system according to claim 8 including computer means receiving output signals from (1) said first phase comparing means, (2) from said second phase comparing means, (3) from said third phase comparing means, (4) from said means for comparing respectively the phase of the recovered signal corresponding to said first single frequency signal and the recovered signal corresponding to said second single frequency signal with the respective first and second reference signals and (5) from said means for comparing the recovered signal corresponding to said third single frequency signal with said third reference signal for providing output signal data representative of distance said third point is from the first, second and fourth points.

13. A position locating system as claimed in claim 12 including means controlled by said computer means for storing and displaying said output signal data.

14. A position locating method comprising:

providing a first frequency standard signal of given frequency and phase;

providing a second frequency standard signal of said given frequency and a predetermined phase relationship to said given phase;

providing a third frequency standard signal of said given frequency and a predetermined phase relationship to said given phase;

modulating a first radio signal related to and controlled by said first standard signal with at least one first, single frequency signal also related to and controlled by said first standard signal;

transmitting the first radio signal from a first point;

modulating a second radio signal related to and controlled by said second standard signal with at least one second, single frequency signal also related to and controlled by said second standard signal;

transmitting the second radio signal from a second point;

generating at a third point under control of said third frequency standard signal at least one first, reference signal related in frequency to said at least one first, single frequency signal and at least one second reference signal related in frequency to said at least one second, single frequency signal;

generating at said third point, also under control of said third frequency standard signal, a third reference signal and a fourth reference signal respectively related in frequency to said first radio signal and to said second radio signal;

recovering at said third point signals corresponding to said at least one first, single frequency signal and said at least one second, single frequency signal and having respective frequencies identical to those of said at least one first reference signal and said at least one second reference signal;

comparing the phase of the signal corresponding to said at least one first, single frequency signal recovered at said third point with that of said at least one reference signal;

comparing the phase of the signal corresponding to said at least one second, single frequency signal recovered at said third point with that of said at least one second reference signal;

developing respectively from said first and said second radio signals received at said third point a first and a second signal identical respectively in frequency to said third reference signal and to said fourth reference signal;

comparing the phase of said third reference signal with that of said signal identical in frequency thereto which is developed from said first radio signal at said third point; and

comparing the phase of said fourth reference signal with that of said signal identical in frequency thereto which is developed from said second radio signal received at said third point.

15. A position locating method according to claim 14 wherein said first frequency standard signal, said second frequency standard signal and said third frequency signal are provided respectively from first, second and third atomic clocks.

16. A position locating method according to claim 14 wherein the step of modulating said first radio signal is the step of amplitude modulating said first radio signal with said first single frequency signal, the step of modulating said second radio signal is the step of amplitude modulating said second radio signal with said second single frequency signal, and the step of recovering signals corresponding to said first single frequency signal and said second single frequency signal comprises steps of amplitude demodulating.

17. A position Locating method according to claim 14 wherein the step of modulating said first radio signal is the step of frequency modulating said first radio signal with said first single frequency signal, the step of modulating said second radio signal is the step of frequency modulating said second radio signal with said second single frequency signal, and the step of recovering signals corresponding to said first single frequency signal and said second single frequency signal comprises frequency demodulating.

18. A position locating method according to claim 14 wherein the step of modulating said first radio signal is the step of phase modulating said first radio signal with said first single frequency signal, the step of modulating said second radio signal is the step of phase modulating said second radio signal with said second single frequency signal, and the step of recovering signals corresponding to said first single frequency signal and said second single frequency signal comprises steps of phase demodulating.

19. The position locating method according to claim 14 including providing a fourth frequency standard signal of the given frequency and a predetermined phase relationship with said given phase, modulating a third radio signal related to and controlled by said fourth standard signal with a third single frequency signal also related to and controlled by said fourth standard signal, transmitting the third radio signal from a fourth point, receiving said third radio signal at said third point, generating at said third point under control of said third standard signal a fifth reference signal having a frequency related to that of said third radio signal, generating at said third point a sixth reference signal having a frequency related to that of said third single frequency signal, recovering at said third point a signal corresponding to said third single frequency signal and having a frequency identical to that of said sixth reference signal, developing from said third radio signal received at said third point a signal identical in frequency to said fifth reference signal, comparing the phase of said fifth reference signal with that of said signal identical in frequency thereto which is developed from said third radio signal received at said third point;

and comparing the phase of the recovered signal corresponding to said third single frequency signal with said sixth reference signal.

20. The position locating method according to claim 19 wherein the step of modulating said third radio signal is the step of amplitude modulating said third radio signal with said third single frequency signal, the step of recovering a signal corresponding to said third single frequency signal is a step of amplitude demodulating, the step of modulating said first radio signal is the step of amplitude modulating said first radio signal with said first single frequency signal, the step of modulating said second radio signal is the step of amplitude modulating said second radio signal with said second single frequency signal, and the step of recovering signals corresponding to said first single frequency signal and said second single frequency signal comprises steps of amplitude demodulating.

21. The position locating method according to claim 19 wherein the step of modulating said third radio signal is the step of frequency modulating said third radio signal with said third single frequency signal, the step of recovering a signal corresponding to said third single frequency signal is a step of frequency demodulating, the step of modulating said first radio signal is the step of frequency modulating said first radio signal with said first single frequency signal, the step of modulating said second radio signal is the step of frequency modulating said second radio signal with said second single frequency signal, and the step of recovering signals corresponding to said first single frequency signal and said second single frequency signal comprises steps of frequency demodulating.

22. The position locating method according to claim 19 wherein the step of modulating said third radio signal is the step of phase modulating said third radio signal with said third single frequency signal, and the step of recovering a signal corresponding to said third single frequency signal is a step of phase demodulating, the step of modulating said first radio signal is the step of phase modulating said first radio signal with said first single frequency signal, the step of modulating said second radio signal is the step of phase modulating said second radio signal with said second single frequency signal, and the step of recovering signals corresponding to said first single frequency signal and said second single frequency signal comprises steps of phase demodulating.

23. A position locating system comprising a plurality of frequency standard sources of signals of given frequency and predetermined phase relationships;

means controlled respectively by each of said plurality of sources for transmitting from respective points respective radio signals, these means including respective modulating means controlled respectively by respective ones of said plurality of frequency standard sources for modulating each of said respective radio signals with at least one respective single frequency signal derived from respective ones of said frequency standard sources;

a further frequency standard source of signal at an additional point having the same given frequency as said plurality of frequency standard sources and a predetermined phase relationship;

means controlled by said further frequency standard source of signals for generating at said additional point a first plurality of reference signals related respectively to said respective radio signals;

means controlled by said further frequency standard source of signal at said additional point for producing a second plurality of reference signals having respective frequencies related respectively to the frequencies of said single frequency signals;

means for receiving said respective radio signals at said additional point;

means at said additional point for deriving from said radio signals received at said additional point a further plurality of signals respectively identical in frequency to said first plurality of reference signals;

phase comparing means at said additional point for comparing respectively the phase of each signal of said further plurality signals derived from said radio signals with the phase of respective signals of said first plurality of reference signals;

means at said additional point for recovering an additional plurality of signals corresponding respectively to respective ones of said single frequency signals and having respective frequencies identical to the frequencies of respective ones of said second plurality of reference signals; and

phase comparing means for comparing respectively the phase of each recovered signal of said additional plurality of signals with the phase of respective signals of said second plurality of reference signals.

24. A position locating system according to claim 23 wherein said plurality of frequency standard sources of signals are two sources of signals and the respective points are two points.

25. A position locating system according to claim 23 wherein said plurality of frequency standard sources of signals are three sources of signals and the respective points are three points.

26. A position locating system according to claim 25 wherein at least one of said plurality of frequency standard sources of signals is carried by a satellite.

27. A position locating system according to claim 25 wherein said source of signal at said additional point is carried by an aircraft.

28. A position locating system according to claim 24 wherein said source of signal at said additional point is carried by an aircraft, said aircraft having an altimeter.

29. A position locating system according to claim 23 wherein each modulating means is an amplitude modulatiNg means.

30. A position locating system according to claim 23 wherein each modulating means is a frequency modulating means.

31. A position locating system according to claim 23 wherein each modulating means is a phase modulating means.

32. A position locating system according to claim 23 wherein said means for receiving said radio signals includes superheterodyne receiver means having mixer means controlled by said additional frequency standard source of signal at said additional point for reducing the frequency of the respective radio signals received.

33. A position locating system according to claim 23 wherein said modulator means comprise respective balanced modulators, the respective radio signals being double side tone suppressed carrier signals.

34. A position locating system according to claim 23 wherein said means for transmitting comprise respective single side band transmitter means.

35. A position locating system according to claim 23 wherein said respective modulating means include means for modulating with bursts of respective ones of said single frequency signals.

36. A transmitting station in a position locating system in which both transmitted radio signals and modulation signals carried thereon are utilized to locate accurately a position and have a fixed phase-time relationship to one another, said transmitting station comprising:

a radio transmitter;

a radiating means coupled to said transmitter;

a stable source of oscillations in the form of a frequency standard;

means controlled by said source of oscillations for supplying a stable radio frequency signal to said transmitter, which stable radio frequency signal provides in its phase as received at a distant point a basis for developing fine distance datum; and

modulating means controlled by said source of oscillations for modulating said transmitter with at least one single frequency signal, which signal provides a basis for developing, at a distant point, coarse distance datum.

37. A radio receiving station comprising a stable source of oscillations, means receiving a plurality of radio frequency signals modulated respectively with at least a respective one of a plurality of single frequency signals, means controlled by said stable source of oscillations for developing a first plurality of reference signals corresponding respectively to said plurality of radio frequency signals, means controlled by said stable source of oscillations for developing a second plurality of reference signals corresponding respectively to said plurality of single frequency signals, means for developing from said plurality of radio signals a further plurality of signals identical in frequency to respective ones of said first plurality of reference signals, first phase comparing means for comparing the phase of each of said further plurality of signals with respective ones of said first plurality of reference signals, means for recovering an additional plurality of signals corresponding respectively to respective ones of said plurality of single frequency signals and having respective frequencies identical to respective ones of said second plurality of reference signals, and second phase comparing means for comparing the phase of each signal of said additional plurality of signals with the phase of respective ones of said second plurality of reference signals.

38. A radio receiving station as claimed in claim 37 wherein said stable source of oscillations comprises an atomic clock.

39. A radio receiving station as claimed in claim 37 wherein said means for receiving said plurality of signals comprises means for receiving two signals.

40. A radio receiving station as claimed in claim 37 wherein said means for receiving said plurality of signals comprises means for receiving three signals.

41. A radio receiving station as claimed in claim 37 wherein said means for recovering an additional plurality of signals comprises amplitude modulation detecting means.

42. A radio receivinG station as claimed in claim 37 wherein said means for recovering an additional plurality of signals comprises frequency modulation detecting means.

43. A radio receiving station as claimed in claim 37 wherein said means for recovering an additional plurality of signals comprises phase modulation detecting means.

44. A radio receiving station as claimed in claim 37 including mixer means responsive to signals derived from said source of oscillations and to each of said plurality of radio frequency signals for reducing the frequency of each of said plurality of radio frequency signals to a plurality of signals of lower frequency.

45. A radio receiving station as claimed in claim 39 wherein said receiving station is carried on a vehicle.

46. A radio receiving station as claimed in claim 39 wherein said vehicle is a ship.

47. A radio receiving station as claimed in claim 40 wherein said receiving station is carried on a device movable in three dimensions.

48. A radio receiving station as claimed in claim 47 wherein said device is an aircraft.

49. A receiving station as claimed in claim 37 including a computer means responsive to output signals from said first phase comparing means and from said second phase comparing means for determining the distance the receiving station is from each of a plurality of transmitting stations and the position of the receiving station located.

50. A receiving station as claimed in claim 49 including means responsive to said output signal data from said computer means for storing and displaying said output signal data.