INTERFEROMETER AND ANGLE ENCODING NAVIGATION SYSTEM

• US 3,697,997 A
• Filed: 10/13/1970
• Issued: 10/10/1972
• Est. Priority Date: 10/13/1970
• Status: Expired due to Term

• Current Assignee: Herbert W. Cooper
• Original Assignee: Herbert W. Cooper
• Inventors: Cooper, Herbert W.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/080,391
• Time in Patent Office: 728 Days
• Field of Search: 343/18R,113R
• US Class Current: 342/413
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured

Abstract

A receiver system for determining the angle and direction between the longitudinal axis of a vehicle such as an aircraft and the direction of propagation from a source of radiation such as a VHF localizer navigation system. The receiver utilizes a pair of antennas having a mutual spacing determined by the desired accuracy and permitted ambiguities, mounted in the forward section of the aircraft such that one antenna is located on each side of the forward section of the aircraft. The antennas define a baseline therebetween which is substantially perpendicular to the longitudinal axis of the aircraft. The system permits the measurement of the direction of arrival of electromagnetic energy from the localizer system with respect to the baseline of the two antennas by converting the difference in RF phase of the signal respectively received by the pair of antennas to a difference in audio phase from a reference frequency generated by and in the receiver itself.

Claims

1. An interferometer navigation system for determining the space angle between the longitudinal axis of a vehicle and a reference course line as established by a remote source of electromagnetic radiation, said system comprising in combination:

a first and a second receiving antenna mounted respectively on each side of the forward portion of said vehicle, said antennas being located along a line substantially transverse to said longitudinal axis of said vehicle;

circuit means coupled to said first and second antenna and being operable to receive a portion of the electromagnetic energy received by said antennas from said source to provide an output signal corresponding to one frequency radiated from said source;

a first and second electronic signal coupler respectively connected to said first and second antenna;

first and second phase modulation means respectively coupled to said first and second electronic signal couplers, said first and second phase modulation means being adapted to operate in opposite phase senses with respect to each other to translate the frequency of electromagnetic energy coupled thereto up and down in frequency respectively to effectively create upper and lower sidebands of said one frequency;

a modulation signal source commonly coupled to said first and second phase modulation means, said source generating and applying a relatively low frequency modulation signal with respect to said one frequency thereto for providing said frequency translation;

an RF signal combining network coupled to the output of said circuit means and said first and second phase modulation means, providing an output therefrom corresponding to said one frequency having a phase component with respect to said low frequency modulation voltage which is a function of the space angle of the vehicle relative to said remote source;

detector means coupled to said RF signal combining network for providing an output therefrom of said relatively low frequency including said phase component and which corresponds to the difference in RF phase of the signals received at said first and second antenna; and

phase comparator means coupled to said envelope detector and said modulation signal source for comparing said relatively low frequency modulation signal and the output of said detector means for providing an output thereof corresponding to the angle of the longitudinal axis of said vehicle with respect to saiD reference course line.

2. The invention as defined by claim 1 wherein said one frequency corresponds to the carrier frequency of said source of radiation and said modulation signal source generates an audio frequency signal.

3. The invention as defined by claim 1 wherein said phase modulation means are respective serrodyne modulators.

4. The invention as defined by claim 1 wherein said predetermined distance of separation between said first and second antenna is in the order of one wavelength of the electromagnetic radiation from said remote source.

5. The invention as defined by claim 1 wherein said circuit means comprises a magic T RF component.

6. The invention as defined by claim 1 wherein said circuit means comprises a hybrid junction RF component.

7. The invention as defined by claim 5 wherein said first and second signal couplers are comprised of RF couplers.

8. The invention as defined by claim 4 and wherein said relatively low frequency modulation signal comprises a video or an audio frequency signal.

9. The invention as defined by claim 8 and wherein said detector means comprises an RF envelope detector.

10. The invention as defined by claim 4 wherein said first and second antenna elements are comprised of antennas mounted on the outside surface of said vehicle.