RADIO DIRECTION FINDER SYSTEM

• US 3,787,862 A
• Filed: 09/27/1971
• Issued: 01/22/1974
• Est. Priority Date: 09/27/1971
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Robert S. Jacobson
• Inventors: Jacobson, Robert S.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/183,934
• Time in Patent Office: 848 Days
• Field of Search: 340/27 343/113R,113DE 235/150.27
• US Class Current: 342/418
• CPC Class Codes: G01S 3/52 using a receiving antenna moving, or appearing to move, in a cyclic path to produce a Doppler variation of frequency of the received signal

Abstract

A radio direction finder system incorporating relatively small antennas is provided with a signal processing arrangement for artificially synthesizing variably shaped high frequency direction finding antenna receptivity patterns useful in a first mode for searching for the general location of a broadcasting high frequency transmitter and in a second mode for precisely tracking such a transmitter for navigation purposes.

Claims

1. Apparatus for determining the direction of arrival of a radio frequency carrier wave comprising:

first receiver means for receiving a phase modulated version of said carrier wave, generator means for deriving solely from said first receiver means a phase reference signal having a characteristic frequency, second receiver means for directly receiving said carrier wave, intermediate frequency phase detector means responsive to said first and second receiver means, audio frequency phase detector means responsive to said intermediate frequency phase detector means and to said generator means, and utilization apparatus responsive to said audio frequency phase detector means.

2. Apparatus for determining the direction of arrival of a radio frequency carrier wave comprising:

first receiver means for receiving a phase modulated version of said carrier wave, generator means for deriving solely from said first receiver means a phase reference signal having a characteristic frequency, second receiver means for directly receiving said carrier wave, local oscillator means for supplying local oscillator signals to said first and second receiver means, intermediate frequency phase detector means responsive to said first and second receiver means, audio frequency phase detector means responsive to said intermediate frequency phase detector means and to said generator means, phase modulator means responsive to said audio frequency phase detector means and to said generator means for phase modulating said local oscillator signal supplied to said first receiving means, and utilization apparatus phase detector means.

3. Apparatus as described in claim 2 additionally including:

quadrature phase detector means responsive to said first and second receiver means, and variable attenuator means coupled between said signal generator means and said phase modulator means, said variable attenuator means being responsive to the output of said quadrature phase detector means.

4. Apparatus for determining the direction of arrival of a radio frequency carrier wave comprising:

first receiver means for receiving a phase modulated version of said carrier wave, generator means for deriving from said first receiver means a phase reference signal having a characteristic frequency, second receiver means for receiving said carrier wave, first phase detector means responsive to said first and second receiver means, second phase detector means responsive to said first phase detector means and to said generator means, local oscillator means for supplying local oscillator signals to said first and second receiver means, phase modulator means responsive to said second phase detector means and to said generator means for phase modulating said local oscillator signal supplied to said first receiver means, quadrature phase detector means responsive to said first and second receiver means, even harmonic filter means responsive to an output of said quadrature phase detector means, said output comprising a direct current component and additional components representing a plurality of even harmonics of said frequency of said phase reference signal, said filter means permitting selective alteration of predetermined ones of said plurality of even harmonics for generating a residual output, and means for utilizing said residual output.

5. Apparatus as described in claim 4 wherein said means for utilization of said residual output of said even harmonic filter means comprises:

rectifier means responsive to said even harmonic filter means for producing a rectified residual output signal, and display means responsive to said rectified residual output signal.

6. Apparatus as described in claim 4 wherein said even harmonics filter means comprises low pass filter means for providing an output voltage E of amplitude expressed substantially by the equation:

E Jo (2 m sin theta 1/2) where;

Jo a Bessel function of zero order, m the index of modulation of said carrier wave by said first receiver means, and theta 1 the azimuth direction of arrival of said carrier signal.

7. Apparatus as described in claim 4 wherein said even harmonic filter means is characterized by means for providing an output voltage E of amplitude expressed substantially by the equation:

E Jo(x) - 4/3J2(x) +1/2J4(x) + 16/3 (J6(x)/36 + . . . . . + Jn/n2) where;

x (2m sin theta 1/2) or the argument of each Bessel function term, m the index of modulation of said carrier signal by said first receiver means, theta 1 the direction of arrival of said carrier signal, and n even integers providing Jn/n2 terms for the range of values of n including all even integral values of n above 8 to an even integer of value less than 22.

8. Apparatus as described in claim 4 wherein:

said even harmonic filter means comprises first and second filter circuit means connected in series relation, said first filter circuit means comprises first amplifier means having capacitive feed back means and inductive feed back means in parallel relation, and said second filter circuit means comprises second amplifier means having capacitive feed back means.

9. Apparatus for determining the direction of arrival of a radio frequency carrier wave comprising:

first receiver means for receiving a phase modulated version of said carrier wave, generator means for deriving from said first receiver means a phase reference signal having a characteristic frequency, second receiver means for receiving said carrier wave, quadrature phase detector means responsive to said first and second receiver means for producing an output signal having components represented by a plurality of odd harmonics of said signal generator means frequency, odd harmonic filter means permitting selective alteration of predetermined ones of said plurality of odd harmonics for generating a residual output, and utilization means responsive to said residual output.

10. Apparatus as described in claim 9 comprising:

local oscillator means for supplying local oscillator signals to said first and second receiver means, and phase modulator means responsive to said generator means for phase modulating said local oscillator signal supplied to said first receiver means.

11. Apparatus as described in claim 10 wherein said utilization means responsive to said odd harmonic filter means comprises audio phase detector means also responsive to said signal generator means for producing a bipolar control signal.

12. Apparatus as described in claim 11 additionally including flight control servo means responsive to said bipolar control signal.

13. Apparatus as described in claim 11 additionally including means for algebraically summing said bipolar control signal and said phase reference signal for supply to said local oscillator phase modulating means.

14. Apparatus as described in claim 11 additionally including display means responsive to said bipolar control signal for displaying the azimuth angle of arrival of said carrier signal.

15. Apparatus as described in claim 11 wherein said odd harmonic filter means and said audio phase detector means have a composite characteristic adapted for producing an output voltage E of amplitude expressed substantially by the equation:

E J1(2m sin theta 1/2) where;

J1 a Bessel function of the first order, m the index of modulation of said carrier wave by said first receiver means, and theta 1 the azimuth direction of arrival of said carrier signal.

16. Apparatus as described in claim 11 wherein said odd harmonic filter means and said audio phase detector means have a composite characteristic adapted for producing an output voltage E of amplitude substantially expressed by the equation:

E J1(x) -4/3 J3(x) + (J7(x)/7 +. . . +Jn(x)/n) where;

x (2m sin theta 1/2) or the argument of each Bessel function term, m the index of modulation of said carrier signal by said first receiver means, theta 1 the direction of arrival of said carrier signal, and n odd integers providing Jn(x)/n terms for the range of values of n including all odd integral values of n above 7 to an odd integer of value less than 21.

17. Apparatus as described in claim 10 wherein:

said odd harmonic filter means comprises first, second and third filter circuit means in series relation, said first filter circuit means comprises first amplifier means having feed back means including capacitive and inductive means in series relation, said second filter circuit means comprises second amplifier means having capacitive feed back means in parallel relation with feed back means including inductive means, and said third filter circuit means comprises passive filter means.

18. Apparatus for determining the direction of arrival of a radio frequency carrier wave comprising:

first receiver means for receiving a phase modulated version of said carrier wave, generator means for deriving from said first receiver means a phase reference signal having a characteristic frequency, second receiver means for receiving said carrier wave first phase detector means responsive to said first and second receiver means, second phase detector means responsive to said first phase detector means and to said generator means, local oscillator means for supplying local oscillator signals to said first and second receiver means, phase modulator means responsive to said second phase detector means and to said generator means for phase modulating said local oscillator signal supplied to said first receiver means, odd harmonic filter means responsive to an output of said first phase detector means, said output comprising components representing a plurality of odd harmonics of said frequency of said phase reference signal, said filter means permitting selective alteration of predetermined ones of said plurality of odd harmonics for generating a first residual output, utilization means responsive to said first residual output, quadrature phase detector means responsive to said first and second receiver means for producing an output signal having components represented by a plurality of even harmonics of said signal generator frequency, even harmonic filter means permitting selective alteration of predetermined ones of said plurality of even harmonics for generating a second residual output, and utilization means responsive to said second residual output.

19. Apparatus as described in claim 18 wherein said utilization means responsive to said odd harmonic filter means first residual output includes display means for displaying the azimuth angle of arrival of said carrier signal.

20. Apparatus as described in claim 18 wherein said utilization means responsive to said odd harmonic filter means first residual output includes flight control servo means.

21. Apparatus as described in claim 18 wherein said means utilizing said second residual output of said even harmonic filter means comprises display means for displaying the elevation angle of arrival of said carrier signal.

22. Apparatus as described in claim 18 wherein:

said second phase detector means is responsive to said first phase detector means and to said signal generator means, and said utilization means responsive to said odd harmonic filter means comprises audio phase detector means also responsive to said signal generator means.

23. Apparatus as described in claim 22 comprising:

sine generator means responsive to said audio phase detector means, first multiplier means responsive to said sine generator means and to said quadrature phase detector means for producing a first product signal, and first display means responsive to said first product signal.

24. Apparatus as described in claim 23 including:

vertical reference means for supplying a roll angle output, and first algebraic adder means between said first multiplier means and said first display means responsive to said first product signal.

25. Apparatus as described in claim 22 comprising:

cosine generator means responsive to said audio phase detector means, second multiplier means responsive to said cosine generator means and to said quadrature phase detector means for producing a second product signal, and second display means responsive to said second product signal.

26. Apparatus as described in claim 25 including:

vertical reference means for supplying a pitch angle output, and second algebraic means between said second multiplier means and said second display means responsive to said second product signal.

27. Apparatus for determining the direction of arrival of a radio frequency carrier signal comprising:

first carrier wave receiver means including motive means for effectively rotating said carrier wave receiver means about a center of revolution at a predetermined rate for imposing a phase modulation on said carrier wave, signal generator means for producing a reference signal of frequency proportional to said rate, second receiver means spaced in fixed relation with respect to said center of revolution for receiving said carrier wave, first phase detector means responsive to said first and second receiver means and to said signal generator means for producing a signal related to the Azimuth angle of arrival of said carrier wave, and second phase detector means responsive to said first and second receiver means and to said signal generator means for producing a signal related to the elevation angle of arrival of said carrier wave.

28. Apparatus as described in claim 27 further including:

means for generating a sine function signal from said signal related to said azimuth angle of arrival of said carrier wave, means for multiplying said sine function signal by said elevation related signal for generating a right-left tracking error signal, and utilization means responsive to said means for multiplying said sine function by said elevation related signals.

29. Apparatus as described in claim 28 further including:

means for generating a cosine function signal from said signal related to said elevation angle of arrival of said carrier wave, means for multiplying said cosine function signal by said elevation related signal for generating a forward-rearward tracking error signal, and utilization means responsive to said means for multiplying said cosine function by said elevation related signal.

30. Apparatus for determining the direction of arrival of a radio frequency carrier wave comprising first receiver means for receiving a phase modulated version of said carrier wave, generator means for deriving from said first receiver means a phase reference signal having a characteristic frequency, second receiver means for receiving said carrier wave, first phase detector means responsive to said first and second receiver means, second phase detector means responsive to said first phase detector means and to said generator means, quadrature phase detector means responsive to said first and second receiver means, local oscillator means for supplying local oscillator signals to said first and second receiver means, phase modulator means responsive to said second phase detector means and to said generator means for phase modulating said local oscillator signal supplied to said first receiver means, variable attenuator means coupled between said signal generator means and said phase modulator means, said variable attenuator means being responsive to the output of said second phase detector means, and display means responsive to said second phase detector means for displaying the elevation angle of arrival of said carrier signal.