System and method for determining the bearing of a source location from a receiver location

• US 20070099627A1
• Filed: 10/31/2005
• Published: 05/03/2007
• Est. Priority Date: 10/31/2005
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Flower, Graham, Trutna, William, Kofol, John
• Granted Patent: US 7,538,727 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 1/30 the synchronised signals being continuous waves or intermittent trains of continuous waves, the intermittency not being for the purpose of determining direction or position line and the transit times being compared by measuring the phase difference
• CPC Class Codes: G01S 19/38 Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system

Abstract

The system comprises a first beatable signal source, a second beatable signal source, a phase reference signal source and a receiver. The first beatable signal source and the second beatable signal source are located at the source location; the receiver is located at the receiver location. The phase reference signal source is operable to generate a phase reference signal. The first beatable signal source is operable to transmit a first beatable signal. The second beatable signal source is spatially offset from the first beatable signal source in a reference direction, and is operable to transmit a second beatable signal differing in frequency from the first beatable signal by a frequency difference. The first beatable signal and the second beatable signal collectively have a phase relationship with the phase reference signal. The receiver is structured to receive the first beatable signal and the second beatable signal and is operable to determine a direction angle, relative to the reference direction, of the source location from the receiver location. The receiver performs operations that comprise measuring a phase difference between a beat signal and either the phase reference signal or an additional beat signal, and determining the direction angle from the measured phase difference. The beat signal obtained by a process involving summing the first beatable signal and the second beatable signal. The additional beat signal is obtained by a process involving summing the first beatable signal and the phase reference signal. The bearing can be determined from the direction angle.

Claims

1. A system for determining the bearing of a source location from a receiver location, the system comprising:

a phase reference signal source operable to generate a phase reference signal;

at the source location, a first beatable signal source operable to transmit a first beatable signal and a second beatable signal source spatially offset from the first beatable signal source in a reference direction, the second beatable signal source operable to transmit a second beatable signal differing in frequency from the first beatable signal by a frequency difference, the first beatable signal and the second beatable signal collectively having a phase relationship with the phase reference signal; and

at the receiver location, a receiver structured to receive the first beatable signal and the second beatable signal and operable to determine a direction angle, relative to the reference direction, of the source location from the receiver location, the receiver performing operations comprising;

measuring a phase difference between a beat signal and one of (a) the phase reference signal, and (b) an additional beat signal, the beat signal obtained by a process comprising summing the first beatable signal and the second beatable signal, the additional beat signal obtained by a process comprising summing the first beatable signal and the phase reference signal, and

determining the direction angle from the measured phase difference.

2. The system of claim 1, in which:

the phase reference signal source transmits the phase reference signal; and

the receiver is structured additionally to receive the transmitted phase reference signal.

3. The system of claim 2, in which the phase reference signal has a frequency equal to one-half of the frequency difference.

4. The system of claim 3, in which the receiver is operable to sum the first beatable signal and the second beatable signal to obtain a sum signal and to demodulate the sum signal to extract the beat signal.

5. The system of claim 3, in which:

the phase reference signal source transmits the phase reference signal by transmitting a modulated signal obtained by modulating a carrier signal with the phase reference signal;

the receiver receives the phase reference signal by receiving the modulated signal; and

the receiver is additionally operable to demodulate the modulated signal to recover the phase reference signal.

6. The system of claim 5, in which the receiver is operable to sum the first beatable signal and the second beatable signal to obtain a sum signal and to demodulate the sum signal to extract the beat signal.

7. The system of claim 2, in which:

the first beatable signal source and the phase reference signal source are collocated;

the first beatable signal, the second beatable signal and the phase reference signal mutually differ in frequency by harmonically-related frequency differences; and

the receiver is operable to;

sum the first beatable signal and the second beatable signal to obtain a first sum signal and to demodulate the first sum signal to extract the beat signal, and

sum the first beatable signal and the phase reference signal to obtain an additional sum signal and to demodulate the additional sum signal to extract the additional beat signal.

8. The system of claim 2, in which the phase reference signal source is collocated with the first beatable signal source.

9. The system of claim 2, in which:

the reference direction, the direction angle, the phase reference signal, the phase reference signal source, the frequency difference, the beat signal, the additional beat signal, the phase difference, the phase relationship and the positional relationship are respectively a first reference direction, a first direction angle, a first phase reference signal, a first phase reference signal source, a first frequency difference, a first beat signal, a first additional beat signal, a first phase difference, a first phase relationship and a first positional relationship; and

the receiver is operable to determine a second direction angle, relative to a second reference direction, of the source location from the receiver location and to determine, from the first direction angle and the second direction angle, the bearing of the source location relative to the first reference direction.

10. The system of claim 9, in which:

the phase reference signal is a first phase reference signal and has a first phase reference frequency;

the phase reference signal source comprises a first phase reference signal generator and a second signal generator, the first reference signal generator transmitting the first phase reference signal, the second phase reference signal source operable to transmit a second phase reference signal at a second phase reference frequency;

at the source location, the system additionally comprises a third beatable signal source spatially offset from the first beatable signal source in a second reference direction, the third beatable signal source, the first phase reference signal source and the phase reference signal source having a second positional relationship, the third beatable signal source operable to transmit a third beatable signal having a third frequency greater than the second frequency and differing from the first frequency by a second frequency difference harmonically related to the second phase reference frequency, the first beatable signal and third beatable signal collectively having a second phase relationship with the second phase reference signal; and

the receiver is structured additionally to receive the third beatable signal and the second phase reference signal, and additionally performs operations comprising;

measuring a second phase difference between a second beat signal and one of (a) the second phase reference signal, and (b) a second additional beat signal, the second beat signal obtained by a process comprising summing the first beatable signal and the third beatable signal, the second additional beat signal obtained by a process comprising summing the first beatable signal and the phase reference signal, and

determining the second direction angle from the second measured phase difference.

11. The system of claim 9, in which:

at the source location, the system additionally comprises;

a third beatable signal source spatially offset from the phase reference signal source in a second reference direction orthogonal to the first reference direction, the third beatable signal source operable to transmit a third beatable signal having a third frequency, and

a fourth beatable signal source spatially offset from the phase reference signal source in a direction opposite the second reference direction, the fourth beatable signal source operable to transmit a fourth beatable signal having a fourth frequency, the fourth frequency differing from the third frequency by a second frequency difference, the third beatable signal and the fourth beatable signal collectively having a second phase relationship with the phase reference signal; and

the receiver is structured additionally to receive the third beatable signal and the fourth beatable signal, and performs additional operations comprising;

measuring a second phase difference between a second beat signal obtained by a process comprising summing the first beatable signal and the third beatable signal and one of (a) the phase reference signal, and (b) the additional beat signal, and

determining the second direction angle from the measured second phase difference.

12. The system of claim 9, in which:

the phase reference signal source is collocated with the first beatable signal source;

at the source location, the system additionally comprises a third beatable signal source spatially offset from the first beatable signal source in a second reference direction, non-parallel to the first reference direction, the third beatable signal source operable to transmit a third beatable signal having a third frequency, the first beatable signal and the third beatable signal collectively having a second phase relationship with the phase reference signal;

the receiver is structured additionally to receive the third beatable signal, and additionally performs operations comprising;

measuring a second phase difference between a second beat signal and one of (a) the phase reference signal, and (b) the additional beat signal, the second beat signal obtained by a process comprising summing the first beatable signal and the third beatable signal and

determining the second direction angle from the second measured phase difference.

13. The system of claim 12, in which:

the third frequency differs from the second frequency, and additionally differs from the first frequency by a second frequency difference harmonically-related to the first frequency difference;

the phase reference signal has a frequency harmonically related to the first frequency difference; and

.

the receiver measures the second phase difference between the second beat signal and the phase reference signal.

14. The system of claim 12, in which:

the phase reference signal has a phase reference frequency;

the third frequency and the phase reference frequency differ from the second frequency and differ from the first frequency by different harmonics of the first frequency difference, and

the receiver measures the second phase difference between the second beat signal and the additional beat signal.

15. The system of claim 12, in which the second reference direction is orthogonal to the first reference direction.

16. The system of claim 12, in which:

the system additionally comprises, at the source location, a fourth beatable signal source spatially offset from the first beatable signal source in a third reference direction, non-coplanar with the first reference direction and the second reference direction, the fourth beatable signal source operable to transmit a fourth beatable signal having a fourth frequency, the first beatable signal and the third beatable signal collectively having a second phase relationship with the phase reference signal;

the first beatable signal and the fourth beatable signal collectively having a third phase relationship with the phase reference signal; and

the receiver is structured additionally to receive the fourth beatable signal, and is additionally operable to determine a third direction angle, relative to the third reference direction, of the source position from the receiver position, and to determine, from the first direction angle, the second direction angle and the third direction angle, the bearing of the source position from the receiver position by performing operations comprising;

measuring a third phase difference between a third beat signal and one of (a) the phase reference signal, and (b) the additional beat signal, the third beat signal obtained by a process comprising summing the first beatable signal and the fourth beatable signal and

determining the third direction angle from the third measured phase difference.

17. The system of claim 16, in which:

the third frequency and the fourth frequency differ from the second frequency and differ from the first frequency by different harmonics of the first frequency difference;

the phase reference signal has a frequency harmonically-related to the first frequency difference; and

the receiver measures the third phase difference between the third beat signal and the phase reference signal.

18. The system of claim 16, in which:

the phase reference signal has a phase reference frequency; and

the phase reference frequency, the third frequency and the fourth frequency differ from the second frequency and differ from the first frequency by different harmonics of the first frequency difference; and

the receiver measures the third phase difference between the third beat signal and the additional beat signal.

19. The system of claim 16, in which the first reference direction, the second reference direction and the third reference direction are mutually orthogonal.

20. The system of claim 1, in which:

the phase reference signal source comprises a source clock and a receiver clock, each of the source clock and the receiver clock operable to generate a respective instance of the phase reference signal;

the source clock constitutes part of the first beatable signal source, a beat signal obtained from the first beatable signal as transmitted by the first beatable signal source and the second beatable signal as transmitted by the second beatable signal source having a phase relationship with the instance of the phase reference signal generated by the source clock; and

the receiver clock constitutes part of the receiver and provides the instance of the phase reference signal thereto.

21. The system of claim 1, in which:

the first beatable signal source and the second beatable signal source have a positional relationship; and

the receiver determines the direction angle based in part on the phase relationship and the positional relationship.

22. A method of determining the bearing, relative to a reference direction, of a source location from a receiving location, the method comprising:

receiving at the receiving location a first beatable signal transmitted from a first position at the source location, the first beatable signal having a first frequency;

receiving at the receiving location a second beatable signal transmitted from a second position at the source location, the second position spatially offset from the first position in the reference direction, the second beatable signal having a second frequency differing from the first frequency by a frequency difference;

determining from the first beatable signal and the second beatable signal received at the receiving location a direction angle, relative to the reference direction, of the source location from the receiving location, the determining comprising;

measuring a phase difference between a beat signal and one of (a) a phase reference signal, and (b) an additional beat signal, the beat signal obtained by a process comprising summing the first beatable signal and the second beatable signal, the additional beat signal obtained by a process comprising summing the first beatable signal and the phase reference signal,

calculating the direction angle from the measured phase difference; and

determining the bearing of the source location from the direction angle.

23. The method of claim 22, additionally comprising:

transmitting the phase reference signal from the source location; and

receiving the phase reference signal at the receiving location.

24. The method of claim 22, additionally comprising:

generating respective instance of the phase reference signal at the source location and the receiving location; and

determining a phase difference between a beat signal obtained from the first beatable signal as transmitted from the first position and the second beatable signal as transmitted from the second position and the instance of the phase reference signal generated at the source location.

25. A system for determining the bearing of a source location from a receiving location, the system comprising:

means for generating a phase reference signal;

at the source location, means for transmitting a first beatable signal and a second beatable signal from locations spatially offset from one another in a reference direction, the second beatable signal differing in frequency from the first beatable signal by a frequency difference, the first beatable signal and the second beatable signal collectively having a phase relationship with the phase reference signal; and

at the receiving location, means for receiving the first beatable signal and the second beatable signal and for determining a direction angle, relative to the reference direction, of the source location from the receiver location, the determining comprising;

obtaining a beat signal, the obtaining comprising summing the first beatable signal and the second beatable signal,

measuring a phase difference between the beat signal and one of (a) the phase reference signal and (b) an additional beat signal obtained by a process comprising summing the first beatable signal and the phase reference signal, and

calculating the direction angle from the phase difference.

26. The system of claim 25, in which:

the system additionally comprises means for transmitting the phase reference signal from the source location; and

the means for receiving is additionally for receiving the phase reference signal.

27. The system of claim 25, in which:

the means for generating the sourced reference signal comprises means for generating respective instances of the phase reference signal at the source location and the receiving location; and

the means for determining additionally comprises means for determining a phase difference between a beat signal obtained from the first beatable signal and the second beatable signal as transmitted from the source location and the instance of the phase reference signal generated at the source location.