Impulse radio receiver and method for finding angular offset of an impulse radio transmitter

• US 6,760,387 B2
• Filed: 09/21/2001
• Issued: 07/06/2004
• Est. Priority Date: 09/21/2001
• Status: Active Grant

• Current Assignee: Humatics Corporation
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Langford, David W., Nieburg, Michael J., Shreve, Gregory A.
• Primary Examiner(s): Vo, Don N.
• Application Number:
  US09/957,745
• Publication Number:
  US 20030058971A1
• Time in Patent Office: 1,019 Days
• Field of Search: 375/139, 375/142, 375/150, 375/343, 375/347, 375/267, 375/299, 375/354, 342/424, 342/442
• US Class Current: 375/267
• CPC Class Codes: G01S 3/50 the waves arriving at the antennas being pulse modulated and the time difference of their arrival being measured

Abstract

A system and method for determining angular offset of an impulse radio transmitter using an impulse radio receiver coupled to two antennae. The antennae are separated by some known distance, and, in one embodiment, one antennae is coupled to the radio with cable delay. Impulse signals from the antennae are measured to determine the time difference of arrival of one such signal received by one antenna compared to that of the other antenna. Time differential is measured by autocorrelation of the entire impulse radio scan period, by detecting the leading edges of both incoming signals or various combinations of these methods. Using a tracking receiver, the pulses may be continuously tracked thus providing real time position information.

Claims

1. An impulse radio receiver, comprising:

an impulse radio;

a first antenna coupled to said impulse radio by a first coupling;

a second antenna coupled to said impulse radio by a second coupling; and

a receiver processor coupled to said impulse radio;

said impulse radio is a direct conversion impulse radio that includes at least one scanning correlator which scans at least one interval in a time domain to enable said receiver processor to locate a leading edge of impulse radio pulses received by said first antenna and to locate a leading edge of impulse radio pulses received by said second antenna which enables said receiver processor to approximate a position of an impulse radio transmitter by calculating an angular offset based upon arrival times of the impulse radio pulses transmitted by said impulse radio transmitter and received at said first antenna and second antenna.

2. The impulse radio receiver according to claim 1, further comprising three or more antennae coupled to said impulse radio by couplings, such that one such coupling length is less than the remainder of said couplings'"'"' lengths and all coupling lengths are unique.

3. The impulse radio receiver according to claim 1, wherein said impulse radio further includes at least one tracking correlator.

4. The impulse radio receiver according to claim 1, wherein said second coupling is of greater length than said first coupling.

5. The impulse radio receiver according to claim 4, further comprising a third antenna coupled to said impulse radio by a third coupling, said third coupling being greater than said first coupling and unequal to said second coupling.

6. The impulse radio receiver according to claim 5, further comprising a fourth antenna coupled to said impulse radio by a fourth coupling, said fourth coupling being greater than said first coupling and unequal to said second coupling and said third coupling.

7. An impulse radio receiver comprising:

a first antenna and a second antenna;

a first impulse radio coupled to said first antenna;

a second impulse radio coupled to said second antenna;

a synchronizing signal generator having an output coupled to said first impulse radio and an output coupled to said second impulse radio for synchronously engaging said first and second impulse radios; and

a processor having an input responsive to said first and said second impulse radios, said processor being enabled to locate the leading edges of impulse radio pulses transmitted by an impulse radio transmitter and received at said first antenna and said second antenna and to approximate a position of the impulse radio transmitter by calculating an angular offset based upon arrival times of the impulse radio pulses.

8. A method for finding angular offset of an impulse radio transmitter from an impulse radio receiver comprising the steps of:

receiving from a said impulse radio transmitter an impulse radio signal using an impulse radio receiver, said impulse radio receiver comprising a first antenna coupled to an impulse radio by a first coupling and a second antenna coupled to said impulse radio by a second coupling, wherein said second coupling is of greater length than said first coupling;

determining an arrival delay of a second pulse with respect to a first pulse, said first pulse being received by said first antenna and said second pulse being received by said second antenna, wherein said step of determining an arrival delay further includes;

locating said first leading edge of said first pulse;

tracking said first leading edge;

correlating over a first interval, said first interval corresponding to the duration of a pulse, said first interval commencing prior to said first leading edge;

correlating over a second interval, said second interval corresponding to the distance separating said first and said second antennae and occurring after said first pulse; and

approximating an angle of arrival of said pulses with respect to a point between said first antenna and said second antenna based upon said arrival delay.

9. The method according to claim 8, wherein said step of determining said arrival delay further comprises locating and tracking said first pulse and said second pulse with respect to time.

10. The method according to claim 8, wherein said step of determining an arrival delay further comprises auto-correlating a waveform comprised of said first and said second pulses over an interval enveloping the arrival time of said first and said second pulses.

11. The method according to claim 8, wherein said step of determining an arrival delay further comprises measuring a time of arrival of a first leading edge of said first pulse.

12. The method according to claim 8, wherein said step of determining an arrival delay further comprises measuring a time of arrival of a second leading edge of a second pulse.

13. The method according to claim 8, wherein said impulse radio receiver further comprises a third antenna coupled to said impulse radio by a third coupling, said third coupling being of greater length than said first coupling and unequal to said second coupling length.

14. The method according to claim 13, wherein said step of determining an arrival delay further comprises determining an arrival delay of a third pulse received by said third antenna.

15. The method according to claim 14, wherein the step of approximating an angle of arrival further comprises approximating a first angle of arrival in the horizontal plane and a second angle of arrival in the vertical plane.

16. The method according to claim 13, wherein said impulse radio receiver further comprises a fourth antenna coupled to said impulse radio by a fourth coupling, said fourth coupling being of greater length than said first coupling and unequal to said second and third coupling lengths.

17. A method for finding angular offset of an impulse radio transmitter from an impulse radio receiver comprising the steps of:

receiving from a the impulse radio transmitter an impulse radio signal using an impulse radio receiver, said impulse radio receiver comprising a first antenna coupled to a direct conversion impulse radio and a second antenna coupled to said direct conversion impulse radio that includes at least one scanning correlator which scans at least one interval in a time domain to enable a processor to locate a leading edge of the impulse radio signal received by said first antenna and to locate a leading edge of the impulse radio signal received by said second antenna;

measuring the arrival time of the leading edge of a first pulse of said impulse radio signal received by said first antenna;

measuring the arrival time of the leading edge of a first pulse of said impulse radio signal received by said second antenna; and

approximating a position of the impulse radio transmitter by calculating an angular offset based upon arrival times of the impulse radio pulses transmitted by said impulse radio transmitter and received at said first antenna and second antenna.

18. The method according to claim 17, wherein said direct conversion impulse radio tracks said leading edge of a first pulse of said impulse radio signal received by said first antenna.

19. The method according to claim 18, wherein said direct conversion impulse radio tracks said leading edge of a first pulse of said impulse radio signal received by said second antenna.

20. The method according to claim 18, wherein said impulse radio receiver is further comprised of a third antenna coupled to said direct conversion impulse radio.

21. The method according to claim 20, further comprising measuring the arrival time of a leading edge of a first pulse of said impulse radio signal received by said third antenna.

22. The method according to claim 21, wherein said impulse radio receiver is further comprised of a fourth antenna coupled to said direct conversion impulse radio.

23. The method according to claim 22, further comprising measuring the arrival time of a leading edge of a first pulse of said impulse radio signal received by said fourth antenna.

24. The method according to claim 23, wherein the step of calculating an angle of arrival further comprises approximating a first angle of arrival in the horizontal plane and a second angle of arrival in the vertical plane.

25. A method for determining a position of the impulse radio transmitter relative to an impulse radio receiver comprising the steps of:

receiving from a the impulse radio transmitter an impulse radio signal using the impulse radio receiver, said impulse radio receiver comprising a first antenna coupled to a first impulse radio by a first coupling and a second antenna coupled to a second impulse radio by a second coupling, said first and second impulse radios being synchronously engaged;

determining an arrival delay of a second pulse with respect to a first pulse, said first pulse being received by said first impulse radio and said second pulse being received by said second impulse radio; and

approximating an angle of arrival of said pulses with respect to a point between said first antenna and said second antenna based upon said arrival delay which enables the determination of the position of the impulse radio transmitter.

26. The method according to claim 25, wherein said step of determining an arrival delay further comprises:

correlating said first pulse using said first impulse radio; and

correlating said second pulse using said second impulse radio.

27. The method according to claim 26, wherein said step of determining an arrival delay further comprises measuring the time of arrival of a first leading edge of said first pulse and of a second leading edge of said second pulse.