System and method for position determination by impulse radio

• US 20080136709A1
• Filed: 10/31/2007
• Published: 06/12/2008
• Est. Priority Date: 03/23/1998
• Status: Active Grant

• Current Assignee: Humatics Corporation
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Richards, James L., Fullerton, Larry W., Cowie, Ivan A.
• Granted Patent: US 7,710,320 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/76 wherein pulse-type signals are transmitted
• CPC Class Codes: H04B 1/7183 Synchronisation
• CPC Class Codes: H04B 2001/6908 using time hopping

Abstract

A system and a method for position determination by impulse radio using a first transceiver having a first clock providing a first reference signal and a second transceiver placed spaced from the first transceiver. The system determines the position of the second transceiver. The second transceiver has a second clock that provides a second reference signal. A first sequence of pulses are transmitted from the first transceiver. The first sequence of pulses are then received at the second transceiver and the second transceiver is then synchronized with the first sequence of pulses. A second sequence of pulses are transmitted from the second transceiver. The first transceiver receives the second sequence of pulses and the first transceiver is synchronized with the second sequence of pulses. A delayed first reference signal is generated in response to the synchronization with the second sequence of pulses. A time difference between the delayed first reference signal and the first reference signal is then measured. The time difference indicates a total time of flight of the first and second sequence of pulses. The distance between the first and the second transceiver is determined from the time difference. The direction of the second transceiver from the first transceiver is determined using a directional antenna. Finally, the position of the second transceiver is determined using the distance and the direction.

Claims

1. A method for producing a time base for an ultra wideband radio, said method comprising the steps of:

a. obtaining a time reference signal; and

b. phase locking a clock signal to said time reference signal to produce said time base.

2. The method of claim 1, further comprising:

counting down said clock signal using a counter to produce said time base.

3. The method of claim 2, wherein said counter is a binary counter.

4. The method of claim 2, wherein said counter has a modulo count equal to a modulo repeat length of a code corresponding to an ultra wideband signal.

5. The method of claim 1, wherein said time reference signal is provided by a crystal reference.

6. The method of claim 1, wherein said modulo repeat length is longer than a distance to be measured between said ultra wideband radio and a second ultra wideband radio.

7. The method of claim 6, further comprising the step of:

c. measuring a phase difference between said time base and a second time base of said second ultra wideband radio, said phase difference corresponding to a time difference between said ultra wideband radio transmitting said ultra wideband signal and said ultra wideband radio receiving a second ultra wideband signal transmitted by said second ultra wideband radio after having received said ultra wideband signal.

8. The method of claim 7, further comprising the step of:

d. determining, from said time difference, said distance between said ultra wideband radio and said second ultra wideband radio.

9. The method of claim 6, wherein said ultra wideband radio and said second ultra wideband radio are synchronized.

10. The method of claim 9, wherein said ultra wideband radio and said second ultra wideband radio are synchronized using at least one of a universal clock, an external clock, or an atomic clock.

11. The method of claim 9, wherein said ultra wideband radio is configured as one of a transmitter, a receiver, or a transceiver.

12. The method of claim 9, wherein said second ultra wideband radio is configured as one of a transmitter, a receiver, or a transceiver.

13. The method of claim 8, further comprising the step of:

e. determining a position of said second ultra wideband radio using a direction finding antenna and said distance.

21. The system of claim 10, wherein said distance between said ultra wideband radio and said second ultra wideband radio is determined from said time difference.

26. The system of claim 21, further comprising:

a direction finding antenna, said direction antenna and said distance being used to determine a position of said second UWB radio.

14. A system for producing a time base for an ultra wideband radio, said system comprising:

a time reference signal; and

a clock signal, said clock signal phase locked to said time reference signal to produce said time base.

15. The system of claim 14, further comprising:

a counter used to count down said clock signal to produce said time base.

16. The system of claim 15, wherein said counter is a binary counter.

17. The system of claim 15, wherein said counter has a modulo count equal to a modulo repeat length of a code corresponding to an ultra wideband signal.

18. The system of claim 14, wherein said time reference signal is provided by a crystal reference.

19. The system of claim 14, wherein said modulo repeat length is longer than a distance to be measured between said ultra wideband radio and a second ultra wideband radio.

20. The system of claim 19, further comprising:

a processor, said processor determining a phase difference between said time base and a second time base of said second ultra wideband radio, said phase difference corresponding to a time difference between said ultra wideband radio transmitting said ultra wideband signal and said ultra wideband radio receiving a second ultra wideband signal transmitted by said second ultra wideband radio after having received said ultra wideband signal.

22. The system of claim 19, wherein said ultra wideband radio and said second ultra wideband radio are synchronized.

23. The system of claim 22, further comprising:

at least one of a universal clock, an external clock, or an atomic clock, said at least one of said universal clock, said external clock, or said atomic clock being used to synchronize said ultra wideband radio and said second ultra wideband radio.

24. The system of claim 22, wherein said ultra wideband radio is configured as one of a transmitter, a receiver, or a transceiver.

25. The system of claim 22, wherein said second ultra wideband radio is configured as one of a transmitter, a receiver, or a transceiver.