System and method for position determination by impulse radio

• US 20080100497A1
• Filed: 10/31/2007
• Published: 05/01/2008
• Est. Priority Date: 03/23/1998
• Status: Active Grant

• Current Assignee: Plus Location Systems Pty. Limited
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Richards, James, Fullerton, Larry, Cowie, Ivan
• Granted Patent: US 7,495,613 B2
• Time in Patent Office: Days
• US Class Current: 342/21
• 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 synchronization of a plurality of ultra wideband radios, said method comprising the steps of:

a. obtaining at each of said plurality of ultra wideband radios a synchronization signal corresponding to an external clock; and

b. synchronizing internal clocks of each of said plurality of ultra wideband radios with said synchronization signal.

2. The method of claim 1, wherein said external clock is one a universal clock or an atomic clock.

3. The method of claim 1, wherein said internal clocks correspond to voltage controlled oscillators.

4. The method of claim 1, wherein at least one of said plurality of ultra wideband radios is configured as a receiver.

5. The method of claim 1, wherein at least one of said plurality of ultra wideband radios is configured as a transmitter.

6. The method of claim 1, further comprising the steps of:

c. receiving at each of said plurality of ultra wideband radios an ultra wideband signal transmitted by another ultra wideband radio; and

d. determining a position of said another ultra wideband radio.

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

synchronizing an internal clock of said another ultra wideband radio with said synchronization signal.

8. The method of claim 6, wherein said position is determined using at least one direction finding antenna.

9. The method of claim 6, wherein at least one of said plurality of ultra wideband radios is not coplanar with said other of said plurality of ultra wideband radios.

10. The method of claim 1, further comprising:

transmitting from each of said plurality of ultra wideband radios a plurality of ultra wideband signals;

receiving said plurality of ultra wideband signals at another ultra wideband radio; and

determining a position of said another ultra wideband radio.

15. The system of claim 1, wherein at least one of said plurality of ultra wideband radios is configured as a transmitter.

11. A system for synchronization of a plurality of ultra wideband radios, said system comprising:

an external clock; and

a synchronization signal corresponding to said external clock, said synchronization signal being obtained by each of said plurality of ultra wideband radios, each of said plurality of ultra wideband radios synchronizing its internal clock with said synchronization signal.

12. The system of claim 11, wherein said external clock is one a universal clock or an atomic clock.

13. The system of claim 11, wherein said internal clock corresponds to a voltage controlled oscillator.

14. The system of claim 11, wherein at least one of said plurality of ultra wideband radios is configured as a receiver.

16. The system of claim 11, further comprising:

a processor for determining a position of another ultra wideband radio having transmitted a ultra wideband signal based upon times of arrival of said ultra wideband signal at said plurality of ultra wideband radios

17. The system of claim 16, wherein an internal clock of said another ultra wideband radio is synchronized with said synchronization signal.

18. The system of claim 16, further comprising:

at least one direction finding antenna.

19. The system of claim 16, wherein at least one of said plurality of ultra wideband radios is not coplanar with said other of said plurality of ultra wideband radios.

20. The system of claim 11, further comprising:

a processor for determining a position of another ultra wideband radio having received a plurality of ultra wideband signals transmitted by a plurality of ultra wideband radios.