Time transfer using ultra wideband signals

• US 7,873,099 B2
• Filed: 10/31/2007
• Issued: 01/18/2011
• Est. Priority Date: 06/14/1999
• Status: Expired due to Term

• Current Assignee: Humatics Corporation
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Fullerton, Larry W., Richards, James L., Roberts, Mark D.
• Primary Examiner(s): Payne; David C
• Assistant Examiner(s): Guarino; Rahel
• Application Number:
  US11/980,529
• Publication Number:
  US 20080151967A1
• Time in Patent Office: 1,175 Days
• Field of Search: 375/149, 375/130, 375/219, 375/342, 375/295, 375/145, 375/345, 375/358, 370/503, 370/208, 342/61, 342/88, 342/118, 342/64, 342/109, 342/104, 342/146, 342/125, 342/357.08, 342/257.09
• US Class Current: 375/149
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 7/4052 by simulation of echoes
• CPC Class Codes: G01S 7/4065 involving a delay line
• CPC Class Codes: G01S 7/4069 involving a RF signal injection
• CPC Class Codes: G01S 7/4082 using externally generated reference signals, e.g. via remote reflector or transponder
• CPC Class Codes: G06K 7/10306 ultra wide band
• CPC Class Codes: H04B 1/7183 Synchronisation

Abstract

Time is transferred from an ultra wideband (UWB) transmitter to UWB receiver by transmitting a signal structure having an associated timing reference point together with a time value for the timing reference point. The UWB receiver receives the timing signal structure by synchronizing a receiver time base to the signal structure, demodulating the time value information, and using the demodulated time value information to set a receiver clock value. Propagation delay information is used to adjust the receiver clock value by advancing the receiver clock value to account for the propagation delay. In one embodiment, propagation delay is determined from a known distance between the transmitter and receiver. In another embodiment, the transmitter and receiver are part of a two-way link wherein propagation delay is measured by round trip timing measurements.

Claims

1. A method for wireless synchronization of a pair of Ultra Wideband (UWB) radios, said method comprising the steps of:

a. transmitting a first synchronization signal from a first UWB radio of said pair of UWB radios, said first synchronization signal having a signal structure comprising a synchronizing pattern and a data stream;

b. receiving said first synchronization signal at a second UWB radio of said pair of UWB radios;

c. synchronizing said second UWB radio with said first UWB radio based upon said synchronizing pattern of said first synchronization signal; and

d. setting a clock of said second UWB radio based upon said data stream of said first synchronization signal for locating an object.

2. The method of claim 1, wherein the step of c. synchronizing said second UWB radio with said first UWB radio based upon said synchronizing pattern of said first synchronization signal further comprises the step of:

c1. synchronizing a receiver time base with said synchronizing pattern of said received first synchronization signal.

3. The method of claim 2, wherein the step of d. setting a clock of said second UWB radio with said first UWB radio based upon said data stream of said first synchronization signal further comprises the step of:

d1. setting a receiver clock in accordance with said receiver time base and said data stream of said first synchronization signal.

4. The method of claim 2, wherein said signal structure includes a code and the step of c. synchronizing said second UWB radio with said first UWB radio based upon said synchronizing attern of said first synchronization signal comprises using said code to synchronize said receiver time base with said synchronizing pattern of said first synchronization signal.

5. The method of claim 4, wherein said code is periodically changed to effectively extend a code repeat length.

6. The method of claim 4, wherein said code is applied to groups of UWB signals and the spacing between groups of UWB signals is changed to effectively extend a code repeat length.

7. The method of claim 3, further comprising the step of:

d2. determining propagation delay and adjusting the receiver clock in accordance with propagation delay.

8. The method of claim 7, wherein the step of d2 determining propagation delay comprises one of a leading edge algorithm and a pattern matching algorithm.

9. The method of claim 3, wherein said data stream of said first synchronization signal comprises a time reference point and a time value related to a time of the time reference point.

10. The method of claim 1, wherein a distance between said first UWB radio and said second UWB radio is known and said setting a clock of said second UWB radio with said first UWB radio is based upon said distance.

11. The method of claim 10, wherein said distance was determined using one of an UWB range finding technique, a map, a blueprint, a survey, or a direct measurement.

12. The method of claim 10, wherein distances between each pair of UWB radios of a plurality of UWB radios have been determined using UWB range finding techniques.

13. The method of claim 1, wherein positions of said first UWB radio and second UWB radio are known in relation to each other and said setting a clock of said second UWB radio with said first UWB radio is based upon said positions.

14. The method of claim 13, wherein said positions were determined using UWB position determination techniques.

15. The method of claim 14, wherein relative positioning has been determined between each pair of UWB radios of a plurality of UWB radios.

16. The method of claim 1, wherein steps a through d are performed by each pair of UWB radios of a plurality of UWB radios.

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

e. transmitting a second synchronization signal from said second UWB radio of said pair of UWB radios, said second synchronization signal having a second signal structure comprising a second synchronizing pattern and a second data stream;

f. receiving said second synchronization signal at said first UWB radio of said pair of UWB radios;

g. synchronizing said first UWB radio with said second UWB radio based upon said second synchronizing pattern of said second synchronization signal; and

h. setting a clock of said first UWB radio based upon said second data stream of said second synchronization signal.

18. The method of claim 17, wherein steps a through h are performed by each pair of UWB radios of said plurality of UWB radios.

19. A method for synchronizing a first transceiver and a second transceiver, said method comprising the steps of:

a. transmitting an ultra wideband signal from said first transceiver;

b. receiving said ultra wideband signal at said second transceiver;

c. synchronizing a second transceiver receiver time base in accordance with a synchronization pattern of said received ultra wideband signal;

d. setting a second transceiver clock in accordance with a data stream of said received ultra wideband signal;

e. transmitting a return ultra wideband signal from said second transceiver;

f. receiving said return ultra wideband signal at said first transceiver; and

g. synchronizing a first transceiver receiver time base in accordance with a synchronization pattern of said received return ultra wideband signal; and

h. setting a first transceiver clock in accordance with a data stream of said received return ultra wideband signal and determining the location of an object.

20. A method for synchronizing a first ultra wideband radio with a second ultra wideband radio, said method comprising the steps of:

a. transmitting an ultra wideband signal from said first ultra wideband radio in accordance with a first time base;

b. receiving said transmitted ultra wideband signal at said second ultra wideband radio;

c. synchronizing a second time base of said second ultra wideband radio with said first time base of said first ultra wideband radio based upon a synchronization pattern of said received ultra wideband signal; and

d. setting a clock of said second ultra wideband radio based upon a data stream of said received ultra wideband signal and a determined distance between said first ultra wideband radio and said second ultra wideband radio.