ULB location system for rescuing avalanche victims

• US 7,612,717 B2
• Filed: 06/07/2005
• Issued: 11/03/2009
• Est. Priority Date: 06/07/2004
• Status: Expired due to Fees

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Daniele, Norbert, Denis, Benoit
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US11/628,620
• Publication Number:
  US 20070176826A1
• Time in Patent Office: 1,610 Days
• Field of Search: 34235701-35717, 342/465, 455/456.1
• US Class Current: 342/465
• CPC Class Codes: A63B 29/021 Means for indicating the location of accidentally buried, e.g. snow-buried, persons
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence

Abstract

A method for locating a UWB transmitter, without a previously-set reference, using at least one first set of at least three UWB searching transceivers, including first, second, and third transceivers. The method a) synchronizes the three UWB searching transceivers, arranged at three different points, and estimates the relative position of these three points; b) receives, by the three transceivers, signals transmitted by the transmitter to be located; and c) calculates the relative position, with respect to the three searching transceivers, of the transmitter to be located according to the time of travel of the signals, transmitted by the transmitter to be located, to the three searching transceivers.

Claims

1. A method for locating a UWB transmitter, without a previously-set position reference, using at least one first set of n UWB searching transceivers, n≧

3, said method comprising;

A) synchronizing the UWB searching transceivers in a grouped state, deploying the searching transceivers at different points, and estimating the relative distances between the searching transceiver;

B) receiving, by the transceivers, signals transmitted by the transmitter to be located;

C) calculating, by the transceivers, respectively, n durations between arrival time of signals transmitted by the transmitter to be located, and a reference time common to the searching transceivers;

D) then, transmitting, to one of the transceivers, the durations calculated, relating to the signals transmitted by the transmitter to be located and received by the other transceivers;

E) calculating the relative position, with respect to the searching transceivers, of the transmitter to be located according to the time of travel of the signals, transmitted by the transmitter to be located, to the searching transceivers, and said relative distances between the searching transceivers.

2. A method according to claim 1, wherein the UWB signals used have a frequency range of less than 1 GHz.

3. A method according to claim 1, wherein the pulse frames transmitted comprise a synchronization preamble, a delimitation of the preamble, then useful data.

4. A method according to claim 1, wherein the method further comprises, before the synchronizing A), synchronizing the searching transceivers in an attached state.

5. A method according to claim 1, further comprising displaying points at which the transceivers are located and the transmitter to be located.

6. A method according to claim 1, wherein each searching transceiver implements, in the receiving B), one or more observation windows each corresponding to a range of distances.

7. A method according to claim 6, wherein all of the distance ranges enable a distance range between 0 and a few hundred meters around each transceiver to be covered.

8. A method according to claim 1, wherein the method comprises refreshing, by a repetition of A), B), and C), the position of the transmitter to be located.

9. A method according to claim 1, wherein the C) for calculating the position of the transmitter to be located provides a position in a two-dimensional surface.

10. A method according to claim 1, wherein one of the transceivers is moved with respect to the other two transceivers.

11. A method according to claim 1, further comprising:

transmitting, by a first transceiver, a reference signal, and reception of the reference signal by the other transceivers;

receiving, by the searching transceivers, signals transmitted by the transmitter to be located;

transmitting, to the first transceiver, information relating to times of arrival of the reference signal and the signals transmitted by the transmitter to be located.

12. A method according to claim 1, wherein the synchronization A) comprises:

transmission of a reference signal from the first transceiver to the other transceivers, and

estimating or calculating, by the other transceivers, of the transit times of the reference signal to themselves.

13. A method according to claim 1, further comprising:

transmitting, by a first transceiver to the other transceivers, a signal comprising at least;

a second duration, calculated by the second transceiver,

a second transit time of the reference signal; and

calculating or estimating, by a third transceiver, a third transit time from the second transceiver to the third transceiver, equal to the transit time of the signal transmitted by the second transceiver.

14. A method according to claim 13, further comprising calculating or estimating, by the first transceiver, a transit time from the second transceiver to the first transceiver, equal to the transit time of said signal transmitted by the second transceiver to the first transceiver.

15. A method according to claim 1, further comprising:

transmitting by a third transceiver, to at least a first transceiver, a signal, comprising at least;

a third transit time from the second transceiver to the third transceiver,

a third duration calculated by the third transceiver, and

a third transit time of the reference signal.

16. A method according to claim 15, further comprising calculating or estimating, by the first transceiver, a transit time from the third transceiver to the first transceiver, equal to the transit time of the signal transmitted by the third transceiver to the first transceiver.

17. A method according to claim 1, wherein an additional transceiver is synchronized with the first set of at least three transceivers and positioned with respect to the at least three transceivers.

18. A method according to claim 17, wherein the first set of transceivers includes three transceivers and the additional transceiver is a fourth transceiver.

19. A method according to claim 18, further comprising:

transmitting, by the first transceiver, a reference signal;

receiving, by the four searching transceivers, signals transmitted by the transmitter to be located;

transmitting, to the first transceiver, information relating to transit time of the reference signal and to times that have passed between an arrival time of the signals transmitted by the transmitter to be located and a reference time common to the four transceivers.

20. A method according to claim 18, wherein the synchronizing A) comprises:

transmitting a first reference signal from the first transceiver to the second, third, and fourth transceivers,

estimating or calculating, by the second and third transceivers, the transit times of the reference signal to the second and third transceivers,

synchronizing the fourth transceiver with the first transceiver, and estimating or calculating, by the fourth transceiver, the transit time of a signal between the first and the fourth transceivers.

21. A method according to claim 20, further comprising:

transmitting, by the fourth transceiver, an adherence request signal;

then transmitting, by the first transceiver, an acknowledgement signal, and

calculating, by the fourth transceiver, the transit time of the acknowledgement signal from the first transceiver to the fourth transceiver.

22. A method according to claim 18, further comprising, between B) and C):

calculating by the first, second, third, and fourth transceivers, respectively, a first, a second, a third, and a fourth duration between the times of reception by the transceivers of signals transmitted by the transmitter to be located, and a reference time common to the four transceivers,

then, transmitting, to the first transceiver, the second, third, and fourth calculated durations.

23. A method according to claim 22, further comprising:

transmitting, by the fourth transceiver to the first, second, and third transceivers, a signal comprising at least the fourth duration calculated,

calculating or estimating, by the first, second, and third transceiver, respectively, a fourth, fifth, and sixth transit time from the fourth transceiver to the first, second, and third transceivers, equal to the transit time of the signal transmitted by the fourth transceiver.

24. A method according to claim 23, further comprising:

transmitting, by the second transceiver to the first, third, and fourth transceivers, a signal comprising at least;

the second duration calculated by the transceiver signal, and

the fifth transit time;

calculating or estimating, by the first, third, and fourth transceivers, respectively, a seventh, eighth, and ninth transit time from the second transceiver, respectively, to the first, fourth, and third transceivers, equal to the transit time of the signal transmitted by the second transceiver to each of the first, third, and fourth transceivers.

25. A method according to claim 24, further comprising:

transmitting, by the third transceiver to the first, second, and fourth transceivers, a signal comprising at least;

the third duration calculated by the third transceiver,

a sixth transit time, and

a ninth transit time;

calculating or estimating, by the first, second, and fourth transceivers, respectively, a tenth, eleventh, and twelfth transit time from the third transceiver, respectively, to the first, fourth, and second transceivers, equal to the transit time of the signal transmitted by the third transceiver to each of the first, fourth, and second transceivers.

26. A method according to claim 18, wherein the fourth transceiver is part of a second set of three transceivers.

27. A method according to claim 1, wherein a second set of at least three transceivers implements A) through E) in parallel with, or independently of, the first set.

28. A method according to claim 1, wherein the transmitter to be located is buried under snow.

29. A method according to claim 28 wherein, in E), a correction is made to take into account delays in times of arrival due to the propagation of signals in the snow.

30. A Method according to claim 1, wherein the transceivers use, in the transmission, by default, identical spreading sequences.

31. A device for locating a UWB transceiver, comprising at least three searching transceivers, programmed to implement a method according to claim 1.