System and method for real-time locating

• US 20120019413A1
• Filed: 07/26/2010
• Published: 01/26/2012
• Est. Priority Date: 07/26/2010
• Status: Active Grant

• Current Assignee: ENSCO, Incorporated (Teris LLC)
• Original Assignee: ENSCO, Incorporated (Teris LLC)
• Inventors: Fretenburg, Russell Alan, Kazemir, Steven Scott, Leung, Henry Hon-You, Pyner, Derek John, Taylor, David W.A. Jr., McNeill, Charles Elmer IV
• Granted Patent: US 8,334,801 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A locating system, includes at least one initiator configured to operate at a first clock frequency, and to transmit a measurement signal including a first preamble; and at least one transponder configured to operate at a second clock frequency, to receive the measurement signal, and to transmit a response signal to the initiator, the response signal including a second preamble. The initiator is further configured to calculate, based on the response signal, a distance between the initiator and the transponder for determining a location of the transponder.

Claims

1. A locating system, comprising:

at least one initiator configured to operate at a first clock frequency, and to transmit a measurement signal including a first preamble; and

at least one transponder configured to operate at a second clock frequency;

wherein the transponder includes;

a first transceiver configured to receive the measurement signal and to perform synchronization with the first preamble;

a first programmable device configured to detect a first plurality of skips during the performance of synchronization, and to count a first plurality of numbers of clock cycles for the first plurality of skips; and

the first transceiver configured to transmit a response signal to the initiator, the response signal including a second preamble and a data payload including the first plurality of numbers of clock cycles; and

wherein the initiator includes;

a second transceiver configured to receive the response signal and to perform synchronization with the second preamble;

a second programmable device configured to detect a second plurality of skips during the performance of synchronization, and to count a second plurality of numbers of clock cycles for the second plurality of skips; and

a microcontroller configured to calculate a first time adjustment based on the first plurality of numbers of clock cycles, to calculate a second time adjustment based on the second plurality of numbers of clock cycles, and to calculate, based on a coarse time estimate, the first time adjustment, and the second time adjustment, a distance between the initiator and the transponder for determining a location of the transponder.

2. The system of claim 1, wherein the first programmable device is further configured to:

monitor a number of clock cycles in each data cycle; and

detect a change of the number of clock cycles in a data cycle to detect a skip.

3. The system of claim 1, wherein the second programmable device is further configured to:

monitor a number of clock cycles in each data cycle; and

detect a change of the number of clock cycles in a data cycle to detect a skip.

4. The system of claim 1, wherein the initiator further comprises:

a processor configured to relay the calculated distance as distance data to a primary initiator or a computer.

5. The system of claim 1, wherein the initiator further comprises:

a control panel for providing a user control interface.

6. The system of claim 1, wherein the initiator further comprises:

an interface for outputting distance data and for charging a battery which provides operating power to the initiator.

7. The system of claim 1, wherein the initiator is a first initiator and the system includes a plurality of second initiators, the first initiator being further configured to collect distance data from the second initiators, and to provide its own distance data and the collected distance data for a computer to determine the location of the transponder.

8. The system of claim 1, wherein the initiator further comprises:

an oscillator configured to provide a reference clock signal.

9. The system of claim 8, wherein the second programmable device comprises:

a phase-locked loop (PLL) clock generator configured to generate the first clock frequency based on the reference clock signal.

10. The system of claim 1, wherein:

the first programmable device is further configured to count a first number of clock cycles between the reception of the measurement signal and the transmission of the response signal;

the second programmable device is further configured to count a second number of clock cycles between the transmission of the measurement signal and the reception of the response signal; and

the microcontroller is further configured to calculate the coarse time estimate based on the first number of clock cycles and the second number of clock cycles.

11. The system of claim 1, wherein the second radio transceiver is further configured to resynchronize with the second preamble by adjusting ahead or back a predetermined fraction of one clock cycle corresponding to the first clock frequency.

12. The system of claim 1, wherein the transponder further comprises:

a control panel for providing a user control interface.

13. The system of claim 1, wherein the transponder further comprises:

an interface for configuring the transponder and for charging a battery which provides operating power to the transponder.

14. The system of claim 1, wherein the transponder further comprises:

an oscillator configured to provide the second clock frequency.

15. The system of claim 1, wherein the first radio transceiver is further configured to resynchronize with the first preamble by adjusting ahead or back a predetermined fraction of one clock cycle corresponding to the second clock frequency.

16. A locating method, comprising:

transmitting, by a first radio device operating at a first clock frequency, a measurement signal including a first preamble;

receiving, by a second radio device operating at a second clock frequency, the measurement signal;

performing, by the second radio device, synchronization with the first preamble;

detecting, by the second radio device, a first plurality of skips during the performance of synchronization, and counting a first plurality of numbers of clock cycles for the first plurality of skips;

transmitting, by the second radio device, a response signal to the first radio device, the response signal including a second preamble and a data payload including the first plurality of numbers of clock cycles;

receiving, by the first radio device, the response signal;

performing, by the first radio device, synchronization with the second preamble;

detecting, by the first radio device, a second plurality of skips during the performance of synchronization, and counting a second plurality of numbers of clock cycles for the second plurality of skips;

calculating, by the first radio device, a first time adjustment based on the first plurality of numbers of clock cycles, and a second time adjustment based on the second plurality of numbers of clock cycles; and

calculating by the first radio device, based on a coarse time estimate, the first time adjustment, and the second time adjustment, a distance between the first and second radio devices for determining a location of the second radio device.

17. The method of claim 16, wherein detecting the first plurality of skips comprises:

monitoring a number of clock cycles in each data cycle; and

detecting a change of the number of clock cycles in a data cycle to detect a skip.

18. The method of claim 16, wherein detecting the second plurality of skips comprises:

monitoring a number of clock cycles in each data cycle; and

detecting a change of the number of clock cycles in a data cycle to detect a skip.

19. The method of claim 16, further comprising:

collecting, by the first radio device, distance data indicating a distance between a third radio device and the second radio device; and

providing, by the first radio device, the collected distance data for a computer to determine the location of the second radio device.

20. The method of claim 16, further comprising:

generating, by a phase-locked loop (PLL) clock generator, the first clock frequency based on a reference clock signal.

21. The method of claim 16, further comprising:

counting, by the first radio device, a first number of clock cycles between the transmission of the measurement signal and the reception of the response signal;

counting, by the second radio device, a second number of clock cycles between the reception of the measurement signal and the transmission of the response signal; and

calculating, by the first radio device, the coarse time estimate based on the first number of clock cycles and the second number of clock cycles.

22. The method of claim 16, comprising resynchronizing the first radio device with the second preamble by adjusting ahead or back a predetermined fraction of one clock cycle corresponding to the first clock frequency.

23. The method of claim 16, comprising resynchronizing the second radio device with the first preamble by adjusting ahead or back a predetermined fraction of one clock cycle corresponding to the second clock frequency.

24. A computer-readable storage medium including instructions, executable by a processor, for instructing first and second radio devices to perform a locating method, the first radio device being configured to operate at a first clock frequency, the second radio device being configured to operate at a second clock frequency, the method comprising:

transmitting, by the first radio device, a measurement signal including a first preamble;

receiving, by the second radio device, the measurement signal;

performing, by the second radio device, synchronization with the first preamble;

detecting, by the second radio device, a first plurality of skips during the performance of synchronization, and counting a first plurality of numbers of clock cycles for the first plurality of skips;

transmitting, by the second radio device, a response signal to the first radio device, the response signal including a second preamble and a data payload including the first plurality of numbers of clock cycles;

receiving, by the first radio device, the response signal;

performing, by the first radio device, synchronization with the second preamble;

detecting, by the first radio device, a second plurality of skips during the performance of synchronization, and counting a second plurality of numbers of clock cycles for the second plurality of skips;

calculating, by the first radio device, a first time adjustment based on the first plurality of numbers of clock cycles, and a second time adjustment based on the second plurality of numbers of clock cycles; and

calculating by the first radio device, based on a coarse time estimate, the first time adjustment, and the second time adjustment, a distance between the first and second radio devices for determining a location of the second radio device.

25. The computer-readable storage medium of claim 24, wherein the instructions generate a graphic user interface (GUI) on the computer, to show information regarding the location of the second radio device.

26. A first radio device configured to operate at a first clock frequency for use in a locating system, comprising:

a transceiver configured to transmit to a second radio device a measurement signal including a first preamble, to receive from the second radio device a response signal including a second preamble, and to perform synchronization with the second preamble;

a programmable device configured to detect a plurality of skips during the performance of synchronization, and to count a plurality of numbers of clock cycles for the plurality of skips; and

a microcontroller configured to calculate a time adjustment based on the plurality of numbers of clock cycles, and to calculate, based on a coarse time estimate and the time adjustment, a distance between the first radio device and the second radio device for determining a location of the second radio device.

27. The first radio device of claim 26, wherein the programmable device is further configured to:

monitor a number of clock cycles in each data cycle; and

detect a change of the number of clock cycles in a data cycle to detect a skip.

28. The first radio device of claim 26, further comprising:

a processor configured to relay the calculated distance as distance data to a third radio device or a computer.

29. The first radio device of claim 26, further comprising:

a control panel for providing a user control interface.

30. The first radio device of claim 26, further comprising:

an interface for outputting distance data and for charging a battery which provides operating power to the first radio device.

31. The first radio device of claim 26, further comprising:

an oscillator configured to provide a reference clock signal.

32. The first radio device of claim 31, wherein the programmable device comprises:

a phase-locked loop (PLL) clock generator configured to generate the first clock frequency based on the reference clock signal.

33. The first radio device of claim 26, wherein:

the programmable device is configured to count a number of clock cycles between the transmission of the measurement signal and the reception of the response signal; and

the microcontroller is further configured to calculate the coarse time estimate based on the number of clock cycles.

34. The first radio device of claim 26, wherein the radio transceiver is further configured to resynchronize with the second preamble by adjusting ahead or back a predetermined fraction of one clock cycle corresponding to the first clock frequency.

35. A first radio device configured to operate at a first clock frequency for use in a locating system, comprising:

a transceiver configured to receive from a second radio device a measurement signal including a first preamble and to perform synchronization with the first preamble; and

a programmable device configured to detect a plurality of skips during the performance of synchronization, and to count a plurality of numbers of clock cycles for the plurality of skips;

wherein the transceiver is configured to transmit to the second radio device a response signal, the response signal including a second preamble and a data payload including the plurality of numbers of clock cycles.

36. The first radio device of claim 35, wherein the programmable device is further configured to:

monitor a number of clock cycles in each data cycle; and

detect a change of the number of clock cycles in a data cycle to detect a skip.

37. The first radio device of claim 35, wherein the programmable device is further configured to:

count a number of clock cycles between the reception of the measurement signal and the transmission of the response signal.

38. The first radio device of claim 35, further comprising:

a microcontroller configured to control the programmable device and the radio transceiver.

39. The first radio device of claim 35, further comprising:

a control panel for providing a user control interface.

40. The first radio device of claim 35, further comprising:

an interface for configuring the first radio device and for charging a battery which provides operating power to the first radio device.

41. The first radio device of claim 35, further comprising:

an oscillator configured to provide the first clock frequency.

42. The first radio device of claim 35, wherein the radio transceiver is further configured to resynchronize with the first preamble by adjusting ahead or back a predetermined fraction of one clock cycle corresponding to the first clock frequency.

43. A locating method for use by a first radio device in a locating system, the first radio device being configured to operate at a first clock frequency, the method comprising:

transmitting to a second radio device a measurement signal including a first preamble;

receiving from the second radio device a response signal including a second preamble;

performing synchronization with the second preamble;

detecting a plurality of skips during the performance of synchronization;

counting a plurality of numbers of clock cycles for the plurality of skips;

calculating a time adjustment based on the plurality of numbers of clock cycles;

counting a number of clock cycles between the transmission of the measurement signal and the reception of the response signal;

calculating a coarse time estimate based on the number of clock cycles; and

calculating, based on the coarse time estimate and the time adjustment, a distance between the first radio device and the second radio device for determining a location of the second radio device.

44. A locating method for use by a first radio device in a locating system, the first radio device being configured to operate at a first clock frequency, the method comprising:

receiving from a second radio device a measurement signal including a first preamble;

performing synchronization with the first preamble;

detecting a plurality of skips during the performance of synchronization;

counting a plurality of numbers of clock cycles for the plurality of skips;

counting a number of clock cycles between the reception of the measurement signal and transmission of a response signal; and

transmitting to the second radio device the response signal, the response signal including a second preamble and a data payload including the plurality of numbers of clock cycles and the number of clock cycles, for the second radio device to determine a distance between the first radio device and the second device.

45. A computer-readable storage medium including instructions, executable by a processor, for instructing a first radio device to perform a locating method, the first radio device being configured to operate at a first clock frequency, the method comprising:

transmitting to a second radio device a measurement signal including a first preamble;

receiving from the second radio device a response signal including a second preamble;

performing synchronization with the second preamble;

detecting a plurality of skips during the performance of synchronization;

counting a plurality of numbers of clock cycles for the plurality of skips;

calculating a time adjustment based on the plurality of numbers of clock cycles;

counting a number of clock cycles between the transmission of the measurement signal and the reception of the response signal;

calculating a coarse time estimate based on the number of clock cycles; and

calculating, based on the coarse time estimate and the time adjustment, a distance between the first radio device and the second radio device for determining a location of the second radio device.

46. A computer-readable storage medium including instructions, executable by a processor, for instructing a first radio device to perform a locating method, the first radio device being configured to operate at a first clock frequency, the method comprising:

receiving from a second radio device a measurement signal including a first preamble;

performing synchronization with the first preamble;

detecting a plurality of skips during the performance of synchronization;

counting a plurality of numbers of clock cycles for the plurality of skips;

counting a number of clock cycles between the reception of the measurement signal and transmission of a response signal; and

transmitting to the second radio device the response signal, the response signal including a second preamble and a data payload including the plurality of numbers of clock cycles and the number of clock cycles, for the second radio device to determine a distance between the first radio device and the second device.