One way time of flight distance measurement

• US 9,383,436 B2
• Filed: 09/05/2014
• Issued: 07/05/2016
• Est. Priority Date: 01/18/2012
• Status: Active Grant

• Current Assignee: Humatics Corporation
• Original Assignee: TDC Acquisition Holdings, Inc (Humatics Corporation)
• Inventors: Dewberry, Brandon Scott, Pedersen, Gert Frlund, Eggers, Patrick Claus Friedrich
• Primary Examiner(s): Sotomayor, John B
• Assistant Examiner(s): WINDRICH, MARCUS E
• Application Number:
  US14/479,236
• Publication Number:
  US 20150029053A1
• Time in Patent Office: 669 Days
• Field of Search: 342/118, 342/127, 342/132, 342/134
• US Class Current: 1/1
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 11/08 using synchronised clocks

Abstract

Determination of distance and/or position relative to one or more points by transmission of a wideband signal by a first antenna, reception of the transmitted wideband signal by a second antenna and comparison of the time delay between the transmitted and received signals. The first and second antennas are connected to a timer/processor unit. One or more of the first or second antennas is movable to an unknown position to be measured, but maintains connection to the timer/processor through a fixed or known delay communication link. The timer/processor contains a time base for generating the transmitted signal and an offset timer for measuring the time delay of the received signal. The received signal may be processed to determine a start time or leading edge that may resolve RF cycle and modulation bandwidth ambiguities and may allow positive determination of distance much shorter than a wavelength at the operation center frequency.

Claims

1. A range monitoring system, the system comprising:

a first antenna configured to be located at a first location;

a second antenna configured to be located at a second location, the first antenna to be spaced from the second antenna;

and a transceiver, said transceiver comprising a co-located transmitter and receiver, said transceiver coupled to said first antenna through a first communication link and said transceiver coupled to said second antenna through a second communication link;

said first communication link adapted for maintaining a known or fixed time delay in the presence of relative motion of said first location relative to said second location;

said first communication link adapted for maintaining a known or fixed time delay in the presence of operative relative motion of said first antenna relative to said transceiver;

said transceiver configured for transmitting a transmitted wide band signal using said first antenna and receiving a received wide band signal responsive to said transmitted wide band signal using said second antenna, said transceiver configured to measure a first time difference between said transmitted wide band signal and said received wide band signal, said first time difference indicative of said range

wherein the first communication link is a flexible transmission line sufficiently flexible to allow said operative relative motion of said first antenna relative to said transceiver.

2. The range monitoring system in accordance with claim 1, wherein said transceiver comprises a correlation based scanning receiver configured to determine a leading edge of the received wide band signal to determine said first time difference.

3. The range monitoring system in accordance with claim 2, wherein said transceiver is operable to calculate a first range between said first location of the first antenna and said second location of the second antenna based on said first time difference between said transmitted wide band signal and said received wide band signal.

4. The range monitoring system in accordance with claim 3, wherein said transceiver is operable to calculate a reference range between said first location of the first antenna and said second location of the second antenna, and said transceiver is operable to calculate a range difference between said reference range and said first range.

5. The range monitoring system in accordance with claim 1, wherein said transceiver comprises electronics and said transceiver is configured to calculate a corrected time difference based on said first time difference and a known delay due to said electronics.

6. The range monitoring system in accordance with claim 1, wherein said transceiver is configured to calculate a corrected time difference based on said first time difference and a known delay due to said first communication link.

7. The range monitoring system in accordance with claim 1, wherein said first location and said second location are connected by a flexible member, said first range being responsive to flexing of said flexible member;

and wherein the system is configured to calculate said first range when both the first antenna and second antenna are capable of motion relative to said transceiver.

8. The range monitoring system in accordance with claim 1, wherein said transmitted wide band signal comprises a chirp or a swept sine wave.

9. The range monitoring system in accordance with claim 1, wherein the transceiver further comprises at least one additional receiver and at least one additional antenna connected to said at least one additional receiver;

said at least one additional receiver receiving said transmitted signal and computing a second time difference and a second range;

said system combining said first range and said second range using trilateration to determine a position of said first location.

10. The range monitoring system in accordance with claim 1, further including a wind power blade;

wherein said first antenna is positioned on the tip half of said wind power blade and said second antenna is positioned on the root half of said wind power blade.

11. The range monitoring system in accordance with claim 10, further including a wind power blade controller;

wherein said wind power blade controller is configured to control a pitch or angle of attack of said wind power blade based on said first time difference.

12. The range monitoring system in accordance with claim 1, wherein said transceiver is configured to determine a channel impulse response from said first antenna to said second antenna, and said transceiver is configured to determine said first time difference based on said channel impulse response.

13. The range monitoring system in accordance with claim 12, wherein said transceiver is configured to determine a leading edge based on said channel impulse response, and said transceiver determines said first time difference based on said leading edge.

14. The range monitoring system in accordance with claim 13, wherein the transceiver is configured to apply a scanning receiver scan window to monitor for determination of said leading edge.

15. The range monitoring system in accordance with claim 1, further including a wind blade structure, and wherein the first receiver is an impulse wideband receiver;

wherein a pulse repetition rate is low enough to allow decay of multipath from a tower structure to decay at least 10 dB before a subsequent pulse is received.

16. A method for range monitoring, the method comprising the steps of:

providing a first antenna at a first location;

providing a second antenna at a second location, the first antenna spaced from the second antenna;

said first antenna and said second antenna configured to allow a first operative motion between said first antenna and said second antenna;

providing a transmitter coupled to said first antenna through a first communication link;

said first communication link sufficiently flexible to allow a second operative motion between said first antenna and said transmitter;

providing a first receiver coupled to said second antenna through a second communication link;

said first receiver synchronized in time to said first transmitter based on a time synchronization signal from a common time base;

said first receiver comprising a processor;

said transmitter transmitting a transmitted signal from said transmitter through the first antenna;

said first receiver receiving a received signal through said second antenna responsive to said transmitted signal;

said first receiver measuring a reference time difference between said received signal and said transmitted signal;

said processor determining a reference time of flight of said transmitted signal for a known configuration of said first antenna and said second antenna based on said reference time difference;

said processor determining a first time of flight of said transmitted signal for an unknown configuration of said first antenna and said second antenna;

said processor determining a first change in time of flight of said transmitted signal for said unknown configuration by comparing said first time of flight and said reference time of flight; and

said processor calculating a first change of range between the first antenna and the second antenna based on said first change of time of flight of said signal transmitted from the first antenna;

wherein the first communication link comprises a flexible transmission line sufficiently flexible to allow said first operative motion and said second operative motion.

17. The method in accordance with claim 16, wherein the first receiver comprises a correlation based scanning receiver, further including the step:

said processor determining a leading edge of the received signal to determine said first of time of flight.

18. The method for range monitoring in accordance with claim 17, wherein the first receiver is configured to apply a scanning receiver scan window for said determination of said leading edge.

19. The method for range monitoring in accordance with claim 16, further including a flexible member connected between said first location and said second location, said first time of flight being responsive to flexing of said flexible member;

further including the step;

moving the first antenna and second antenna relative to said first receiver.

20. The method for range monitoring in accordance with claim 19, further including a second receiver and a third antenna connected to said second receiver;

said third antenna generating a second received signal responsive to said transmitted signal;

said second receiver computing a second time of flight based on said second received signal, and said second receiver computing a second change of range by comparing said second time of flight with a second reference time of flight;

said method further including step;

said processor combining said first change of range and said second change of range using trilateration to determine a change of position of said first antenna.

21. The method for range monitoring in accordance with claim 20, further including a wind power blade having said first antenna on a tip half of said wind power blade and having said second antenna on a root half of said wind power blade;

and the change of position is a relative position of said first antenna compared with a position of said second antenna.

22. The method for range monitoring in accordance with claim 21, further including a step:

said processor controlling a pitch or angle of attack of the wind power blade based on said relative position of said first antenna.

23. A lift sensor for controlling a wind power blade comprising:

a first antenna disposed at a first location on said wind power blade;

a second antenna disposed at a second location on said wind power blade, said second location spaced longitudinally along said wind power blade;

a transceiver coupled through a first communication link to said first antenna for transmitting a transmitted signal;

said transceiver configured to receive a received wideband signal responsive to said transmitted wideband signal;

said transceiver configured to determine a time of arrival of said received wideband signal relative to said transmitted wideband signal;

said transceiver configured to calculate a lift value based on said time of arrival.

24. The lift sensor in accordance with claim 23, wherein said transceiver is configured for

measuring a reflection arrival time of a reflection back along said first communication link to said transceiver;

said transceiver further configured for comparing said reflection arrival time with a reference reflection arrival time for said reflection to derive a correction time; and

said transceiver further configured for correcting said time of arrival based on said correction time.

25. The lift sensor in accordance with claim 24, wherein said transceiver comprises a reflection receiver and said reflection is coupled from said first communication link through a circulator to said reflection receiver for determination of said reflection arrival time.

26. The lift sensor in accordance with claim 25, wherein the first receiver comprises a correlation based scanning receiver, said first receiver configured for determining a leading edge of the received wideband signal to determine said time of arrival.

27. A method for sensing a lift value for a wind turbine blade comprising:

providing a transceiver comprising a processor;

said transceiver measuring a time of flight by comparing a transmitted time to a received time for a signal transmitted between a pair of antennas, at least one antenna of said pair of antennas disposed on a tip half of said wind turbine blade, said time of flight responsive to a bending of said wind turbine blade due to aerodynamic loading; and

said transceiver determining said lift value as a direct function of said time of flight.

28. The method in accordance with claim 27, wherein the determining step comprises:

said processor comparing said time of flight with a predetermined reference time of flight to generate a comparison value and determining said lift value based on said comparison value.

29. The method in accordance with claim 27, wherein at least one antenna of said pair of antennas is disposed toward a low pressure side of said wind turbine blade.

30. The method in accordance with claim 27, wherein the first receiver comprises a correlation based scanning receiver, further including the step:

said receiver determining a leading edge of the received signal to determine said time of flight.

31. The method for range monitoring in accordance with claim 30, wherein the first receiver is configured to apply a scanning receiver scan window for said determination of said leading edge.

32. The method for range monitoring in accordance with claim 31, wherein said transmitted signal comprises an ultra wideband signal.