Distance and Velocity Measurements Using Carrier Signals

1. A measurement method, the method comprising: transmitting a first signal from an originator device to a transponder device, the first signal having a first carrier frequency; determining a carrier phase of the first signal at the transponder device; transmitting a second signal from the transponder device to the originator device, the second signal having a second carrier frequency; determining a carrier phase of the second signal at the originator device; and estimating a distance between the originator device and the transponder device using the carrier phase of the first carrier signal and the carrier phase of the second carrier signal, wherein estimating the distance between the originator device and the transponder device further comprises calculating a wavelength ambiguity factor and using the wavelength ambiguity factor to estimate the distance.

2. The measurement method of claim 1 , further comprising: using a frequency difference between the first carrier frequency and the second carrier frequency to estimate the distance between the originator device and the transponder device.

3. The measurement method of claim 1 , wherein the carrier phase of the first signal is determined at a predetermined part within the first signal; and the carrier phase of the second signal is determined at a predetermined part within the second signal.

4. The measurement method of claim 3 , wherein the predetermined part within the first signal corresponds to a synchronization word of the first signal; and the predetermined part within the second signal corresponds to a synchronization word of the second signal.

5. The measurement method of claim 1 , wherein the carrier phase of the first signal is determined by calculating the arctangent of a quadrature channel over an in-phase channel at the transponder device; and the carrier phase of the second signal is determined by calculating the arctangent of a quadrature channel over an in-phase channel at the originator device.

6. The measurement method of claim 1 , wherein the carrier phase of the first signal is determined by calculating a first instantaneous phase of a received IQ constellation of the first signal with respect to a local oscillator phase at the transponder device; and the carrier phase of the second signal is determined by calculating a second instantaneous phase of the received IQ constellation of the first signal with respect to the local oscillator phase at the originator device.

7. The measurement method of claim 1 , wherein calculating the wavelength ambiguity factor comprises: performing a round-trip time-of-flight measurement between the originator device and the transponder device.

8. The measurement method of claim 1 , wherein estimating the distance between the originator device and the transponder device further comprises: determining a relative distance based on the carrier phase of the first carrier signal and the carrier phase of the second carrier signal; and adding a distance representing the wavelength ambiguity factor to the relative distance.

9. The measurement method of claim 8 , further comprising: using a frequency difference between the first carrier frequency and the second carrier frequency to determine the relative distance.

10. The measurement method of claim 1 , further comprising: using the estimated distance as an input to a tracking filter; and estimating a position of at least one of the transponder device and the originator device using the tracking filter.

11. The measurement method of claim 1 , further comprising: estimating a rate of change of the distance between the originator device and the transponder device; and estimating a new distance between the originator device and the transponder device using the rate of change and the estimate of the distance.

12. A measurement system, comprising: an originator device including a first radio, the first radio being configured to transmit a first signal to a transponder device, the first signal having a first carrier frequency; the transponder device including a second radio, the second radio being configured to transmit a second signal to the originator device, the second signal having a second carrier frequency; the transponder device being configured to determine a carrier phase of the first signal at the transponder device; the originator device being configured to determine a carrier phase of the second signal at the originator device; and at least one processor configured to estimate a distance between the originator device and the transponder device using the carrier phase of the first signal at the transponder device and the carrier phase of the second signal at the originator device, acid a frequency difference between the first carrier frequency and the second carrier frequency, wherein the at least one processor is further configured to calculate a wavelength ambiguity factor and use the wavelength ambiguity factor to estimate the distance.

13. The measurement system of claim 12 , wherein the at least one processor is further configured to use a frequency difference between the first carrier frequency and the second carrier frequency to estimate the distance between the originator device and the transponder device.

14. The measurement system of claim 12 , wherein the transponder device is configured to determine the carrier phase of the first signal at a predetermined part within the first signal; and the originator device is configured to determine the carrier phase of the second signal at a predetermined part within the second signal.

15. The measurement system of claim 14 , wherein the predetermined part within the first signal corresponds to a synchronization word of the first signal; and the predetermined part within the second signal corresponds to a synchronization word of the second signal.

16. The measurement system of claim 12 , wherein the transponder device is further configured to determine the carrier phase of the first signal by calculating the arctangent of a quadrature channel over an in-phase channel at the transponder device; and the originator device is further configured to calculate the carrier phase of the second signal by calculating the arctangent of a quadrature channel over an in-phase channel at the originator device.

17. The measurement system of claim 12 , wherein the at least one processor is further configured to calculate the wavelength ambiguity factor by calculating a round-trip time-of-flight distance between the originator device and the transponder device.

18. The measurement system of claim 12 , wherein the at least one processor is further configured to estimate the distance between the originator device and the transponder device by determining a relative distance based on the carrier phase of the first carrier signal and the carrier phase of the second carrier signal; and adding a distance representing the wavelength ambiguity factor to the relative distance.

19. The measurement system of claim 18 , processor is further configured to estimate the distance between the originator device and the transponder device by using a frequency difference between the first carrier frequency and the second carrier frequency to determine the relative distance.

20. The measurement system of claim 12 , wherein the at least one processor is further configured to use the estimated distance as an input to a tracking filter; and estimate a position of at least one of the transponder device and the originator device using the tracking filter.

21. The measurement system of claim 12 , wherein the at least one processor is further configured to estimate a rate of change of the distance between the originator device and the transponder device; and estimate a new distance between the originator device and the transponder device using the rate of change and the estimate of the distance.

22. A method for determining a relative velocity between a plurality of objects, the method comprising: determining a rate of change of a first carrier phase at a transponder device, the first carrier phase corresponding to a first signal transmitted from an originator device to the transponder device; determining a rate of change of a second carrier phase at the originator device, the second carrier phase corresponding to a second signal transmitted from the transponder device to the originator device; determining a relative motion between the originator device and the transponder device based on the rate of change of the first carrier phase and the rate of change of the second carrier phase; and determining a frequency offset between the first signal and the second signal based on the rate of change of the second carrier phase and a carrier frequency of the second signal.

23. The method of claim 22 , further comprising: determining a frequency offset between the first signal and the second signal based on the rate of change of the first carrier phase and the rate of change of the second carrier phase.

24. The method of claim 23 , further comprising: using the frequency offset as part of the determining the relative motion between the originator device and the transponder device.

25. The method of claim 22 , further comprising: using the frequency offset as part of the determining the relative motion between the originator device and the transponder device.

26. The method of claim 22 , wherein determining the rate of change of the first carrier phase comprises determining a plurality of carrier phases of the first signal and calculating a rate of change of the plurality of carrier phases of the first signal; and determining the rate of change of the second carrier phase comprises determining a plurality of carrier phases of the second signal and calculating a rate of change of the plurality of carrier phases of the second signal.

27. The method of claim 26 , wherein the determining a plurality of carrier phases of the first signal includes determining the carrier phases of at least part of a first data packet transmitted from the originator device to the transponder device, and the determining a plurality of carrier phases of the second signal includes determining the carrier phases of at least part of a second data packet transmitted from the transponder device to the originator device.

28. The method of claim 27 , wherein the at least part of the first data packet corresponds to a preamble of the first data packet, and the at least part of the second data packet corresponds to a preamble of the second data packet.

29. The method of claim 22 , further comprising: estimating a distance between the originator device and the transponder device based on the determined relative motion between the originator device and the transponder device.

30. The method of claim 22 , further comprising: using the determined relative motion as an input to a tracking filter; and updating an estimate of a position of at least one of the originator device and the transponder device using the tracking filter.

31. A method for determining a relative velocity between a plurality of objects, the method comprising: determining a plurality of distances between an originator device and a transponder device at a plurality of times; and determining a relative motion between the originator device and the transponder device based on the plurality of distances, wherein determining the plurality of distances includes: determining a first transponder carrier phase at the transponder device, the first transponder carrier phase corresponding to a first measurement signal transmitted from the originator device to the transponder device, determining a first originator carrier phase at the originator device, the first originator carrier phase corresponding to a first response signal transmitted from the transponder device to the originator device in response to the first measurement signal, estimating a first distance between the originator device and the transponder device using the first transponder carrier phase and the first originator carrier phase, determining a second transponder carrier phase at the transponder device, the second transponder carrier phase corresponding to a second measurement signal transmitted from originator device to the transponder device, determining a second originator carrier phase at the originator device, the second originator carrier phase corresponding to a second response signal transmitted from the transponder device to the originator device in response to the second measurement signal, estimating a second distance between the originator device and the transponder device using the second transponder carrier phase and the second ode motor carrier phase at the originator device, and wherein determining the relative motion between transponder radio and the originator radio includes determining a relative velocity between the originator device and the transponder device using the first distance and the second distance.

32. The method of claim 31 , further comprising: using a frequency difference between a carrier frequency of the first measurement signal and a carrier frequency of the first response signal to estimate the first distance.

33. The method of claim 32 , wherein determining the plurality of distances further includes: estimating the second distance between the originator device and the transponder device using the second transponder carrier phase, the second originator carrier phase at the originator device, and a frequency difference between a carrier frequency of the second measurement signal and a carrier frequency of the second response signal.

34. The method of claim 31 , further comprising: estimating a distance between the originator device and the transponder device based on the determined relative motion between the originator device and the transponder device.

35. The method of claim 31 , further comprising: using the determined relative motion as an input to a tracking filter; and updating an estimate of a position of at least one of the originator device and the transponder device using the tracking filter.

36. A measurement method, the method comprising: determining a rate of change of a first carrier phase at a transponder device, the first carrier phase corresponding to a first signal transmitted from an originator device to the transponder device; determining a rate of change of a second carrier phase at the originator device, the second carrier phase corresponding to a second signal transmitted from the transponder device to the originator device; and determining a frequency offset between the first signal and the second signal based on the rate of change of the first carrier phase and the rate of change of the second carrier phase, wherein determining the frequency offset comprises determining a difference between the rate of change of the first carrier phase and the rate of change of the second carrier phase.

37. The measurement method of claim 36 , further comprising: using the frequency offset to determine a relative motion between the originator device and the transponder device.

38. The measurement method of claim 36 , further comprising: using the frequency offset to estimate a distance between the originator device and the transponder device.

39. The measurement method of claim 36 , wherein the first carrier phase is determined at a predetermined part within the first signal; and the second carrier phase is determined at a predetermined part within the second signal.

40. The measurement method of claim 36 , wherein determining the rate of change of the first carrier phase comprises determining a plurality of carrier phases of the first signal and calculating a rate of change of the plurality of carrier phases of the first signal; and determining the rate of change of the second carrier phase comprises determining a plurality of carrier phases of the second signal and calculating a rate of change of the plurality of carrier phases of the second signal.

41. The method of claim 40 , wherein the determining a plurality of carrier phases of the first signal includes determining the carrier phases of at least part of a first data packet transmitted from the originator device to the transponder device, and the determining a plurality of carrier phases of the second signal includes determining the carrier phases of at least part of a second data packet transmitted from the transponder device to the originator device.