Apparatus for high accuracy distance and velocity measurement and methods thereof

• US 7,202,941 B2
• Filed: 11/26/2003
• Issued: 04/10/2007
• Est. Priority Date: 11/26/2002
• Status: Expired due to Fees

• Current Assignee: James F. Munro
• Original Assignee: James F. Munro
• Inventors: Munro, James F.
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Ratcliffe; Luke D.
• Application Number:
  US10/722,889
• Publication Number:
  US 20040135992A1
• Time in Patent Office: 1,231 Days
• Field of Search: 356/5.01
• US Class Current: 356/5.01
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 7/483 Details of pulse systems

Abstract

A system and method for measuring a parameter of a target in accordance with embodiments of the present invention includes transmitting at least one signal towards a target and receiving at least a portion of the transmitted signal back from the target. The measured parameter is one of distance velocity, or reflectivity. The transmitted signal is of the coherent burst waveform, and upon reception is processed with equivalent time sampling, AGC with minimal, if any, error, and a discrete Fourier transform.

Claims

1. A method for measuring a parameter of a target, the method comprising:

transmitting at least one signal towards a target;

receiving at least one of a return signal sent in response to a detection of the transmitted signal at the target and at least a portion of the transmitted signal back from the target;

equivalent time sampling at two or more times of at least one portion of the received signal to obtain a sampled signal, wherein a time period between the times for sampling is greater than a period of the at least one transmitted signal;

determining a measured parameter based on at least one of an amplitude of the sampled signal and a phase of the sampled signal.

2. The method as set forth in claim 1 wherein the measured parameter is a distance to the target.

3. The method as set forth in claim 1 further comprising generating a signal for the transmitting.

4. The method as set forth in claim 3 further comprising filtering the generated signal, wherein the filtering generates a sinusoidal signal for the transmitting.

5. The method as set forth in claim 3 wherein generating a signal further comprises encoding data on the signal for transmitting.

6. The method as set forth in claim 1 wherein the transmitted signal is a coherent burst modulation waveform.

7. The method as set forth in claim 6 wherein the coherent burst modulation waveform has a power of less than about 5 mW.

8. The method as set forth in claim 7 wherein the coherent burst modulation waveform has an average power of less than about 1 mW.

9. The method as set forth in claim 1 further comprising amplifying and filtering the received portion of the transmitted signal back from the target.

10. The method as set forth in claim 1 wherein the sampling further comprises sampling multiple portions of the received signal and the determining further comprises determining the measured parameter based on an average of the phase differences between the transmitted signal and the sampled portions of the received signal.

11. The method as set forth in claim 10 wherein the sampled multiple portions of the received signal comprise at least twenty samples.

12. The method as set forth in claim 10 wherein the sampling multiple portions of the received signal is conducted in parallel and further comprising adjusting an amplitude of the multiple sampled portions of the received signal in parallel and convening the multiple, gain adjusted, sampled portions of the received signal to digital signals in parallel, wherein the determining a measured parameter is based on an average of the phase differences between the transmitted signal and the multiple sampled portions of the digital signals.

13. The method as set forth in claim 1 further comprising determining a phase offset from a baseline, wherein the measured parameter is based on the phase offset and the phase difference.

14. The method as set forth in claim 1 further comprising using a look-up table to correct for one or more errors in the measured parameter.

15. The method as set forth in claim 1 further comprising determining a refractive index of a medium in which the transmitted signal propagates, wherein the measured parameter is based on the refractive index of the medium and the phase difference.

16. The method as set forth in claim 15 wherein determining the refractive index further comprises obtaining a temperature reading and a pressure reading of the medium, wherein the refractive index is based on the temperature reading and the pressure reading.

17. The method as set forth in claim 1 wherein the transmitting further comprises adding a code on to the transmitted signal and further comprising preventing the determining a measured parameter until the received code on the received signal substantially matches the added code.

18. The method as set forth in claim 1 wherein the measured parameter is a distance to the target, the method further comprising:

comparing the measured distance against a threshold distance; and

providing a collision alert when the comparing indicates the measured distance is less than the threshold distance.

37. The method as set forth in claim 1 wherein the measured parameter is a distance to the target and the determining further comprises determining the distance based on the phase difference between the transmitted signal and the sampled signal.

38. The method as set forth in claim 1 wherein the measured parameter is a velocity of the target and the determining further comprises determining the velocity based on the phase difference between at least two of the sampled signals.

19. A system for measuring a parameter of a target, the system comprising:

a transmission system which transmits at least one signal towards a target;

a receiving system that receives at least one of a return signal sent in response to a detection of the transmitted signal at the target and at least a portion of the transmitted signal back from the target;

an equivalent time sampling system that at two or more times samples at least one portion of the received signal to obtain a sampled signal, wherein a time period between the times for sampling is greater than a period of the at least one transmitted signal; and

a parameter processing system that determines a measured parameter based on at least one of an amplitude of the sampled signal and a phase of the sampled signal.

20. The system as set forth in claim 19 wherein the measured parameter is a distance to the target.

21. The system as set forth in claim 19 further comprising a signal generator that generates a signal for the transmission system.

22. The system as set forth in claim 21 further comprising a filter that filters the generated signal and generates a sinusoidal signal for the transmission system.

23. The system as set forth in claim 21 wherein the signal generator further comprises a data encoder that encodes data on the signal for transmitting.

24. The system as set forth in claim 19 wherein the transmission system transmits a coherent burst modulation waveform as the transmitted signal.

25. The system as set forth in claim 19 wherein the coherent burst modulation waveform has a power of less than about 5 mW.

26. The system as set forth in claim 25 wherein the coherent burst modulation waveform has an average power of less than about 1 mW.

27. The system as set forth in claim 19 further comprising an amplifier that amplifies and filters the received portion of the transmitted signal back from the target.

28. The system as set forth in claim 19 wherein the sampling system samples multiple portions of the received signal and the parameter processing system determines the measured parameter based on an average of the phase differences between the transmitted signal and the sampled signals.

29. The system as set forth in claim 28 wherein the sampled multiple portions of the received signal comprise at least twenty samples.

30. The system as set forth in claim 28 wherein the sampling system samples the multiple portions of the received signal in parallel and further comprising a plurality of gain control systems that adjust an amplitude of each of the multiple sampled portions of the received signal in parallel and a plurality of analog-to-digital converters that convert the multiple sampled portions of the received signal to digital, wherein the parameter processing system determines the measured parameter based on an average of the phase differences between the transmitted signal and the multiple digital, gain adjusted, sampled portions of the received signal.

31. The system as set forth in claim 19 further comprising a calibration system that determines a phase offset from a baseline, wherein the parameter processing system determines the measured parameter is based on the phase offset and the phase difference.

32. The system as set forth in claim 19 wherein the parameter processing system further comprises a stored look-up table used to correct for one or more errors in the measured parameter.

33. The system as set forth in claim 19 further comprising a sensing system used in determining a refractive index of a medium in which the transmitted signal propagates, wherein the parameter processing system determines the measured parameter based on the refractive index of the medium and the phase difference.

34. The system as set forth in claim 33 wherein sensing system comprises:

at least one temperature sensor that obtains at least one temperature reading; and

at least one pressure sensor that obtains at least one pressure reading of the medium;

wherein the parameter processing system determines the refractive index based on the temperature reading and the pressure reading.

35. The system as set forth in claim 19 wherein the transmission system adds a code on to the transmitted signal and wherein the parameter processing system prevents the determination of the measured parameter until the received code on the received signal substantially matches the added code.

36. The system as set forth in claim 19 wherein the measured parameter is a distance to the target, the parameter processing system compares the measured distance against a threshold distance and provides a collision alert when the comparison indicates the measured distance is less than the threshold distance.

39. The system as set forth in claim 19 wherein the measured parameter is a distance to the target and the parameter processing system determines the distance based on the phase difference between the transmitted signal and the sampled signal.

40. A method for measuring the distance of a target, the method comprising:

transmitting at least one coherent burst signal towards a target;

receiving a portion of the transmitted signal back from the target;

equivalent time sampling at two or more times at least one portion of the received signal to obtain a sampled signal, wherein a time period between the times for sampling is greater than a period of the at least one coherent burst signal; and

determining the distance based on the sampled signal and a phase difference between the transmitted signal and the sampled signal.

41. The method as set forth in claim 40 further comprising generating a signal for the transmitting.

42. The method as set forth in claim 40 further comprising amplifying and filtering the received portion of the transmitted signal back from the target.

43. The method as set forth in claim 40 wherein the sampling further comprises sampling multiple portions of the received signal and the determining further comprises determining the distance based on an average of the phase differences between the transmitted signal and the sampled portions of the received signal.

44. The method as set forth in claim 40 further comprising using a discrete Fourier transform to determine the phase difference between the transmitted and received signal.

50. The method as set forth in claim 43 wherein the sampling multiple portions of the received signal is conducted in parallel and further comprising adjusting an amplitude of the multiple sampled portions of the received signal in parallel and converting the multiple, gain adjusted, sampled portions of the received signal to digital signals in parallel, wherein the determining a measured parameter is based on an average of the phase differences between the transmitted signal and the multiple sampled portions of the digital signals.

45. A system for measuring the distance of a target, the system comprising:

a transmission system which transmits at least one coherent burst signal towards a target;

a receiving system that receives a portion of the transmitted signal back from the target;

an equivalent time sampling system that samples at two or more times at least one portion of the received signal to obtain a sampled signal, wherein a time period between the times for sampling is greater than a period of the at least one coherent burst signal; and

a distance processing system that determines the distance based on the sampled signal and a phase difference between the transmitted signal and the sampled signal.

46. The system as set forth in claim 45 further comprising a signal generation system that generates a signal for the transmission system.

47. The system as set forth in claim 45 further comprising an amplification and filtering system that amplifies and filters the received portion of the transmitted signal back from the target.

48. The system as set forth in claim 45 wherein the sampling system samples multiple portions of the received signal and the distance processing system determines the distance based on an average of the phase differences between the transmitted signal and the sampled portions of the received signal.

49. The system as set forth in claim 45 wherein the distance processing system uses a discrete Fourier transform to determine the phase difference between the transmitted and received signal.

51. The system as set forth in claim 48 wherein the sampling system samples the multiple portions of the received signal in parallel and further comprising a plurality of gain control systems that adjust an amplitude of each of the multiple sampled portions of the received signal in parallel and a plurality of analog-to-digital converters that convert the multiple sampled portions of the received signal to digital, wherein the parameter processing system determines the measured parameter based on an average of the phase differences between the transmitted signal and the multiple digital, gain adjusted, sampled portions of the received signal.