DISTANCE MEASURING DEVICE

• US 20100207820A1
• Filed: 09/04/2007
• Published: 08/19/2010
• Est. Priority Date: 09/05/2006
• Status: Abandoned Application

• Current Assignee: Chugoku Electric Power Company Incorporated, Radio Communications System Inc.
• Original Assignee: Radio Communications System Inc.
• Inventors: Kawano, Hironori, Kawano, Minori, Takeuchi, Yasunori
• Application Number:
  US12/439,962
• Publication Number:
  US 20100207820A1
• Time in Patent Office: Days
• US Class Current: 342/393
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence

Abstract

Problems The present invention relates to a distance measuring device that measures the distance between a single signal transmitting means and a single signal receiving means with high accuracy by the signal transmitting means transmitting radio frequency signals.

Means for Solving the Problems A distance measuring device is comprised of a signal transmitting means (101), a signal receiving means (102) and a signal processing means (103). The signal transmitting means transmits radio frequency signals, the components of which are a plurality of measuring signals in synchronization with an output reference signal of a reference oscillator (7). The signal receiving means (102) generates a first local oscillating signal in synchronization with an output reference signal of a reference oscillator (34), mixes the first local oscillating signal with a received signal, converts the mixed signal to first intermediate signals with at least a plurality of different frequencies, mixes the first intermediate signals corresponding to the measuring signals with a plurality of second local oscillating signals with at least different frequencies in synchronization with or orthogonal to an output signal of a second mixer (35), and converts the mixed signal to a plurality of second intermediate signals. The signal processing means (103) detects a phase difference of the second intermediate signals and measures the distance between the signal transmitting means (101) and the signal receiving means (102) with high accuracy.

Claims

1-36. -36. (canceled)

37. A distance measuring device in a system that performs distance measurement using an ultrasonic signal, radio frequency signal or optical signal comprising:

a signal transmitting means that transmits an ultrasonic signal, radio frequency signal or optical signal containing a plurality of measuring signals that differ at least in frequency and are synchronized with or orthogonal to each other;

a signal receiving means that receives the ultrasonic signal, radio frequency signal or optical signal transmitted from said signal transmitting means, reproduces said plurality of measuring signals, and mixes or despread the plurality of reproduced signals with a plurality of local oscillating signals that differ at least in frequency and are synchronized with or orthogonal to each other to convert the plurality of reproduced signals into intermediate frequency signals, modulation signals or baseband signals having a common frequency; and

a signal processing means that processes said intermediate frequency signal, modulation signal or baseband signals output from said signal receiving means to achieve distance measurement,

wherein said signal processing means detects the frequency and/or phase of a first intermediate frequency signal, modulation signal or baseband signal corresponding to a first measuring signal serving as a reference, detects the frequency and/or phase of a second intermediate frequency signal, modulation signal or baseband signal corresponding to a second measuring signal that differs from the first measuring signal serving as a reference at least in frequency, and determine the distance between said signal transmitting means and said signal receiving means based on the result of the detections.

38. The distance measuring device according to claim 37, wherein said measuring signals are carrier signals, sub-carrier signals, spread spectrum codes, modulation signals and/or baseband signals.

39. The distance measuring device according to claim 37, wherein said signal processing means has a synchronous oscillator capable of controlling the frequency, phase and/or delay time, a synchronization establishing/retaining means that establishes and retains a synchronization between a clock signal output from said synchronous oscillator and said intermediate frequency signals, modulation signals or baseband signals, and a phase and frequency detector that detects the frequency and/or phase of said intermediate frequency signals, modulation signals or baseband signals with reference to the clock signal output from said synchronous oscillator, and

said synchronization establishing/retaining means controls said synchronous oscillator to establish a synchronization between the first intermediate frequency signal, modulation signal or baseband signal corresponding to the first measuring signal serving as a reference and the clock signal output from said synchronous oscillator, and the frequency and/or phase of said intermediate frequency signals, modulation signals or baseband signals is detected in a state where the synchronization between said first intermediate frequency signal, modulation signal or baseband signal and the clock signal is retained.

40. The distance measuring device according to claim 37, wherein the frequency, phase and/or delay time of a local oscillating signal oscillator in said signal receiving means can be controlled, and

said synchronization establishing/retaining means controls said local oscillating signal oscillator to establish a synchronization between said first intermediate frequency signal, modulation signal or baseband signal serving as a reference and a clock signal output from a clock oscillator having a fixed frequency, phase and/or delay time, and the frequency and/or phase of said second intermediate frequency signal, modulation signal or baseband signal is detected in a state where the synchronization between said first intermediate frequency signal, modulation signal or baseband signal and said clock signal is retained, and the distance between said signal transmitting means and said signal receiving means is determined based on the result of the detection.

41. The distance measuring device according to claim 37, wherein, in said signal receiving means, said plurality of reproduced measuring signals are mixed with a local oscillating signal having a fixed or semifixed frequency to convert the plurality of reproduced measuring signals into a plurality of intermediate frequency signals, modulation signals or baseband signals that differ at least in frequency,

the frequency, phase and/or delay time of the synchronous oscillator in said signal processing means can be controlled,

said synchronization establishing/retaining means controls said synchronous oscillator to establish a synchronization between said first intermediate frequency signal, modulation signal or baseband signal serving as a reference and a clock signal output from said synchronous oscillator, the frequency and/or phase of said first intermediate frequency signal, modulation signal or baseband signal is detected in a state where the synchronization between said first intermediate frequency signal, modulation signal or baseband signal and the clock signal is retained, the frequency of said clock signal is then multiplied or divided to convert the clock signal into a clock signal corresponding to said second intermediate frequency signal, modulation signal or baseband signal having a different frequency, the frequency and/or phase of said second intermediate frequency signal, modulation signal or baseband signal is detected with reference to said converted clock signal, and the distance between said signal transmitting means and said signal receiving means is determined based on the result of the detection.

42. The distance measuring device according to claim 37, wherein, in said signal receiving means, said plurality of reproduced measuring signals are mixed with a first local oscillating signal having a fixed or semi-fixed frequency to convert the plurality of reproduced measuring signals into a plurality of first intermediate frequency signals, modulation signals or baseband signals that differ at least in frequency,

the frequency, phase and/or delay time of a second local oscillating signal oscillator in said signal receiving means or signal processing means can be controlled,

said plurality of first intermediate frequency signals, modulation signals or baseband signals that differ at least in frequency are mixed with said second local oscillating signal to convert the plurality of first intermediate frequency signals, modulation signals or baseband signals into second intermediate frequency signals, modulation signals or baseband signals that are the same at least in frequency,

said signal processing means has a synchronous oscillator capable of controlling the frequency, phase and/or delay time, a synchronization establishing/retaining means that establishes and retains a synchronization between a clock signal output from said synchronous oscillator and said second intermediate frequency signals, modulation signals or baseband signals, and a phase and frequency detector that detects the frequency and/or phase of said second intermediate frequency signals, modulation signals or baseband signals with reference to the clock signal output from said synchronous oscillator, and

said synchronization establishing/retaining means controls said synchronous oscillator to establish a synchronization between a first second intermediate frequency signal, modulation signal or baseband signal corresponding to the first measuring signal serving as a reference and the clock signal output from said synchronous oscillator, and the frequency and/or phase of said second intermediate frequency signals, modulation signals or baseband signals is detected in a state where the synchronization between said first second intermediate frequency signal, modulation signal or baseband signal and the clock signal is retained.

43. The distance measuring device according to claim 37, wherein, in said signal receiving means, said plurality of reproduced measuring signals are mixed or modulated with a spread code output from a spread code oscillator the chip rate, phase and/or delay time of which can be controlled to convert the plurality of reproduced measuring signals into intermediate frequency signals, modulation signals or baseband signals having a common frequency, and

said synchronization establishing/retaining means controls said spread code oscillator to establish a synchronization between said reproduced first spread code serving as a reference and a spread code output from said spread code oscillator, the frequency and/or phase of said reproduced first spread code is detected in a state where the synchronization with said reproduced first spread code is retained, said spread code oscillator then oscillates a second spread code that is orthogonal to the first spread code and differs from the first spread code at least in chip rate, the frequency and/or phase of the reproduced second spread code is detected, and the distance between said signal transmitting means and said signal receiving means is determined based on the result of the detections.

44. The distance measuring device according to claim 37, wherein said signal transmitting means transmits said first measuring signal and said second measuring signal by changing the phase difference between the first measuring signal and the second measuring signal plurality of times, and said signal receiving means perform measurement in response to the plurality of times of changes of the phase difference between said first measuring signal and said second measuring signal, thereby improving the accuracy of distance measurement.

45. The distance measuring device according to claim 37, wherein the plurality of measuring signals generated in said signal transmitting means that differ at least in frequency and are synchronized with or orthogonal to each other are composed of a variable part and a fixed part, the plurality of local oscillating signals generated in said signal receiving means that differ at least in frequency and are synchronized with or orthogonal to each other are composed of a variable part and a fixed part, and at least the variable part of the measuring signals generated in said signal transmitting means and the variable part of the local oscillating signals generated in said signal receiving means are equal, similar or analogous to each other.

46. The distance measuring device according to claim 37, wherein a plurality of antennas or transceivers connected to said signal transmitting means and/or signal receiving means are periodically switched in response to said signal transmitting means generating the plurality of measuring signals that differ at least in frequency and are synchronized with or orthogonal to each other, thereby determining the distance and direction between said signal transmitting means and said signal receiving means.

47. The distance measuring device according to claim 37, wherein, in said signal transmitting means and/or signal receiving means, the plurality of measuring signals that differ at least in frequency and are synchronized with or orthogonal to each other are generated by using a particular frequency, phase, delay time and/or timing as a control start point, by using a fixed control start point and generating a plurality of spread codes or performing hopping between a plurality of frequencies, chirp modulation or frequency shift keying between a plurality of frequencies, or by using a fixed control start point and performing amplitude modulation, double side band modulation or single side band modulation with an arbitrary modulation signal or baseband signal.

48. The distance measuring device according to claim 37, wherein, during a plurality of generations of the plurality of measuring signals that differ at least in frequency and are synchronized with or orthogonal to each other, the intervals between the control start points corresponding to said plurality of measuring signals are equal to or integer multiples of each other, or the numbers of cycles of said plurality of measuring signals generated at intervals of said control start points are multiples of or equal to each other.

49. The distance measuring device according to claim 48, wherein said control start points are zero crossing points or particular points of the plurality of measuring signals, and activation or generation of a measuring signal is started in synchronization with the zero crossing point or particular point of the immediately preceding measuring signal, and the variation to a measuring signal from the immediately preceding signal is smooth and continuous.

50. The distance measuring device according to claim 37, wherein, in a case where the plurality of measuring signals synchronized with or orthogonal to the reference oscillator transmitted from said signal transmitting means are spread by a spread spectrum code, said plurality of measuring signals are reproduced by despreading or frequency multiplication.

51. The distance measuring device according to claim 37, wherein said signal transmitting means transmits an ultrasonic signal, radio frequency signal or optical signal modulated with a plurality of modulation signals or baseband signals that differ at least in frequency and are synchronized with or orthogonal to each other, and

said receiving means receives said ultrasonic signal, radio frequency signal or optical signal, demodulates said plurality of modulation signals or baseband signals, and mixes said plurality of demodulated modulation signals or baseband signals with a plurality of local oscillating signals that differ at least in frequency and are synchronized with or orthogonal to each other to convert the plurality of demodulated modulation signals or baseband signals into intermediate frequency signals having a common frequency.

52. The distance measuring device according to claim 37, wherein said local oscillating signal oscillator and/or synchronous oscillator starts oscillation from a particular frequency, phase and/or delay time, are set, reset or switched to a particular frequency, phase and/or delay time, or are synchronized with the frequency, phase and/or delay time of a particular signal at said control start points.

53. The distance measuring device according to claim 37, wherein said local oscillating signal oscillator, synchronous oscillator and/or spread code oscillator has a digital phase comparator or digital delay locked loop that detects the phase difference between the plurality of measuring signals as a digital signal and a digitally controlled oscillator capable of controlling the frequency, phase and/or delay time using said digital signal and is capable of establishing a synchronization between a plurality of signals input to said phase comparator or delay locked loop and retaining said synchronization.

54. The distance measuring device according to claim 53, wherein a register that sets the oscillation frequency and/or oscillation phase of a numerically controlled oscillator is set or reset at said control start points.

55. The distance measuring device according to claim 37, wherein, in said phase and frequency detector, the frequency and/or phase of said intermediate frequency signals, modulation signals or baseband signals is detected by converting said intermediate frequency signals, modulation signals or baseband signals into digital signals by an analog-to-digital converter and performing the multiply and accumulation operation of said digital signals using a sine look-up table using (0, 1, 0, −

1) as a base unit and a cosine look-up table using (1, 0, −

1,

     0) as a base unit.

56. The distance measuring device according to claim 37, wherein, in said phase and frequency detector, the frequency and/or phase of said intermediate frequency signals, modulation signals or baseband signals is detected by outputting I/Q signals by direct conversion of said intermediate frequency signals, modulation signals or baseband signals or achieving a zero beat and converting the I/Q signals into a digital signals by an analog-to-digital converter.

57. The distance measuring device according to claim 37, wherein, in said signal processing means, a window function is provided over a plurality of cycles of said intermediate frequency signals, modulation signals or baseband signals, and/or a plurality of clock signals serving as a reference are generated by branching, frequency division or frequency multiplication of clock signals output from a clock signal oscillator that correspond to said intermediate frequency signals, modulation signals or baseband signals, and the frequency and/or phase of said intermediate frequency signals, modulation signals or baseband signals is calculated in real time.

58. The distance measuring device according to claim 37, wherein said signal processing means has a statistical processing means that statistically processes the result of a plurality of measurements of the distance between said signal transmitting means and said signal receiving means and uses the statistical processing means to estimate a propagation path distribution of the ultrasonic signal, radio frequency signal or optical signal transmitted from said signal transmitting means or height pattern or multi-path occurrence and improve the accuracy of the distance measurement based on the result of the estimation.

59. The distance measuring device according to claim 58, wherein, in said statistical processing means, the distance from a particular signal transmitting means is measured successively a plurality of times or measured by switching between a plurality of antennas or transceivers, and said propagation path distribution or multi-path occurrence is estimated by comparing the distribution of the measurement results with a distance measurement distribution model.

60. The distance measuring device according to claim 58, wherein, in said statistical processing means, measurement of the distance from a particular signal transmitting means is performed successively a plurality of times and/or performed for each antenna of a particular signal transmitting means and/or signal receiving means, the accuracy of distance measurement can be improved by estimating a propagation path distribution of said distance measuring signals or multi-path occurrence, and/or a weighted average or moving average of relatively short distance measurement results is determined.

61. The distance measuring device according to claim 37, wherein the ultrasonic signal, high frequency signal or optical signal transmitted from said signal transmitting means contains an identification signal that allows identification of said signal transmitting means and/or information about said signal transmitting means.

62. The distance measuring device according to claim 37, wherein the plurality of measuring signals transmitted from said signal transmitting means are transmitted by being multiplexed and/or in a time-sharing manner.

63. The distance measuring device according to claim 37, wherein said signal transmitting means and said signal receiving means are installed at different heights, the difference in height is known, and the horizontal distance between said signal transmitting means and said signal receiving means is determined based on the result of measurement of the distance between said signal transmitting means and said signal receiving means.

64. The distance measuring device according to claim 37, wherein said signal receiving means has a plurality of antennas or transceivers and switching means that switches between the plurality of antennas or transceivers, and the direction of said signal receiving means and/or signal transmitting means, the direction of movement of said signal receiving means and/or signal transmitting means and/or the distance between said signal receiving means and said signal transmitting means is detected.

65. The distance measuring device according to claim 37, wherein said signal transmitting means is a base station in a mobile radio system, and said signal receiving means is a mobile terminal in the mobile radio system.

66. The distance measuring device according to claim 37, wherein said signal receiving means is a base station in a mobile radio system, and said signal transmitting means is a mobile terminal in the mobile radio system.

67. The distance measuring device according to claim 37, wherein said signal receiving means is fixed at a reference point or on a transit in a survey system, said signal transmitting means is installed at a standing point or on a pole, and the distance to the standing point or pole and the direction and/or height of the standing point or pole are measured.

68. The distance measuring device according to claim 37, wherein the signal receiving means are discretely installed at intervals, said signal transmitting means is attached to a mobile body, carried by a mobile body or fixed at an observation point, and the position or variation in position of said signal transmitting means is spotted.

69. The distance measuring device according to claim 37, wherein the signal transmitting means are discretely installed at intervals, said signal receiving means is attached to a mobile body, carried by a mobile body or fixed at an observation point, and the position or variation in position of said signal receiving means is spotted.

70. The distance measuring device according to claim 37, wherein said signal transmitting means and said signal receiving means are attached to or carried by the same mobile body or different mobile bodies.

71. The distance measuring device according to claim 37, wherein said signal transmitting means includes the signal receiving means and transmits the ultrasonic signal, high frequency signal or optical signal containing said plurality of carrier signals or sub-carrier signals that differ at least in frequency and are synchronized with or orthogonal to each other in response to receiving a transmission request transmitted from another signal transmitting means.

72. The distance measuring device according to claim 37, wherein distances are measured based on the plurality of signals received by said signal receiving means by changing the range stepwise from a long range to a short range by changing stepwise the variation in frequency or chip rate between the plurality of signals transmitted from said signal transmitting means.