Method for measuring distance and position using spread spectrum signal, and an equipment using the method

• US 7,969,347 B2
• Filed: 01/04/2010
• Issued: 06/28/2011
• Est. Priority Date: 06/27/2000
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kuwahara, Mikio, Tsunehara, Katsuhiko, Ishifuji, Tomoaki, Doi, Nobukazu
• Primary Examiner(s): Gregory; Bernarr E
• Application Number:
  US12/651,780
• Publication Number:
  US 20100103047A1
• Time in Patent Office: 540 Days
• Field of Search: 342 42- 59, 342/118, 342125-127, 342145-147, 342/175, 342195-197, 342450-465, 375130-153, 4554561-4566, 455/457, 455/403, 455/422.1
• US Class Current: 342/47
• CPC Class Codes: G01S 1/026 of associated receivers
• CPC Class Codes: G01S 1/045 Receivers
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04B 1/70755 Setting of lock conditions, e.g. threshold
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.

Claims

1. A position measuring device which measures a position of a signal transmitting device, comprising:

a delay profile calculating unit which creates a delay profile representing a correlation between a predetermined code and a signal which is received by a signal receiving device;

a received timing calculating unit which determines an incoming wave determination timing which is used to determine a reception of a particular incoming wave transmitted by said signal transmitting device in said signal receiving device and that is a point in time when a value of said delay profile becomes equal to a first threshold, determines a rising timing when said delay profile rises from a noise level and that is a point in time when each value of said delay profile becomes equal to a second threshold which is lower than said first threshold before said incoming wave determination timing, and determines each received timing when said signal receiving device receives said signal as to said incoming wave with reference to said rising timing; and

a position calculating unit which calculates each distance between a plurality of said signal receiving devices and said signal transmitting device on the basis of said received timing and measures said position of signal transmitting device from said distances.

2. The position measuring device according to claim 1,

wherein said first threshold value and said second threshold value are set on the basis of a maximum correlation value in said delay profile.

3. The position measuring device according to claim 2,

wherein said first threshold value is obtained by multiplying said maximum correlation value by a first predetermined coefficient, and

wherein said second threshold value is obtained by multiplying said maximum correlation value by a second predetermined coefficient.

4. The position measuring device according to claim 1,

wherein said first threshold value and said second threshold value are set on the basis of a noise value in said delay profile.

5. The position measuring device according to claim 4,

wherein said first threshold value is obtained by multiplying said noise value by a first predetermined coefficient, and

wherein said second threshold value is obtained by multiplying said noise value by a second predetermined coefficient.

6. The position measuring device according to claim 1,

wherein said received timing is delayed by a predetermined time behind said rising timing.

7. The position measuring device according to claim 1, wherein said position calculating unit calculates said distance on the basis of time difference between said received timing and a point of time when said signal transmitting device transmits said signal.

8. A position measuring method comprising the steps of:

creating delay profiles each representing a correlation between a predetermined code and each of signals which a plurality of signal receiving devices receive by calculating a correlation value between said predetermined code and each of said signals;

determining each incoming wave determination timing which is used to determine a reception, in each of said signal receiving devices, of a particular incoming wave transmitted by said signal transmitting device and that is a point in time when each value of said delay profiles becomes equal to a first threshold;

determining each rising timing when each of said delay profiles rises from a noise level and that is a point in time when each value of said delay profiles becomes equal to a second threshold which is lower than said first threshold before said incoming wave determination timing;

determining each received timing when each of said signal receiving devices receives said signal as to said incoming wave with reference to said rising timing;

calculating distances between each of said signal receiving devices and said signal transmitting device on the basis of said received timing; and

measuring said position of signal transmitting device from said distances.