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

• US 6,900,753 B2
• Filed: 10/08/2003
• Issued: 05/31/2005
• Est. Priority Date: 06/27/2000
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kuwahara, Mikio, Doi, Nobukazu, Tsunehara, Katsuhiko, Ishifuji, Tomoaki
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/680,089
• Publication Number:
  US 20040066332A1
• Time in Patent Office: 601 Days
• Field of Search: 375130-153, 342 42- 59, 342/118, 342125-127, 342/175, 342195-197, 342450-465
• 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 section 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 mobile terminal in a terminal positioning system having a mobile terminal and a plurality of base stations, comprising:

a signal receiver for receiving at least a signal transmitted from one of said plurality of base stations;

a delay profile calculator for calculating a correlation value between the received signal and a predetermined code to generate a delay profile representing a correlation between said received signal and said predetermined code; and

a reference timing detector for determining a reference timing according to a value of said delay profile, wherein a received timing of said received signal is determined based on said reference timing, and a position of said mobile terminal is calculated using said received timing.

2. A mobile terminal according to claim 1, wherein said reference timing is a timing at which a correlation value of the delay profile starts up from noise level.

3. A mobile terminal according to claim 1, wherein said reference timing is determined as a timing when said calculated correlation value is equal to a threshold value.

4. A mobile terminal according to claim 1, wherein said received timing is determined as a timing which is later than said reference timing by a predetermined interval.

5. A mobile terminal according to claim 1, wherein said calculation of the position of the mobile terminal is performed in the mobile terminal.

6. A mobile terminal according to claim 1, wherein said reference timing is determined by comparing the delay profile with a noise level at said mobile terminal.

7. A terminal positioning method using received timings of signals transmitted between a plurality of base stations and a terminal, comprising the steps of:

a first step of calculating a correlation value between a received signal and a predetermined code to generate a delay profile representing a correlation between said received signal and said predetermined code;

a second step of determining a referenced timing according to said generated delay profile;

a third step of determining a received timing based on said reference timing; and

a fourth step of calculating a position of the terminal using said received timing relative to each of the plurality of base stations.

8. A terminal positioning method according to claim 7, wherein said reference timing is a timing at least whose correlation value of the delay profile starts up from noise level.

9. A terminal positioning method according to claim 7, wherein said reference timing is determined as a timing when said calculated correlation value is equal to a threshold value.

10. A terminal positioning method according to claim 7, wherein said received timing is determined as a timing which is later than said reference timing by a predetermined interval.

11. A terminal positioning method according to claim 7, wherein said reference timing is determined by comparing the delay profile with a noise level at said mobile terminal.

12. A position measuring apparatus for measuring a position of a mobile terminal using a transmitted signal, comprising:

a signal receiver for receiving a signal from a transmitting station;

a delay profile generator for generating a delay profile representing a correlation between said received signal and said predetermined code by comparing said received signal with a predetermined code;

a timing detector for detecting, based on said delay profile, a reference timing to be used for calculation of the position of said mobile terminal.

13. A position measuring apparatus according to claim 12, wherein said reference timing is a timing at which a correlation value of the delay profile starts up from noise level.

14. A position measuring apparatus according to claim 12, wherein said reference timing is determined as a timing when said calculated correlation value is equal to a threshold value.

15. A position measuring apparatus according to claim 12, wherein said received timing is determined as a timing which is later than said reference timing by a predetermined interval.

16. A position measuring apparatus according to claim 12, wherein said calculation of the position of the mobile terminal is performed in the mobile terminal.

17. A position measuring apparatus according to claim 12, wherein said reference timing is determined by comparing the delay profile with a noise level at said mobile terminal.