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

• US 6,657,579 B2
• Filed: 06/11/2002
• Issued: 12/02/2003
• 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:
  US10/166,090
• Publication Number:
  US 20020149511A1
• Time in Patent Office: 539 Days
• Field of Search: 342/42, 342/43, 342/44, 342/45, 342/46, 342/47, 342/48, 342/49, 342/50, 342/51, 342/52-59, 342/118, 342/125, 342/126, 342/127, 342/175, 342/195, 342/196, 342/197, 342/450, 342/451-465, 455/456--45, 455/457, 375/130-153
• 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

Under a multi-path environment, receive timing for the incoming wave of the minimum propagation delay time cannot be accurately measured using the prior art. 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 position measuring method comprising the steps of:

a first step to calculate a correlation value between a received signal and a predetermined code;

a second step to detect a first timing at which the correlation value is equal to a predetermined threshold value; and

a third step to determine a second timing which is later than the first timing by a predetermined value as a receive timing of the received signal,

thereby measuring a receive position of the received signal on the basis of the receive timing of the received signal.

2. A position measuring method comprising:

a first step to calculate a correlation value between a received signal and a predetermined code;

a second step to detect a first timing at which the correlation value is equal to a first threshold value;

a third step to detect a second timing prior to the first timing and closest to the first timing among timings in which the correlation value becomes equal to a second threshold value; and

a fourth step to determine a timing which is later than the second timing by a predetermined value as the received signal;

wherein the first threshold value is higher than the second threshold value and a receive position of the received signal is measured on the basis of the receive timing of the received signal.

3. A position measuring apparatus using a received signal from a transmitting station comprising:

an antenna to receive the signal;

a delay profile calculation part to create a delay profile from the received signal by calculating a correlation value between a received signal and a predetermined code;

a first threshold value calculation part to calculate a first threshold value;

a second threshold value calculation part to calculate a second threshold value smaller than the first threshold value;

a first threshold value timing detection part receiving the first threshold value as an input, detecting a timing at which the value of the delay profile becomes equal to the first threshold value and outputting the timing;

a reference timing calculation part receiving the second threshold value as an input, detecting a second timing at which the value of the delay profile becomes equal to the second threshold value, the second timing being closest and prior to the timing inputted from the first threshold value timing detection part;

a receive timing calculation part to calculate the receive timing on the basis of the second timing; and

a position measuring part to measure position using the calculated receive timing.

4. A position measuring apparatus for measuring position using a transmitting station comprising:

an antenna to receive the signal;

a delay profile calculation part to calculate a delay profile from the received signal by calculating a correlation value between a received signal and a predetermined code;

a delay profile holding part to hold the calculated delay profile;

a first threshold value calculation part to calculate a first threshold value;

a second threshold value calculation part to calculate a second threshold value;

a first threshold timing detection part receiving the first threshold value as an input and detecting that the value of the delay profile becomes equal to the first threshold value;

a reference timing calculation part receiving the second threshold value as an input, detecting a second timing at which the value of the delay profile becomes equal to the second threshold value, the second timing being closest and prior to the timing inputted from the first threshold value timing detection part;

a receive timing calculation part to calculate the receive timing later than the second timing by a predetermined time; and

a position measuring part to determine position using the calculated receive timing.

5. A position measuring apparatus for measuring position using a transmitting station comprising:

an antenna to receive a signal;

a calculation part to calculate a correlation value between the received signal and a predetermined code;

a holding part to hold the calculated correlation value;

a first threshold value calculation part to calculate first threshold value;

a second threshold value calculation part to calculate a second threshold value;

a first threshold timing detection part receiving the first threshold value and the correlation value as inputs, and detect a first timing at which the correlation value reaches the first threshold value;

a second timing detection part receiving the second threshold value, the correlation value and the first timing as inputs, detecting a second timing at which the correlation value reaches the second threshold value prior to the timing; and

a receive timing calculation part receiving the second timing as an input and calculating the receive timing after the second timing.