POSITIONING APPARATUS

• US 20090289841A1
• Filed: 02/18/2005
• Published: 11/26/2009
• Est. Priority Date: 02/18/2005
• Status: Active Grant

• Current Assignee: Magellan Systems Japan, Inc., Mitsubishi Electric Corporation
• Original Assignee: Magellan Systems Japan, Inc., Mitsubishi Electric Corporation
• Inventors: Hirata, Seiichiro, Ueda, Fumio, Nakamoto, Takayoshi
• Granted Patent: US 7,764,227 B2
• Time in Patent Office: Days
• US Class Current: 342/357.690
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence

Abstract

A positioning apparatus includes a correlator 30 for calculating a correlation between the pseudo pattern code of each of satellites 1 and 2 and each of SPS signals associated with the satellites 1 and 2, and for outputting a correlation value indicating the correlation, sets up effective ranges δ1 and δ2 for the correlation values outputted from the correlator 30 on the basis of a pseudo distance PR1 between the satellite 1 and a SPS reference station 4, and a pseudo distance PR2 between the satellite 2 and the SPS reference station 4, and detects peak values which fall within the effective ranges δ1 and δ2, respectively. As a result, the positioning apparatus can determine the current position correctly even under a receiving environment in which the electric waves directly from the satellites 1 and 2 may become weak.

Claims

1. A positioning apparatus comprising:

a radio wave receiving means for receiving electric waves sent from satellites;

a correlation value output means for calculating correlations between pseudo pattern codes of said satellites and the electric waves received by said radio wave receiving means, and for outputting correlation values indicating the correlations;

a peak value detection means for setting up an effective range for each of the correlation values outputted from said correlation value output means on a basis of a pseudo distance between each of said satellites and a reference station, and for detecting a peak value which falls within the effective range; and

a positioning means for determining a current position from peak values detected by said peak value detection means.

2. The positioning apparatus according to claim 1, characterized in that said apparatus includes an information receiving means for receiving the pseudo distance between each of the satellites and the reference station from the reference station.

3. The positioning apparatus according to claim 1, characterized in that the peak value detection means compares each of the correlation values outputted from the correlation value output means with a predetermined threshold so as to detect, as the peak value, a correlation value which is larger than the threshold.

4. The positioning apparatus according to claim 3, characterized in that when two or more peak values exist within the effective range, the peak value detection means changes the threshold and detects a largest peak value from the two or more peak values.

5. The positioning apparatus according to claim 1, characterized in that when two or more peak values exist within the effective range, the peak value detection means selects a peak value which corresponds to a pseudo distance difference between the two or more satellites.

6. The positioning apparatus according to claim 5, characterized in that said apparatus includes an information receiving means for receiving the pseudo distance difference between the two or more satellites from the reference station.

7. The positioning apparatus according to claim 1, characterized in that said apparatus includes a change receiving means for receiving a change in the effective range set up by the peak value detection means.

8. The positioning apparatus according to claim 1, characterized in that the peak value detection means defines, as parameters, the pseudo distance between each of the satellites and the reference station, and a pseudo distance which is based on a detection candidate'"'"'s peak value, and substitutes them into an evaluation equation, changes the parameters until the evaluation equation is established, and detects the peak value which falls within the effective range.

9. The positioning apparatus according to claim 1, characterized in that the peak value detection means calculates a threshold from each of the correlation values outputted from the correlation value output means, and detects, as the peak value, a correlation value which is larger than the threshold.

10. The positioning apparatus according to claim 1, characterized in that the correlation value output means adds a received signal indicating an electric wave received by the radio wave receiving means for every period of each of the pseudo pattern codes, calculates a correlation between the received signal on which the addition process has been performed, and each of the pseudo pattern codes, and adds a correlation value indicating the correlation for every data modulation period.

11. The positioning apparatus according to claim 1, characterized in that when receiving an electric wave sent from a satellite, the radio wave receiving means detects a frequency error of the electric wave which is caused by a Doppler phenomenon and compensates for the frequency error of the electric wave.

12. The positioning apparatus according to claim 1, characterized in that when detecting the peak value which falls within the effective range, the peak value detection means detects the peak value in consideration of the current position which was determined for a last time by the positioning means.

13. A positioning apparatus comprising:

a radio wave receiving means for receiving electric waves sent from satellites;

a correlation value output means for calculating a correlation between each of pseudo pattern codes of said satellites and the electric waves received by said radio wave receiving means, and for outputting a correlation value indicating the correlation;

a peak value detection means for generating a correlation peak pattern on a basis of a pseudo distance between each of said satellites and a reference station, and for detecting a peak value which matches with the correlation peak pattern mostly from among peak values of the correlation values outputted from said correlation value output means; and

a positioning means for determining a current position from the peak value detected by said peak value detection means.

14. The positioning apparatus according to claim 13, characterized in that when detecting the peak value which matches with the correlation peak pattern mostly, the peak value detection means corrects the peak value using the peak values of the correlation values outputted from the correlation value output means, and values which are before and behind the peak values.