Positioning device, method of controlling positioning device, and recording medium having program for controlling positioning device recorded thereon

• US 20080018529A1
• Filed: 07/17/2007
• Published: 01/24/2008
• Est. Priority Date: 07/20/2006
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Yoshioka, Hiroki
• Granted Patent: US 7,898,474 B2
• Time in Patent Office: Days
• US Class Current: 342/357.01
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/42 Determining position

Abstract

A positioning device 20 receives a satellite signal from a satellite positioning system (SPS) satellite and locates a present position, the positioning device 20 including an azimuth calculation section which calculates an azimuth of the SPS satellite corresponding to the received satellite signal, and a reception environment determination section which determines a reception environment including a multipath environment based on the azimuths of the SPS satellites calculated by the azimuth calculation section.

Claims

1. A positioning device which receives a satellite signal from a satellite positioning system (SPS) satellite and locates a present position, the positioning device comprising:

an azimuth calculation section which calculates an azimuth of the SPS satellite corresponding to the received satellite signal; and

a reception environment determination section which determines a reception environment including a multipath environment based on the azimuths of the SPS satellites calculated by the azimuth calculation section.

2. The positioning device as defined in claim 1,

wherein the positioning device has a plurality of positioning modes which differ in operating signal strength;

and

wherein the reception environment determination section determines whether or not the SPS satellites are biased based on the number of the SPS satellites corresponding to the satellite signals received in each of the positioning modes.

3. The positioning device as defined in claim 1, wherein the reception environment determination section determines whether or not the SPS satellites are biased based on the azimuth of a strong signal satellite which is the SPS satellite corresponding to the satellite signal within a predetermined signal strength range.

4. The positioning device as defined in claim 3, wherein, the reception environment determination section determines that the SPS satellites are biased toward an angle of the center region when a first bias condition is satisfied whereby the number of the strong signal satellites located in a center region is almost equal to the number of the strong signal satellites located in adjacent regions adjacent to the center region in forming angular regions by equally dividing an angular range of 360 degrees into at least eight regions.

5. The positioning device as defined in claim 1, wherein the reception environment determination section calculates a center of gravity of a figure formed by connecting coordinates of each of the SPS satellites specified by an angle of elevation and the azimuth, calculates a vector from the positioning device toward the center of gravity, and determines that the SPS satellites are biased in the direction of the vector when a second bias condition is satisfied whereby magnitude of the vector is equal to or less than predetermined magnitude.

6. The positioning device as defined in claim 4,

wherein the positioning modes include a first positioning mode used under a strong electric field, and a second positioning mode used when a field intensity is weaker than that of the strong electric field;

wherein the weak electric field is classified into a first weak electric field and a second weak electric field specified by a field intensity higher than that of the first weak electric field; and

wherein the reception environment determination section determines whether or not the first bias condition or the second bias condition is satisfied when the number of the SPS satellites corresponding to the satellite signals received in the first positioning mode is almost equal to the number of the SPS satellites corresponding to the satellite signals received in the second positioning mode and having the second weak electric field.

7. The positioning device as defined in claim 4, wherein the reception environment determination section determines that the reception environment is a valley when the number of the SPS satellites corresponding to the satellite signals received in the first positioning mode is almost equal to the number of the SPS satellites corresponding to the satellite signals received in the second positioning mode and having the second weak electric field and the first bias condition or the second bias condition is not satisfied.

8. The positioning device as defined in claim 1, wherein the positioning device locates the position while excluding the SPS satellite in a direction opposite to a direction in which the SPS satellites are biased.

9. The positioning device as defined in claim 1, wherein, when the reception environment is a valley, the positioning device locates the position while excluding the SPS satellite in a predetermined low-angle-of-elevation range.

10. A positioning device which receives a satellite signal from a satellite positioning system (SPS) satellite and locates a present position, the positioning device comprising:

a positioning base value calculation section which calculates positioning base values including a phase and signal strength of the satellite signal based on the satellite signal;

a reception environment determination section which determines a reception environment of the satellite signal based on a reception state of the satellite signals from the SPS satellites; and

a positioning section which locates a position using the positioning base values based on the reception environment determined by the reception environment determination section.

11. The positioning device as defined in claim 10,

wherein the positioning device has a plurality of positioning modes which differ in operating signal strength;

and

wherein the reception environment determination section determines the reception environment based on the number of the SPS satellites corresponding to the satellite signals received in each of the positioning modes.

12. The positioning device as defined in claim 10, wherein the positioning section determines whether or not to exclude the positioning base values or correct the positioning base values based on the reception environment determined by the reception environment determination section.

13. The positioning device as defined in claim 12, wherein the positioning modes include a first positioning mode used under a strong electric field, and a second positioning mode used when a field intensity is weaker than that of the strong electric field.

14. The positioning device as defined in claim 13,

wherein the strong electric field is classified into a first strong electric field, a second strong electric field specified by a field intensity higher than that of the first strong electric field, and a third strong electric field specified by a field intensity higher than that of the second strong electric field;

wherein the weak electric field is classified into a first weak electric field and a second weak electric field specified by a field intensity higher than that of the first weak electric field; and

wherein the reception environment determination section determines that the reception environment is an OpenSky environment when the number of the SPS satellites corresponding to the satellite signals received in the first positioning mode and having the third strong electric field is equal to or larger than a predetermined number.

15. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is a semi-OpenSky environment when the SPS satellite corresponding to the satellite signal received in the first positioning mode and having the third strong electric field, the SPS satellite corresponding to the satellite signal received in the first positioning mode and having the second strong electric field, and the SPS satellite corresponding to the satellite signal received in the second positioning mode exist in combination.

16. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is a first multipath environment when the SPS satellite corresponding to the satellite signal received in the first positioning mode and having the first strong electric field, the SPS satellite corresponding to the satellite signal received in the first positioning mode and having the second strong electric field, and the SPS satellite corresponding to the satellite signal received in the second positioning mode exist in combination.

17. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is a bias environment when the SPS satellite corresponding to the satellite signal received in the first positioning mode and having the third strong electric field and the SPS satellite corresponding to the satellite signal received in the second positioning mode and having the second weak electric field exist in combination and constellation of the SPS satellites is biased.

18. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is a valley environment when the SPS satellite corresponding to the satellite signal received in the first positioning mode and having the third strong electric field and the SPS satellite corresponding to the satellite signal received in the second positioning mode and having the second weak electric field exist in combination and constellation of the SPS satellites is not biased.

19. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is a second multipath environment when the number of the SPS satellites corresponding to the satellite signals received in the second positioning mode is larger than the number of the SPS satellites corresponding to the satellite signals received in the first positioning mode.

20. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is a third multipath environment when the number of the SPS satellites corresponding to the satellite signals received in the first positioning mode is one.

21. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is the first weak electric field when only the SPS satellites corresponding to the satellite signals received in the second positioning mode and having the second weak electric field exist.

22. The positioning device as defined in claim 14, wherein the reception environment determination section determines that the reception environment is the second weak electric field when only the SPS satellites corresponding to the satellite signals received in the second positioning mode and having the first weak electric field exist.

23. A method of controlling a positioning device which receives a satellite signal from a satellite positioning system (SPS) satellite and locates a present position, the method comprising:

an azimuth calculation step of calculating an azimuth of the SPS satellite corresponding to the received satellite signal; and

a reception environment determination step of determining a reception environment including a multipath environment based on the calculated azimuths of the SPS satellites.

25. A computer-readable recording medium having recorded thereon a program for causing a computer included in a positioning device, which receives a satellite signal from a satellite positioning system (SPS) satellite and locates a present position, to execute the method as defined in claim 23.

24. A method of controlling a positioning device which receives a satellite signal from a satellite positioning system (SPS) satellite and locates a present position, the method comprising:

a positioning base value calculation step of calculating positioning base values including a phase and signal strength of the satellite signal based on the satellite signal;

a reception environment determination step of determining a reception environment of the satellite signal; and

a positioning step of locating a position using the positioning base values based on the determined reception environment.

26. A computer-readable recording medium having recorded thereon a program for causing a computer included in a positioning device, which receives a satellite signal from a satellite positioning system (SPS) satellite and locates a present position, to execute the method as defined in claim 24.