Method for determining a position, a positioning system, and an electronic device

• US 6,583,759 B2
• Filed: 08/31/2001
• Issued: 06/24/2003
• Est. Priority Date: 09/01/2000
• Status: Expired due to Term

• Current Assignee: HMD Global Oy
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Syrjarinne, Jari, Pietila, Samuli
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/944,853
• Publication Number:
  US 20020027525A1
• Time in Patent Office: 662 Days
• Field of Search: 342/357.15, 342/359, 701/213
• US Class Current: 342/357.67
• CPC Class Codes: G01S 19/28 Satellite selection

Abstract

The present invention relates to a method for selecting satellites (SV1-SV32) to be used for positioning in a positioning system. The positioning system comprises information on the orbits of the satellites (SV1-SV32). In the method, at least one satellite (SV1-SV32) to be searched for is selected at a time, and a searching step is performed to find out if the signal transmitted by at least one selected satellite (SV1-SV32) can be received. In the method, at least a first searching step and at least one continued selection step are performed, wherein in the continued selection step, at least one satellite (SV1-SV32) is selected at least partly on the basis of the findings of the previous searching step. The selection step is followed by the satellite searching step.

Claims

1. A method for selecting satellites, said satellites to be used for positioning in a positioning system which includes information on the orbits of the satellites, the method comprising the following steps:

performing at least a first selection step and one or more continued selection steps to select at least one selected satellite to be searched for, and

taking a searching step, after each of said first selection step and said one or more continued selection steps, to examine whether a signal transmitted by the at least one selected satellite is detected,

wherein, during the continued selection step, at least one satellite is selected based at least partly on a finding about detectability from the searching step taken previously.

2. The method according to claim 1, wherein in the continued step, the satellite to be searched is selected to be either:

in the direction of the satellite selected in the previous selection step, if the signal transmitted by the satellite selected in the previous selection step is detected, or

substantially on the opposite side of the earth in relation to the satellite searched for in the previous step, if the signal transmitted by the satellite selected in the previous selection step is not detected.

3. The method according to claim 1,

wherein a directional angle matrix is formed,

wherein an element in the directional angle matrix is formed,

wherein an element in the directional angle matrix indicates the directional angle between two satellites in a preferably earth centered coordinate system, and

wherein the values of the elements of said matrix are used in said selection steps for selecting the satellite to be searched next.

4. The method according to claim 3, wherein said directional angle matrix is formed of a set of directional angle vectors, in which one directional angle vector comprises the directional angles from one satellite.

5. A method according to claim 3, wherein said directional angle matrix is formed on the basis of orbit information of the satellites.

6. The method according to claim 5, wherein in the determination of the directional angles, orbit information of the satellites from a determined time span are used, on the basis of which the expected values of the directional angles are calculated.

7. The method according to claim 3, wherein on the basis of the directional angle matrix, a search tree is formed to select the satellite to be used in the selection steps.

8. The method according to claim 4,

wherein the values of the elements of the directional angle vectors are examined, and

wherein, if the signal transmitted by the satellite selected in the first selection step is detected, then the satellite selected in the first continued selection step has a corresponding element that is smallest in said directional angle vector, but otherwise the satellite selected in the first continued selection step has a corresponding element that is largest in said directional angle vector.

9. The method according to claim 1, further comprising sets of steps substantially similar to the method according to claim 1, wherein the sets of steps are performed iteratively until the number of satellites required for the positioning has been found.

10. The method of claim 1, wherein the information on the orbits is used for selection of satellites, to the extent of using angles between directional vectors of satellites.

11. An electronic device comprising:

a positioning receiver;

means for selecting satellites to be used for positioning in a positioning system which includes information on the orbits of the satellites;

means for selecting at least one satellite to be searched for; and

means for searching for at least one selected satellite by finding out if the signal transmitted by the selected satellite is detected,

wherein the electronic device further comprises means for performing at least a first selection step, and means for performing one or more continued selection steps,

wherein the electronic device is arranged to perform a searching step after each of said first selection step and said one or more continued selection steps to examine whether the signal transmitted by at least one selected satellite is detected,

wherein during the continued selection step, the selection of at least one satellite is arranged to be performed at least partly based on a finding about detectability in the searching step previously taken.

12. The electronic device according to claim 11, wherein the electronic device comprises a directional angle matrix, in which an element in the matrix indicates the directional angle between two satellites in a preferably earth centered coordinate system, and wherein the electronic device comprises means for using the values of the elements of said matrix in said selection steps for selecting the satellite to be searched next.

13. The electronic device according to claim 12, wherein said directional angle matrix is formed of a set of directional angle vectors, in which one directional angle vector comprises the directional angles from one satellite to the other satellites.

14. The electronic device according to claim 12, wherein a said directional angle matrix is formed on the basis of orbit information of the satellites.

15. The electronic device according to claim 14, wherein in the determination of the directional angles, orbit information on the satellites from a determined time span are used, on the basis of which the expected values of the directional angles are calculated.

16. The electronic device according to claim 11, wherein the electronic device comprises means for iterating said continued selection steps until the number of required for the positioning is found.

17. The electronic device according to claim 12, wherein on the basis of the directional angle matrix, a search tree is formed, and wherein the electronic device comprises means for using the search tree to select the satellite to be used in the selection steps.

18. A positioning system comprising:

a positioning receiver;

means for selecting the satellites to be used for positioning;

information on the orbits of the satellites;

means for selecting at least one satellite to be searched; and

means for searching at least one selected satellite by finding out if the signal transmitted by the selected satellite is detected,

wherein the positioning system further comprises means for performing at least a first selection step, and means for performing one or more continued selection steps,

wherein the searching means is arranged to perform a searching step, after each of said first selection step and said one or more continued selection steps, to examine whether the signal transmitted by at least one selected satellite is detected,

wherein the selection means is arranged to select, during the continued selection step, at least one satellite that is selected at least partly based on a finding about detectability in the searching step previously taken.