System and method for fast initialization of navigational satellite signal receivers

• US 20060250304A1
• Filed: 05/06/2005
• Published: 11/09/2006
• Est. Priority Date: 05/06/2005
• Status: Active Grant

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Wang, Chi-Shin, Han, Shaowei, Wang, Hansheng, Mo, Jun, Shridhara, Kudrethaya A.
• Granted Patent: US 7,324,045 B2
• Time in Patent Office: Days
• US Class Current: 342/357.670
• CPC Class Codes: G01S 19/28 Satellite selection

Abstract

The present invention provides a method and apparatus for a satellite navigation receiver to lock onto satellite signals in the cold start mode with no information on the receiver position, the satellite position, or time estimates stored in the receiver'"'"'s memory. All satellites in a positioning system are divided into groups based on the satellite constellation structure. In an embodiment, the positioning system is the Global Positioning System (GPS) and all GPS satellites are divided into three groups. During initialization of the receiver, the satellites are searched per group to lock onto at least one satellite signal. Other satellites are then searched in a given order based on their respective distance or proximity to the first satellite acquired. This method reduces the Time-to-First-Fix (TTFF) ordinarily required by conventional receivers in the cold start mode.

Claims

1. A method of reducing initialization time of a satellite signal receiver in cold start mode, comprising the steps of:

dividing navigational satellites of a positioning system into a plurality of groups such that each group has a fixed number of said navigational satellites uniformly distributed over entire surface of Earth; and

configuring said receiver such that in said cold start mode said receiver searches for navigational satellites per group in an assigned order to acquire a first satellite.

2. The method of claim 1, wherein

said groups comprises a first group, a second group, and a third group.

3. The method of claim 2, wherein

said first group and said second group each has 12 navigational satellites.

4. The method of claim 1, further comprising the step of:

selecting two navigational satellites from each orbit plane.

5. The method of claim 1, further comprising the step of:

generating a two-dimensional (2D) matrix based on slot and plane of each of said navigational satellites;

wherein

each row of said matrix contains unique identifiers of said navigational satellites;

wherein

each row has a target satellite; and

wherein

each row is sorted by distance or proximity of each remaining navigational satellite in relation to said target satellite.

6. The method of claim 5, wherein

each of said unique identifiers is a pseudo random noise (PRN) number uniquely identifying one of said navigational satellites.

7. The method of claim 5, further comprising the step of:

determining said distance or proximity based on statistics of positions of said navigational satellites within an orbital period.

8. The method of claim 7, wherein

said orbital period is 11 hours 58 minutes.

9. The method of claim 5, further comprising the step of:

selecting twelve of said navigational satellites from said matrix after said first satellite is acquired in said cold start mode.

10. The method of claim 5, further comprising the step of:

comparing each target satellite with said first satellite;

locating a target satellite whose unique identifier matches that of said first satellite; and

selecting first twelve navigational satellites from a row containing said matched unique identifier.

11. The method of claim 10, further comprising the step of:

searching navigational satellites that follow said first twelve navigational satellites and that are within said row.

12. The method of claim 10, wherein

said positioning system is a global positioning (GPS), Global'"'"'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS), an European satellite navigation system (GALILEO) system, or a combination thereof.

13. An apparatus implementing the method steps of claim 1, comprising said receiver.

14. A method of initializing a satellite signal receiver in cold start mode, comprising the steps of:

searching a first group of twelve navigational satellites uniformly distributed over entire surface of Earth;

acquiring a first navigational satellite from said first group; and

acquiring remaining navigational satellites in said cold start mode based on a two-dimensional matrix containing identification and statistical information of all navigational satellites of a positioning system.

15. The method of claim 14, wherein

each row of said matrix contains unique identifiers of said navigational satellites;

each row has a target satellite; and

each row is sorted by distance or proximity of each non-target navigational satellite in relation to said target satellite.

16. The method of claim 15, wherein

each of said unique identifiers is a pseudo random noise (PRN) number uniquely identifying one of said navigational satellites.

17. The method of claim 14, wherein

said distance or proximity is determined based on statistics of positions of said navigational satellites during an orbital period.

18. The method of claim 17, wherein

said orbital period is 11 hours 58 minutes.

19. The method of claim 14, in which no navigational satellite is acquired from said first group, further comprising the step of:

searching a second group of twelve navigational satellites uniformly distributed over entire surface of Earth; and

acquiring said first navigational satellite in said cold start mode from said second group.

20. The method of claim 14, wherein

said positioning system is a global positioning (GPS), Global'"'"'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS), an European satellite navigation system (GALILEO) system, or a combination thereof.