SATELLITE SEARCH METHOD AND RECEIVER USING THE SAME

• US 20090135063A1
• Filed: 01/21/2009
• Published: 05/28/2009
• Est. Priority Date: 03/28/2006
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Chen, Kun-tso
• Granted Patent: US 7,839,332 B2
• Time in Patent Office: Days
• US Class Current: 342/357.310
• CPC Class Codes: G01S 19/28 Satellite selection

Abstract

A satellite time dynamic search method and a receiver implementing such a method are disclosed. In the present invention, a predetermined period of time is sampled into multiple time samples. The time samples are sieved according to a search result of a satellite selected from candidate satellites each time. By repeatedly doing so, the finally remaining time sample will approach a true satellite system time, and accordingly the candidate satellites converge to the most possible ones as to facilitate satellite search.

Claims

1. A satellite search method comprising steps of:

(a) providing a candidate satellite list containing a plurality of satellites;

(b) calculating mean visibility of each satellite listed in the candidate satellite list for possible time samples in view of an observation location;

(c) selecting a satellite from the candidate satellite list according to the mean visibility of each satellite listed in the candidate satellite list;

(d) searching the selected satellite to obtain a search result;

(e) eliminating at least one time sample from the possible time samples according to the search result; and

(f) repeating steps (b) to (e).

2. The method of claim 1, wherein a satellite with the maximum mean visibility is selected from the candidate satellite list in step (c).

3. The method of claim 1, wherein each time sample that the searched satellite is not visible is eliminated in step (e) if the search result indicates that the searched satellite is acquired.

4. The method of claim 1, wherein each time sample that the searched satellite is visible is eliminated in step (e) if the search result indicates that the searched satellite is unacquired.

5. The method of claim 1, further comprising:

(dl) verifying the search result after step (d) if the obtained search result indicates that the searched satellite is unacquired to make sure that the searched satellite is really unacquired.

6. The method of claim 5, wherein an integration interval for correlation is extended and then correlation of the satellite signal with the code is executed again using the extended integration interval to search the satellite in step (dl).

7. The method of claim 1, further comprising removing one satellite from the candidate satellite list once it has been searched to update the candidate satellite list.

8. The method of claim 1, further comprising removing one satellite from the candidate satellite list once it has been acquired to update the candidate satellite list.

9. The method of claim 1, further comprising repeating step (f) until a predetermined number of satellites have been acquired.

10. The method of claim 1, further comprising repeating step (f) until the candidate satellite list becomes empty.

11. A receiver for receiving and processing satellite signals to conduct a satellite search, the receiver comprising:

a correlation block for correlating the satellite signals with a code of a satellite so as to search the satellite; and

a navigation processor for controlling the correlation block,

wherein the navigation processor provides a candidate satellite list containing a plurality of satellites, calculates mean visibility of each satellite listed in the candidate satellite list for possible time samples in view of an observation location, instructs the correlation block to search a satellite which is selected according to the mean visibility of each satellite to obtain a search result, and eliminates at least one time sample from the possible time samples according to the search result.

12. The receiver of claim 11, wherein the navigation processor selects a satellite with the maximum mean visibility from the candidate satellite list to search.

13. The receiver of claim 11, wherein the navigation processor eliminates each time sample that the searched satellite is not visible if the search result indicates that the searched satellite is acquired.

14. The receiver of claim 11, wherein the navigation processor eliminates each time sample that the searched satellite is visible if the search result indicates that the searched satellite is unacquired.

15. The receiver of claim 11, wherein the navigation processor further instructs the correlation block to verify the search result if the obtained search result indicates that the searched satellite is unacquired to make sure that the searched satellite is really unacquired.

16. The receiver of claim 15, wherein the navigation extends an integration interval for correlation and then instructs the correlation block to execute correlation of the satellite signal with the code again using the extended integration interval to search the satellite so as to verify the search result.

17. The receiver of claim 11, wherein the navigation processor removes a satellite from the candidate satellite list once the satellite has been searched to update the candidate satellite list.

18. The receiver of claim 11, wherein the navigation processor removes a satellite from the candidate satellite list once the satellite has been acquired to update the candidate satellite list.

19. The receiver of claim 11, wherein the navigation processor instructs to stop satellite search when a predetermined number of satellites have been acquired.

20. The receiver of claim 11, wherein the navigation processor instructs to stop satellite search when the candidate satellite list becomes empty.