METHOD AND APPARATUS FOR COLLECTING SUBFRAMES OF SATELLITE NAVIGATION DATA

• US 20100045527A1
• Filed: 11/03/2009
• Published: 02/25/2010
• Est. Priority Date: 01/05/2007
• Status: Abandoned Application

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Huang, Kung-shuan, Li, Kuan-i, Chen, Kun-tso
• Application Number:
  US12/611,361
• Publication Number:
  US 20100045527A1
• Time in Patent Office: Days
• US Class Current: 342/357.640
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence

Abstract

A method and apparatus for collecting subframes of navigation data of satellites are disclosed. In the method of the present invention, the subframe is divided into several sub-units, each sub-units includes one or more words. When a receiver receives a subframe with a subframe ID, the respective required sub-units of the subframe are checked. A dummy sub-unit is not necessary to be considered. Valid ones of the required sub-units are collected. If not all the required sub-units of the subframe have been collected, the absent sub-units are to be collected when the next subframe with the same subframe ID is received. Some protection schemes can be applied to raise the reliability of such sub-unit collection. Especially when the signal is weak or unstable, the present invention may significantly improve the TTFF (Time To First Fix) performance of the receiver.

Claims

1. A method for receiving subframes of navigation data of a satellite, and said subframes including a plurality of sub-units, the method comprising steps of:

receiving GNSS signals with subframes of navigation data;

checking if the sub-units of respective subframes are valid; and

collecting at least one required sub-units to obtain navigation data.

2. The method of claim 1, wherein each sub-unit comprises one word.

3. The method of claim 1, wherein each sub-unit comprises a plurality of words.

4. The method of claim 1, further comprising a step of checking a sub-unit comprising a TLM (telemetry) word of a subframe after the receiving step, if the TLM is not valid, the subframe is discarded and no sub-units will be collected from the subframe.

5. The method of claim 1, further comprising determining if all required subframes have been collected.

6. The method of claim 1, further comprising determining if an update occurs in the navigation data, and abandoning old sub-units which have been collected when an update has occurred.

7. The method of claim 6, wherein IOD (Issue of Data) information is checked to determine whether an update has occurred.

8. The method of claim 1, wherein the checking step comprises firstly checking the sub-units comprising a TLM word and the sub-unit comprising a HOW word of the subframe, if both the TLM and HOW words are valid, then the other sub-units of the subframe are subjected to checking, otherwise the subframe is discarded and no sub-units will be collected from the subframe.

9. The method of claim 1, wherein a sub-unit comprising reserved words is not considered as a required sub-unit.

10. An apparatus for receiving subframes of navigation data of a satellite, and said subframes including a plurality of sub-units, the apparatus comprising:

a decision device receiving the sub-units and check if the respective sub-units are valid; and

a subframe collecting database collecting at least one required sub-unit.

11. The apparatus of claim 10, wherein the subframes subjected to sub-unit collection are transmitted together to update the navigation database after all required sub-units of these subframes are collected.

12. The apparatus of claim 10, wherein a sub-unit comprising reserved words is not considered as a required sub-unit.

13. The apparatus of claim 10, wherein the decision device checks if an update occurs in the navigation data, and indicate to abandon old sub-units which have been collected in the subframe collection database when an update has occurred.

14. The apparatus of claim 13, wherein the decision device checks IOD (Issue of Data) information of the subframe to determine whether an update has occurred.

15. The apparatus of claim 10, wherein the decision device discards and collects no sub-unit from a subframe if the sub-units comprising TLM and HOW words of the subframe are not valid.

16. The apparatus of claim 10, wherein each sub-unit comprises one word.

17. The apparatus of claim 10, wherein each sub-unit comprises a plurality of words.

18. A method for receiving subframes of navigation data of a satellite, and said subframes including a plurality of sub-units, the method comprising steps of:

receiving the sub-units;

checking if the respective sub-units are valid; and

collecting at least one required sub-units to obtain navigation data.