Method and apparatus for collecting subframes of satellite navigation data
First Claim
1. A method for collecting subframes of navigation data of a satellite, the method comprising steps of:
- receiving a subframe consisting of words, the words being divided into a plurality of sub-units;
checking if the respective sub-units are valid;
collecting required sub-units from the valid sub-units;
determining if required sub-units of the subframe are collected; and
waiting for the subframe repetitively transmitted the next time if not all the required sub-units of the subframe have been collected to collect sub-units still absent.
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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.
25 Citations
21 Claims
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1. A method for collecting subframes of navigation data of a satellite, the method comprising steps of:
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receiving a subframe consisting of words, the words being divided into a plurality of sub-units; checking if the respective sub-units are valid; collecting required sub-units from the valid sub-units; determining if required sub-units of the subframe are collected; and waiting for the subframe repetitively transmitted the next time if not all the required sub-units of the subframe have been collected to collect sub-units still absent. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for collecting subframes of navigation data of a satellite, each subframe consisting of words, the words being divided into sub-units, the apparatus comprising:
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a navigation database for storing subframes of the navigation data; a subframe collection database; and a processor checking a subframe, determining if the subframe is one of subframes to be subjected to sub-unit collection, passing the subframe to the navigation database if it is not to be subjected to sub-unit collection, determining if respective sub-units of a subframe to be subjected to sub-unit collection are valid and storing the valid sub-units of the subframe into the subframe collection database, wherein after the subframe collection database has collected all required sub-units of one of the subframes, said one of the subframes is transmitted to update the navigation database. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification