| 摘要 |
PURPOSE:To shorten the time required for collecting a data by dividing an ephemeris data into sub-frames and collecting it, and holding it in a memory. CONSTITUTION:A navigation data is a binary data bit train, and stored successively in a data but use buffer 13. A data bit processing part 14 processes a data of this buffer and stores it in a decoding data use memory 15. When executing its processing, a sub-frame collecting flag 16 is used. A position measurement operating part 17 derives a satellite from the navigation data of this memory 15, and derives a user's position. In such a way, when collecting the ephemeris data, even if a radio wave of the satellite is shielded, the data which has been obtained before that time is held by a sub-frame unit and is effective, therefore, it is unnecessary to collect its sub-frame again. Accordingly, the data collecting time can be shortened.
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