| 摘要 |
PURPOSE:To execute highly accurate position measurement stably, by allotting a long time to PN code matching and Doppler frequency matching for radio waves of low reception level. CONSTITUTION:Radio waves from reception satellites are received 10 sequentially with the respective time slot lengths, position measurement computation 5 for a reception point is conducted on the basis of the received waves, and a prescribed number of reception satellites are selected 8. Then, a time slot length to be assigned to each reception satellite within the period of a reception cycle of a unit determined by a period of one bit of orbit data is computed 9 in accordance with the reception level in the past of each reception satellite so that the length be enlarged when the level is low, and a reception control 10 on each reception satellite is conducted so that the wave of each satellite be received in sequence with the computed time slot length. On the occasion, a long time is allotted to PN code matching and Doppler frequency matching for satellite waves of low reception level, and thereby the satellite waves of low level are caught with high accuracy and without fail.
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