| 摘要 |
PURPOSE:To measure the distance from a radio wave source to a receiving station in a short period by separating and extracting a clock of a modulated code of the objective radio wave source and measuring the phase difference between this clock and clock of the receiving station. CONSTITUTION:A received radio wave is allowed to pass a band pass filter 6 and a frequency converter 7 and has the clock of the modulated code extracted by a modulated clock reproducer 8. The phase difference between this clock and a signal of a reference oscillator 10 of a receiving station 2 is measured with a phase difference measurer 9 to determine the distance between the receiving station and an artificial satellite. Since a Doppler shift frequency to be measured is very lower is comparison with said clock frequency, the clock frequency is reduced while keeping the phase difference in a frequency converter 91 and is converted to an intermediate frequency signal subjected to Doppler shift. This signal and the intermediate frequency signal generated by the reference oscillator in the receiving station are measured by a time interval counter 92 to obtain time intervals.
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