| 摘要 |
The remote time calibrating system comprises a calibrating station (20) with a reference time and a remote station (10) with a local time. In order to adjust the local time to the reference time, the calibrating station (20) comprises first means (12) for receiving telemetry signals sent from said remote station, each of said telemetry signals including data indicating the local time of said remote station at which the telemetry signal is transmitted. Second means (15) are responsive to the output of said first means (18) for detecting a first time difference between the received reference time at which said telemetry signal is received and the transmitted local time derived from the received telemetry signal. Third means (30) calculate the propagation delay of said telemetry signal between said remote station and said calibrating station. Fourth means (16) are responsive to the outputs of said second (15) and third means (30) for detecting a second time difference between said reference time and said local time. The fifth means (17, 18) are responsive to said second time difference for transmitting a time calibrating command to said remote station. This system is capable of transmitting, at any time, a calibrating command from an earth station to a satellite and of calculating the propagation delay on the basis of measured values instead of forecasts. Furthermore, the system achieves, at any time, the time calibration on a satellite. |
