Remote calibrating system for satellite time
First Claim
1. A remote time calibrating system comprising a calibrating station having a reference time and a remote station having a local time, wherein said remote station comprises time adjusting means responsive to a time calibrating command for adjusting said local time, and wherein said calibrating station comprises:
- first means 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 responsive to the output of said first means for detecting a first time difference between the receive reference time at which said telemetry signal is received and the transmitted local time derived from the received telemetry signal;
third means for calculating the propagation delay of said telemetry signal between said remote station and said calibrating station;
fourth means responsive to the outputs of said second and third means for detecting a second time difference between said reference time and said local time; and
fifth means responsive to said second time difference for transmitting a time calibrating command to said remote station.
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Accused Products
Abstract
A remote time calibrating system has a calibrating station with a reference time and a remote station having a local time, the local time having to be adjusted to coincide with the reference time. The calibrating station receives telemetry signals sent from the remote station, each of the telemetry signals including data indicating the local time of the remote station from which the telemetry signal is transmitted. Responsive to any first difference between the receive reference time and the local transmit time is detected and calculated by taking into account the signal propagation delay of the telemetry signal between the remote station and the calibrating station. Responsive thereto, the local time is calibrated at the remote station.
95 Citations
8 Claims
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1. A remote time calibrating system comprising a calibrating station having a reference time and a remote station having a local time, wherein said remote station comprises time adjusting means responsive to a time calibrating command for adjusting said local time, and wherein said calibrating station comprises:
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first means 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 responsive to the output of said first means for detecting a first time difference between the receive reference time at which said telemetry signal is received and the transmitted local time derived from the received telemetry signal; third means for calculating the propagation delay of said telemetry signal between said remote station and said calibrating station; fourth means responsive to the outputs of said second and third means for detecting a second time difference between said reference time and said local time; and fifth means responsive to said second time difference for transmitting a time calibrating command to said remote station. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A process for adjusting the times in a calibration command station and a remotely calibrated station to render these times identical with each other, said process comprising the steps of:
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(a) transmitting telemetry signals from said remote station to said command station; (b) inserting signals representing the local time of said remote station into the telemetry signals upon their transmission from said remote station; (c) detecting at said command station any difference between the actual receipt time of said telemetered signals and the time indicated by the local time signals inserted into said telemetered signals; (d) calculating at said command station the propagation time for said telemetered signals; (e) subtracting the propagation time calculated in step (d) from the difference detected in step (c); (f) transmitting a calibration signal from said command station to said remote station responsive to the subtraction of step (e); and (g) adjusting the time of said calibrated station to be identical with the time of said command station responsive to said calibration signal. - View Dependent Claims (8)
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Specification