Satellite controlled clock
First Claim
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1. A receiver from satellite transmitted radio frequency carrier modulated signals in the form of pulse coded information of time values and satellite position having a known pulse rate, comprising:
- a variable frequency radio frequency stage;
means for scanning said radio frequency stage over a range including the frequency of said radio frequency carrier;
means for detecting said radio frequency carrier;
means responsive to the detection of said radio frequency carrier to terminate frequency scanning and for tracking said carrier thereafter;
a clock having a nominal frequency related to the pulse rate of said time value signals from said satellite;
means responsive to the termination of scanning of said radio frequency stage for synchronizing said clock with the pulse rate of said time value signals from said satellite;
a delay path calculator;
means responsive to a detection of synchronization of said clock with the pulses of said time signals for enabling said delay path calculator for calculating the transmission path delay time to said satellite;
said delay path calculator including;
means for introducing actual receiver location information into said delay path calculator, means for calculating the path delay from satellite position received from said satellite and receiver position data;
means responsive to the delay path calculation for shifting said clock time value corrected by said delay path calculation; and
means for displaying path delay corrected decoded local time code signals.
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Abstract
A satellite disseminated time and date code is received and converted into local time signal and displayed. The ground stations scan a frequency spectrum for signals from geosynchronous satellites. Once found, the position and time information from the satellites is used to compute the correct local time.
59 Citations
24 Claims
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1. A receiver from satellite transmitted radio frequency carrier modulated signals in the form of pulse coded information of time values and satellite position having a known pulse rate, comprising:
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a variable frequency radio frequency stage; means for scanning said radio frequency stage over a range including the frequency of said radio frequency carrier; means for detecting said radio frequency carrier; means responsive to the detection of said radio frequency carrier to terminate frequency scanning and for tracking said carrier thereafter; a clock having a nominal frequency related to the pulse rate of said time value signals from said satellite; means responsive to the termination of scanning of said radio frequency stage for synchronizing said clock with the pulse rate of said time value signals from said satellite; a delay path calculator; means responsive to a detection of synchronization of said clock with the pulses of said time signals for enabling said delay path calculator for calculating the transmission path delay time to said satellite; said delay path calculator including; means for introducing actual receiver location information into said delay path calculator, means for calculating the path delay from satellite position received from said satellite and receiver position data; means responsive to the delay path calculation for shifting said clock time value corrected by said delay path calculation; and means for displaying path delay corrected decoded local time code signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A satellite controlled clock operative to receive time code a standard pulse rate and satellite position modulated radio frequency carrier waves from either of two geostationary satellites operating at predetermined different carrier wave frequencies comprising:
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a variable radio frequency receiving stage including means for detecting radio frequency carrier waves; switch means for allowing the selection of the nominal carrier frequency of the selected one of the two satellites; frequency scanning means for incrementally sweeping said radio frequency receiving stage through a frequency band including the selected satellite carrier frequency responsive to the application of power to the receiver and selection of satellite by said switch means; phase lock loop means for tracking said selected satellite carrier wave responsive to the detection thereof; means responsive to the detection of satellite carrier by said detecting means of said variable radio frequency receiving stage and tracking of said selected satellite carrier by said phase lock loop means for disabling said frequency scanning means; a local clock operating at a nominal frequency related to the pulse rate of transmissions from said satellite; means responsive to disablement of said frequency, scanning means for synchronizing said local clock with pulses received from said satellite; means for decoding the time code transmitted by said satellite; coding switch means for introducing the receiver'"'"'s position into said receiver in coded form; calculator means for calculating the path time delay of signals from said satellite from the known satellite position information and the receiver'"'"'s position as introduced by said coding switch means; means for combining the decoded time signals from said satellie and the path time delay calculator means; and means for correcting the decoded time signals from said satellite by the correction factor calculated by said path time delay calculator means for displaying the corrected local time. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification