US 4,061,974 AGranted

Ultra stable frequency distribution system

OwnerJames C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of Fletcher, Richard L. Sydnor +1inventors

InventorsJames C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of Fletcher, Richard L. Sydnor, John W. MacConnell

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Abstract

A system for synchronizing a signal at a remotely located slave station with the phase and frequency of a signal generated at a master station. The signal transmitted at the master station and received by the slave station provides compensation for the phase shift caused by the transmission path delays between the master and slave station. The slave station transmits a signal to the master station at a frequency that is different from the frequency of the signal being transmitted by the master station. The signal transmitted by the slave station is received by the master station while the master station transmitter is off. The signal transmitted by the master station is received by the slave station while the slave station transmitter is off.

Claims9

Dependent claims

A system for distributing a reference signal to remote locations by radio frequency transmission, said syste comprising:

a master station having a transmitting and receiving means, said master station including:
a variable phase oscillator means generating a signal for application to said transmitting means, said signal having a certain frequency and a phase related to its input signal;
means for receiving a reference signal having a standard frequency and phase;
means for mixing the reference signal with a transmitted signal and a received signal, respectively;
and
comparison means for generating a signal representing the phase difference between the transmitted signal and the received signal from said mixing means, said phase difference signal being supplied to said oscillator as its input signal;
and
a slave station having a transmitting and receiving means, said slave station including:
a variable phase oscillator means generating a signal for application to said transmitting means, said signal having a certain frequency and a phase related to its input signal, the generated signal having a frequency and phase substantially equal to the frequency and phase of the reference signal received at said master station;
and
comparison means responsive to transmitted signal and a received signal for generating a signal representing the phase difference between said transmitted signal and said received signal, said phase difference signal being supplied to said oscillator as its input signal.

8 more elements

Dependencies are inferred from the claim text.