Multifrequency control from a single crystal
AssigneeThe Singer Company
InventorsGeorge F. Schroeder, Lincoln S. Ferriss
Life of this patent
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Abstract
A piezo-electric crystal vibrating in several modes controls several frequencies generated by voltage controlled oscillators simultaneously. The output of each voltage controlled oscillator is fed to a summing amplifier which drives the crystal. The output of the crystal is fed to individual phase detectors; each phase detector is also supplied with the output of a voltage controlled oscillator and generates a voltage proportional to the phase difference between the voltage controlled oscillator and the crystal output for correcting the output frequency of each oscillator.
Claims7
A circuit for regulating the output frequencies of a number of voltage controlled oscillators including a crystal capable of simultaneous vibration in more than one mode at different frequencies, the crystal being connected between the output of a summing amplifier and the input of a buffer amplifier, a number of voltage controlled oscillators each being supplied with a variable DC voltage for controlling its frequency, the outputs of the voltage controlled oscillators being supplied to the summing amplifier, and a phase detector associated with each oscillator for receiving the output of each voltage controlled oscillator and the output of the buffer amplifier for the purpose of generating a DC voltage proportional to the phase difference between the output of the oscillator and the buffer amplifier and supplying it to the associated oscillator to control its frequency.
Dependencies are inferred from the claim text.