The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 13, 1978
Filed:
Jul. 20, 1977
Kazuyoshi Imazeki, Tokyo, JA;
Koichi Kazami, Tokyo, JA;
General Research of Electronics, Inc., Tokyo, JA;
Abstract
A system is disclosed for generating a plurality of preselected frequencies in a radio frequency device such as a receiver, transmitter or transceiver. It comprises two crystal-controlled reference signal oscillators. First and second controllable variable-frequency oscillators (VCO's), first and second mixers, and a programmable frequency divider, together generate first and second output signals, with the first mixer being coupled to the first crystal oscillator and to the first VCO to generate the first output signal having a frequency corresponding to the difference between the frequency of the first reference signal and that of the first VCO. The second mixer is coupled to the second crystal oscillator and to the second VCO to generate the second output signal which has a frequency corresponding to the difference between the frequency of the second reference signal and the frequency of the second VCO. A phase comparator is selectively coupled to the mixers by a switch for selectively comparing the first reference signal with one of the output signals and developing a corresponding control signal which varies systematically in accordance with the frequency difference therebetween, with the control signal being applied to both VCO's to vary the oscillation frequencies thereof until the frequency of the selected output signal is substantially equal to the predetermined frequency of the first reference signal, whereby the output signal of the corresponding VCO has a frequency which corresponds to one of the plurality of predetermined receiver frequencies as selected by both the programmable frequency divider and the mixer output signal selected by the switch.