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:
Sep. 05, 1978
Filed:
Mar. 25, 1977
Geoffrey N Mendenhall, Quincy, IL (US);
Harris Corporation, Cleveland, OH (US);
Abstract
A stereo FM pilot signal generator which includes an automatic phase correction loop so as to automatically synchronize the phase between the pilot signal and the stereo switching signal. A parallel clocked divider/decoder is included for generating a 38 kHz square wave, to be used in a stereo switching modulator, and a 19 kHz square wave so that the two square wave signals are substantially in phase synchronism with one another. The 19 kHz square wave is directed through a controllable phase adjuster and then through a filter which serves to remove higher harmonics therefrom so that only the fundamental, 19 kHz sine wave signal remains. The phase of the 19 kHz square wave signal is compared with the phase of the 19 kHz sine wave signal by a phase comparator which provides a control signal to the phase adjuster, and which adjusts this control signal until the 19 kHz sine wave is substantially in phase synchronism with the 19 kHz square wave. In addition, a specific phase comparator is described which includes two flip-flops which are respectively responsive to lead and lag between two input signals.