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:
Mar. 20, 1984
Filed:
Aug. 03, 1982
Tsuguo Itagaki, Kamakura, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In a channel selection system using a PPL frequency synthesizing method in which the local oscillation frequency of a tuner is frequency-divided and compared with the frequency and the phase of a reference oscillator thereby to control the tuning voltage of a tuner, a channel selection system disclosed by this invention comprises a controller, a variable frequency divider the frequency division ratio of which is controlled by the above controller, an AFC circuit connected to this tuner, a first comparator having a first threshold voltage for detecting an H level of the inverted S character output of the AFC circuit, a second comparator having a second threshold voltage for detecting an L level of the inverted S character output, and a delay circuit connected to the output of at least one of the first and second comparators and delaying the rising edge of the comparison output.