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:
Jul. 10, 1990
Filed:
Apr. 14, 1989
Philip H Bird, Sidcup, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
A television receiver has an a.f.c. arrangement for ensuring the correct tuning of a tuner unit (4) which is tuned to the nominal carrier frequency by a tuning voltage (VT). When the tuner unit (4) is incorrectly tuned to the actual carrier frequency, the a.f.c. system operates in a first mode in which a sweep current produced by a current source (15) is applied by way of a closed switch (16) to an a.f.c. capacitor (17) to produce a swept a.f.c. voltage for the tuner unit (4). The sweep direction is controlled by an RS flip-flop (13) by way of a multiplexer (12) in response to voltage comparators (19, 20) connected to the a.f.c. capacitor (17). When the tuning is sufficiently close such that the received transmission can be correctly decoded, the a.f.c. arrangement goes into a second mode in which the output of a frequency demodulator (6) is applied via the multiplexer (12) to control the current source (15) and hence the voltage across a.f.c. capacitors (17). For this second mode gate pulses (G1, G2) from a processor (11) control the multiplexer (12) paths by a monostable (14) and only cause the switch (16) to be conductive during a given portion of each line period.