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:
Nov. 19, 1985
Filed:
Feb. 14, 1985
Michael Tentler, Wheeling, IL (US);
David L Walker, Arlington Hts., IL (US);
Wayne E Bretl, Schaumburg, IL (US);
Gregory A Williams, Elk Grove Village, IL (US);
Zenith Radio Corporation, Glenview, IL (US);
Abstract
An addressable subscription television decoder includes an input stage including an IF amplifier for converting a scrambled RF television signal to a composite baseband video signal. The baseband video signal comprises either a nominal sync component or a sync component having suppressed horizontal sync pulses during video fields and having non-suppressed sync pulses during vertical intervals, the vertical intervals also including selected encoded data signals. An AGC voltage for controlling the gain of the IF amplifier is developed by a circuit exhibiting a relatively short time constant whenever the composite baseband video signal is characterized by nominal level sync pulses, the time constant being increased in response to suppressed horizontal sync pulses. The sync pulses produced during the vertical intervals of the composite baseband video signal are thereby not subjected to excessive IF gain for facilitating processing of the data signals by the decoder.