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. 04, 1986
Filed:
Dec. 10, 1980
John Schilling, Dresher, PA (US);
Joseph Dolinski, Upper Black Eddy, PA (US);
Jerrold Division, General Instrument Corporation, Hatboro, PA (US);
Abstract
A television signal distribution system protects outgoing programs from unauthorized reception; and marks or tags the conveyed signals with a digital word identifying the class of viewers authorized to receive the program ('level of service'). Basic encription is accomplished by effectively suppressing the horizontal and vertical synchronizing information. Horizontal sync information, and the program-characterizing level of service word which is interleaved in time with prescribed horizontal sync pulses, is distributed via pulse amplitude modulation of the audio carrier. At subscriber receiving stations, the sound carrier amplitude modulation is recovered to permit level of service authorization verification; and to reconstitute the video carrier to receivable form by an amplitude modulation which is the inverse of the sync-suppressing modulation of the head end. In accordance with one feature of the present invention, a further data channel may be employed to very subscriber service authorizations--as to permit pay-per-view billing.