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. 17, 1985
Filed:
Jun. 10, 1983
Jeffrey L Cooper, Syracuse, NY (US);
Brian C Johnson, Syracuse, NY (US);
North American Philips Corporation, New York, NY (US);
Abstract
A method for scrambling and descrambling television programs in which the horizontal synchronizing information is suppressed at a CATV supplier's head-end and then regenerated at the subscriber's converter. The pulse frequency is multiplied by a factor N/M, in which N and M are integers thereby generating a synthesized pulse stream which is, in turn, encoded with data identifying the values for N and M. This encoded pulse stream is modulated onto the audio subcarrier wave in the TV video signal and transmitted to the converter. The converter then demodulates and recovers the encoded pulse stream, decodes the same to recover the identifying data, using this data to obtain the correct values for N and M which have been transmitted separately on a digital data channel. The converter then multiplies the synthesized pulse stream by M/N regenerating the horizontal synchronizing pulse stream and inserts the same into the TV video signal at the proper phase.