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Article #4965Re: Descramble Cable Using Filter?
From: Gordon Hlavenka
Date: Wed, 04 Jul 1990 01:55
Date: Wed, 04 Jul 1990 01:55
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ON-TV used a system (back in the goodle days...) where the sync pulses were attenuated. The sync information was then AM'd as a sine wave onto the FM audio subcarrier, which in turn was in a non-standard location. You had to retune the audio tank, recover the sync, phase shift it by some amount, integrate it, then mix the spikes back into the video. The easier-to-build boxes had their own audio and speaker; you just turned the volume down on the TV... Nowadays, of course, most of this scrambling stuff is done with digital encryption, or at least digital access to the descrambler box. ---------------------------------------------------------- Gordon S. Hlavenka cgordon@vpnet.chi.il.us Disclaimer: He's lying
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!wuarchive!zaphod.mps.ohio-state.edu!usc!ucsd!pacbell.com!pacbell!att!mcdchg!ddsw1!obdient!vpnet!cgordon From: cgordon@vpnet.chi.il.us (Gordon Hlavenka) Newsgroups: sci.electronics Subject: Re: Descramble Cable Using Filter? Message-ID: <26912307-29c.5sci.electronics-1@vpnet.chi.il.us> Date: 4 Jul 90 01:55:04 GMT References: <3525@umbc3.UMBC.EDU> <866@ssc.UUCP> Lines: 13