Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!pilchuck!ssc!markz
From: markz@ssc.UUCP (Mark Zenier)
Newsgroups: sci.electronics
Subject: Re: Descramble Cable Using Filter?
Message-ID: <866@ssc.UUCP>
Date: 29 Jun 90 19:45:47 GMT
References: <3525@umbc3.UMBC.EDU>
Organization: SSC, Inc., Seattle, WA
Lines: 23

In article <3525@umbc3.UMBC.EDU>, yhu@umbc5.umbc.edu (Mr. Ying Hu; CMSC (GRAD)) writes:
> 
> I have seen different type of descrambler of cable signal, but have no
> idea how the filter works. Anyone knows about connecting a filter to
> the cable and descramble the signal? Any article talking about that. It
> seems the filter knows not to filter when the signal is not scrambled.

One of the early methods of "Scrambling" a cable channel was to add
a signal.  Judging from the effects on the signal, where the sound
was overridden and ripples in the video from a signal about 1 Mhz
away, I guess it was an FM sound signal added 4.5 Mhz below the
color subcarrier.  (or 4.5 - 3.579 Mhz below the video carrier).

When you paid the premium, the cable company would put filter in line 
to take this jamming out.

A couple of folks built filters from a photocopy of an article
from an Austin Texas newspaper with varying degrees of success.

With adressable decoders, Videochipher, Orion, and other stuff, I
assume this is ancient history.

markz@ssc.uucp