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From: amigo@milton.u.washington.edu (The Friend)
Newsgroups: sci.electronics
Subject: Re: Scrambling Techniques
Message-ID: <1991May17.014231.24059@milton.u.washington.edu>
Date: 17 May 91 01:42:31 GMT
Organization: University of Washington, Seattle
Lines: 59


     Here's what I got back from my question on flashing video &
beeping audio type of scrambling:

--------

If the audio is beeping and the picture is flashing it is *not*
scrambled, just blocked out by an additional very strong interference
signal next to the picture info, like this:
   (bear with me and imagine this is a drawing of the frequency
spectrum of a tv channel)

   |sync| picture information           |sound|  added interference|

"Scrambling", using the methods you described above, does nonstandard
things with the sync pulse.  Your TV or VCR expects a very regular
sync pulse in a very specific form, and if that is altered it cannot
lock onto and display the picture information correctly.  What a
descrambler does is to replace or alter the messed - up sync so that
it's normal again, so that your TV or VCR can display or record the
signal.  Since you don't need a descrambler, you're going to get off
cheap in your startup expenses as a cable pirate. :)  What you need is
a plain-vanilla converter box, not a descrambler.  It should output on
a standard VHF channel such as 2,3, or 4.  Then you need to get a
magazine such as Video or Popular Science or Radio Electronics, and
look for ads for companies that sell "Interference Filters".  You call
them up and tell them you want to order a filter because you're
experiencing "severe beeping interference" on several of your cable
channels.  (They don't want to know that you're going to be using it
illegally)  Order the filter to match the OUTPUT channel of your
plain-vanilla cable box.  The filter should set you back 30 or 40
dollars, and it will have the effect of giving you all the currently
beeping channels IN THE CLEAR, while letting everything else pass
through because it's only letting the exact bandwidth of the TV
channel through and not letting the interference by.
   This technique worked well for SOMEONE I know... :) 
Just be careful that the little filter is taken off if and when ever
you have to have to cable company come for service.  Since it's not
one of the hi-tech electronic methods, you don't have to worry about
signal "bullets" coming down your cable line to get you busted either.

----------

     These are also called notch filters - they're tunable to limited
range (usually 2-4 channels), and have adjustable attenuation. Those from
Radio Electronics companies (in the back) run about $25-$30 each, depending
on how many you buy. Additionally for your security (if its a problem for
your situation), they make one-way boxes (let cable signal in but nothing
back). They make sure you can't be checked for a notch-filter, descrambler,
 etc... those run $40. Since this is the lowest type of scrambling, it is 
not used often by most companies - they've all gone to more elaborate setups.



-- 
                                      ///
       Scott Rowin                   ///  amigo@milton.u.washington.edu
       ***********                  /// 
 - SPACE OPEN FOR LEASE -      \-\_///    Amigas really do it better...