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From: dcm@pyrite.nj.pyramid.com (David C. Miller)
Newsgroups: sci.electronics
Subject: Cable TV question
Message-ID: <471@pyrite.nj.pyramid.com>
Date: 27 Feb 91 02:00:51 GMT
Organization: Pyramid Technology -- Professional Services
Lines: 46

I recently added one of the pay channels to my cable service and
hit the following snag:

I can set my VCR to use its own tuner and can program it to record
programs from any of the unscrambled channels.

OR

I can set it to use the tuner supplied by the cable service and can
record only the one channel that it is tuned to.


Since this is an 8 event VCR, I find it frustrating to have to
switch between the internal and external tuner.  If I go away
for a weekend, I have to choose to record only the unscrambled
channels or only the scrambled channel.

What I'm looking for is a way of adding a circuit that will
effectively unscramble the pay channel in place.  The cable
company's converter unscrambles channel 28 and emits the clear
signal on channel 3.  I want something to take this signal and
put it back on channel 28 and merge it back with the other cable
channels.  The idea being that all but channel 28 comes straight
off the cable while channel 28 come in via the descrambler.


                           Cable Tuner  +----- Channel 3 out
                           Descrambler  |
Incoming cable with          +-----+    v
scrambled signal on   +------|     |----+
channel 28           /       +-----+     \+----+
--------------------+                     |    |------------+
                    ^\                   /+----+
cable splitter -----+ +-----------------+   ^
                                            |
                                            |
Device that blanks out channel 28 on      --+
straight through line, then map channel 3
from the tuner to channel 28.

I figure that there must be at least 1 video hacker on the
net who's done this.  Is there some insurmountable problem
that I'm not seeing?

David
dcm@pyrite.nj.pyramid.com