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From: shaprkg@sdcrdcf.UUCP (Bob Shapiro)
Newsgroups: net.consumers
Subject: Re: Cable ready TV, etc.
Message-ID: <1684@sdcrdcf.UUCP>
Date: Fri, 18-Jan-85 13:41:56 EST
Article-I.D.: sdcrdcf.1684
Posted: Fri Jan 18 13:41:56 1985
Date-Received: Mon, 21-Jan-85 02:54:11 EST
References: <293@mhuxm.UUCP> <248@terak.UUCP> <282@lsuc.UUCP> <1597@ittvax.UUCP> <712@cbosgd.UUCP> <2640@sdcc3.UUCP>
Reply-To: shaprkg@sdcrdcf.UUCP (Bob Shapiro)
Organization: System Development Corp. R+D, Santa Monica
Lines: 82
Summary: 

In article <2640@sdcc3.UUCP> brian@sdcc3.UUCP (Brian Kantor) writes:
>> if you can buy a cable tuner from Jerrold (the same ones
>> the cable company rents you) why is an unscrambler box any different?
>
>More and more cable companies (especially those serving hi-tech areas
>like silicon valley and the like) are going to descramblers which are
>digitally addressable.  These are individually numbered and can be
>individually turned on or off for each scrambled channel by the cable
>company.  Thus buying a descrambler from a legit manufacturer would gain
>you nothing (except saving the monthly rental, if any) because you would
>still have to get the cable company to enable it for each scrambled
>channel you wanted to watch.
>
>Of course, a pirate descrambler could be built that ignores the on-off
>codes - probably would be cheaper that way too.  I haven't seen any at
>our local swap meets, but its probably just a matter of time.
>

   I think you will find out that recently almost all cable systems that are
installed are either put in with return channels allocated on the cable or
a dual cable system which permits bidirectional traffic.  The reason for this
is that the cable people intend to get into many fields above and beyond the
broadcasting of television and many of these require 2-way communication.
Examples are home security (which I believe is already in existence in some
cable systems), polling of viewer opinions (also implemented in some systems),
and even such things as data channels so you can hook up your modem and
transfer data at rates considerably faster than what is practical today over
standard phone lines.  Along with this capability is the ability of the cable
company to read your tuner and see what it is set to.  Perhaps you might be
able to put a second tuner in parallel and they might not be able to tell, but
I suspect that if you merely replaced their select box with yours they would
know in a big hurry.  There are laws on the books which make such actions
theft and you might be treated accordingly.

   Just as an aside I believe cable systems come in 3 flavors.

   1. The real old ones use blocks (typically at the pole) to allow only those
channels through which you pay for.  If you want to cheat you have to climb
the pole and remove the blocks.  These systems would probably never be 2-way.
They have a real advantage to the user in that they permit the user to use
the cable with a cable-ready TV and watch pay channels without a descrambler.
When you wish to change your pay channel selections then the company must send
a person to the pole to redo the blocks.  Obviously a slow and expensive
process. The disadvantage is that none of the goodies of the future will be
available and even current goodies such as the ability to watch special events
(boxing matches, 1st run movies, et al) which are pay as you go is usually
not available.

   2. The next is a tuner which unscrambles those channels which a signal from
the host permits it to.  This only requires 1-way communication as typically
they send out an addressable reset followed by the channels they wish you to
watch.  The advantages and disadvantages are directly opposite to the above
case.  Most newer cable systems work this way even if they have a 2-way cable
capability.  This is because they have only reserved the right for the future
but haven't gone to the expense of implementing it yet.

   3. Finally the 2-way system which is pretty much as I described above.  The
problem with playing games with method 2 is that the company can switch to
method 3 without your knowledge and you could get caught.

   As to the scrambling techniques other than the direct block it appears that
almost all systems use a form of screwing up the horizontal sync.  The sound
appears to be untouched.  My cable company also has a tuner which is smart
enough so that after it senses a couple of seconds of scrambled channel it
totally turns the channel off and I see and hear nothing.  If I look at the
same channel with my cable-ready VCR I can see the distorted picture and the
voice is fine.  One of the most interesting things that occurs in my system
is that if I have side-by-side pay channels (e.g. 43 And 44) and I only have
rights to 1 of them I can see a poor reception of the other by adjusting my
TV set from its normal channel 3 to either channel 2 or 4 (to go up or down).
Apparently the signals slop over the 6mz band.

   I have often thought about a system which would read one channel and output
another.  e.g. channel 43 I pay for and 44 I don't.  If I could push the cable
down 6mz per channel and then feed it into my tuner I might be able to watch
44 instead of 43 even though I told the box it was 43.  Obviously the amount
to be moved has to be variable and probably in both directions, and it also
relies on a principle which I think is true - all channels are scrambled via
the same algorithm.  Moving 6mz channels around may not be too difficult.
After all the box itself moves everything to channel 3.

			Bob Shapiro