tomb@tekecs.UUCP (04/17/85)
I strongly suspecct the utility of cable ready TVs is nearing "end-of-life"! Most local cable companies are now moving to FULLY SCRAMBLED service in order to combat what they perceive as a threat by folks with cable-ready TVs. Once all your cable channels are scrambled you can't get anything without a box. Of course they'll give you a second box for your VCR at a significant discount. :-) One other point. I know of no cable systems that "scramble" signals at the junction box. What's at the junction box is a filter. The signal is unscrambled but the carrier is taken out with a notch filter so you are unable to receive it. Locally, some of the cable operators filter HBO and Showtime and scramble Disney and Cinemax. Enjoy while you can! Tom ..!tektronix!tekecs!tomb -- Tom Beach email: ..tektronix!tekecs!tomb
seifert@mako.UUCP (Snoopy) (04/18/85)
In article <5250@tekecs.UUCP> tomb@tekecs.UUCP writes: >Most local cable companies are now moving to FULLY SCRAMBLED >service in order to combat what they perceive as a threat by >folks with cable-ready TVs. Once all your cable channels are >scrambled you can't get anything without a box. Of course >they'll give you a second box for your VCR at a significant >discount. :-) At the apt complex I used to live at, they put in a rather hacker-hostile system. They brought in two fiber optic lines, one brought in a single channel, and the other sent control signals to the distribution box. The cable-box had connections for these two fibers, power, and a 75 Ohm line to your tv. It sent signals to the distribution box requesting whatever channel you wanted, and if you were subscribed, the distribution box would send it down. The quality wasn't as good as broadcast, there was no way to get two channels at once, and for US$30/month there were two or three movies worth watching. Needless to say, when the free trial period ran out they got their box back. What was really sad was the people who couldn't pay their rent, utility bills, or even buy *food*, but they *had* to have cable. -sigh- _____ |___| the Bavarian Beagle _|___|_ Snoopy \_____/ tektronix!mako!seifert \___/
jer@peora.UUCP (J. Eric Roskos) (04/19/85)
> One other point. I know of no cable systems that "scramble" > signals at the junction box. What's at the junction box is > a filter. The signal is unscrambled but the carrier is taken > out with a notch filter so you are unable to receive it. CableVision here in Orlando does "scramble" signals at the junction box. More accurately, they apparently inject some signal into the channels you don't pay for so that the horizontal sync occurs at the wrong place. The picture comes out "shifted" to the right so that the edges of the picture are in the center; but the picture (and sound) are still there. Actually, here it's more complicated (and interesting). One channel (Cinemax) uses both the above method, and some kind of modification (or elimination) of the vertical sync. What is interesting is that for that channel, there is apparently a "descrambler" built into the cable tuner. The cable from the tuner to the control box contains wires for a switch which may be connected such that the switch turns on for particular channels (only Cinemax in this area); when the switch is on, vertical sync is restored. Incidentally, this raises an interesting question. Recently HBO bought a new scrambling system for their satellite signal, which uses an encryption key (so that even if you have a descrambler, you can't descramble it unless you can keep getting the new encryption keys each time they change them). The facility for doing this was a new, low-cost one. Have they started using it yet? It would seem to be a strong reason for not buying an "earth station" satellite receiver. -- Full-Name: J. Eric Roskos UUCP: ..!{decvax,ucbvax,ihnp4}!vax135!petsd!peora!jer US Mail: MS 795; Perkin-Elmer SDC; 2486 Sand Lake Road, Orlando, FL 32809-7642
brown@nic_vax.UUCP (04/22/85)
> > One other point. I know of no cable systems that "scramble" > > signals at the junction box. What's at the junction box is > > a filter. The signal is unscrambled but the carrier is taken > > out with a notch filter so you are unable to receive it. > > CableVision here in Orlando does "scramble" signals at the junction box. > More accurately, they apparently inject some signal into the channels you > don't pay for so that the horizontal sync occurs at the wrong place. The > picture comes out "shifted" to the right so that the edges of the picture > are in the center; but the picture (and sound) are still there. Sounds like sine-wave-sync-suppress to me, which is too expensive to do at the juction box. Even physically impossible as the electronics needed to do that wouldn't fit in a junction box. Even more expensive to duplicate in each and every juction box. But, I would have to see it to believe it. > Actually, here it's more complicated (and interesting). One channel > (Cinemax) uses both the above method, and some kind of modification (or > elimination) of the vertical sync. What is interesting is that for that > channel, there is apparently a "descrambler" built into the cable tuner. > The cable from the tuner to the control box contains wires for a switch > which may be connected such that the switch turns on for particular > channels (only Cinemax in this area); when the switch is on, vertical sync > is restored. If the system is a sine-wave-synce-suppress system, as I mentioned above, the sine-wave signal tends to also destroy the vertical sync. I know, we have the 2fh system here in Madison, WI. > Incidentally, this raises an interesting question. Recently HBO bought a > new scrambling system for their satellite signal, which uses an encryption > key (so that even if you have a descrambler, you can't descramble it unless > you can keep getting the new encryption keys each time they change them). > The facility for doing this was a new, low-cost one. Have they started > using it yet? It would seem to be a strong reason for not buying an "earth > station" satellite receiver. HBO has been shipping descrambling units to the west coast area first. The east coast feed will be next. There are other companys going that route as well. ESPN wants to do it, SHOWTIME and THE MOVIE CHANNEL want to do it, and of course CINEMAX, because they belong to HBO. Mr. Video
guy@anasazi.UUCP (Guy Finney) (04/24/85)
> > Recently HBO bought a > > new scrambling system for their satellite signal, which uses an encryption > > key (so that even if you have a descrambler, you can't descramble it unless > > you can keep getting the new encryption keys each time they change them). > > The facility for doing this was a new, low-cost one. Have they started > > using it yet? It would seem to be a strong reason for not buying an "earth > > station" satellite receiver. > > HBO has been shipping descrambling units to the west coast area first. The > east coast feed will be next. There are other companys going that route > as well. ESPN wants to do it, SHOWTIME and THE MOVIE CHANNEL want to do it, > and of course CINEMAX, because they belong to HBO. > True, HBO has announced, and has spent gobs of money on developing, a nontrivial (to crack) scrambling method. Everyone else (the above mentioned channels included) is jumping on the announcement bandwagon, but as far as I know, is eagerly awaiting the market test results from HBO before doing anything. Everyone's wondering what will happen to HBO's market share. Will the cost of the units be so expensive that some small-time cable companies (like the one in my front yard) will be hurt by the extra cost passed on to the viewer? Will MA/Com or some enterprising distributor sell/rent the decoders to individuals at bargain basement prices? What will that mean to cable companies? All sorts of interesting marketing questions swirl around this issue. As for me, I'll keep my dish, thank you, and rent movies from my local store before coughing up $20 a month for a crummy decoder. The best sports on satellite are the live feeds, anyway, and they won't be scrambled. -- Guy Finney {decvax|ihnp4|hao}!noao!terak!anasazi!guy
jer@peora.UUCP (J. Eric Roskos) (04/25/85)
brown@nic_vax.UUCP ("Mr. Video" at Nicolet Instrument Corp. Madison WI),
commenting on my description of the scrambling method used by CableVision
of Central Florida, writes:
> Sounds like sine-wave-sync-suppress to me, which is too expensive
> to do at the juction box. Even physically impossible as the
> electronics needed to do that wouldn't fit in a junction box.
> Even more expensive to duplicate in each and every juction box.
> But, I would have to see it to believe it.
But, I have seen it! Hence, I tend to believe it. Here is the evidence.
(1) My cable tuner is a "dumb" tuner, not one of the new digital ones;
the inside looks like a typical TV tuner, and tuning is done through a large,
unwieldy box with a slide switch that selects one of a number of
potentiometers mounted on a PC board inside the box. Thus I don't think
they are sending it commands from outside to program it.
(2) When I discontinued HBO, they did not have to come inside to turn on
the scrambling for HBO.
However, I tend to believe the auxiliary method used to scramble Cinemax is
indeed possibly a sine wave sync suppress method. Someday when I have time
to take my TV apart, I will connect up an oscilloscope and see what I can
see about it. More then.
--
Full-Name: J. Eric Roskos
UUCP: ..!{decvax,ucbvax,ihnp4}!vax135!petsd!peora!jer
US Mail: MS 795; Perkin-Elmer SDC;
2486 Sand Lake Road, Orlando, FL 32809-7642jc@mit-athena.UUCP (John Chambers) (04/26/85)
> What was really sad was the people who couldn't pay their rent, utility > bills, or even buy *food*, but they *had* to have cable. -sigh- Reminds me of the sociological study I read about last year that verified the widespread belief that the higher the family income, the fewer TV sets in the home. The correlation and signifigance levels were impressively high. The lowest rate of TV ownerset was among the top management of broadcast firms. Most of them have no TV in their homes at all. They see no need for wasting their own money on such things, and certainly don't wand their own children exposed to such stuff. Looks like good ol' Karl Marx is outdated. The masses now have a better opiate than religion. And back when TV was first being introduced, they promised us that it would be so educational! -- John Chambers [...!decvax!mit-athena] He who has made no mistakes has probably made nothing at all.
brown@nic_vax.UUCP (04/27/85)
> (1) My cable tuner is a "dumb" tuner, not one of the new digital ones; > the inside looks like a typical TV tuner, and tuning is done through a large, > unwieldy box with a slide switch that selects one of a number of > potentiometers mounted on a PC board inside the box. Thus I don't think > they are sending it commands from outside to program it. I just tried calling your cable company, but since it is only Saturday, Customer service is the only ones there. To find out for sure I will have to call on Monday and ask an engineer there. But, from your description I believe the following. That same kind of box is used by two different cable companies around here. One of which IS addressable from the main plant. The unwieldy box selects the channel, but the other circuitry determines if you are allowed to receive the pay channel or not. If the system is not addressable (like the other cable system around here), there is an extra board inside of the channel selection box that has resistors on it. Some are shorted some are not. If the resistor is shorted out, then no pay channel restoration takes place. If the short is cut, so that the 680 ohm resistor is again in the circuit path, the pay channel connected to that resistor is restored. If there are channels 2 thru 36 on the box, there are that many resistors. This method would be used for your pay channels of Cinemax, Showtime and Disney. As for HBO, it sounds like they use a filter to remove the main vision carrier. That is the method used in my cable system and one of the others. That way, the signal is sent down the cable unscrambled, for the best possible picture. The sine-wave-sync suppress system, in my opinion, is the worst method ever devised for scrambling. It causes gain riding that shows up in the picture as a band of clean and noisy picture areas. If you have a video deck, just hook up the scope to the video output and dial up a channel that has a pay channel, other than HBO. You should see a sine wave riding on the signal, either at the 15750 Hz rate or at the 31500 Hz rate. The Horizontal sync pulse will be riding on the positive peak of the sine wave. > (2) When I discontinued HBO, they did not have to come inside to turn on > the scrambling for HBO. Reason for that mentioned above. This discussion could go on forever, but I'm sure we don't want it to. I will call your cable company on Monday as find out what I can and post it to the net. If anyone as the answer, they sure must. Mr. Video
jer@peora.UUCP (J. Eric Roskos) (04/29/85)
[The parent article asserts that HBO has obtained scramblers, but nobody
knows if they will be cost effective or if some company will rent them at
bargain basement prices.]
My original comments on this subject were based on an article in
_Electronics_Week_ magazine, which described the scramblers. They are not
made by HBO; they are made by another company. HBO is just their first
major customer. The scramblers ARE supposed to be very low-cost; I have
forgotten why, I think they use custom VLSI parts or something. But
renting them to home users wouldn't do any good at all, because there is
essentially a "password" required to descramble the signal, and all you
have to do is change the password (encryption key) and you change the
scrambling. People would have to keep up with the encryption keys through
some security leak or something in order to "beat the system" with this
method.
--
Full-Name: J. Eric Roskos
UUCP: ..!{decvax,ucbvax,ihnp4}!vax135!petsd!peora!jer
US Mail: MS 795; Perkin-Elmer SDC;
2486 Sand Lake Road, Orlando, FL 32809-7642