Cable TV De-Scramblers

Factual Questions
21

Primal,

You wrote:

I’m not sure how to answer that without it sounding like a flame… TDRs are very real devices. They can and are used as I described.

Well, I’m not sure about the legal rammifications… The subscribers sign a contract agreeing not to connect any unauthorized equipment to the line and the contract clearly states that a violation may result in termination of service… However, I suspect that any cable company doing this will try not to be too obvious about it - after all, they don’t want to chase away their customer base, they just want them to pay for the service they receive.

22

I’m not doubting that this TDR gizmo could detect that there was a discontinuity on the line, and even detect where that break was (in fact, if they’re the same things that our systems guys use to check ethernet cable, I KNOW they can do that) on a single segment.

However, it would be surprising if they could tell the difference between a pirate descrambler box, their own descrambler box, your VCR, your DCD player, your cable modem, the signal filter on your cable modem, a signal splitter you’ve installed, a video game, etc. with any degree of reliability whatsoever, and do so despite the fact that there may be several perfectly legitimate splitters or A/B switches or signal amplifiers along the line between the TDR and your TV(s).

23

torq,

I think the TDR technique only works on cable system requiring a cable converter box. In this case, it doesn’t make any sense to run your cable to any other devices from the source side and there’s no reason to add a splitter unless you’re planning on doing something not entirely legal. Any signal splitting on the output side of the descrambler would not be detectable, I think.

Unless the bogus descrambler is designed just right, it will present a different impedance to the TDR and the reflected ‘fingerprint’ will be different.

24

I have a Sony TV that has several inputs/outputs on the back panel. Right now I run the cable line through the VCR first, then directly into the “Cable/Ant.” input on the TV. I can then run a line from an output called “To Converter Box”, then back into another input called “From Converter Box” (I believe this is so I can use the remote control for the TV to control everything and don’t have to use the box to change the channles). Since I currently don’t have any premium channles, I don’t use the box provided by the cable company. My question is, what if I hooked a descrambler between the Converter Box inputs and outputs? Would I still run the risk of being detected with the TRD method or one of the other methods mentioned above?

25

Okay, this is getting silly and I can’t stand it anymore, I have to jump in with my own WAGs.

First, the time domain reflectometer is a real device - I’ve seen them used many times troubleshooting (computer) network problems. I remember one time my workstation wouldn’t connect to the server, a tech showed up, plugged in his magic box and basically said ‘Well, there’s the problem, there’s a bad junction at 50 feet from here, plus or minus 5 percent, I’ll be back in a few minutes’. This description is a bit frivolous, but the magic box did find the bad connection and I connected fine after that. What this has to do with Cable TV … dunno, seems to me it’s a completely different technology, I’d be hard pressed to tell you how the two cross over this way.

Next, yes - hooking up a bootleg descrambler is illegal, and the violators should be punished somehow. From the discussion so far, though, it sounds like the cable companies pretty much have thier hands tied - they can warn you but they can’t cut off service? Or just annoy you until you give up? Some people I know; this isn’t going to work too well - they’ll outlast the annoyers every time.

Two closing thoughts here: one, I had two registered and paid for cable outlets in a house - one for the TV and one for the receiver. At some point, I realized that I never listened to cable radio, so I called the provider and asked that they disconnect the receiver feed. Guy showed up at the front door, handed me a form to sign and then turned around. I said ‘Hey, don’t you want to disconnect it?’; he said ‘What’s the point?’ and walked away. The implication was that as soon as he left the driveway, I’d just hook it up again and they had no way of detecting this.

Two, I have a personal phobia about ‘Wheel Of Fortune’, hate, hate, hate. Years ago, I heard about a magic truck that could drive past your house and tell them what you were watching just then (to get ratings data, I suppose). I’ve spent the next several years making DAMN sure that if I fell asleep there was no way that WOF could possibly and accidentally be on my set in case they drove by. On the surface, this sounds like another UL but who knows - all they have to do is look at the IF signals that your set’s radiating back out, it should be fairly simple to work that back to a channel. Take it one step further - if they could tell what’s on the tube, they could probably tell if you can legally get that show or not.

For that matter, I ran a across a link a while ago about a guy that had built a box that would let him, from hundreds of meters away, see what was on your computer monitor - why wouldn’t couldn’t you build a similar box that worked on TVs? Okay, the site had an odd feel to it that made me doubt a lot of what he was claiming - I’ll have to find the link and share it with you, see what you think.

Working …

26

In the last paragraph, please replace “wouldn’t couldn’t” with one word or the other, take your pick.

Thank you.

27

Wow, I’d expect a super nerd to know that both Ethernet and cable TV can run over the same medium (i.e. coaxial cable).

Of course sending a pulse and looking at the response would work on any conductor. The TDR would have to be designed/calibrated for that to tell you anything useful, I’d think.

28

In reply to therealbubba’s question–yes, there are DSS boxes that get everything for free including the pay-per-view and the sports packages. My brother works with a guy who always has everyone over to his house to watch the free football package and the boxing events. But he only paid $200 for the box and installation. I don’t have info on how it works, I just thought I’d answer the question.

Born O.K. the first time…

If you are born again, do you have two belly buttons?

29

ravenous, I was having some trouble with this statement:

The boxes I’ve personally seen don’t do this - they just report on signal quality end to end and report if there are any unusual reflections along the way (i.e., noisy connections). Maybe the cable police have more sophisticated ones, the ones I’ve personally seen just tell you about the wires, not the devices connected to them; feel free to correct me.

Next, unless you’ve signed up for some really bizzare cable modem scam, the coax that carries cable is a very different form factor than the coax that carries ethernet signals. This requires different connectors, terminators, etc, and these would all react differently to the test gear. And, finally - if you’re still running ethernet over coax, jeez - get with the program. That’s in the same league as dial telephones; I can buy a 10baseT hub at my local ‘drug’ super store (aka ‘anything for a buck mart’) for under $40; 100baseT for maybe double that. I’ve got a thousand feet of cat 5 cable in the basement that I paid about $80 for, compare that to the cost of coax. The only people I personally know that still use coax are … well, the last one switched over about eight months ago, and I would have paid half of their cost just to simplify my life.

Okay, sorry and end of rant. Nothing to see here, folks - move on …

30

SuperNerd said: (I love that name)

And I explained how Ethernet and cable TV could theoretically both run over the same medium. Of course everyone runs twisted pair these days so I won’t get into coax types.

What I should’ve said is that what they’re testing with the magic box is not the technology but the wire. Now I could go into all this stuff about delta functions and Fourier transforms but I’ve forgotten all that, so I’ll stop here.

Personally I also doubt they can see much about what you’ve got connected to the wire. There’re gonna be all kinds of reflections coming off and figuring out whether it’s a VCR, a splitter, or a TV would be a major WAG.

31

Dirty Devil,

I would think that if you have the kind of cable that can be received with standard “cable-ready” equipment and do not use the cable box, the TDR methodology would not be capable of detecting unauthorized equipment. Basically, there would be too many possible legitimate interfaces… But then don’t come crying to me if you get caught, I could be wrong.

On the subject of the TDR… Time Domain Reflectometry is somewhat independent of the medium. Any pair of conductors can be TDR’d. I work in the electronics industry and we use TDR equipment to suss out ethernet problems, analog transmission lines, and even PC boards. They all have different characteristics, of course, but the principles are fundamentally the same. My understanding of the way the cable company’s TDR works is that when they first do an installation, they TDR the line with a complex frequency sweep and record a sort of ‘fingerprint’. This fingerprint is unique for each subscriber configuration. Apparently, the natural drift of this ‘fingerprint’ is fairly predictable and nominal. The cable company periodically rescans the configuration and compares the current ‘fingerprint’ with the one they have on record. If they are radically different, then bogus equipment is suspected and they take action to have it removed. I have no idea what the frequency of these rescans are, but suspect you could go a long time with unauthorized equipment connected without being detected.

All of this is moot for me. Even if I wanted to steal cable, I couldn’t (and for the record, I don’t want to steal cable). My cable system is setup such that the signals are trapped at a sealed junction box, along with my neighbors’ cable.

32

Okay, so over the last three years, I have had: swapped out the TV; added a DVD player; moved the cable over to an AV receiver; flipped to a different VCR; and then flipped back to the original. There’s at least four major changes to the configuration and no one’s come to the door to check. This still doesn’t sound very plausible.

Okay, I’ll agree that they could check if they wanted to, but think about the logistics of it. My little town is 900,000 people, be conservative and figure that’s about 250,000 cable drops. How are they going to maintain, monitor, and update the fingerprint for all of us?

Thank you. This alias has been mine for years now, has gotten me a wife online and I’m never giving it up … so don’t ask.

33

I’m going to start a thread about the grammatical errors that always seem to creep into these things. The above was written as I was getting ready to go to work, I was in a hurry, please ignore any random inconsistencies. Bye, I’m off now …

34

What ever happened to sharing your neighbors’ cable connection with a splitter? Fun.

Still, it baffles me why they charge $4.25 per month for their own splitter if you want it on two tvs.

35

Turns out that the job I had to do this morning only took an hour. The bad news is, I’m not getting much income this morning. The good news is, I can annoy people here some more.

Assume that cableco actually does have the equipment and energy to look at individual fingerprints. Assume that the average customer doesn’t actually change his/her setup all that often, so the fingerprint tells you something useful. I could just drop in a distribution amp (available at any Radio Shark for about $20) - correct me if I’m wrong but when they swept the wires they’d see the amp and nothing past it, right? If you’re going to the expense of buying the descrambler, what’s another twenty bucks?

Handy, if you’re sharing the cable with your neighbors, the distribution amp is the only way to go. You get a much cleaner signal, especially when you have to run the wires around the shrubbery; over the fence; etc.

36

If the amplifier had an isolator (passes signal one direction, and not the other) built into it, they’d be hard pressed to see beyond it. I don’t know whether amplifiers routinely include isolators, but it wouldn’t surprise me.

The way they’d detect a descrambler would be to use the TDR on several descramblers, and look for characteristic patterns in the return signal that are different from patterns they see from other devices (splitters, VCR, TV, etc.). They could’nt necessarily tell between an illegal descrambler and one of their own, but they KNOW whether you should have one of theirs.

Certainly, the more stuff you hook up, the harder this all becomes.

It is too clear, and so it is hard to see.

37

Okay, I found the site I was thinking about: http://www.eskimo.com/~joelm/tempest.html - this covers the Tempest project. As a bonus, I also stumbled on: http://www.spyking.com/datascan.html which appears to be a commercially available product. Both of these are concerned with grabbing the contents of a computer monitor from a distance of ‘over a 1000 yards’ and with no physical connection at all to the targetted machine.

Since a lot of the technology in a TV is pretty much identical to a computer monitor, I’d have to assume that you could build a similar box that allows remote viewing of a TV screen (say, from that cable company van that’s parked across the street there). From a purely practical standpoint, this sounds a lot more effective than doing the fingerprint analysis. Just drive slowly down a block at 8 or 9 pm, and see if the houses without descramblers are watching a particular movie …

38

Hmm. I seem to be the only one who doesn’t have an illegal descrambler box…I have an illegal descrambler CHIP. You install it in your legal cable box (since I live in the sticks where they still have these) and it unscrambles from inside your box.

Manhattan: It’s strange; I know what I’m doing is stealing, but somehow I feel no compunction. And I should note that I am extremely law-abiding and I feel bad if the light turns yellow while I’m under it. But somehow on this issue, I’m morally inert.

39

NO! NO! NO! You guys still are not getting it. The TDR only works on cable systems that REQUIRE a cable box. The TDR only sees the cable line and the cable box - anything else shows up as an anomally. You can’t put anything between the wall and the cable box (including splitters and distribution amps) or the TDR will see it. It doesn’t matter what you put on the output side of the cable box - it’s not reflected back. Unfortunately, once you’re past the cable box there’s no scrambled signals to be had.

eden,

You wrote:

Human nature. People always rest easier when they’re pretty sure they can get away with a crime. That gives the ego defense mechanisms a chance to kick in and dream up all sorts of rationalizations and justifications for why it’s OK… One word of advice: make sure you swap back in the stock chip when you return your cable box.

40

I don’t know much about this, but for what its worth, I just recently got cable (legally) and saw a commercial from the cable company saying that they had the technology to detect black boxes from outside the house and the would by in my neighborhood soon! Spooky!

meredith
“Everybody needs underwear!”-Rob Petrie