How to Jam a Worldwide Satellite TV Broadcast 326
An anonymous reader submits: "According to an MSNBC article, 'it's simply a matter of aiming a strong signal at the uplink transponder on the satellite and overwhelming the...broadcaster's signals...You need a dish, some power, not too much. You put up a test pattern ... and do a sweep and find the transponder on the satellite you want to jam. It could even be smaller than the standard 6-meter dish. It could be a small dish with a lot of power.' This was apparently how an Iranian satellite television station was knocked off of Loral Skynet's TelStar-12 a few days ago. Loral contacted TLS, a company which specializes in satellite broadcast security, who quickly located the source of the jamming to Cuba."
Re:Countermeasures (Score:5, Informative)
Huh? By definition, spread spectrum bounces all over the given band of frequencies in some predetermined patern. It makes it a bit harder to jam, because you'd have to cover all of the frequencies with the jamming signal, but not impossible if the attacker can just jam the whole frequency range.
Furthermore, spread spectrum makes things a whole lot harder on the transmitters on the ground. Let's use a simple example, imagine a satellite with channel space for 6 upbound signals coming from 6 different TV networks that are located at 6 different studios. In simple frequency division, they'd each get 1 slot of bandwidth, and so long as nobody retunes their transmitter to somebody else's frequency it all works. But, in spread spectrum, they'd each be all over the band... unless coordination was very tight between the spreading patern, the 6 sources would keep jamming each other by being on the same frequency at the same moment... you'd need a ton of retransmitting and error correction to get around that.
Re:Countermeasures (Score:5, Informative)
A sophisticated antenna system will provide steerable nulls in its radiation pattern. Once the source of the interference is localized, the antenna can be adjusted to place the null over the source of interference.
Re:How to find out the location of a jammer? (Score:5, Informative)
If you pay them lots of money they'll send out helicopter
(assuming its not in Cuba!) to find the exact antenna causing the problem.
Re:Umm... How'd they figure out Cuba? (Score:4, Informative)
Here's TLS's website. They talk about how they do it.
http://www.tls2000.com/Site/Equip.html [tls2000.com]
--PatRe:Noooo! (Score:5, Informative)
Your average satellite receiver is setup to deliberately receive and amplify a particular signal, to make it usable by a decoder.
The satellite LNB (the device at the focal point of a satellite dish) is tuned when installed, and is specifically set to give the decoder a signal of a particular strength. This is usually measured in the order of a particular number of decibells (dB).
Most receivers will actually shut down if you overload them with signal however. It's possible for you to encounter problems when you tune an LNB, and someone goes and jacks up the output level on the satellite for some reason (like, say, they need to use it to broadcast military signals
This means, that on the satellite that's receiving the uplink, you'll find that if you overload it, it'll just shut down the receiver instead of overriding the signal.
Don't let anyone fool you into thinking you can drive everyone nuts by replacing their favorite shows with reruns of the original odd couple
ashridah
Re:Countermeasures (Score:3, Informative)
Not really. A pre-determined psudeo-random frequency hopping system sync'ed with a time signal from, say WWV, GPS, NTP, or a sync signal from the transponder itself would do fine. However, you are solving the wrong problem with this solution. (Police Fire and Ambulance use something called "trunking" that's quite a bit like this.)
The problem is that a stronger signal at the receiver can't be rejected based on transmission charateristics absent directional receiving antenna. That signal is going to be there, and it's going to interfere. Yes, you can use authintication to select the correct signal, but if the Automatic Gain Control (AGC) on the receiver is de-sensitized to the point that it can't get the correct signal (by virtue of the fact the the jammer is using more power than you are) then you are up a creek.
Using a directional antenna for the uplink receiver will mean that the jammer will have to be in the same geographic area your transmitter is in to jam you. The more directional the antenna on the receiver, the closer the jammer has to be to your uplink.
The advantage to that is to keep the jammer in the same jurisdiction you are in and all kinds of things can be done, up to and including a raid from armed police to stop it. You won't be able to prevent it, but retalliation in this situation would be swift and sure.
In an earlier post, someone asked how the jammer can be located. When sending a signal up to the transponder, the signal is sent using a directional antenna. Even the best antennas will have some broadcast leakage. At these frequencies, you can also detect the area of the beam from scatter introduced by dust, water vapor, and pollution. You can get at least a general sense of where the transmitter is, though pinning it down to 1000 feet would be a bit more difficult until you have a receiver in the area.
To see this in action, go outside at night and shine a flashlight up at the sky. You can see the beam going up. Same principal, different equipment.
Re:Cuba, eh? (Score:2, Informative)
Even though they've made it illegal for Americans to import them, the Americans have a major hardon for Cuban cigars. Must be all that Cuban siliva. If you smoke those things, and don't know how they're made, you really MUST have a look at a video on traditional Cuban cigar manufacturing. Might help with that whole stop-smoking thing.
Think sweatshops full of old ladies rolling tobacco leaves, frequently licking their hands and the tobacco leaves to help the leaves stay together.
Re:Cuba / Guantanamo Bay listening stations (Score:5, Informative)
Armchair punditry at it's worst.
If you'd do some research about NITV [cbsnews.com] The TV station is actually broadcasted from the US into Iran. That's right. National Iranian TV (NITV) is produced in the US. And no, I am not making this up.
NITV, not being state run, has government enemies in Iran for doing things like making fun of the leaders there. So the Mullahs in Iran call the Castro gang in Cuba and get them to do a favor for them.
This is something the US military would not want to block.
A number of reasons (Score:3, Informative)
Then there is also the idea that you aren't supposed to deliberatly interfere with others' communications. Both you and I are welcome to operate devices in the 2.4ghz specturm without liscence. Perhaps I want to operate a phone, and you want to operate a wireless data link. However, if you make a device for the purpose of interfering with my phone signals, expect to get in trouble.
It seems to me that kind of a common hacker/cracker logical fallicy is that just because you have the ability to do something, means it should be ok to do it, that if the other side can't stop you technologically, it is ok for you to walk on their rights.
Well I like to compare breaking in to a system, even with no intent of doing damage, to breaking in to a house. See most residential locks are very easy for a trained locksmith to pick. With the right tools, a few minutes of work is all it takes them. Now, how would you feel if you come home and there is a locksmith poking around your place. You get mad and he tells you "You should have had a better lock." He'd have a point, the falws with your lock are well known and documented and you can get better locks with just a little effort. So you go and locate a Medeco dealer and get yourself a high security lock. These are much harder to pick because of their odd pin design. However harder does not mean impossable, and good locksmiths can still do it given time. So again the locksmith is back. Where do you go from here? There are solutions out there, you can get a system that not only requires a phusical lock to be unlocked, but a code to be entered to electronicly unlock a second lock. However that too has problems. And of course the real problem with these increasing solutions is that they are increasingly expensive. A Medeco deadbolt costs almost $200, all said and done. That's a hell of a lot more than an average lock. Most of the electronic locking systems are a good deal more than that, and are kind of difficult to track down as an ordinary person.
So just because you can hack past someone's computer security or just because you can override someone's satalite signal, doesn't give you the right to do so.
Re:Countermeasures (Score:3, Informative)
The satellite in question went into service in 1999, thirteen years after Capt Midnight demonstrated how to take over an uplink. It's not like they haven't had time to figure this out, or that the expense involved is large compared to the cost of a communication satellite. So why haven't they done it? The only plausible explanations are inertia and incompetence.
Re:Hah! That's nothing. (Score:2, Informative)
An Iranian's View on the matter... the REAL story. (Score:5, Informative)
We have 6 channels. One is news, one is sport and the other four are mixed channels, showing anything from soccer to documentaries to dubbed American films and series (yeah, death to america baby!!) to English films in original language to japanese samurai black and white films to cartoons etc.. you name it. Ofcourse the news biased towards the evils of America and the poor Palestinians getting killed and so on (one interesting thing is that when 5 Palestinians get killed, they are Martyred (and if there are any kids / women in between the killed, they are mentioned loudly, but if a school bus of Jew kids are killed, then "20 zionists were killed"
Satellite Receivers and Dishes are 'illegal' in Iran and every now and then the media's attention is focused on the matter and so the local police bitches about and raids a few houses, taking away their equipment and fining them... then gives up. This has become the norm. Since Tehran (the capital city) has over 14 million in population, going round every house and taking away their equipments was not a feasable task. I have written (at the end of this post) what they have done NOW to get the channels jammed and it seems to be working... 90 cm dishes are the norm here. They're big enough to do the job and yet small enough to be concealed easily. 60 cm versions are also available but you need a *really* good LNB (such as Nokia) to get a good signal. Now on to the NITV matter:
The National Iranian TV station (NITV) is a station based in USA and it mostly broadcasts talk shows and documentaries AGAINST the current regime in Iran so they are America's friend and Iranian government's enemy. Currently, there are 6 or 7 Iranian language satellite channels that can be received in Iran. All are transmitted from "TelStar 12" satellite. About two years ago, the only Iranian satellite channels were NITV and another one I can't remember. Both used to be broadcasted from Hotbird satellite. That
was until their signals were jammed multiple times (after a few months of broadcasting) and at the end they made the decision of moving to TelStar 12. I remember they issued a statement that Hotbird has received jamming signal FROM IRAN that has worked against the Iranian channels and so on... the funny thing is that the Iranian gov. broadcasts 4 or 5 propaganda channels to the very same "hotbird" satellite and they continued to broadcast their programmes even after Hotbird had found about their dirty trick. Don't you think those hotbird guys should have stopped broadcasting their programmes as a result ?
Since then, everyone has had to either add a new satellite dish or just add another LNB to their dish (which is set to Hotbird to get those music shows) and receive the Iranian channels as well. Recently there was a lot of talk in the "Majles" which is parliament about jamming signals being broadcast locally to stop people receive the
channels. And there was debate on whether these signals could be cancerous or not. At the end, they started to send jamming signals while the case remained open in the parliament.
At first, I laughed at the idea because a satellite dish works by concentrating bounced microwaves to a point where the LNB receives them and converts them to electrical signal. But if the government broadcasts signals locally, then the point of concentration would not be at the LNB part and so it shouldn't really matter huh ? Well, I am wrong and they have been successful (up to a certain level) to annoy the hell out of people and in some areas people can't get a signal. The jamming they are using is sweep based. From what I experienced at a friend's house, the sweep signal was on *any* channel