This isn't that hard to do. You just need a dish, a suitable power source and point it at the satellite. Because of the, in general, wide area that a satellite is looking down on the transmitter can be anywhere in quite a wide area (even when you are talking about the relatively narrow uplink antenna).
Given that these satellites are geostationary they can be seen from a very wide area on the ground. Back in 2003 Telstar-12 was jammed from a station in Cuba apparently run by Iran (http://www.atimes.com/atimes/Middle_East/EH22Ak03.html) to block transmissions to the Americas and Europe.
You seem to describe satellite uplink jamming: perturbing the link going from the content provider to the satellite. I would expect this uplink would be redundant and encrypted in some way. Maybe even using optical communication for it, which would enable having a very narrow uplink receiver.
Thinking about it, jamming the downlink in a large area to get the same effect seems to be much harder than jamming the uplink.
To jam the downlink, you'd need to be between the satellite and the
ground receiving dish, or have line-of-sight to the receiving dish and a
ton of power. This only disrupts the one receiving dish, so the attack
is isolated.
Jamming the uplink is much easier. All you have to do is over-power the
signal from the transmission station(s) up to the satellite. Encryption
doesn't do you any good. Having redundant uplinks also doesn't do much
good since the resources of the satellite are limited, and the amount of
power you can get here on the ground is more or less unlimited by
comparison. There are multiple uplink transponders (chunks of spectrum
used as carrier frequencies), and you can allocate them in a redundant
fashion, but it's expensive due to the limited resources on the sat.
The interesting, and undisclosed, question is whether or not the attack
is only affecting the BBC? If so, then it's a more sophisticated attack
targeting just the carrier frequencies (uplink transponders) being used
by the BBC. A high power wide-band attack is crude but easier to
perform, and would jam all of the channels broadcast from the satellite
since it would over-load all of the uplink transponders.
Sadly, there are still a lot of old and poorly designed satellites
still in use; it's kinda like finding unfixable Win95 systems on your
network infected with malware. Since they're in orbit and cost a whole
lot of money, fixing or replacing them aren't a viable options.
The only good news for older satellites is both the uplink (to
satellite) and the downlink (to ground receivers) often have somewhat
adjustable footprints. If you can identify the ground location of the
jamming signal, you might be able to exclude its region from the
uplink footprint. The trouble is, if the satellite is also being used
for things like sat-phones, then you just cut off all customers in the
excluded area of the uplink footprint.
By the fact that this was made public, there's probably nothing that can
be technically done about the jamming.
> ...if the satellite is also being used for things like sat-phones...
And, reading between the lines, that right there is possibly your biggest clue. Beyond the juvenile intrigue of someone breaking something just to see if they can, or even some chintzy politically motivated anti-propaganda operation, another motive might lie in assisting/disrupting (depending on whose side your on) clandestine operations in a specific geographic area.
It's tempting to wonder if maybe it's just some Greek crypto-anarchists horsing around, but more likely it'd be someone with heavy-weight resources and know-how like CIA/GRU agents operating in Syria.
From the article:
"...together with a number of other broadcasters, is experiencing deliberate, intermittent interference to its transmissions to audiences in Europe and the Middle East."
I think you hit the nail on the head. This is very interesting in light of Turkey intercepting "radar" equipment from Russia to Syria.
If the jamming is coming from Syria, I'd say it's the government trying to jam the encrypted satellite radios of the rebels. (Some of the aid to the rebels from the US and Europe was for secure comms.)
The best way to learn is relentless curiosity. There's always a big
difference between the stuff you need to know and the stuff you want to
know. If you're truly fascinated by how things work and you really want
to know how they work, learning is much easier and far more enjoyable.
The best part is, even if the learning is actually horribly difficult,
you never notice you're suffering since you're having a lot of fun.
I started messing around with satellite based data broadcast systems in
high school during the mid 80's due to my dad's work. The systems
delivered real time stock, commodities, and futures data at a time long
before the craze of web based "Internet Trading". Back then, only the
most serious trading businesses had real time quotes and the systems
were connected by either satellite or dedicated lines. Since it was a
"broadcast" systems (one-to-many), it's fundamentally similar to
satellite television broadcasting.
The two-way satellite data/voice systems work on similar principles but
there are a few major designs in use. Some satellite phones work with
an array of sats in Low Earth Orbit (LEO) and only require an adequate
pole/stick antenna. Other satellite phones work with satellites in
geostationary orbit and require a two-way dish for both broadcast and
receive. All of the satellite based Internet Service Providers (ISP)
serving rural areas use geostationary satellites.
Some people wonder how Steve Wozniak can live in (near) the Silicon
Valley and still complain about broadband speeds/coverage in the US.
He doesn't live too far from me up in the hills above the valley, and
the odds of fast broadband every reaching up here are very slim. As you
might expect, I've run a satellite based Internet connection in the
past, so I got a chance to learn the internals of those systems as well.
Satellite based Internet connections have very high latency. The minimum
ping time is roughly about 480 ms ... umm, I think, but for fun, let's
do the math:
Geostationary Orbit: 35,786,000 meters elevation.
Speed of light: 299,792,458 metres per second.
The ping request would travel from you up to the satellite and then back
down to the ground station, so it travels twice the distance of
geostationary orbit (up and back).
The ping reply would also travel from the ground station up to the
satellite and then back down to you, so it also travels twice the
distance of geostationary orbit.
(4 * 35,786,000) / 299,792,458 = 0.47747
Yep, pretty close to the 480 ms I remembered, but that's just the raw
travel time under totally unrealistic conditions. In reality, you're a
lot farther away from the satellite rather than directly below it at sea
level, and there would also be some over-head for the computer systems
involved.
The above also assumes you're on a dedicated transponder (i.e. you have
a very expensive chunk of frequency dedicated to your sole use), but
since you never get a dedicated transponder on a consumer service, ping
times can be in excess of 3000 ms on a regular basis. The transponder
space allocated to the ISP is shared amongst all of the ISP's customers
via TDMA. FDMA, FTDMA, and I think occasionally CDMA. Even when you know
how to tune your own TCP/IP stack and all of your applications to adjust
for the high latency, using a lot of typical things (like web browsing)
are still absolutely miserable. Think about it this way; every time you
click on something, you have to wait 3 seconds for anything to happen.
It drives most people nuts, so using a satellite based ISP is a last
resort, and in some ways it sucks more than using a 14,400 baud phone
line modem.
You see, once you learn some of the basics, then you have a base for
learning more fun stuff, but most importantly, you also gain the
advantage of being able to "reason" about how other related things work.
But it might be worth noting that you can use spread-spectrum techniques (http://en.wikipedia.org/wiki/Spread_spectrum) to overcome jamming. Spread spectrum has some similarities to an encryption scheme, because the method used to smear the signal around uses a pseudorandom sequence which is known to the encoder and the decoder.
Right, and you now have variables under your control to drive their power requirements arbitrarily high -- namely, the better your timing, the higher your effective S/N ratio (because your spread-spectrum signal can be, in effect, very-very narrowband, but hopping all over).
You increase your timing accuracy by 10x, and the jammer's power requirements increase by 10x (crudely speaking -- not a 1:1 trade, but directly linked).
That's a different kind of spread-spectrum. That's a frequency-hopper, where the carrier changes frequency (the first SS- an idea attributed to Hedy Lemarr in the lore).
We're talking about direct sequence, which increases the bandwidth of the signal but keeps the same carrier. To jam that (theoretically) you need large power through the entire band.
I was talking about both -- for the purposes of explanation, frequency-hopping is more intuitive. (I was trying to be responsive to @Redfern above, who mentions frequency-domain jamming.)
Both frequency-hopping and direct-sequence spread energy over a larger bandwidth. Direct-sequence does not explicitly frequency-hop, but the time-domain switching it uses will spread the energy out in Fourier space.
The most basic of jamming is to drown out all other communications with high-power noise. But in the case of illegal/covert activities this isn't ideal as your transmitter will be pretty easy to find.
So then you have to pretend to look like a legitimate signal. Which is where encryption and modulation can help. But then application level encryption isn't going to help against basic jamming.
You might expect so, but apparently a lot of satellites are just dumb repeaters. Remember that they have a low power budget and you can't upgrade the hardware once they're in the sky. If you design something that relies on a particular modulation scheme it's going to become obsolete once everyone moves to a beeter one.
In unrelated news, the EU forced persian TV channels off these transponders a few days ago, citing the "targeted" sanctions intended to prevent Iran from drifting further afield.
The word ‘persian’ there is a little misleading. The European satellite providers stopped carrying the Iranian government's channels, not Persian-language channels in general.
Apparently the BBC opposes the removal of the iranian/persian channels as well. From the article "we strongly condemn any practice designed to disrupt audiences’ free access to news and information."
It maybe true that the BBC opposes this, but at the same time the BBC is beholden to UK and EU law; i.e. follow the law or be fined and/or loose all your licenses.
Since I'm not a native English speaker, I had to google what "Jamming" was about and found this article in Wikipedia where actually explains the difference between Jamming and Interference.
Does anyone have any information on how this could be done? Does this require high tech broadcasting equipment to intercept the transmissions (government sponsored?) or is it something that anyone could do?
anyone can do it, for some values of "anyone" that includes having a good power source, some rf equipment and a few books. mostly the problem involves defending the equipment when people unhappy about said behavior arrive.
I can't say for sure how "they" do it, but there are a number of options available. Radio in general is very leaky - even rather low power and directional beams can be detected off axis if they travel enough distance and you have sensitive enough equipment. In general you just need a few antennas (or even one, if your're a masochist) and an ability to point them at things. Check for when the signal is the strongest, and check for timing between the receivers and you can get a very good idea of where the transmission comes from. In practice you could do this with multiple antennas (an array) on a single satellite, multiple other satellites or spacecraft, or simply an aircraft or trucks if you control the ground space. I'm willing to bet it's usually done on the targeted bird itself, they aren't completely cut off from communication, have multiple antennas and can even adjust their attitude if it was necessary.
This is broadly how the SETI program works for example.
If you'd like a good demonstration of how a jamming device could be found, simply buy a high-power 10 meter radio transciever and set it up to constantly transmit music at 28.400 MHz. You'll effectively monopolize the frequency over a large distance, and within a very short period of time the FCC will arrive to demonstrate their RF tracking techniques.
The FCC will care if you are transmitting without a license, broadcasting (rather than performing 2-way communications), and sending music--all three of these are violations of FCC regulations. Once they determine that it's an ongoing disruption, they will come out with a direction-finding rig, as they have in the past for "pirate" operators causing disruption.
Think of it this way: radio is light. There's a light sensor on a satellite that the BBC shines at. Someone else is shining a really-bright light at the satellite so it can't "see" the BBC's light through the glare of the other bright light.
Kind of like trying to see a flashlight when someone's shining headlights at you.
But ... if you're shining a really bright light then everyone who cares to look can see where it's coming from.
Very possible. In fact, some aircraft and ship navigation systems (prior to GPS) at a very basic level determine position through triangulation based on direction to known RF emitters. (See Loran, NDB, etc).
Its also a popular sub-activity of HAM radio, in which its called "Foxhunting."
I have to wonder why the BBC would release this. What is the motivation?
Obviously whoever is "jamming" them is not going to read this, say, "My bad" and just stop.
I am really wondering who their real audience, in this case, is. Is this an attempt to influence government actions in the U.K. or the EU itself? Is this part of a public opinion swaying operation to sway the British people so that more of them will support the idea of military action in Syria?
It's all speculation at this point, but I do wonder.
If you were a global international media company and someone were jamming your signal over a region of the planet wouldn't you put out a short, factual press release too?
If nothing else, it will help some of the affected viewers know to quit smacking their televisions on the side.
Given that these satellites are geostationary they can be seen from a very wide area on the ground. Back in 2003 Telstar-12 was jammed from a station in Cuba apparently run by Iran (http://www.atimes.com/atimes/Middle_East/EH22Ak03.html) to block transmissions to the Americas and Europe.