Imposing a TV and radio blackout.

[cadebertezim]

Setting: Corrupt police state in a modern fantasy world, mostly 70's/80's level technology but some more modern and futuristic stuff as well, no internet, completely state-run media. A small island,  has been placed under blockade. It's about 10 miles by 5,  in an archipelago of other small islands, about 50 miles off the mainland and with the

Comments

[samtyr]

Personally, I think it would be easier to keep things running and just replace the regular newscasters with 'puppet' ones; and then say that the regular people "are on vacation" -- meaning dead or detained, your choice. Hope this helps.

[cadebertezim]

I don't think I was clear enough - this state controls, and broadcasts to, the whole mainland, several other countries, and this archipelago off the coast of which this island is a part. Until now, the island would have been receiving the same programmes as everyone else (with maybe some archipelago-specific local programming, I'm not sure). The state now wants to isolate this ONE, very small, island. It's not worth disrupting its state-wide broadcasts just for that.

The news is, of course, only its own propaganda anyway, and always has been - but it does provide some information about what's happening in the world and the state wants to stop this island from receiving even that.

[tylik]

Not that this is my thing, but it would seem feasible to monitor what signals are available from the outside. Set up stronger local signals in those frequencies - these don't have to carry content, just enough noise to cover up the outside signal.

[beccastareyes]

That could work. I know that in radio astronomy, the military occasionally uses bands that are supposed to be reserved for scientific use, and it really screws with the astronomers' attempts to work when a satellite passes into the field and is transmitting at the same band they are observing at. (I have friends who are radio astronomers.)

Downside would be that the neighboring islands would probably notice the static as well (though probably not as bad), given the distances, though you could make up a cover story about solar flares or something making TV transmission spotty. And a clever engineer might be able to filter out some of the noise depending.

[reapermum]

The situation seems to point to each island having it's own relatively low power transmitter relaying the programmes from the mainland. Take out the transmitter and they have no programmes, without affecting the other islands. Their transmitters won't be powerful enough to be picked up on neighbouring islands and the more powerful transmitters on the mainland will be too far away.

Much easier to take out one transmitter than to find every receiver on the island.

That will only work for TV signals. Radio waves travel a lot further. I remember the days when it was difficult to listen to BBC Radio3 in the evening because of the interference from Radio Albania.

[melannen]

Okay, first: you get to pick their tech level. So let's look at the possibilities.

Using an actual island with modern tech level in the '70s or '80s, it would be really hard, because there would probably be at least a couple hobbyists who know how to set up a short-wave set, and shortwave radio can pick up signals from the other side of the world using only very basic equipment. My dad set one up as a ten-year-old using scrap metal and electronics

[melannen]

The other possibility is to have them not use broadcast media at all (or at least not long-distance broadcast.) If your planet is different from Earth, you can kludge things so that the atmosphere, and the surface, don't propagate radio waves as well, which would limit the distance which signals can be picked up to basically only places where you can actually see the transmission tower. This would take either a lot of kludging, or willingness to not worry about the science, though

[melannen]

Oh, I should have mentioned - jamming might or might not affect the nearby islands, depending on how you did it: broad-spectrum jamming would almost certainly have some effect on the nearby islands. Jamming that is tuned to cover only specific stations might be low-power enough that they would only occasionally notice it and put it down to normal static

[cadebertezim]

That's some wonderful stuff, thank you very much. I think I might take a combination of options - cutting cables seems easiest and most appropriate for television - I assume I can say they just don't use analogue for TV.

As for radio, hmm. Yes, I think people would have been able to learn to build short wave radios, and I think analogue broadcasting would continue to happen. So, jamming - the Wikipedia article says this:

A transmitter, tuned to the same frequency as the opponents' receiving equipment and with the same type of modulation, can with enough power override any signal at the receiver.

One thing I'm not certain I'm understanding -where would the transmitter need to be to jam the radio frequencies reaching the island - assuming this wasn't broad-spectrum jamming? On the island itself? (From your comment about broad-spectrum jamming above I think so, but I'm not quite sure.)

Once they've at least made things difficult they'd probably just police the island like crazy and worry about things like pirate radio as and when.

[stickmaker]

After the fall of the Soviet Union, a former high-ranking official said he knew it was all over when the people sent out to confiscate TV satellite dishes found that they were being hastily removed before the teams could get to them.

Communication had become so quick and easy that word spread faster than the government could act.