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The interesting Politics SE question To what extent can a government control satellite internet compared to internet from a local ISP? asks from the perspective of politics and international law, but here I'd like to ask about technology.

The jamming of short wave radio news broadcasts has a long and colorful story, but there are several differences between that technology and blocking satellite constellation-based internet access.

Those satellites will be transmitting tens of watts only, and only over distances of hundreds of kilometers.

However signals will take advantage of a far wider bandwidth than a voiced news broadcast over AM radio and utilize substantial error correction and spread-spectrum techniques.

Also, unlike short wave reception of yester-century, the far-shorter wavelengths used by satellites mean that reception antennas can be quite directional. Compact, flat, computer-steered phased array receivers will soon become commonplace.

Question: What is the technical feasibility of a country at least partially preventing use of internet from satellite constellations? Consider blocking for large cities or population centers as one example of partial blocking.

update: @lijat points out that prevention doesn't have to be jamming, it can also take the form of detection/prosecution since conventional internet protocol use requires bidirectional communication; to get something using a satellite server (or whatever they are called), you have to request it and probably do some other handshaking.

Ideally, an answer should be based on citable studies or basic engineering principles (e.g. power-bandwidth product) rather than oratory or generalizations.

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    $\begingroup$ In 1994 Iran banned satellite dishes, so people could not access foreign TV & news services. Also the destruction of 100,000 dishes in 2016 indicates it is difficult to prevent people from using satellite communications. It seems the Iranians have not been able to jam the satellite signals & have resorted to a ban on owning communications hardware. Also this $\endgroup$ – Fred Nov 1 at 3:05
  • $\begingroup$ @Fred really interesting links, thanks! $\endgroup$ – uhoh Nov 1 at 5:14
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    $\begingroup$ Any reason you are focusing on jamming rather than detecting and prosecuting users? The later should be simple as users have to send to the sattelites as well as receiving. $\endgroup$ – lijat Nov 1 at 5:41
  • $\begingroup$ @lijat that is a good point and I hadn't thought of that. The ground links can be mobile (on a truck, car, motorcycle, backpack or even quadcopter with WiFi to ground) so a detection and identification system would be quite a challenge to effectively implement. But I think you are right, I should open it up to interventions beyond jamming. I've made an edit. Thanks! $\endgroup$ – uhoh Nov 1 at 5:51
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    $\begingroup$ Not technically related, but culturally: during the cold war East Germany could watch "West-TV" and the East German govt made it illegal to watch. Which of course didn't stop East Germans to watch "West-TV". Apart from two regions in which reception was technically not possible... en.wikipedia.org/wiki/Tal_der_Ahnungslosen $\endgroup$ – user2705196 Nov 2 at 13:11
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With the development of phased-array antenna's, blocking of satellite communications will become increasingly difficult to impossible. Prosecution of users and/or a ban on importing/using antennas is probably the only feasible option to avoid the majority of people from using the service.

Phased array antennas use a number of antennas to shape the combined antenna pattern. This works two ways: when transmitting, you maximise the power in the desired direction and minimise the power in unwanted directions. This allows you to use the available power as efficient as possible. However, you can never fully have zero emission in undesired directions.

When receiving, you use the phased array principle to maximise the antenna sensitivity in the direction of the transmitter, while minimising the sensitivity in other directions. This allows you to suppress (intentional) interference.

phased array principe

(source)

In principle, the more antennas in your array, the more precise you can form the antenna pattern to your liking. With sufficient processing power to adapt the antenna pattern in real-time to track the satellite your communicating with, it is really hard to impossible to block that communication. Jamming sources would be on or near the ground and these can be fairly easily suppressed by an appropriate null in the radiation pattern, so one would need to block the line-of-sight.

Phased arrays with adaptive beam forming are already used for 5G MIMO antennas, so this technology is already sufficiently mature. If you can hide your array from the authorities (both visually and in the RF spectrum by blocking the side lobe signals while transmitting), I don't think it can be blocked.

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    $\begingroup$ Why does jamming have to be from the ground, what prevents a high altitude baloon system for example? $\endgroup$ – lijat Nov 1 at 17:54
  • $\begingroup$ How would you keep the balloon in place? $\endgroup$ – Ludo Nov 1 at 20:26
  • $\begingroup$ Instead of a balloon it could be a circling drone,or drones - possibly solar powered - that are periodically replaced. $\endgroup$ – Fred Nov 2 at 3:00
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    $\begingroup$ Note that you can still jam the signal TO the satellite by having a jammer station physically near the user. The required nearness would depend on the beam width of the Satellite end, and not sure if spaceX has released much on that yet. $\endgroup$ – GremlinWranger Nov 2 at 3:03
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    $\begingroup$ @Ludo, it's that last one that I suspect could get interesting, providers of space based internet might find themselves being asked to block by nation to avoid being jammed across an entire region. Generally assumed aim of a nation here is to force users onto ground based ISPs that they own. $\endgroup$ – GremlinWranger Nov 3 at 0:00

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