[Starlink] Starlink and Iran

[Ulrich Speidel <u.speidel@auckland.ac.nz>]

I guess you would have all been following the reporting on Iran & how 
Starlink is being used a communication backroute out of the country, but 
also how it's being jammed by the Iranian government. Today, I received 
a petition request from an NGO asking me to sign a petition to get Elon 
to turn on D2C (direct-to-cell) over Iran, and it's phrasing it in such 
a way that it'd "turn the lights on".

My 5 cents worth:

Jamming: Over every location in Iran, there are several dozen Starlink 
satellites visible at any one time that Dishys on the ground can in 
principle communicate with (read: 25 deg plus above the horizon and 
clear of the geostationary arc). There are purportedly tens of thousands 
of Dishys in the country. Each of those Dishys (when working) 
communicates with one of the satellites, and does so by pointing a beam 
at the satellite - which points a beam back. Even two Dishys in close 
vicinity of each other generally talk to different satellites.

To jam communication between a Dishy and a satellite you have to insert 
the jammer into the transmission path - either by pointing it at the 
satellite's receiver, or by pointing it at the Dishy. In either case, 
you want to do so ideally from the direction of the respective 
transmitter that the receiver is listening to, because there isn't all 
that much sensitivity if you're jamming off beam. Basically, because 
signal power drops of with the square of the distance, you need to be 
fairly close to a Dishy in order to out-shout the transmitter at the far 
end of the beam if you're trying to jam from outside the beam.

Jamming the main traffic channels to Dishy is an uphill task - for a 
total blackout, you'd have to cover a good part of the 2 GHz total in 
Ku with sufficient power in terms of spectral density to cause mischief. 
Not easy.

Likewise, pointing your jammer at the satellite(s) is mission impossible 
because there's every chance that the satellites will be listening to 
Dishys that are in a different direction from you.

There would I guess be some opportunity in terms of jamming management 
channels (e.g., access grant channel) but even this is complex with that 
number of satellites around.

Plus those babies move, so you need jammers that can track. And 15 
seconds after you're worked out what you need to point where, Starlink 
changes the game on you.

The Independent quotes "a specialist in digital repression and associate 
director of the Technology Threats and Opportunities Program at Witness" 
https://www.independent.co.uk/news/world/middle-east/iran-internet-blackout-protest-starlink-musk-b2900101.html 
saying that they think it's GPS jamming. For all I know Starlink doesn't 
need GPS - while Dishys have GPS receivers, Starlink's got its own 
positioning system, too. Also, GPS jamming is fairly common globally and 
it's not known to be impairing Starlink all that much.

D2C: Maybe someone should have asked the NZ Commerce Commission for 
advice first. They figured out a long time ago that D2C isn't quite 
there yet (and may never get fully there). It's only capable of 
supporting a comparatively small number of devices per unit area on the 
ground, and apart from a small number of premium phones, with text and 
perhaps RCS/MMS only. And that's with a telco on the ground that's 
actually cooperating and making frequencies available. One NZ, the New 
Zealand telco who partners with SpaceX on the D2C here, had its 
marketing department shouting the virtues from the rooftops until the 
Commerce Commission filed criminal charges. They're still in the game 
but when I bought a new mobile phone the other day, it took me several 
minutes to find the page that listed compatible phones. The service is 
now a little less prominent on their home page - you have to scroll a 
little to find it. Also, word doesn't seem to have gotten around that 
your mobile phone - even if satellite-capable - will connect to 
terrestrial networks with priority. So Iranians would have to go pretty 
far out into the desert just to TXT. Oh, and cellphones are a lot easier 
to jam than Dishys...

Of course, that's not the only consideration here. Using Starlink is 
illegal in Iran, and I guess getting caught with a Dishy is a bit risky 
there at the moment. But RF direction finding 50k+ Dishys that change 
transmit frequency a couple of times a minute isn't trivial: It requires 
specialised equipment and skill, both of which are likely to be in short 
supply at the moment. So I suppose visual identification of Dishys (from 
the air or high rise buildings) might be a more promising tactic. But of 
course they can be camouflaged to an extent as well as moved.

Also, Starlink tends to be more of a technology for underserved rural 
areas rather than cities in countries with high Internet penetration 
rates - which Iran is one of. So it's likely that many of the tens of 
thousands of Dishys are in rural locations where there haven't been any 
large protests.


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Dr. Ulrich Speidel

School of Computer Science

Room 303S.594 (City Campus)

The University of Auckland
u.speidel@auckland.ac.nz
http://www.cs.auckland.ac.nz/~ulrich/
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