[Starlink] Re: Starlink and Iran

[Colin_Higbie <CHigbie1@Higbie.name>]

Ulrich, thanks. That's a great description and you're right that I had not appreciated how much more directional these are today  (in fact, in the early military applications, before it was available in cell phones, the lack of directionality was important to protect our teams from being located, even as they were transmitting from close to an enemy location).

However, this creates a follow-up question: working as you describe, which I accept as correct, why the big concern from Jeff Bezos and others about the sky coverage of the Starlink LEO constellation making it tough for them? If the signal is as hyperdirectional as you've described (also saw your laser pointer example in response to Hayden Simon), I would think that means very low risk of significant interference between two nearby layers of satellites. Even with thousands zipping around the Earth, I would think the probability is quite low of any two of them being on the same line to a home dish. What kind of interference are Starlink's competitors complaining about? Is it that while it's tight beam, it's still not *that* tight, so if they're within a few miles of each other, that's enough to trigger interference?

Thanks,
Colin


-----Original Message-----
From: Ulrich Speidel via Starlink <starlink@lists.bufferbloat.net>
Sent: Friday, 16 January 2026 9:27 am
To: starlink@lists.bufferbloat.net
Subject: [Starlink] Re: Starlink and Iran

On 16/01/2026 6:42 am, Colin_Higbie via Starlink wrote:
> Can't the traditional approach of just flooding the air with noise reduce the SNR to the point that most packets are indecipherable? I don't believe this requires a digital or technically advanced approach nor a focus on GPS or anything else so specific, just sufficient power and ability to broadcast fully across the same spectrum bands to drown out the valid signals. Starlink, like cellular technology, uses excellent methods to operate amidst a lot of noise and find its packets, but it's still not immune to noise.
>
> Iran is a large area, and probably the government lacks the ability to block the entire nation simultaneously, but I would think they could drown out the signal in specific geographic regions, effectively jamming the signal entirely or almost entirely in those areas.
>
> Perhaps some of the cellular or satcom experts here can expand on or correct me if I'm mistaken. My physics knowledge on this has not updated much since the original spread spectrum work decades ago.

The original spread spectrum work concerned much much lower frequencies (in the MHz rather than the GHz) and the physics that goes with lower frequencies (not just spread spectrum) is that at the time, jamming was mostly used against receivers with fairly omnidirectional antennas. 
Read: It doesn't really matter where you transmit your interfering signal from - the receiver will hear it. It also helps that the (free
space) path loss of RF signals is proportional to the square of the frequency, so low frequency means you can hit a receiver over a substantial distance with relatively little power.

Starlink is a different ballgame: It operates in Ku-band above 10 GHz. 
This means highly directional antennas - so you literally need to transmit into the receive beam from the beam's preferred direction to be able to jam at all. Plus having to invest more power to bridge the distance means that flooding just isn't an option here.

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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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