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In Iran, not only mobile and fixed networks are jammed, but also Starlink. We explain how this is likely achieved despite thousands of satellites.

The situation in Iran has been escalating since early January. What began as demonstrations by business people at the end of December, expressing their anger over the poor economic situation, has developed into mass protests that the Iranian regime is brutally suppressing. Thousands of deaths are now being reported. The aim is to prevent as many images and news as possible from reaching the public, which is why the Iranian government is blocking communication networks.

Reliable information is challenging to come by, as practically the entire country has been offline since the evening of January 8; the content delivery network Cloudflare registers almost no more data traffic from Iran, and the internet observation group Netblocks also speaks of a complete communication blockade.

One of the few digital ways out currently leads via satellite through the global network Starlink by SpaceX. Although usage is forbidden in Iran, terminals are smuggled into the country, and SpaceX tolerates their use; since January 13, it has even been free of charge. However, activists are reporting that Starlink is also functioning increasingly poorly in Iran, and users are being actively tracked. But how can a system of thousands of satellites be jammed from the ground, and how does the regime find users of the devices without access to customer data or the network?

The US organization Holistic Resilience, which helps Iranians secure their internet access, speaks of around 50,000 users in the country. In this article, we will explore how Starlink works, why it functions in Iran, and how the Iranian government is likely jamming the network. While neither the regime nor SpaceX likes to reveal their cards, hackers and journalists are not deterred by this, and the laws of physics apply to everyone.

Orbit Network

Starlink is a satellite constellation built by SpaceX in low Earth orbit (LEO) to provide internet access. The primary goal of tech billionaire and SpaceX founder Elon Musk: fast, low-latency, and affordable internet access for remote regions of the world, wherever other access methods fail or are not economically viable. Developed since 2015, launched into orbit since 2019, and available for private customers since 2021, the network now has over 9 million paying customers. It is also the largest satellite network in the world to date, with around 9,500 active satellites, which now constitute the majority of man-made objects in Earth orbit. In Germany, Starlink currently charges 50 euros per month for stationary use without volume limits. The monthly tariff for the portable Starlink terminal, which serves motorhomes for example, is pricier.

Internet access via satellite is not new and has been available via geostationary satellites since the early 2000s. Due to its low orbit of around 550 kilometers, Starlink can deliver significantly better results compared to these: Instead of around 120 milliseconds of signal transit time for 35,800 kilometers (geosynchronous orbit), it is only about 2 milliseconds with Starlink.

Furthermore, customers are distributed across numerous satellites, each of which has up to 48 separate spot beams, resulting in better reception and thus higher data rates. Typical private customers with stationary terminals can expect between 150 and 400 Mbit/s downlink and 10 to 50 Mbit/s uplink data rates with 25 to 100 milliseconds latency. This is a significant improvement over the 50 to 100 Mbit/s downlink rate, 600 millisecond latency, and often limited data volume of geostationary offerings.

For this to work optimally, the user must set up the satellite modem in a location with at least 100 degrees of clear view of the sky. Currently, there is the standard set for stationary home users, the Mini for on-the-go use, the Mini X with an additional Mini router, and Performance and Enterprise models for business customers. There are also several special versions for more demanding scenarios, such as maritime and aviation applications.

Tracking without Movement

Starlink uses frequencies between 10.7 and 14.5 GHz (in the so-called Ku-band) for communication between the satellite and the customer antenna, as well as blocks between 17.8 and 30 GHz for communication between the ground station and the satellite. These short wavelengths exhibit high path loss, so directional antennas are always necessary for long distances. At the same time, SpaceX has no other choice, because anyone who wants to supply many customers with high data rates needs broad frequency blocks. The transmission frequencies of digital satellite television DVB-S2 are also in the Ku-band.

To enable the service in its quality and simplicity, SpaceX has made phased array antennas suitable for mass production, both for its satellites and for the customer satellite modems. Such antennas are, in rough terms, electronically steerable directional antennas without moving parts. They consist of numerous small antenna elements that are dynamically controlled and synchronized in groups.

A simple phased array was developed as early as 1905 and consists of three radiators whose arrangement forms an equilateral triangle with a side length of slightly more than a quarter wavelength. Operated individually, each radiator is omnidirectional, radiating equally in all directions and receiving signals equally well from all directions. However, if fed in parallel at two radiators at the base in a triangular arrangement, and the radiator at the apex via a phase delay line a quarter wavelength later, the array gains the characteristic of a directional antenna. It has a preferred direction towards the apex and base of the triangle. If the delay line is connected to one of the other radiators, the preferred direction of the array also changes accordingly by 60 degrees.

By drastically increasing the number of antenna elements – Starlink terminals are said to have up to 1500 – both antenna performance and beamforming can be increased dynamically during operation. The principle is therefore the key to Starlink's success and is used both from the satellite to the ground and in the reverse direction; both try to direct their transmissions as precisely as possible towards each other.

Unlike satellite dishes, as known from satellite television, with phased arrays in Starlink terminals, it is no longer important to precisely align the antenna with a satellite: the receiving unit simply adjusts the preferred direction of the array until it receives the satellite as well as possible, and vice versa. By continuously readjusting, it can keep the satellite in view until the next Starlink satellite takes over and the array is adjusted to it.

The first two versions of the Starlink "dishes" did have motors for alignment, but these were only for initial positioning, not for active tracking of the antenna to the currently used satellite. Nowadays, alignment is only necessary for optimal results; due to the large number of satellites, Starlink has been working for some time in any orientation towards the sky and also in motion (car, boat, aircraft, etc.).

Deployment in Iran

Ground stations are necessary to connect the satellite constellation to the internet on Earth, but not every Starlink satellite needs to see one: since satellite version 1.5, the orbiters also have laser links for connections to other satellites on board. According to SpaceX, these operate at up to 200 Gbit/s, while a satellite is supposed to provide up to 100 Gbit/s bandwidth for customers. Data is forwarded via the lasers as in a large mesh network until a satellite in range of a gateway can beam the packets back to Earth. Thus, Starlink can now offer internet access worldwide, and the service works even without a ground station in Iran.

Thousands of user reports from all over the world show that this works well. Starlink actively advertises the service despite lacking frequency usage permits in many places and speaks of "over 150 [covered] countries and territories" in its plan overviews.

However, those who want to use the access must dig very deep into their pockets by Iranian standards, as roaming plans cost around 50 US dollars per month for 100 GByte of data volume and 100 US dollars for unlimited access. In addition, there are significantly higher prices for hardware, as it is smuggled into the country at great risk and must be activated using complex payment transfers: prices between 700 and 2000 US dollars per set are circulating online – a fortune in a country where the average monthly wage is around 200 US dollars.

Therefore, only privileged individuals can afford it, and they take a high personal risk because Starlink use has been punishable in Iran since the end of June 2025: six months to two years in prison, officially. However, in the current situation, one must fear worse.

There are several options for smuggling in Iran's neighborhood: Starlink is already officially operational in Armenia, Azerbaijan, Kazakhstan, Yemen, and Oman.

Easy to Jam

Fundamentally, radio transmissions can be easily jammed with the right equipment. In digital systems, information transfer usually takes place by shifting the phase and amplitude of electromagnetic waves (QAM). Amplitude modulation, i.e., changes in transmission power, can only be evaluated cleanly by the receiver if the signal is strong enough compared to background noise and other interference sources.

If another, stronger transmitter, or one closer to the receiver, overlaps the useful signal (jamming), the receiver can evaluate significantly less of it, or none at all. The effects depend heavily on the bandwidth of the signal being jammed and how the transmitter and receiver handle it. With transmission methods like orthogonal frequency-division multiplexing (OFDM), which uses many narrow-band carriers in succession, more resilient systems can simply exclude jammed areas. This reduces the data rate, but communication with a low error rate remains possible.

If the signal is jammed across its entire bandwidth but not completely overlapped, the transmitter can switch to less complex modulations and, for example, use only phase changes without amplitude jumps for data transmission (Quadrature Phase Shift Keying, QPSK). This also reduces the data transfer rate.

There is no reliable and detailed information on the means by which the Iranian regime is jamming Starlink. However, there are only certain possibilities: The government could try to target satellites specifically from the ground and jam the frequency range between 14.0 and 14.5 GHz with high power. The terminals use this 500 MHz block to transmit to the satellite, which would then have difficulty decoding these signals. However, we consider this method unlikely. The regime would have to deploy a considerable amount of equipment and operate it with high precision continuously, as a Starlink terminal often has more than ten satellites in sight. Since Starlink is designed for rapid changes due to its low orbit, selectively jamming individual satellites would only have a short-term effect.

It is more likely that the security services are jamming the downlink frequencies between 10.7 and 12.7 GHz in certain regions. This is because the protests in larger cities are what’s primarily dangerous for the Iranian government, meaning only in geographically limited areas. Jammers on the roofs of taller buildings could significantly impair the service, because the Starlink signal would be inferior to them at least within a radius of a couple hundred to a few thousand meters around an omnidirectional jammer. Although Starlink terminals point towards the sky, antennas typically also receive and transmit weakly outside their main beam direction – these are known as side lobes in RF engineering. With sufficient power, terminals can therefore also be jammed from the side.

It is likely these side lobes that enable the regime to roughly triangulate and track Starlink users. This involves using large directional antennas to determine the direction from which a signal is coming. If this is done from two or more positions and the directions are combined as lines on a map, one obtains the approximate location of the transmitter.

Position Shift

The regime is almost certainly using one jamming method: GNSS spoofing. This does not interfere with the reception of satellite navigation systems (GNSS, Global Navigation Satellite System) like GPS, Galileo, or GLONASS, but manipulates it. This is critical for Starlink because the terminals rely on knowing their exact position to precisely align their group antennas with the used satellite. The same applies to the satellite, which needs a correct position indication from the terminal to be able to precisely direct its beam at it.

The simplest form of GNSS spoofing: the spoofer receives genuine GNSS packets from orbit and re-emits them with a delay, so that the signal transit time determined by the receiver is incorrect, and thus its calculated position. However, it can also be more sophisticated: complex GNSS spoofers can simulate an entire satellite network for receivers, leading to extreme deviations. The calculated position can then be several hundred kilometers away from the actual position.

The advantage of GNSS spoofing over jamming is that a few watts of transmission power from an elevated position can falsify position determination within a radius of several kilometers; a spoofer on board an aircraft can easily jam entire regions. GNSS satellites are in medium Earth orbit (MEO) at an altitude of about 20,000 kilometers, and their transmission power is tens or a few hundred watts. The signal arriving on earth is extremely weak. Therefore, GNSS receivers are very sensitive and prefer the highest reception levels – thus, if present, a nearby spoofer.

Today, spoofer hardware can be ordered in larger quantities from China at prices very affordable for governments. Currently, much indicates that Tehran has done so: Iranian opposition activist Nariman Gharib recently published debug data [1] from a Starlink modem in Iran. The data shows indications of GNSS spoofing with delay attacks, but also that Starlink detects these and no longer uses GNSS for position determination. While SpaceX states that Starlink can function without GNSS reception by determining positions from its own signal transit times, the data also shows about 20 percent packet loss on average over 5 minutes, along with a beam direction deviating by 1 degree. This suggests that this function is not yet fully mature in Starlink.

However, the terminal reports normal signal-to-noise ratio in the dataset, which would not be the case with uplink or downlink interference.

Countermeasures

As long as the regime has no means to precisely jam Starlink's uplink frequencies at the satellite, there are several countermeasures that people in situations like in Iran right now can use to maintain communication. The most important aspect: a jammer causes interference with the receiver, it doesn’t change the signal the receiver is meant to receive. Electromagnetic waves of the same frequency can coexist in space without affecting each other. Therefore, if the receiver is shielded from the jammer, it only "hears" the intended transmitter again, even though the transmissions from the jammer and the transmitter "meet" on their way. This physical fact applies to both the up- and downlink frequencies used by Starlink and to GNSS signals.

This principle can be exploited, especially with satellite systems that are jammed by ground-based jammers: for example, by digging a small pit and placing the terminal in it, it "sees" significantly fewer signals from the surroundings. This method is already in use in Ukraine.

In urban environments, the terminal could be placed in an inconspicuous plastic box, in a mock air conditioner, or in an empty plastic water tank on the roof. Tehran has many flat roofs covered with small and large air conditioners; reports from campers show that Starlink also works through thin plastic or wooden surfaces.

Lining the inside of the camouflage from below and on the sides with aluminum foil shields the terminal from ground-level jammers and significantly attenuates triangulable side emissions. In our article from 2021, we prove [2] that even thin household aluminum foil causes very strong attenuation; at 5.2 GHz, it is already over 70 decibels, and in the Ku-band, the attenuation is likely to be significantly higher. However, since the wavelength is very short – 1 to 2.5 centimeters – there must be no gaps. The strips should be glued with overlap. Due to the limited view of the sky with the aluminum foil on the sides, Starlink will not work optimally from within the camouflage, but likely better than with strong Ku-band and GNSS interference.

Unfortunately, the risk of being detected by a reconnaissance aircraft overflight remains. But for some brave people, it seems worth the risk to show the world the truth about the protests and send calls for help to democracies. (amo [3])

URL dieses Artikels:
https://www.heise.de/-11147133

Links in diesem Artikel:
[1] https://github.com/narimangharib/starlink-iran-gps-spoofing/blob/main/starlink-iran.md
[2] https://www.heise.de/hintergrund/WLAN-Daempfung-Wie-Alufolie-Metallgitter-Beton-Co-Funkwellen-daempfen-6011028.html?from-en=1
[3] mailto:amo@ct.de
[4] https://www.facebook.com/heiseonlineEnglish
[5] https://www.linkedin.com/company/104691972
[6] https://social.heise.de/@heiseonlineenglish
[7] https://www.heise.de/hintergrund/Starlink-im-Iran-Wie-das-Regime-den-Dienst-stoert-und-was-dagegen-hilft-11141283.html

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