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GPS antenna mods make Starlink terminal immune to jammers
- adql 3y agoQuestion: Would using GPS antenna that only points at the sky (vs more omni-directional ones that mobile devices must have to work in any position) would "fix" the jamming problem ?
- morcheeba 3y agoThat's essentially what he's doing. The patch antenna he's using have a null at the horizon, where ground-based jammers would be.
- denton-scratch 3y agoOK, thanks. That info wasn't in TFA, nor in the article it linked to.
- yencabulator 3y agoIt is in the linked-to article, including discussion about lobes, polarization, more directional replacement antennas, and comparative measurements while being jammed. https://olegkutkov.me/2023/11/07/connecting-external-gps-antenna-to-the-starlink-terminal/ https://olegkutkov.me/2023/11/07/connecting-external-gps-ant...
- ceejayoz 3y agoI can't find it in a quick Google, but I read an article a while back talking about them putting the receivers in foxholes; can see the sky just fine, but any ground-based jammers nearby have to push through the dirt.
- sandworm101 3y ago>> GPS antenna that only points at the sky On paper. In reality, most every antenna has "side lobes" through which jamming signals can spoil the actual signal. In some cases the more directional an antenna becomes, the more significant are the side lobes.
- jandrese 3y agoRemember that GPS satellites may be near the horizon relative to you. That said there are enough of them in orbit that you can usually get away with only using the ones that are more overhead.
- deleted 3y ago[deleted]
- toomuchtodo 3y agohttps://olegkutkov.me/2023/11/07/connecting-external-gps-antenna-to-the-starlink-terminal/ https://olegkutkov.me/2023/11/07/connecting-external-gps-ant...
- matthberg 3y agoThis should be the main link instead of the hackaday article. Fascinating stuff.
- deleted 3y ago[deleted]
- sandworm101 3y ago>> IMMUNE TO JAMMERS No. That is not a thing. At most, one can make equipment less susceptible to jamming. Jamming is not like hacking, it isn't a matter of whether an attack works or does not. It cannot be fixed via a patch. Pump out enough energy close enough to the target and even a hyper-directional antenna can be jammed. Have a look at military GPS jammers. They aren't the little dongles that you can buy online and run off USB battery packs.
- baq 3y agoBut how do these jammers work? They can't point at the sky to blind the satellite because there's no receiver; they broadcast from above ground, so in theory putting your receiver in a metal box with the top removed solves the problem?
- dwighttk 3y agoWait, starlink is one way? How does it know what to send?
- sandworm101 3y agoThis is about the GPS antenna on the starlink terminal. GPS is one-way. The terminal needs that GPS signal to predict where the starlink satellites are going to be at a given time. The real "hack" answer is to bypass the GPS system and just feed the starlink terminal its true/known ground position/timing.
- kbknapp 3y agoGPS satellites don't "send" your coordinates to your receiver. Your receiver is just listening to the broadcast signal from several (usually 4+) satellites and based on the strength of that signal determining how far it is from each of those satellites. Which means the receiver is able to triangulate it's own position.
- meindnoch 3y ago>and based on the strength of that signal Wrong. Utterly wrong.
- mezeek 3y agoQuestion: How come aircraft can so easily get jammed then? They use GPS for precise positioning in flight, so I'm guessing they have the very best antennas...
- MPSimmons 3y agoGPS signal is comparatively weak. The satellites are far away, and terrestrial signal sources can be much stronger.
- jandrese 3y agoGPS jamming defense in the US is mostly provided by the FCC bringing the hammer of God down on people who run GPS jammers. The penalties for interfering with navigation signals are severe.
- mmh0000 3y agoHAMMER OF GOD[1][2][3][4][5] [1] https://www.fcc.gov/general/jammer-enforcement https://www.fcc.gov/general/jammer-enforcement [2] https://www.fcc.gov/document/fcc-fines-florida-driver-48k-jamming-communications https://www.fcc.gov/document/fcc-fines-florida-driver-48k-ja... [3] https://www.cnet.com/culture/truck-driver-has-gps-jammer-accidentally-jams-newark-airport/ https://www.cnet.com/culture/truck-driver-has-gps-jammer-acc... [4] https://www.fcc.gov/document/fcc-upholds-fine-jammer-used-block-workers-phone-use https://www.fcc.gov/document/fcc-upholds-fine-jammer-used-bl... [5] https://docs.fcc.gov/public/attachments/DOC-339560A1.pdf https://docs.fcc.gov/public/attachments/DOC-339560A1.pdf
- outworlder 3y ago> They use GPS for precise positioning in flight Large airliners, for the most part, don't. They use inertial navigation. GPS is a source of calibration for their inertial navigation system. There are some (non-precision) approaches that use GPS.
- thrtythreeforty 3y agoDoes Starlink have a mode where you can manually tell it its lat/long? For a semi-stationary receiver, surely that would be a better way to bootstrap a connection.
- auspiv 3y agoI'm currently messing around with a u-blox timing chip, the LEA-6T. It (and many other slightly-above-consumer grade u-blox chip) has a "survey-in" mode, where you tell it "yes, you are stationary" and it essentially averages into a fixed location. This was a $30 chip from China and it gets to 4cm accuracy in 10 min with a $10 antenna. Do that once and you have a location. If the chip reboots, you can either survey-in again, or just tell it where it is. Highly likely the GPS module inside the Starlink device has this ability. Whether or not that functionality is exposed is up to the Starlink engineers I suppose.
- TaylorAlexander 3y agoSurvey-in won’t help if your system is being jammed.
- gorkish 3y agoI would assume that Starlink needs the GPS signal more for timing than for position though it certainly does need to know its position as well. Some of it is probably also driven by regulatory and UX requirements -- from a consumer standpoint there is a benefit of using GPS reception as a checkpoint before the process proceeds. Under normal operation if the terminal can't receive GPS then it is likely also unable to communicate with Starlink satellites. One could use a GNSS emulator and this modification to test how the system performs under various GPS fault conditions to quantify it. My hunch is that it's more of a regulatory check than an operational requirement. I suspect the signals from the Starlink satellites themselves are sufficient for the terminal to derive timing and position without having to rely on GPS at all.
- denton-scratch 3y agoSo "immune to jammers" seems to be hyperbole; perhaps "more resistant to jammers" wuld be a more accurate phrasing.
- yencabulator 3y agoIt's really a question of distance, which is not mentioned in the article. Russian style is to park jammer vehicles pretty much evenly spread out on a line behind their defensive boundary. I'll easily believe "immune to Russian GPS jammers as typically deployed when used X kilometers behind active battles".
- CrzyLngPwd 3y agoSurely, a satellite in orbit could easily jam Starlink boxes on the ground.
- BHSPitMonkey 3y agoMaybe, but unless your goal was to deny service to a small, fast-moving window of the earth's surface you would need quite a lot of these.
- lazide 3y agoIf I was a nation state adversary, I’d put pretty high on my TODO list getting a handful of jamming satellites with a decent power supply at geostationary locations above all my adversaries. Since a single geostationary satellite has line of sight covering about 1/3 of the planets surface, I bet if they had a decent sized reactor onboard and a well thought out transmitter/antenna array, the ROI would look pretty good. And I’m just some random punter.
- nradov 3y agoThat is not feasible at a cost any current nation state could afford. Due to the inverse square law, the power output requirements to achieve any noticeable jamming from geostationary orbit would be enormous. There have been limited tests of fission reactors in space but they are too complex to operate reliably unattended for long. So, satellites are going to limited to solar or RTG power.
- lazide 3y agoOnly if using old school ‘blanket the area’ monopole antennas or if the goal was to cover the entire potential area all at once -but that seems unlikely to be desirable most of the time. Phased arrays and beam steering would allow them to pick and choose the area at will with high resolution - or even specific targets like several hundred airliners at once. Notably, the same things that starlink needs for being able to properly track base stations and communicate at the timescale/numbers it needs, and the tech is widely used in everything from cell phone towers to military. Starlink has it a lot easier due to LEO, but they’re also a private company with a much harder problem and on a shoestring budget compared to a nation state. TDP would be a lot lower if they could get it focused well enough. And it wouldn’t need to be operating all the time - a ‘war’ mode vs sleep mode seems like it would work too. When not jamming, it could be a passive signals intelligence platform. Or build a couple dozen and put in a lower orbit. Not like it would make a dent in China or Russias military budget, or require any tech newer than 20 years old for them.
- diebeforei485 3y agoWhy does Starlink need to use GPS if it can use its own satellite constellation to make time of flight measurements?
- BenjiWiebe 3y agoDo StarLink satellites have the same level of clock stability and precision that GPS satellites do? IDK but I really doubt it.
- yencabulator 3y agoThe linked-to original article says GPS works better and faster. > Calculating position based on Starlink constellation requires more resources, and it’s not so fast. Plus, It can’t be used correctly in motion. Accumulated errors may be so significant that Starlink will not be able to work.