GPS antenna mods make Starlink terminal immune to jammers
hackaday.com
hackaday.com
I'll easily believe "immune to Russian GPS jammers as typically deployed when used X kilometers behind active battles".
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.
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.
[1] https://www.fcc.gov/general/jammer-enforcement
[2] https://www.fcc.gov/document/fcc-fines-florida-driver-48k-ja...
[3] https://www.cnet.com/culture/truck-driver-has-gps-jammer-acc...
[4] https://www.fcc.gov/document/fcc-upholds-fine-jammer-used-bl...
[5] https://docs.fcc.gov/public/attachments/DOC-339560A1.pdf
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.
https://olegkutkov.me/2023/11/07/connecting-external-gps-ant...
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.
> 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.
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.
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.
Which seems pretty hilarious considering how much is getting spent on all this tech, and how much of an arms race it clearly is.
Especially considering how TS programs in general are usually a decade or two ahead tech wise anyway.
[https://www.defenseone.com/threats/2022/04/dia-warns-chinas-...]
If you think there aren’t surprises hiding in the Chinese or Russian’s pockets on this front, you’re far more optimistic than I.
Maybe they’ll just shoot down all the GPS satellites though.
Are you skimming over this part? Of course enemy nation states have invested in jamming capability... just not on this front
While not responding to my other comments?
Look at this animation[1] for a moment (click the >> or >>> button to speed up) and think about what it would actually take to get "in front" of enough satellites to block out a given geographic region; even just a single city. There are hundreds of satellites in each orbital plane, rapidly cycling through and taking each others' place.
You obviously cannot have counter-satellites in a geosynchronous "position", and you also can't have satellites simply move between greatly different orbits (or phases of existing orbits) willy nilly; The delta-V requirements are just too great. This just isn't a feasible strategy.
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.
The real "hack" answer is to bypass the GPS system and just feed the starlink terminal its true/known ground position/timing.
Wrong. Utterly wrong.
what you did wasn't that -- but I would just like to point out that simple concise explanations helps the community as a whole; it's not just the ignorant that lose out.
Yes, I know it's likely not your job to educate, and maybe it's a bother that someone acts expert on something that they're clearly not -- but those that care to educate serve everyone in the context of an online forum, not just the naive or ignorant.
I'm no GPS expert, I've read some of the theory had enough of a working understanding to deal with tactical navigation systems, but that was in my past. I remember using El-Rabbany's "Introduction to GPS" text.
No, GPS positioning uses the precise time information encoded in the data from the satellites.
With signals from 4 satellites one can triangulate oneself in 3D space, with 5 signals, in 4D! (3D + time). I once did the math and astounded myself that it worked.
It will get another signal from another satellite, which could have the timestamp before X, because it left earlier and took longer to get to your receiver.
As I said, if you do the math, with 5 signals you can then determine your location in 3D space, and time!
GPS doesn't use the strength of the signal at all. Instead, each signal contains precise information about the current time at the highly-accurate atomic clocks onboard the corresponding satellite (plus some important metadata about each satellite, including things like their orbit parameters). If the receiver already knew the precise time, it could calculate the distance to each satellite from the difference between the true time and the received time (and the speed of the light), and 3 satellites would be enough to triangulate its position. Since the receiver usually doesn't know the precise time, it needs an extra satellite because there are now 4 unknowns (3 for its position plus 1 for the current time).
(Obviously, that's a very simplified explanation, there are plenty of other things which complicate the calculations.)
Also, the more directional you get, the more it may be possible to determine where you are.
No. Radio can turn around corners. It can also bounce off things. Radio is light, but at a much longer wavelength. It is less like blocking a laser and more akin to blocking out sound waves. Blocking line-of-sight to the transmitter would block the laser but would do little to block sound waves.
The other really annoying thing about radio waves is that even relatively long wavelengths can leak through really narrow cracks (<1mm) if they are long enough (eg a wavelength) in the right polarization.
Isn't that above the critical frequency you'd get ionosphere reflection at? (Which makes sense, since the signals are coming from outside it at LEO)
Pretend you're having a conversation. Now pretend you're having a conversation at a concert/club/any loud place. So like this[0]
> so in theory putting your receiver in a metal box with the top removed solves the problem?
You'd think so, but not actually. Think about it this way: you're trying to toss a ball into a cup (or box).
Is it easier or harder if that cup has a wide mouth or a narrow one? Make it V shaped for easier visualization and we'd be talking about the angle of that cone. Obviously the wider one right? The extreme other end of this is like a carnival ball tossing game where the cup is just as big (or they cheat and its smaller) than the ball you're trying to throw in. Now pretend you're trying to make that shot from a moving car. You come from far away and drive right past it and you get more points in this game the more shots you score.
That's analogous to what then satellite is doing. Remember it comes from over the horizon and then passes to the other horizon. You want to maximize your viewing angle because that gives the satellites more chances to make contact. This is more complicated because you need to kinda do this in parallel as you're handing off data collection to the next satellite coming through so the better viewing angle the more chances you have to smoothly negotiate that pass over.
Then there's the whole issue that we're talking about waves instead of particles but I'll let someone else handle that. You can actually find some cool visualizations on the internet about these. See knife edge diffraction.
The next gen replacement sounds like an absolute monster too, but without some of the donwsides like the need for a ram air turbine to power it.
So you just lob in a heat seeker at the middle of the noise, and hope.
Then again, if you have an airborne source of jamming, you know you have bigger problems following. How much effort do you spend trying to knock out the jamming vs preparing for what is inevitably following? Flying in jammers from the opposite direction of an attack to draw in fighters to the wrong area is as elementary as attack options go.
There's already another category of missile for that:
For large power amplifiers, especially with power and power-density considerations, nothing beats a travelling wave tube.
And on the ground with "unlimited" power and cooling? Well, there's always the Klystron...