Brexit and GPS
The story of the English plane carrying a minister who, passing over Kaliningrad, found that he could no longer use the on-board GPS has hit the news. And this poses some interesting questions, to understand which I need a concise explanation of how GPS works. Vertical experts stay calm, I'm disclosing.
A positional satellite (GPS, GLONASS, Galileo, Beidou) is nothing more than a very precise clock that sits in orbit and transmits a time signal. You will say: huh? And how can I understand my position just by knowing the time?
These are very precise time signals generated by a small atomic clock on the satellite, which is also corrected using ground stations, but that's not the point. The point is that the sent signal, which contains the exact time of sending, position and speed of the satellite, is delayed due to the theory of relativity.
The receiver, therefore, is able to estimate the distance to the satellite very well using the delay, and therefore triangulate its position. There are other details too, like the Doppler effect and other things, but that's the point.
All satellite positional systems work on this principle.
What's the problem?
The trouble is that anyone can send a signal, pretending to be a satellite, giving it a wrong time, and a fictitious speed and position of the satellite. Even if it's on the ground. And this is GPS jamming.
But then, you might ask, why does the military trust it so much that it entrusts systems like GPS with the guidance of drones, missiles, JDAM bombs, and more?
The truth is that there are more than one network. Some in clear, others encrypted. Once upon a time, encryption was only done "on request", i.e. in war zones. Now there is also a similar signal, but encrypted, which covers practically everything. Since the signal is encrypted and the enemy does not have the keys, he cannot emit a fake signal and confuse the systems. To start learning more, search for M-Code:
https://en.wikipedia.org/wiki/GPS_signals
So why didn't the English plane use that? Eh… because GPS is American. And only the US has the keys to encrypted GPS. It's their thing, and they give it to whoever they want.
Excluding using GLONASS, which is from the Russians, and Beidou, which is from the Chinese, it would remain to use Galileo. Obviously, the keys to the encrypted Galileo are held by those who manage Galileo, which is a European project.
But the English “Brexited”.
Or rather: this is the only reasonable explanation, because it is not clear how the GPS of a plane that is in fact military is subject to such jamming.
According to what they say, that is, the British did not lose the GPS signal (which comes from above, while the disturbance was generated on the ground, from Kaliningrad), but they were reading wrong positions. And this is not possible on encrypted GPS.
The other point is that if we use clear signals, Galileo could also be used to replace GPS, once it was realized that it was jammed. Even top-of-the-range cell phones manage to use more than one positional system.
Other countries have solved it in other ways. If you are in Japan, you can use the “Quasi Zenit” system, which is not an autonomous and complete satellite network, but these are additional satellites, placed into orbit with the aim of adding precision and robustness to the existing GPS.
But the English never built anything like this.
Personally, I attribute to Brexit the reason why the English plane could only use unencrypted, i.e. unprotected, positioning systems. The use of encrypted frequencies, that is, is subject to license and authorization from local authorities.
And it is time to ask ourselves this question, given that in the end, it is unthinkable that the protection of aircraft of that type is not under the direct control of the military.
Uriel Fanelli
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