Regarding jamming, how easy would it be to build a GPS receiver that knows what direction the signal is coming from? If this can be done, it would be useful in 2 ways:
(1) it can check that the real signal is coming from a satellite, which would be overhead.
(2) a drone could be build that would home in on the fake signal, destroying the transmitter. I'm sure if lots of drones like this were built, Ukraine would be happy to fire them off against Russia.
Ponti, you’re thinking like an electronic warfare officer, and I mean that as a compliment. In theory, yes, it’s absolutely possible to build a GPS receiver that knows not just what it’s hearing, but where it’s coming from. That’s the basis of what we call a direction-finding (DF) antenna array or CRPA (controlled radiation pattern antenna). Instead of a single stubby GPS antenna like you have on your phone, you use multiple antennas spaced apart. By comparing the phase differences of incoming signals, the receiver can tell the angle of arrival.
Now, apply that logic to GPS. Real satellites are 20,000 kilometers overhead, so their signals should always appear to be coming from above. If your GPS receiver suddenly thinks the satellite is sitting on the horizon, or worse, beaming from a truck parked outside Kaliningrad, you know you’ve been spoofed. Modern military GPS receivers do exactly this kind of sanity check, blending it with inertial navigation so they don’t get walked off into the Black Sea.
As for your second idea: a kamikaze drone that hunts the jammer by flying toward the strongest fake signal? Brilliant, and not far-fetched. Ukraine already fields drones with passive RF homing, basically sniffers that follow enemy emitters. The challenge is scale and survivability. Jammers tend to sit behind layered air defenses, so your drone needs range, speed, and stealth to make it through. But conceptually? Totally doable. Build enough of them, and you’ve turned Russia’s giant EW systems into giant bullseyes.
The irony here is delicious. Jammers are supposed to hide troops from precision weapons. But the moment they transmit, they announce their presence to anyone with an antenna and a grudge. Ukraine has already blown up multiple Russian Pole-21 and Zhitel systems this way. Turning spoofing signals into homing beacons for kamikaze drones is just the next logical step.
So yes, direction-aware GPS receivers are real, spoof detection is possible, and drone homing on jammers is both technically sound and tactically satisfying. After all, nothing ruins a Russian EW officer’s day faster than watching his million-dollar jammer attract a $5,000 Ukrainian suicide drone.
Ponti, great question. The short answer is: yes, some GPS signals are cryptographically protected, but not the ones most people actually use.
The civilian GPS L1 C/A signal that runs your phone, car, and most commercial drones? Wide open. It was never designed with cryptographic signing. The U.S. wanted it free and universally accessible, and for decades, no one thought adversaries would bother spoofing it on a large scale. That decision is what makes it so easy for Russia to generate counterfeit signals. They just mimic the pseudorandom noise codes and navigation messages, transmit them slightly louder than the satellites, and your receiver happily believes the lie.
On the military side, it’s a different story. U.S. and allied forces have access to encrypted signals: first the P(Y)-code and now the newer M-code. These are cryptographically keyed, and without the right hardware and crypto keys, you can’t just fake them. If a Russian spoofer tried, the receiver would reject the signal outright. That’s why spoofing is mostly a civilian headache, not a Pentagon one.
There’s also Galileo over in Europe. Its Public Regulated Service (PRS) signal is encrypted and designed specifically to resist spoofing. Same concept: without the key material, you can’t impersonate it. The open Galileo E1 signals, though? Just as spoofable as civilian GPS.
So to your point: if all navigation signals were cryptographically signed, spoofing would be impossible without access to the keys. But in practice, only militaries and select government agencies get those keys. Everyone else is stuck with “open skies” signals, which is why spoofing works so well against airlines, shipping, and commercial drones.
And that’s where the irony comes in. Russia’s spoofing tricks don’t fool U.S. M-code receivers, but they sure do mess with commercial airliners flying into Helsinki. It’s a cheap way for Moscow to poke NATO in the eye without ever firing a missile.
Some outlets have been posting hysterical headlines about GPS spoofing, using "maps"and possible airline accidents. Pilots have been trained how to use the other navigational methods. Indeed, that was the "normal" until the advent of GPS. Pilots are aware of the spoofing, so by being alert and having the right charts in their iPad/flight bags, it's more of a nuisance. It may become necessary to use multiple methods at the same time in areas like Central and Western Europe.
Question: How effective would missiles like the AGM45 Shrike be against these transmitters?
Bender, you nailed it on the aviation side. A lot of the “sky is falling” headlines about GPS spoofing forget that pilots didn’t suddenly discover flight in 1995. Before GPS, entire generations of aviators flew safely with nothing but VOR, DME, NDBs, and a good set of charts. The airlines know how to revert to that world, and they already are. GNSS spoofing is an operational headache, not an extinction-level threat. It’s the military applications, precision weapons, drones, and timing systems, where the real pain shows up.
Now, onto your Shrike question. The AGM-45 Shrike was America’s first serious attempt at an anti-radiation missile (ARM), designed in the 1960s to home in on Soviet radar emissions. It was the “see radar, kill radar” weapon of its day, fired from Navy A-4s and Air Force F-105s over Vietnam. The principle is simple: enemy radar switches on, missile seeker locks onto the lobe, and the radar crew has a very short career.
Would it work on Russian GPS jammers? In theory, yes, any transmitter is a target if you can build a seeker for its frequency. A Shrike tuned for 1575 MHz (GPS L1) could certainly ride the energy right into a Pole-21 mast or a Zhitel truck. But here’s the catch: Shrike was retired for a reason. It had a limited seeker, narrow band coverage, and if the enemy simply shut off the radar mid-flight, the missile often went dumb. Against mobile jammers that “jam and scoot,” Shrike would be a blunt instrument.
Modern successors like the AGM-88 HARM or AARGM are far better. They can remember the last known emitter location, switch between multiple frequencies, and have smarter guidance to nail targets even if they shut down. That’s why Ukraine has been so keen on receiving HARM missiles; they’ve already been used against Russian air defense radars. With the right seeker package, the same principle applies to GNSS jammers.
The Russians know this, which is why their EW units don’t just sit in the open belching RF all day. They move, they decoy, and they park under air defense umbrellas. That makes them harder to kill, but not invulnerable. Ukraine has already destroyed plenty of Pole-21 and R-330Zh Zhitel units with drones and artillery, proving that once you detect the emitter, it’s only a matter of time.
Regarding jamming, how easy would it be to build a GPS receiver that knows what direction the signal is coming from? If this can be done, it would be useful in 2 ways:
(1) it can check that the real signal is coming from a satellite, which would be overhead.
(2) a drone could be build that would home in on the fake signal, destroying the transmitter. I'm sure if lots of drones like this were built, Ukraine would be happy to fire them off against Russia.
Ponti, you’re thinking like an electronic warfare officer, and I mean that as a compliment. In theory, yes, it’s absolutely possible to build a GPS receiver that knows not just what it’s hearing, but where it’s coming from. That’s the basis of what we call a direction-finding (DF) antenna array or CRPA (controlled radiation pattern antenna). Instead of a single stubby GPS antenna like you have on your phone, you use multiple antennas spaced apart. By comparing the phase differences of incoming signals, the receiver can tell the angle of arrival.
Now, apply that logic to GPS. Real satellites are 20,000 kilometers overhead, so their signals should always appear to be coming from above. If your GPS receiver suddenly thinks the satellite is sitting on the horizon, or worse, beaming from a truck parked outside Kaliningrad, you know you’ve been spoofed. Modern military GPS receivers do exactly this kind of sanity check, blending it with inertial navigation so they don’t get walked off into the Black Sea.
As for your second idea: a kamikaze drone that hunts the jammer by flying toward the strongest fake signal? Brilliant, and not far-fetched. Ukraine already fields drones with passive RF homing, basically sniffers that follow enemy emitters. The challenge is scale and survivability. Jammers tend to sit behind layered air defenses, so your drone needs range, speed, and stealth to make it through. But conceptually? Totally doable. Build enough of them, and you’ve turned Russia’s giant EW systems into giant bullseyes.
The irony here is delicious. Jammers are supposed to hide troops from precision weapons. But the moment they transmit, they announce their presence to anyone with an antenna and a grudge. Ukraine has already blown up multiple Russian Pole-21 and Zhitel systems this way. Turning spoofing signals into homing beacons for kamikaze drones is just the next logical step.
So yes, direction-aware GPS receivers are real, spoof detection is possible, and drone homing on jammers is both technically sound and tactically satisfying. After all, nothing ruins a Russian EW officer’s day faster than watching his million-dollar jammer attract a $5,000 Ukrainian suicide drone.
HARM missiles? Trouble is $200k+ a pop.
> Spoofing is more devious. Instead of silencing GPS, spoofers transmit counterfeit signals that mimic legitimate satellites.
Are the signals cryptographically signed? If they are, this would make spoofing impossible unless you have the right private key.
Ponti, great question. The short answer is: yes, some GPS signals are cryptographically protected, but not the ones most people actually use.
The civilian GPS L1 C/A signal that runs your phone, car, and most commercial drones? Wide open. It was never designed with cryptographic signing. The U.S. wanted it free and universally accessible, and for decades, no one thought adversaries would bother spoofing it on a large scale. That decision is what makes it so easy for Russia to generate counterfeit signals. They just mimic the pseudorandom noise codes and navigation messages, transmit them slightly louder than the satellites, and your receiver happily believes the lie.
On the military side, it’s a different story. U.S. and allied forces have access to encrypted signals: first the P(Y)-code and now the newer M-code. These are cryptographically keyed, and without the right hardware and crypto keys, you can’t just fake them. If a Russian spoofer tried, the receiver would reject the signal outright. That’s why spoofing is mostly a civilian headache, not a Pentagon one.
There’s also Galileo over in Europe. Its Public Regulated Service (PRS) signal is encrypted and designed specifically to resist spoofing. Same concept: without the key material, you can’t impersonate it. The open Galileo E1 signals, though? Just as spoofable as civilian GPS.
So to your point: if all navigation signals were cryptographically signed, spoofing would be impossible without access to the keys. But in practice, only militaries and select government agencies get those keys. Everyone else is stuck with “open skies” signals, which is why spoofing works so well against airlines, shipping, and commercial drones.
And that’s where the irony comes in. Russia’s spoofing tricks don’t fool U.S. M-code receivers, but they sure do mess with commercial airliners flying into Helsinki. It’s a cheap way for Moscow to poke NATO in the eye without ever firing a missile.
Galileo has OS-NMA, which provides an authentication signature to the E1 signals. But it's new and an existing GNSS receiver may not support it.
The PRS signal is encrypted, and thus secret. Cryptography has multiple uses.
Some outlets have been posting hysterical headlines about GPS spoofing, using "maps"and possible airline accidents. Pilots have been trained how to use the other navigational methods. Indeed, that was the "normal" until the advent of GPS. Pilots are aware of the spoofing, so by being alert and having the right charts in their iPad/flight bags, it's more of a nuisance. It may become necessary to use multiple methods at the same time in areas like Central and Western Europe.
Question: How effective would missiles like the AGM45 Shrike be against these transmitters?
Bender, you nailed it on the aviation side. A lot of the “sky is falling” headlines about GPS spoofing forget that pilots didn’t suddenly discover flight in 1995. Before GPS, entire generations of aviators flew safely with nothing but VOR, DME, NDBs, and a good set of charts. The airlines know how to revert to that world, and they already are. GNSS spoofing is an operational headache, not an extinction-level threat. It’s the military applications, precision weapons, drones, and timing systems, where the real pain shows up.
Now, onto your Shrike question. The AGM-45 Shrike was America’s first serious attempt at an anti-radiation missile (ARM), designed in the 1960s to home in on Soviet radar emissions. It was the “see radar, kill radar” weapon of its day, fired from Navy A-4s and Air Force F-105s over Vietnam. The principle is simple: enemy radar switches on, missile seeker locks onto the lobe, and the radar crew has a very short career.
Would it work on Russian GPS jammers? In theory, yes, any transmitter is a target if you can build a seeker for its frequency. A Shrike tuned for 1575 MHz (GPS L1) could certainly ride the energy right into a Pole-21 mast or a Zhitel truck. But here’s the catch: Shrike was retired for a reason. It had a limited seeker, narrow band coverage, and if the enemy simply shut off the radar mid-flight, the missile often went dumb. Against mobile jammers that “jam and scoot,” Shrike would be a blunt instrument.
Modern successors like the AGM-88 HARM or AARGM are far better. They can remember the last known emitter location, switch between multiple frequencies, and have smarter guidance to nail targets even if they shut down. That’s why Ukraine has been so keen on receiving HARM missiles; they’ve already been used against Russian air defense radars. With the right seeker package, the same principle applies to GNSS jammers.
The Russians know this, which is why their EW units don’t just sit in the open belching RF all day. They move, they decoy, and they park under air defense umbrellas. That makes them harder to kill, but not invulnerable. Ukraine has already destroyed plenty of Pole-21 and R-330Zh Zhitel units with drones and artillery, proving that once you detect the emitter, it’s only a matter of time.
Thank you for the explanation. (I meant the AGM-88. Stupid old man brain farts! 😆 )
I'm a pilot and just rolled my eyes at that coverage. I haven't flown in decades, but the basics never change and are still taught.
What happened to "Russia’s Pole-21 System no credit, because Fuck them."
Updated lol