I had been wondering about GPS spoofing and jamming as cheap UAV attacks ramp up in the Ukraine. The GPS systems of the U.S. and Russia have military functionality as their base reason. The military can control functionality to various degree and apparently in particular areas. I have seen news notices of purposeful glitching announced when some military games, testing, etc… might be going on. Rare events as far as I can see.
Do the competing systems have ability to spoof or jam, built into them? Can they transmit false information on the other ones frequency? Or just transmit a jam signal on it? From the actual satellites, not from the ground.
I just ran across this article. Is someone sending a message by sending bad data?
This article says it is common, but seems to say it is more local, ground based in nature.
You could be pretty sure that any such jamming or spoofing capability installed on the satellites would be a seriously classified secret. OTOH, it would also be trivial to detect. So would not remain a secret for very long. Some jamming and spoofing techniques may well be being held back of both sides, as both may regard the current conflict not important enough to warrant revealing their hand.
Spoofing civilian GPS sadly isn’t too hard, but the military systems use a much stronger level of encryption, so spoofing becomes more involved and limited in capability.
Jamming is always a much easier task. But since you are jamming a signal from the sky, it helps to have the jamming transmitter in the sky as well. But ground based jamming has the advantage of being much closer to the thing being jammed, as well as being much cheaper.
Given that even garden variety civilian GPS chipsets can use GPS, GLONAS, and Galileo to build an accurate location, jamming and spoofing to useful effect is a two edged sword.
I happened to fly into and out of DFW while the stuff described in the OP’s cite was going on. It was an irritant, not a crisis. At the same time it was a reminder of how much GPS is becoming deeply woven into the total aviation infrastructure, and how older tech that was once primary is increasingly relegated to backup status. Both the airlines and ATC can operate just fine completely without GPS, but with some alterations to procedures and some loss of total system throughput.
Separately, it is very common that there is GPS jamming in the area of the White Sands Missile Range which is generally between Las Cruces NM & El Paso TX. But the jamming is done by the US military on a more-or-less published schedule. I can’t say if they’re testing the effectiveness of jammers or testing the effectiveness of the jamming countermeasures installed in military navigation systems, or both.
Is the former just one more of instance of the latter but on a larger scale, or was this incident something else? Heck if I know.
I recall reading about an accident in Canada in the early days of GPS use in aviation. Two small charter aircraft collided head on in northern Canada. Indications are both were following the “line” from A to B. The result of this was a recommendation to fly a certain distance to the right(?) off the centerline between two points.
The thing I wonder about was whether it would be possible to spoof GPS signals from the ground, thus localizing the GPS malfunction (and without the need for satellite launches or high-flying aircraft). If the object gets with the range of this transmitter suddenly it “discovers” it’s several miles off target. Set up a network of these and have the devices fly in circles until they run out of fuel.
It’s somewhat surprising if the Iranian drones (or Russian) use GPS. If your major antagonist (USA) controls the guidance signals, why would you make that an integral part of the operation of the devices? Is inertial guidance good enough to accurately hit a target?
Lotta separate issues there.
Yeah, back in the old days two airplanes on the same but opposite courses between radio beacons would be spread apart by the random differences in signal propagation, receiver calibration, pilot technique, etc. Being a couple miles off while your instruments showed centered was totally normal day-to-day experience. Nowadays we see them coming head-on offset by at most a couple dozen feet laterally. Thank goodness for vertical separation.
In certain airspace not under radar control it is now routine to offset to the right a bit. Not only for head-on collision avoidance, but for wake turbulence avoidance from the aircraft immediately in front of you going the same way whose path you’re following very exactly.
IANA expert on GPS technical internals.
ISTM most jamming simply sends up enough noise that the receiver can’t “hear” the satellites, or at least not enough satellites, well enough to form an acceptable fix. At which point GPS itself throws up its hands and says “I have no clue where I am”. Which was exactly what we saw around DFW the other day.
Which is also why substantially none of the nav systems built into airplanes (and I assume into most expendable military drones & missiles) rely purely on the output of a GPS receiver for position. There will almost always be some other means of position tracking and fixing, whether inertial, star tracker, or another of several different radio beacon systems. In these blended nav systems, GPS is generally primer inter pares, but it’s not indispensable. In a real sense, GPS is precise but unreliable, whereas the other legs of the nav stool are reliable but imprecise. The sum is much better than the parts.
Spoofing, where the GPS receiver still successfully builds a position it believes to be reliable, but due to enemy action the position is actually faulty is a much harder goal for the enemy.
Each actual satellite that can be seen/heard delivers a piece of the total position puzzle. The enemy cannot know for certain which satellites are being received how well by any receiver, much less by all receivers in the spoofer’s range. As such it cannot know what any receiver’s partial puzzle looks like. So cannot deliver a carefully crafted puzzle piece that is close enough to pass the “looks about right” test while also being faulty enough to fool the receiver enough to matter.
Or at least that’s the goal of the GPS receiver designers: to ensure that bogus data coming in is rejected before it results in a bogus position coming out.
The higher-end military receivers go a step further and use the encrypted info stream coming from the satellites. Any spoofer would also have to be sending properly encrypted data that the receiver would then decrypt correctly to then absorb the poisoned pill of faked data. That’s a tall order.
An enemy planning to use the other side’s nav tech is not so crazy. In most wars, especially recent Mideastern-style highly unequal / asymmetrical wars, the US would lose more combat capability than would the e.g. Iranians, if GPS was denied. So the e.g. Iranians can assume the USA will keep GPS up and unjammed near their own forces = the Iranian’s targets.
As well, the Europeans, the Russians, and now the Chinese have their own nav satellite constellation conceptually similar to GPS, albeit different in most details. A receiver that can process all 4 system’s signals is not that much harder than one which can process only one such set. The US turning off GPS would have no material effect on a receiver also processing European and Russian signals.
Purely inertial systems are very good these days. Whether one is good enough for your targeting needs is mostly a matter of time of flight versus willingness to pay vs the nature of the target. If you need +/- 10-foot accuracy, no, inertial isn’t going to fill the bill. Putting a big bomb into a large warehouse, oil refinery, or enemy military base? Inertial is more than good enough for that task. The more you’re willing to spend on the inertial navigator in your bomb/missile, the closer it’s going to get to the aim point.
Then again, how confident are you that your maps of the enemy’s positions are accurate to 10 feet either? As the US has learned in several conflicts to its chagrin, hitting a set of coordinates is not the same as hitting the building you want to hit.
Nice explanations. I figured as much on the points you cover. Nobody seems to be giving up any big secrets so far.
Overall I suspect that even jamming from the ground must be tough. GPS patch antennas don’t pick up much near the horizon. Helical ones a bit more.
I wonder if there might be dedicated military sats that might do it. Separate from the actual GPS sats.
Might find out more in the news.
Even commercial cell phones use a lot of different data sources for their location services, not just GPS. There’s also listening for what WiFi signals are nearby, and inertial guidance, and heuristics like “If you’re moving at 60 MPH roughly parallel to an interstate and very close to it, you’re probably on it”, and so on.
In the days before GPS, the most advanced guided munitions had cameras to visually follow the terrain. That technology has to be still around, too, and far better than it used to be (there’s been a lot of progress in machine vision).