Whats really sad for aviation is there was already an extensive network of ground based navaids. As GPS has proliferated, they've slowly been decommissioned as they age out to save on cost. I'm specifically referring to VORs which provide azimuth and range to station.
GPS is fantastic and as a primary source everyone loves the benefits it brings. However, in a century of aviation, everyone has kinda sorted out that you can't have too many backups to critical items... unless you let the accountants and bureaucrats run the show.
VOR is extremely short range and requires an extraordinary number of transmitters to provide any volume of coverage. Additionally it cannot provide coverage over oceanic areas. We USED TO have a nearly global long-range land based navigation system called LORAN, which only required one master station and a few remote stations to provide continent-scale coverage. But it was decommissioned in a cost savings move after it was determined that it could be replaced by GPS. It worked perfectly fine until it was decommissioned in 2010, not that long ago.
In the '90s I used to fly light aircraft back and forth between Seattle and Alaska. You were frequently out of range of any VOR transmitters, but that LORAN always worked.
NDBs? That didn't work so great for Ron Brown.
On VOR: It's also a PITA to use, and for inexperienced people, or someone who rarely uses it, they can confuse flying towards and away from the station.
If you are a general aviation goober like me, flying a 1960's propeller airplane, sure, that is true.
However, in a modern commercial aircraft, all position sources including VOR-DMEs, GPS, and IRS are cross-compared by the flight management system and turned into a latitude, longitude, and circular error of probability. There is no TO/FROM flag to worry about in a 777, and no reverse sensing on the back side of a localizer approach.
Yeah that makes sense. My experience is mostly in 70s to early 90's prop planes, I have had the opportunity to use a glass cockpit a few times and it was much easier. I guess i did the typical thing and contextualized this on my experiences and ignored that 99.9% of flights are not GA haha.
Time was, if you didn't understand how to use VORs, you couldn't really fly. We used them as primary en route nav, as well as for approaches, for many decades. As a CFI I think most of the confusion around VORs these days comes down to poor or inadequate training.
That's fair. I replied to someone else with a similar remark, but essentially doing most of my flying in 70s to 90s prop planes, I imagine the tools I'm most used to are just dated. Your point around training is likely very accurate, I had some great teachers but I also had a few instances of being given inaccurate information and having to teach the teacher so to speak.
I don't fly and I wouldn't call my self someone that plays a lot of flight simulator. But I do enjoy navigation methods and I did learn the basics and practices of VOR navigation. I got an Android app that simulates flying courses, holding patterns etc, but only the navigation part. I would say I learned some intuition to it.
> Additionally it cannot provide coverage over oceanic areas.
It's really hard to jam oceanic areas though, you need a vessel capable of sustaining human life autonomously at least for days plus dealing with the high seas.
Buoys could theoretically be used for that purpose, yes, but good luck getting them stationary enough. Maybe some of the secret services could pull off such a trick but at least no ordinary civilian.
All VORs provide a radial that you’re on. Not all provide a distance to the station. VOR/DME or VORTACs provide both. Plain VORs do not.
As more and more are decommissioned, the percentage that support distance-measuring goes up, as the ones being decommissioned are more likely to be the less-useful ones, which are less likely to have supported DME in the first place. So most remaining ones support both, but it’s not assured without checking.
There's GPS jamming by the military, mostly in war zones. This seldom effects airliners because they steer clear of active war zones.
Then there's GPS jamming by delivery drivers who don't want their boss watching over their shoulder all the time. When the article mentions jammers as small as a cellphone and costing less than $100, those are sold to drivers.
Delivery drivers don't jam LORAN or VOR, though - so it's not jammed by the second type.
GPS jamming is fairly detectable right? I wonder if we could create some crowd souced map of jammers. I think this kind of already exists as fairly course data but if a bunch of people installed fixed GPS sensors at home and wired them up to note every time their location lock is lost or moves. It could create a hyper detailed map of where the jammers are and track them moving in realtime.
I’d bet a lot of money that the NTSB will determine that the pilots’ failure to maintain clearance from terrain during a visual approach will be the primary cause with contributing factors of dark, moonless night and GPS jamming.
That one’s going to be on the flight crew, not the GPS jamming test.
I'm not going to argue that as it's always easy to blame dead people, but there's two different types of jamming.
One is to actually jam the signal IOW preventing reception. The other is to overpower the satellites' signals and replace them with your own. That defeats the doppler calculations of GPS needed for triangulation, and instead the receiver believes it's where the jammer wants it to be.
If the latter includes altitude information, then it's a huge problem.
If you overpower a signal, is there a difference? I'm not saying you're right or wrong here. I'm just saying there's a long history of coverups in the government and military.
If you can say, "oh we were only jamming" when in fact you were spoofing, well that's certainly a super easy excuse to hide behind.
In either case, asking for and being cleared for a visual approach (as the crew did and was) puts the onus on them to maintain continuous visual contact with the airport and to maintain their own terrain and obstacle clearance, which it’s safe to say they didn’t do.
Eh a month or two before the October 2023 Israel conflict - there were many reports of GPS jamming in the middle east impacting air transport aircraft. To the point where it basically caused various failure modes that shouldn't have happened with avionics (think the things you'd expect in a fuzzing scenario). It was pretty eye opening example of just how poor modern avionics are (and their integrations) when they get unpredictable inputs & the dependant downrange systems that rely upon that data.
Being much closer to the receiver and tied into terrestrial power grids, ground-based beacons can transmit at higher powers than GNSS signals and be received at much higher powers.
Received GNSS power is on the order of -130dBm (10e-16 W) - you can jam that with a 1W terrestrial source for hundreds of meters around. Way more if you're willing to scale the power from car USB power levels to bigger grid-connected supplies.
LORAN, from my quick googling, looks to be about 6-7 orders of magnitude higher received power.
I would be curious on and interested in guidance from a GNSS expert on what the risk profile is when you're using jam resistant frequencies with a multi GNSS constellation chipset (GPS, Galileo, BeiDou), WAAS (GNSS corrections received via satellite), and when close enough to airports that support it, LAAS (GNSS corrections broadcast from airports). Follow up questions would be what countermeasures are available to bolster GNSS reliability during critical phases of flight (takeoff and landing), as well as how cellular tower networks could be used as distributed sensor fabrics for constantly monitoring for and triangulate GNSS jamming using SDR (or perhaps start with a handful of GNSS reference monitoring stations at major airports for this monitoring).
Because GPS and other GNSS have only a very weak signal strength there are no jam resistant frequencies, you can jam them all very efficiently, or you can jam them very efficiently in selective way (jam BeiDou, but not GPS).
GPS was jammed even as early as Iraq war.
"Coalition troops also got a glimpse of GPS’s greatest weakness during the Gulf War. Iraqi forces installed jammers, for example, on top of landmarks such as Saddam Hussein’s palaces to prevent them from being hit, Mastalir says. This helped the military realize early on that it would have to further develop its laser-guided munitions and other weapons that acquire targets when GPS is unavailable"
A lot of work is being done to make GPS more jam resistant, and - just as important - more spoof resistant. The latest batch of satellites has a whole raft of countermeasures to help a receiver to identify whether the received signal is genuine or whether it was spoofed. Receivers too can do a lot to detect spoofing by just observing the signal (for instance: unrealistic power levels on reception, impossible response to vehicle movement and others besides), but quite a few of those are unrealistic or too expensive for regular (non military) applications. Jam resistant frequencies do not exist as you already mentioned, from a physics perspective. But GP might mean this to refer to the new M-Code signal, and these are sent out on different frequency offsets from the main carrier, so effectively different frequencies.
L5 is considered to be more jam resistant, but it is still in the process of being rolled out and most receivers do not have that capability. It will take the better part of a decade to be rolled out completely but the space side should be done by 2027 so if you need it you can get it but you'll need a completely new receiver.
For obvious reasons hard information about all this is tricky to come by, you can read what is available from non-classified sources though and you can glean quite a bit from there.
> L5-band signals are 30x harder to jam and interfere with compared to L1, and they offer superior performance in difficult-to-navigate areas such as urban canyons and tree-covered regions.
Probably be easier and more reliable to use star navigation with modern cameras, computers and atomic clocks. Especially for commercial aircraft flying above the weather.
With a quick calculation 50 ms time offset would mean about 20 meter difference. You can get that accuracy with NTP over residential internet and a better TCXO could hold that for a day. You could sync clocks and download the almanac at each airport. The almanac could be digitally signed and NTP has an option for authentication, too. That's about 10 USD of hardware (plus what you need for image capture and processing).
I'm pretty sure with dedicated hardware and better solutions you could get much better accuracy.
Maybe the starlink clocks could continuously calibrate from gps? Clock drift is usually a slow thing (like thermals). Their inter-satellite data links have all sorts of relative clocking info.
IIUC, GPS picks one satellite and 3 more to establish time differences between the first one and the other 3. There's only one point in universe where the set of differences would match what was observed, given the broadcast orbital data of satellites, and that gives the location of the receiver. It's like you are provided radii and center coordinates of 3 circles on a paper that intersect at 1 point and you are to math that point.
So GPS-like systems need precise orbital data and coherent clock from each satellites, or otherwise the receiver cannot figure out those radii.
Presumably you can have each sats reflect a clock from the same master ground station but that's not how GPS is implemented currently.
Coherency is a state. My question is if that state can be achieved by just tuning the individual clocks/locations based on GPS as a master. And, there's other tricks, with all the inter-satellite communication [1].
And, there's a contextual difference here between civilian GPS and military GPS. Much of the precision in the existing GPS satellites is to support the military use of GPS, with intentionally error injected into the civilian side.
And, by the nature of the hostile environment the military operates, military craft don't have as strong of a reliance on something that's ephemeral, like a GPS signal on a battlefield.
What I want is a tiny portable bluetooth jammer for those who insist everyone in public must be listening to their music. Sadly they are too clunky to haul around each day.
If I am not mistaken, this type of jammer can severily affect people with pacemakers. But, as a Brazilian citizen, I can understand the feeling of being forced to listen other's people music.
its myth youre mistaken because that would mean all the wifi devices and normal bt devices will also stop pacemaker. only early version of pacemaker before internet would be affected modern pacemakers have protection as long as you keep a safe 6 inch distance
You can brute-force jam the entire 80MHz range. However, it would require roughly 13dB more power compared to jamming a narrow-band signal.
In theory, you could try to exploit the adaptive frequency hopping that bluetooth does, nudging it to switch to specific bands, which you will then jam; this could save on energy, but I don't know if anybody's done it.
With all the man made EM emitters in the world, it seems like passively matching what can be “seen” to a database of known emitters (with signal profiles and locations) could be extremely accurate where people are (less helpful on the open ocean and remote wilderness). Similar to what’s already being done with Wi-Fi and Bluetooth but general purpose, perhaps?
They record spots for all wireless access points too, unless you opt-out by naming them certain ways and the surveillance-capitalism company decides to honor it. (e.g. The _nomap suffix.)
I hope some future Wifi standard makes it much easier to anonymize or obscure persistent access points.
That's always existed with Hidden SSID. If you are particularly paranoid you can set it up like that. But unless you insert personally identifiable info in your wifi name there is not really any privacy risk for this data being mapped.
> That's always existed with Hidden SSID. If you are particularly paranoid you can set it up like that.
It's actually the opposite, a hidden SSID will backfire and hurt your privacy when it comes to phones and laptops.
With a normal network, your phone can passively listen for when it approaches MyHomeNetwork and then connect. If you change that to a 802.11 hidden SSID, then whenever you aren't connected your phone will be constantly emitting a very distinctive mating-call: "Any hidden networks? Hello, if you're MyHomeNetwork, please then let me in." That makes it easy for someone to uniquely identify your phone as it moves around, and it also takes up more battery power with the often-fruitless transmissions.
Both issues could be reduced by restricting it to only auto-seek the SSID based on other clues, like GPS regions or neighbors' public SSIDs, but that usually isn't a feature.
> But unless you insert personally identifiable info in your wifi name there is not really any privacy risk for this data being mapped.
How often do you reset/rename it? Surely it's at least weird that some big companies, via sensors carried by your neighbors, know you moved your apartments from X to Y even when you don't use any of their products.
Some phone-apps will have access to the network name too, but that seems just marginally worse compared to other identifying info they could track and exfiltrate.
"In trials conducted by the General Lighthouse Authorities of UK and Ireland, a 1.5W radio jammer was able to knock out GPS signals over a range of 30 kilometers. However, to do the same to the Loran system, you'd need a 40ft tower — and around 25kW of juice to power it."
Well certainly, no one thing is impervious. But if you have GPS, LORAN, VORs, NDBs, astronavigation, etc. you have many more options at your disposal and present a much more complex attack target.
It's 2026: we have more ways to defeat jamming, or make it irrelevant, at unit costs trivial for commercial and most private applications. 1) atomic clocks can be smaller than a closed fist and allow GPS to work with 3 satalites with ocassional drops to 2. 2) the same clocks can be used to filter out radio sources from the wrong direction. 3) star navigation (commercial is often above weather, most weather is clear in some IR bands) 4) Terain following (easy to store maps now) 5) Inertial. 6) magnetic
When combined it is very hard to break the position fix. I expect the issue with the system is it's a military tech. with all it's that'll associated legal problems. After all. it'd bypass most the protections built into GPS modules.
Good luck finding a pilot trained on doing this, or an aircraft with high enough window cutouts that allow for the use of a sextant. Old Boeings had them [1], but no modern aircraft does.
I think even among navies you'll be hard pressed to find a navigator who still can do astronavigation. IIRC even the US Navy discontinued astronavigation, but recently-ish reintroduced training for it again.
In the 21st century you don't do astronavigation by hand, you use cameras, computers and software.
Astro-inertial guidance is used for example in submarine-launched ballistic missiles.
"Astro-inertial guidance, or stellar-inertial guidance, is a sensor fusion-information fusion of inertial guidance and celestial navigation. It is usually employed on submarine-launched ballistic missiles. Unlike silo-based intercontinental ballistic missiles, whose launch point does not move and thus can serve as a reference, SLBMs are launched from moving submarines, which complicates the necessary navigational calculations and increases circular error probable. Stellar-inertial guidance is used to correct small position and velocity errors that result from launch condition uncertainties due to errors in the submarine navigation system and errors that may have accumulated in the guidance system during the flight due to imperfect instrument calibration."
Yeah but good luck getting that approved for new airliner designs, much less retrofitting it into existing airliners. For the older ones, you'd probably need to rework half their computers.
Not so simple. For one the distances to the transmitter are much smaller, for another the amount of power available to the transmitters is pretty much whatever you want to hook it up to, whereas GPS satellites are on a pretty strict power budget. On the reception side the power levels are many orders of magnitude apart.
Not really. It uses 2MHz band, with the wavelength of around 160m.
This means that it's easy to receive via a ferrite bar antenna but hard to transmit. You need an antenna of at least around 40m size for that to be efficient.
Even a 160m guy-wire tower is cheap. 40m.. my friend installed 32m one just to have better internets, not exactly out of pocket cash, but nothing compared to say swapping a car.
This is likely just the start. With growing consumer reliance on GPS, jammer proliferation will mirror what we see in military contexts. Same thing will happen to starlink and jamming in contested zones
Better use a software defined radio like hackrf or a more dedicated gps thingy, esp32 with gps addon and some machine learning? (‘Some’ doing a lot of heavy lifting here)
I feel like gps nav software should start considering the jamming and spoofing cases as real conditions they will encounter that should throw up an INOP warning.
It wouldn't take much smarts for it to consider the type of vessel it's in and the max and current speeds. If the calculated position of a 10 knot vessel suddenly jumps 100 km away in seconds, that sure seems like a spoof. And if you had 10 satellites locked and then you have none, that sure seems like jamming, or you're in a tunnel; INOP either way.
The systems jamming in Hormuz and Ukraine aren't exactly cheap and low powered, nor are those used by the US military in one of their many jamming exercises every year. Cheap GPS jammers fit in a cigarette lighter and are used by truckers who don't want their boss snooping on them, but they don't quite threaten aviation.
That aside, you don't need to give up on GPS just yet. As expensive as airplanes are, there is no reason not to have at least 8 element CRPA receivers in them. Mostly a military niche product in the past they are rapidly proliferating, and most fuselages make for a great ground plane.
> Cheap GPS jammers fit in a cigarette lighter and are used by truckers who don't want their boss snooping on them, but they don't quite threaten aviation.
They absolutely do threaten air and maritime navigation, because those trucks drive in and near ports and airports.
First of all, starlink has been jammed in conflict zones.
Secondly, the number of satellites doesn’t really matter, the jamming happens at the end user level not at the satellite.
Finally, where are you getting that 20k number from? It’s not like there’s 20k starlink satellites in LOS to your station at all times. The earth will be obscuring many of those, they are below your feet on the other side of the planet.
That's near orders of magnitude more than reality. The only number that matters is the number of satellites that are in communication line of site. A satellite on the other side of the world doesn't help you.
It's not rocket science to make a GPS jammer. GPS Spoofing is more complex and causes way more damage or chaos. I would seriously avoid touching this subject whatsoever this is the kind of thing that will have the FBI and FCC so far up your ass you will feel it in the back of your eyeballs. On the off chance the feds don't catch you and you cause a serious accident you will be charged with 1st degree murder of how many people were on the aircraft that crashed along with a litany of other federal offences meaning life without parole is basically a guarantee.
The magnetic approach is very interesting. I can't imagine it would ever be reliable enough for a primary instrument since its susceptible to solar weather and certain regions with more geological activity.
I'm sorry, but a multi-kilogram (at a guess), five-figure-priced (at a conservative guess) device with kilometer-scale error (per their actual press release) is not a substitute for a GPS.
And you probably can't improve on many of those specs no matter how much "inventing" you do. There's just not that much information in magnetic fields, especially if you don't spend an infeasible amount of money on keeping maps up to date. You're probably jammable, too.
The same applies to the gravitational hacks, and the mapping issue applies even to visual navigation.
Those guesses, by the way, are because not only is AQNav's "data sheet" worthless fluff, but they seem to be allergic to letting anybody even see a picture of the product. Which makes me doubt that they actually have what a normal person would think of as a "product" to begin with.
Datasheets that look like that are a pretty strong indicator you're dealing with something that is giga export controlled, not as in "can only go to some countries, you have to declare it and theres a LOT of paperwork", more "attempting to, or even making plans about trying to leave the country with one is a pile of federal crimes"
Virtually anything navigational that cannot be easily or reliably jammed falls into this category far before meeting any of the accuracy/drift requirements.
Whats really sad for aviation is there was already an extensive network of ground based navaids. As GPS has proliferated, they've slowly been decommissioned as they age out to save on cost. I'm specifically referring to VORs which provide azimuth and range to station.
GPS is fantastic and as a primary source everyone loves the benefits it brings. However, in a century of aviation, everyone has kinda sorted out that you can't have too many backups to critical items... unless you let the accountants and bureaucrats run the show.
VOR is extremely short range and requires an extraordinary number of transmitters to provide any volume of coverage. Additionally it cannot provide coverage over oceanic areas. We USED TO have a nearly global long-range land based navigation system called LORAN, which only required one master station and a few remote stations to provide continent-scale coverage. But it was decommissioned in a cost savings move after it was determined that it could be replaced by GPS. It worked perfectly fine until it was decommissioned in 2010, not that long ago.
In the '90s I used to fly light aircraft back and forth between Seattle and Alaska. You were frequently out of range of any VOR transmitters, but that LORAN always worked. NDBs? That didn't work so great for Ron Brown.
https://en.wikipedia.org/wiki/Loran-C
On VOR: It's also a PITA to use, and for inexperienced people, or someone who rarely uses it, they can confuse flying towards and away from the station.
If you are a general aviation goober like me, flying a 1960's propeller airplane, sure, that is true.
However, in a modern commercial aircraft, all position sources including VOR-DMEs, GPS, and IRS are cross-compared by the flight management system and turned into a latitude, longitude, and circular error of probability. There is no TO/FROM flag to worry about in a 777, and no reverse sensing on the back side of a localizer approach.
Yeah that makes sense. My experience is mostly in 70s to early 90's prop planes, I have had the opportunity to use a glass cockpit a few times and it was much easier. I guess i did the typical thing and contextualized this on my experiences and ignored that 99.9% of flights are not GA haha.
Time was, if you didn't understand how to use VORs, you couldn't really fly. We used them as primary en route nav, as well as for approaches, for many decades. As a CFI I think most of the confusion around VORs these days comes down to poor or inadequate training.
That's fair. I replied to someone else with a similar remark, but essentially doing most of my flying in 70s to 90s prop planes, I imagine the tools I'm most used to are just dated. Your point around training is likely very accurate, I had some great teachers but I also had a few instances of being given inaccurate information and having to teach the teacher so to speak.
I don't fly and I wouldn't call my self someone that plays a lot of flight simulator. But I do enjoy navigation methods and I did learn the basics and practices of VOR navigation. I got an Android app that simulates flying courses, holding patterns etc, but only the navigation part. I would say I learned some intuition to it.
> Additionally it cannot provide coverage over oceanic areas.
It's really hard to jam oceanic areas though, you need a vessel capable of sustaining human life autonomously at least for days plus dealing with the high seas.
Buoys could theoretically be used for that purpose, yes, but good luck getting them stationary enough. Maybe some of the secret services could pull off such a trick but at least no ordinary civilian.
> sustaining human life
Not really. Drone ships are very much a thing these days.
maybe we need to update those giant concrete arrows on the ground...
https://en.wikipedia.org/wiki/Transcontinental_Airway_System
and have giant concrete QR codes
All VORs provide a radial that you’re on. Not all provide a distance to the station. VOR/DME or VORTACs provide both. Plain VORs do not.
As more and more are decommissioned, the percentage that support distance-measuring goes up, as the ones being decommissioned are more likely to be the less-useful ones, which are less likely to have supported DME in the first place. So most remaining ones support both, but it’s not assured without checking.
By taking a bearing from TWO VORs simultaneously, the distance to each can be computed. That's why planes have two VOR receivers and instruments.
Seems like we'd need a modern version that's less susceptible to jamming, otherwise aren't we just replacing one jammable service with another?
There are two types of GPS jamming.
There's GPS jamming by the military, mostly in war zones. This seldom effects airliners because they steer clear of active war zones.
Then there's GPS jamming by delivery drivers who don't want their boss watching over their shoulder all the time. When the article mentions jammers as small as a cellphone and costing less than $100, those are sold to drivers.
Delivery drivers don't jam LORAN or VOR, though - so it's not jammed by the second type.
> boss watching over their shoulder all the time
Sounds like the root cause to me. It should be illegal to use GNSS to track employees, or anyone really.
Jamming is starting to sound a lot like self-defense against surveillance.
GPS jamming is fairly detectable right? I wonder if we could create some crowd souced map of jammers. I think this kind of already exists as fairly course data but if a bunch of people installed fixed GPS sensors at home and wired them up to note every time their location lock is lost or moves. It could create a hyper detailed map of where the jammers are and track them moving in realtime.
GPS jamming was being investigated by the NTSB as a possible reason for this air crash that killed 4 people near White Sands Missile Range.
The plane reported GPS signal loss 5 minutes after the jamming started by WSMR. Three other planes in the area also reported GPS loss.
https://www.stripes.com/theaters/us/2026-08-05/ntsb-medevac-...
I’d bet a lot of money that the NTSB will determine that the pilots’ failure to maintain clearance from terrain during a visual approach will be the primary cause with contributing factors of dark, moonless night and GPS jamming.
That one’s going to be on the flight crew, not the GPS jamming test.
HN discussion: https://news.ycombinator.com/item?id=49181099
I'm not going to argue that as it's always easy to blame dead people, but there's two different types of jamming.
One is to actually jam the signal IOW preventing reception. The other is to overpower the satellites' signals and replace them with your own. That defeats the doppler calculations of GPS needed for triangulation, and instead the receiver believes it's where the jammer wants it to be.
If the latter includes altitude information, then it's a huge problem.
I believe it’s been made public that this was a jamming test, not a spoofing test.
If you overpower a signal, is there a difference? I'm not saying you're right or wrong here. I'm just saying there's a long history of coverups in the government and military.
If you can say, "oh we were only jamming" when in fact you were spoofing, well that's certainly a super easy excuse to hide behind.
In either case, asking for and being cleared for a visual approach (as the crew did and was) puts the onus on them to maintain continuous visual contact with the airport and to maintain their own terrain and obstacle clearance, which it’s safe to say they didn’t do.
Eh a month or two before the October 2023 Israel conflict - there were many reports of GPS jamming in the middle east impacting air transport aircraft. To the point where it basically caused various failure modes that shouldn't have happened with avionics (think the things you'd expect in a fuzzing scenario). It was pretty eye opening example of just how poor modern avionics are (and their integrations) when they get unpredictable inputs & the dependant downrange systems that rely upon that data.
Being much closer to the receiver and tied into terrestrial power grids, ground-based beacons can transmit at higher powers than GNSS signals and be received at much higher powers.
Received GNSS power is on the order of -130dBm (10e-16 W) - you can jam that with a 1W terrestrial source for hundreds of meters around. Way more if you're willing to scale the power from car USB power levels to bigger grid-connected supplies.
LORAN, from my quick googling, looks to be about 6-7 orders of magnitude higher received power.
Most pre-GPS navigation systems have shorter baselines than GPS and therefore accuracy is much worse, on top of generally being more complicated
And LORAN. But it may make a come-back.
GPS signals are just incredibly weak so it takes next to nothing to drown them out, easier still if you are above the receiver.
I would be curious on and interested in guidance from a GNSS expert on what the risk profile is when you're using jam resistant frequencies with a multi GNSS constellation chipset (GPS, Galileo, BeiDou), WAAS (GNSS corrections received via satellite), and when close enough to airports that support it, LAAS (GNSS corrections broadcast from airports). Follow up questions would be what countermeasures are available to bolster GNSS reliability during critical phases of flight (takeoff and landing), as well as how cellular tower networks could be used as distributed sensor fabrics for constantly monitoring for and triangulate GNSS jamming using SDR (or perhaps start with a handful of GNSS reference monitoring stations at major airports for this monitoring).
https://news.ycombinator.com/item?id=49186101
https://news.ycombinator.com/item?id=49184484
GPSJam: Daily maps of possible GPS interference - https://news.ycombinator.com/item?id=37868106 - October 2023 (89 comments)
GPSJam: Daily Maps of GPS Interference - https://news.ycombinator.com/item?id=32245346 - July 2022 (82 comments)
https://en.wikipedia.org/wiki/Transmitter_hunting | https://en.wikipedia.org/wiki/Pseudo-range_multilateration | https://www.arrl.org/direction-finding
https://geodesy.noaa.gov/CORS/ | https://arcg.is/18fWq8
Because GPS and other GNSS have only a very weak signal strength there are no jam resistant frequencies, you can jam them all very efficiently, or you can jam them very efficiently in selective way (jam BeiDou, but not GPS).
GPS was jammed even as early as Iraq war.
"Coalition troops also got a glimpse of GPS’s greatest weakness during the Gulf War. Iraqi forces installed jammers, for example, on top of landmarks such as Saddam Hussein’s palaces to prevent them from being hit, Mastalir says. This helped the military realize early on that it would have to further develop its laser-guided munitions and other weapons that acquire targets when GPS is unavailable"
https://web.archive.org/web/20160208233555/http://www.scient...
A lot of work is being done to make GPS more jam resistant, and - just as important - more spoof resistant. The latest batch of satellites has a whole raft of countermeasures to help a receiver to identify whether the received signal is genuine or whether it was spoofed. Receivers too can do a lot to detect spoofing by just observing the signal (for instance: unrealistic power levels on reception, impossible response to vehicle movement and others besides), but quite a few of those are unrealistic or too expensive for regular (non military) applications. Jam resistant frequencies do not exist as you already mentioned, from a physics perspective. But GP might mean this to refer to the new M-Code signal, and these are sent out on different frequency offsets from the main carrier, so effectively different frequencies.
Jam resistance and spoof resistantance are very different.
What work is done to make GPS more jam resistant?
L5 is considered to be more jam resistant, but it is still in the process of being rolled out and most receivers do not have that capability. It will take the better part of a decade to be rolled out completely but the space side should be done by 2027 so if you need it you can get it but you'll need a completely new receiver.
https://insidegnss.com/onenav-l5-direct-technology-enables-d...
For obvious reasons hard information about all this is tricky to come by, you can read what is available from non-classified sources though and you can glean quite a bit from there.
https://en.wikipedia.org/wiki/GPS_signals#L5
The third edition of 'Kaplan' is still excellent reading on the subject even though it is 10 years old now.
> L5-band signals are 30x harder to jam and interfere with compared to L1, and they offer superior performance in difficult-to-navigate areas such as urban canyons and tree-covered regions.
Impressive performance.
https://gps.stanford.edu/research/current-and-continuing-gps...
Single element antennas, adaptive antennas, beam steering antennas. Basically attempting to pull good RF while avoiding bad RF.
(this has been applied in the Russo-Ukrainian war in modified Starlink equipment)
GPS antenna mods make Starlink terminal immune to jammers - https://news.ycombinator.com/item?id=39616417 - March 2024 (72 comments)
https://olegkutkov.me/2023/11/07/connecting-external-gps-ant...
Probably be easier and more reliable to use star navigation with modern cameras, computers and atomic clocks. Especially for commercial aircraft flying above the weather.
Celestial navigation requires an accurate clock and an almanac that needs to be updated. It is completely impractical for non-military applications.
Is that really that impractical?
With a quick calculation 50 ms time offset would mean about 20 meter difference. You can get that accuracy with NTP over residential internet and a better TCXO could hold that for a day. You could sync clocks and download the almanac at each airport. The almanac could be digitally signed and NTP has an option for authentication, too. That's about 10 USD of hardware (plus what you need for image capture and processing).
I'm pretty sure with dedicated hardware and better solutions you could get much better accuracy.
They did it in the 60s for the B2 bomber[0]. I think computers are slightly faster and more reliable today, so it at least seems plausible.
[0] https://www.righto.com/2026/04/B-52-star-tracker-angle-compu...
Does the almanac need updating? I regularly use plate solving with my telescope and I've never had to update it's stars database
Guess its back to the good ol' map, compass and stopwatch.
We have starlink I am sure they can figure something out.
Starlink lacks the high precision atomic clocks on board of the satellites, that is also why Starlink needs a GPS fix to bootstrap itself.
Maybe the starlink clocks could continuously calibrate from gps? Clock drift is usually a slow thing (like thermals). Their inter-satellite data links have all sorts of relative clocking info.
IIUC, GPS picks one satellite and 3 more to establish time differences between the first one and the other 3. There's only one point in universe where the set of differences would match what was observed, given the broadcast orbital data of satellites, and that gives the location of the receiver. It's like you are provided radii and center coordinates of 3 circles on a paper that intersect at 1 point and you are to math that point.
So GPS-like systems need precise orbital data and coherent clock from each satellites, or otherwise the receiver cannot figure out those radii.
Presumably you can have each sats reflect a clock from the same master ground station but that's not how GPS is implemented currently.
Coherency is a state. My question is if that state can be achieved by just tuning the individual clocks/locations based on GPS as a master. And, there's other tricks, with all the inter-satellite communication [1].
And, there's a contextual difference here between civilian GPS and military GPS. Much of the precision in the existing GPS satellites is to support the military use of GPS, with intentionally error injected into the civilian side.
And, by the nature of the hostile environment the military operates, military craft don't have as strong of a reliance on something that's ephemeral, like a GPS signal on a battlefield.
[1] https://arxiv.org/pdf/2501.05302
We have starlink I am sure we can figure it out. Like... launch a better GPS system with one rocket?
doesn't take sat swarms. what you need are some cash and bunch of educated and motivated smart people. that can be tricky sometimes
I wish there were cheap Bluetooth jammers to prevent speakers from playing when hiking
Wouldn’t they also stop AirPods from working?
What I want is a tiny portable bluetooth jammer for those who insist everyone in public must be listening to their music. Sadly they are too clunky to haul around each day.
Unfortunately for me, when I hear music it's from the horrible audio of a cell phone speaker.
https://stfu.pankajtanwar.in/
Are they? You can make one pretty easily and sew it into your backpack for added camouflage. I heard.
If I am not mistaken, this type of jammer can severily affect people with pacemakers. But, as a Brazilian citizen, I can understand the feeling of being forced to listen other's people music.
its myth youre mistaken because that would mean all the wifi devices and normal bt devices will also stop pacemaker. only early version of pacemaker before internet would be affected modern pacemakers have protection as long as you keep a safe 6 inch distance
how i even make a clunky one ? need one for a neighbor in 3rd world country with lowest civic sense.
i tried that esp32 that uses nRF24 but it doesnt seem to jam all the time. i heard about hackrf one dont know if its can properly do that.
You can brute-force jam the entire 80MHz range. However, it would require roughly 13dB more power compared to jamming a narrow-band signal.
In theory, you could try to exploit the adaptive frequency hopping that bluetooth does, nudging it to switch to specific bands, which you will then jam; this could save on energy, but I don't know if anybody's done it.
With all the man made EM emitters in the world, it seems like passively matching what can be “seen” to a database of known emitters (with signal profiles and locations) could be extremely accurate where people are (less helpful on the open ocean and remote wilderness). Similar to what’s already being done with Wi-Fi and Bluetooth but general purpose, perhaps?
I think that is already done by the two big smartphone OS vendors.
They record spots for all wireless access points too, unless you opt-out by naming them certain ways and the surveillance-capitalism company decides to honor it. (e.g. The _nomap suffix.)
I hope some future Wifi standard makes it much easier to anonymize or obscure persistent access points.
That's always existed with Hidden SSID. If you are particularly paranoid you can set it up like that. But unless you insert personally identifiable info in your wifi name there is not really any privacy risk for this data being mapped.
> That's always existed with Hidden SSID. If you are particularly paranoid you can set it up like that.
It's actually the opposite, a hidden SSID will backfire and hurt your privacy when it comes to phones and laptops.
With a normal network, your phone can passively listen for when it approaches MyHomeNetwork and then connect. If you change that to a 802.11 hidden SSID, then whenever you aren't connected your phone will be constantly emitting a very distinctive mating-call: "Any hidden networks? Hello, if you're MyHomeNetwork, please then let me in." That makes it easy for someone to uniquely identify your phone as it moves around, and it also takes up more battery power with the often-fruitless transmissions.
Both issues could be reduced by restricting it to only auto-seek the SSID based on other clues, like GPS regions or neighbors' public SSIDs, but that usually isn't a feature.
> But unless you insert personally identifiable info in your wifi name there is not really any privacy risk for this data being mapped.
How often do you reset/rename it? Surely it's at least weird that some big companies, via sensors carried by your neighbors, know you moved your apartments from X to Y even when you don't use any of their products.
Some phone-apps will have access to the network name too, but that seems just marginally worse compared to other identifying info they could track and exfiltrate.
Aren’t most modern receivers multi-constellation? What is the technical feasibility of jamming every GNSS provider?
This explains why my drone occasionally loses signal near commercial areas. A real nuisance to deal with.
I saw some rumblings (can't find an article) that there's interest in restarting LORAN to provide an alternative to GPS for this reason.
eLoran has been proposed as more accurate version of LORAN competitive with GPS.
The Wikipedia page says that China has deployed an eLoran network but I can't tell if used for navigation or just high-precision timing.
See UK and France:
* https://insidegnss.com/uk-and-france-renew-ties-resilient-pn...
LORAN can be jammed.
"In trials conducted by the General Lighthouse Authorities of UK and Ireland, a 1.5W radio jammer was able to knock out GPS signals over a range of 30 kilometers. However, to do the same to the Loran system, you'd need a 40ft tower — and around 25kW of juice to power it."
https://www.engadget.com/2013-01-21-uk-eloran-navigation-sys...
Well certainly, no one thing is impervious. But if you have GPS, LORAN, VORs, NDBs, astronavigation, etc. you have many more options at your disposal and present a much more complex attack target.
It's 2026: we have more ways to defeat jamming, or make it irrelevant, at unit costs trivial for commercial and most private applications. 1) atomic clocks can be smaller than a closed fist and allow GPS to work with 3 satalites with ocassional drops to 2. 2) the same clocks can be used to filter out radio sources from the wrong direction. 3) star navigation (commercial is often above weather, most weather is clear in some IR bands) 4) Terain following (easy to store maps now) 5) Inertial. 6) magnetic
When combined it is very hard to break the position fix. I expect the issue with the system is it's a military tech. with all it's that'll associated legal problems. After all. it'd bypass most the protections built into GPS modules.
And the military has JDAM with HOJ as a solution for jamming
I was thinking G-man and a suprise helicopter on your lawn. The government hasn't made a spectical of throwing the book at a jammer recently.
> astronavigation
Good luck finding a pilot trained on doing this, or an aircraft with high enough window cutouts that allow for the use of a sextant. Old Boeings had them [1], but no modern aircraft does.
I think even among navies you'll be hard pressed to find a navigator who still can do astronavigation. IIRC even the US Navy discontinued astronavigation, but recently-ish reintroduced training for it again.
[1] https://virginflightdeck.blogspot.com/2010_09_01_archive.htm...
In the 21st century you don't do astronavigation by hand, you use cameras, computers and software.
Astro-inertial guidance is used for example in submarine-launched ballistic missiles.
"Astro-inertial guidance, or stellar-inertial guidance, is a sensor fusion-information fusion of inertial guidance and celestial navigation. It is usually employed on submarine-launched ballistic missiles. Unlike silo-based intercontinental ballistic missiles, whose launch point does not move and thus can serve as a reference, SLBMs are launched from moving submarines, which complicates the necessary navigational calculations and increases circular error probable. Stellar-inertial guidance is used to correct small position and velocity errors that result from launch condition uncertainties due to errors in the submarine navigation system and errors that may have accumulated in the guidance system during the flight due to imperfect instrument calibration."
https://en.wikipedia.org/wiki/Missile_guidance
Yeah but good luck getting that approved for new airliner designs, much less retrofitting it into existing airliners. For the older ones, you'd probably need to rework half their computers.
> Good luck finding a pilot trained on doing this
Not necessary. ICBMs have been able to do this autonomously for a very long time [0]
[0] https://en.wikipedia.org/wiki/Celestial_navigation
Not so simple. For one the distances to the transmitter are much smaller, for another the amount of power available to the transmitters is pretty much whatever you want to hook it up to, whereas GPS satellites are on a pretty strict power budget. On the reception side the power levels are many orders of magnitude apart.
Not really. It uses 2MHz band, with the wavelength of around 160m.
This means that it's easy to receive via a ferrite bar antenna but hard to transmit. You need an antenna of at least around 40m size for that to be efficient.
Even a 160m guy-wire tower is cheap. 40m.. my friend installed 32m one just to have better internets, not exactly out of pocket cash, but nothing compared to say swapping a car.
Sure, but such an antenna will be extremely conspicuous and easy to triangulate. You can't install it covertly.
Meanwhile, GPS can be jammed or spoofed with a briefcase-sized device for a couple of kilometers around you.
This is likely just the start. With growing consumer reliance on GPS, jammer proliferation will mirror what we see in military contexts. Same thing will happen to starlink and jamming in contested zones
Is there a reliable app to detect these without using excessive amounts of battery?
Better use a software defined radio like hackrf or a more dedicated gps thingy, esp32 with gps addon and some machine learning? (‘Some’ doing a lot of heavy lifting here)
I feel like gps nav software should start considering the jamming and spoofing cases as real conditions they will encounter that should throw up an INOP warning.
It wouldn't take much smarts for it to consider the type of vessel it's in and the max and current speeds. If the calculated position of a 10 knot vessel suddenly jumps 100 km away in seconds, that sure seems like a spoof. And if you had 10 satellites locked and then you have none, that sure seems like jamming, or you're in a tunnel; INOP either way.
> At the quantum-sensing firm SandboxAQ, an Alphabet spinoff…
This was an interesting article up to the point where the writer started taking SandboxAQ seriously.
For why you shouldn't take SandboxAQ seriously as a creator of actual technology or real products, start here: https://www.theinformation.com/articles/lavish-spending-weak...
The systems jamming in Hormuz and Ukraine aren't exactly cheap and low powered, nor are those used by the US military in one of their many jamming exercises every year. Cheap GPS jammers fit in a cigarette lighter and are used by truckers who don't want their boss snooping on them, but they don't quite threaten aviation.
That aside, you don't need to give up on GPS just yet. As expensive as airplanes are, there is no reason not to have at least 8 element CRPA receivers in them. Mostly a military niche product in the past they are rapidly proliferating, and most fuselages make for a great ground plane.
> Cheap GPS jammers fit in a cigarette lighter and are used by truckers who don't want their boss snooping on them, but they don't quite threaten aviation.
They absolutely do threaten air and maritime navigation, because those trucks drive in and near ports and airports.
https://insidegnss.com/fcc-fines-operator-of-gps-jammer-that...
https://ilwulocal94.org/news/2024/CSA%2001-24%20GPS%20Jammin...
https://archive.is/zUA3D
Starlink can be uses as GPS. Good luck jamming 20 thousand satellites.
First of all, starlink has been jammed in conflict zones.
Secondly, the number of satellites doesn’t really matter, the jamming happens at the end user level not at the satellite.
Finally, where are you getting that 20k number from? It’s not like there’s 20k starlink satellites in LOS to your station at all times. The earth will be obscuring many of those, they are below your feet on the other side of the planet.
Do they have atomic clocks on board?
I was under the impression that Starlink needs GPS for initial acquisition.
That's near orders of magnitude more than reality. The only number that matters is the number of satellites that are in communication line of site. A satellite on the other side of the world doesn't help you.
I wonder how many are in view?
gps is 31 total satellites 12,000 miles up
starlink is 10,000 satellites at ~ 300 miles. (and what orbit?)
EDIT: I found this:
-- starlink:
"In any given place there are 3-4 Starlink satellites visible at a time"
https://news.ycombinator.com/item?id=42445512 :)
in december 2024, there were 4,000 starlink satellites in orbit
so starlink is ~ 8 at all times?
-- GPS:
This 24-slot arrangement ensures users can view at least four satellites from virtually any point on the planet.
- https://www.gps.gov/space-segment
Remember there's also BeiDou, Galileo, and GLONASS as well.
Our RTK base station (a Ublox ZED-F9P receiver, with a cheap patch antenna on the roof) can currently see 45 GNSS satellites.
They've removed the in-built PNT service
Those cheap GPS jammers, which sites should I avoid to not buy them by accident?
It's not rocket science to make a GPS jammer. GPS Spoofing is more complex and causes way more damage or chaos. I would seriously avoid touching this subject whatsoever this is the kind of thing that will have the FBI and FCC so far up your ass you will feel it in the back of your eyeballs. On the off chance the feds don't catch you and you cause a serious accident you will be charged with 1st degree murder of how many people were on the aircraft that crashed along with a litany of other federal offences meaning life without parole is basically a guarantee.
No worries in the long run; similar to the "energy crisis," new inventions and technology will mitigate the issue:
Quantum Compass: https://en.wikipedia.org/wiki/Quantum_compass
Also see: https://www.sandboxaq.com/post/sandboxaq-and-acubed-achieve-...
The magnetic approach is very interesting. I can't imagine it would ever be reliable enough for a primary instrument since its susceptible to solar weather and certain regions with more geological activity.
Also see https://q-ctrl.com/ironstone-opal
I'm sorry, but a multi-kilogram (at a guess), five-figure-priced (at a conservative guess) device with kilometer-scale error (per their actual press release) is not a substitute for a GPS.
And you probably can't improve on many of those specs no matter how much "inventing" you do. There's just not that much information in magnetic fields, especially if you don't spend an infeasible amount of money on keeping maps up to date. You're probably jammable, too.
The same applies to the gravitational hacks, and the mapping issue applies even to visual navigation.
Those guesses, by the way, are because not only is AQNav's "data sheet" worthless fluff, but they seem to be allergic to letting anybody even see a picture of the product. Which makes me doubt that they actually have what a normal person would think of as a "product" to begin with.
Datasheets that look like that are a pretty strong indicator you're dealing with something that is giga export controlled, not as in "can only go to some countries, you have to declare it and theres a LOT of paperwork", more "attempting to, or even making plans about trying to leave the country with one is a pile of federal crimes"
Virtually anything navigational that cannot be easily or reliably jammed falls into this category far before meeting any of the accuracy/drift requirements.
No need to be sorry.
My "no worries" comment was a bit tongue-in-cheek. Who knows how far the tech will go or how cheap it will get.