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.
* https://insidegnss.com/uk-and-france-renew-ties-resilient-pn...
https://www.engadget.com/2013-01-21-uk-eloran-navigation-sys...
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.
[1] https://virginflightdeck.blogspot.com/2010_09_01_archive.htm...
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."
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.
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.
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...
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.
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...
I was under the impression that Starlink needs GPS for initial acquisition.
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.
Quantum Compass: https://en.wikipedia.org/wiki/Quantum_compass
Also see: https://www.sandboxaq.com/post/sandboxaq-and-acubed-achieve-...
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.
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.
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
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.
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.
Not really. Drone ships are very much a thing these days.
https://en.wikipedia.org/wiki/Transcontinental_Airway_System
and have giant concrete QR codes
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.
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-...
That one’s going to be on the flight crew, not the GPS jamming test.
HN discussion: https://news.ycombinator.com/item?id=49181099
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.
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.
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.
GPS signals are just incredibly weak so it takes next to nothing to drown them out, easier still if you are above the receiver.
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
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...
What work is done to make GPS more jam resistant?
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.
Impressive performance.
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...
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.