GPS Needs to Toughen Up, or Get Trampled Down(aviationweek.com)
aviationweek.com
GPS Needs to Toughen Up, or Get Trampled Down
https://aviationweek.com/business-aviation/safety-ops-regulation/gps-needs-toughen-or-get-trampled-down
88 comments
It feels like we are on the tipping point of a total technology collapse. Newspapers are publishing AI hallucinated news and don't understand why their editors aren't catching it. GPS and mobile communications are subject to jamming/spoofing. Public utilities are subject to hacking. Air traffic control is teetering on the edge of a cliff. And our best technical minds are working on keeping teenagers addicted to 15 second dopamine hits.
> Newspapers are publishing AI hallucinated news
Is there an example of a reputable (subjective, sure) news source having done this?
Is there an example of a reputable (subjective, sure) news source having done this?
The likely example on most people's minds in the most recent news cycle would be the Chicago Sun-Times: https://www.npr.org/2025/05/20/nx-s1-5405022/fake-summer-rea...
The article it published was a nationally syndicated piece, though. Maybe they thought somebody else was vetting?
The article it published was a nationally syndicated piece, though. Maybe they thought somebody else was vetting?
the latest thing I've seen: https://www.npr.org/2025/05/20/nx-s1-5405022/fake-summer-rea...
At least in the case of stocks, even before LLMs entered the scene, stock articles were being written by machines rather than journalists. [1]
I'd bet money this isn't the only place that has machine generated content. Proving exactly what is and isn't that would be a bit tricky.
[1] https://www.gsb.stanford.edu/insights/robo-journalism-good-n...
I'd bet money this isn't the only place that has machine generated content. Proving exactly what is and isn't that would be a bit tricky.
[1] https://www.gsb.stanford.edu/insights/robo-journalism-good-n...
Almost all index pages are zero effort machine generated pages. I'm not entirely sure about it being an effect over time but Newspapers use to have tiny articles summarizing page 12 which later(?) became "more on page 12".
For a while (until I got to lazy) I maintained a front page article that talked about everything going on in the blog linking to tag pages that should have (but didn't) enjoy the same love. It was challenging to have a single sentence describe a group of articles and string those sentences into an article that sufficiently hides the truth that the blog randomly rambled all over the place. There was a lack of urgency for new articles to appear (except from the rss feed) in stead the front page article revealed missing posts. You could compare it to a wiki (while html offers the same utility) but the blog had 3 clear levels and blog like articles that rarely got updated.
It had me spend some thoughts on the absurdity of putting a log file on the front page or attempting to massage that automation into something nice? Everyone is doing it so it must be right.
For a while (until I got to lazy) I maintained a front page article that talked about everything going on in the blog linking to tag pages that should have (but didn't) enjoy the same love. It was challenging to have a single sentence describe a group of articles and string those sentences into an article that sufficiently hides the truth that the blog randomly rambled all over the place. There was a lack of urgency for new articles to appear (except from the rss feed) in stead the front page article revealed missing posts. You could compare it to a wiki (while html offers the same utility) but the blog had 3 clear levels and blog like articles that rarely got updated.
It had me spend some thoughts on the absurdity of putting a log file on the front page or attempting to massage that automation into something nice? Everyone is doing it so it must be right.
It seems perfectly appropriate for machines to write 'Stock X goes down as Y happens' articles.
They have the same explanatory power as similar drivel written by humans, and you walk away feeling similarly uninformed.
They have the same explanatory power as similar drivel written by humans, and you walk away feeling similarly uninformed.
The reason is that everything is nearshored and outsourced, where starting from age 35 they stop responding to your CV. Then everyone are hired on some form of "1 person company" B2B basis where software professional has no power to push back.
You probably read too many news articles that were written to put you in a state of despair about the present and the future. Mass media and social media want you to feel miserable; don't let them.
That has always been the case. https://en.wikipedia.org/wiki/Yellow_journalism was a problem in the 1890s.
And even earlier. Thomas Jefferson, writing in 1807:
"Nothing can now be believed which is seen in a newspaper. Truth itself becomes suspicious by being put into that polluted vehicle. The real extent of this state of misinformation is known only to those who are in situations to confront facts within their knolege with the lies of the day. I really look with commiseration over the great body of my fellow citizens, who, reading newspapers, live & die in the belief, that they have known something of what has been passing in the world in their time; whereas the accounts they have read in newspapers are just as true a history of any other period of the world as of the present, except that the real names of the day are affixed to their fables. General facts may indeed be collected from them, such as that Europe is now at war, that Bonaparte has been a successful warrior, that he has subjected a great portion of Europe to his will, &c., &c.; but no details can be relied on. I will add, that the man who never looks into a newspaper is better informed than he who reads them; inasmuch as he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. He who reads nothing will still learn the great facts, and the details are all false."
"Nothing can now be believed which is seen in a newspaper. Truth itself becomes suspicious by being put into that polluted vehicle. The real extent of this state of misinformation is known only to those who are in situations to confront facts within their knolege with the lies of the day. I really look with commiseration over the great body of my fellow citizens, who, reading newspapers, live & die in the belief, that they have known something of what has been passing in the world in their time; whereas the accounts they have read in newspapers are just as true a history of any other period of the world as of the present, except that the real names of the day are affixed to their fables. General facts may indeed be collected from them, such as that Europe is now at war, that Bonaparte has been a successful warrior, that he has subjected a great portion of Europe to his will, &c., &c.; but no details can be relied on. I will add, that the man who never looks into a newspaper is better informed than he who reads them; inasmuch as he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. He who reads nothing will still learn the great facts, and the details are all false."
but what if we can get that down to 5 seconds?
catastrophic thinking is a mental state.. what you say is true but not new to many.. constructive engagement is called for in this age of precision and network
"A single 1-kW jammer can take down GPS for a 300-nm radius.[...] A CRPA can shrink the effective radius of the 1-kW jammer to 3 nm. The jammer’s area of effectiveness is slashed from 280,000 m² to 28 m²."
An example of the kind of unit confusion that could crash a Mars orbiter?
I thought we were talking about nanometers and square meters here for a second. But this only makes sense if "m²" means square miles and "nm" means nautical miles. How about at least using "mi" for miles to reduce confusion?
An example of the kind of unit confusion that could crash a Mars orbiter?
I thought we were talking about nanometers and square meters here for a second. But this only makes sense if "m²" means square miles and "nm" means nautical miles. How about at least using "mi" for miles to reduce confusion?
Well, nautical miles are the standard unit in the context of aviation, so I don't think it's all that bad. "mi" refers to a different unit.
True, "nm" initially seemed to be nautical miles, but then this square meters thing appeared. The point is that "m" should be meters, but "mi" would be a more customary abbreviation for miles in the U.S.
They shouldn't have switched from nautical miles to miles. The area should have been expressed in square nautical miles.
mile and nautical mile are not the same so it still doesn't make any sense
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Agreed, though there's a space between the number & the unit which generally indicates non-SI units (SI should never have a space). The switch from nautical to statute miles is still really weird though.
Are you sure? NIST says there should be a space:
> There is a space between the numerical value and unit symbol, even when the value is used in an adjectival sense, except in the case of superscript units for plane angle.
https://physics.nist.gov/cuu/Units/checklist.html
> There is a space between the numerical value and unit symbol, even when the value is used in an adjectival sense, except in the case of superscript units for plane angle.
https://physics.nist.gov/cuu/Units/checklist.html
> SI should never have a space
You are mistaken. SI units and their numbers always have a space. For reference [1], [2].
[1] https://www.npl.co.uk/si-units cf. Numerical Notation
[2] https://physics.nist.gov/cuu/Units/checklist.html cf. #15
EDIT: Scooped ;)
You are mistaken. SI units and their numbers always have a space. For reference [1], [2].
[1] https://www.npl.co.uk/si-units cf. Numerical Notation
[2] https://physics.nist.gov/cuu/Units/checklist.html cf. #15
EDIT: Scooped ;)
That's nonsense. There is a space between the number and the unit in SI.
From https://news.ycombinator.com/newsguidelines.html:
Please don't complain about tangential annoyances—e.g. article or website formats, name collisions, or back-button breakage. They're too common to be interesting.
Please don't complain about tangential annoyances—e.g. article or website formats, name collisions, or back-button breakage. They're too common to be interesting.
For anyone as confused as I was, this article uses nm to mean nautical miles not nanometers.
Oof, especially regarding GPS, nm (nanometer) and ns (nanosecond) are frequently used units of measurement. Nautical miles seems like it'd be more of a seafaring term?
It's good for anything that goes a good distance over the (spherical) earth's surface. 1 nautical mile is just 1/60th of a degree around.
Slight technical nit-pick: 1 nautical mile is 1/60th of a degree of latitude only, since the distance represented by angular longitudes varies depending on where you are on earth.
With single-digit precision like the article (appropriately) uses: 4×10⁴ km ≈ Earth’s circumference.
Aeronautical navigation also uses nautical miles. And as the article says: "A quarter century ago, the primary use for GPS was aviation and marine navigation".
I wish I had your GPS receiver if you associate nanometers with GPS. ;-)
Its an US article, dont expect much. Anything but metric system is the mantra and people's egos won't allow any change
Maybe don't bag on an entire country without examining your own prejudices.
Nautical miles are used in this article by an aviation magazine presumably because they are the global standard for marine and aeronautical navigation, and have been since well before the metric system was a global standard. It is also worth noting that the US does not use nautical miles as a standard, they use statute miles.
FYI, nautical miles are a useful standard for global navigation since they are referenced to the size of the earth itself.
Nautical miles are used in this article by an aviation magazine presumably because they are the global standard for marine and aeronautical navigation, and have been since well before the metric system was a global standard. It is also worth noting that the US does not use nautical miles as a standard, they use statute miles.
FYI, nautical miles are a useful standard for global navigation since they are referenced to the size of the earth itself.
GPS jamming is certainly a fun problem to deal with... I've been getting into GPS for timing data, and especially if you're building a global network or coordinated system using GPS as the time source, you have to account for it if you care at all about time stability.
Apparently (I haven't had this happen personally, yet) many truckers install GPS jamming cigarette lighter accessories in their trucks when they want to mask their location from trucking companies that track them everywhere. That can wreak havoc on GPS receivers at facilities, especially if you have, say, a logistics building right next to a datacenter.
Apparently (I haven't had this happen personally, yet) many truckers install GPS jamming cigarette lighter accessories in their trucks when they want to mask their location from trucking companies that track them everywhere. That can wreak havoc on GPS receivers at facilities, especially if you have, say, a logistics building right next to a datacenter.
I live on a main road and I've seen my JAMIND pop positive a number of times.
Now that I'm building a CCTV setup, I should see if I can connect the two and save images of the vehicles passing by when it happens.
Now that I'm building a CCTV setup, I should see if I can connect the two and save images of the vehicles passing by when it happens.
> "A single 1-kW jammer can take down GPS for a 300-nm radius."
This is one of those occasions when capitalisation really matters: "nm" (lowercase) is nanometer, the tiniest of scales. On the other hand, "NM" (uppercase) is nautical miles, used in aviation (because aviation is stuck in the age of sail, and measures distance in boat miles and speeds in boat miles per hour)
All Aviation literature will tell you to never spell it lowercase, and this is why. There's a lot of physics in aviation, and it's too easy to misread things. Always get your units right.
This is one of those occasions when capitalisation really matters: "nm" (lowercase) is nanometer, the tiniest of scales. On the other hand, "NM" (uppercase) is nautical miles, used in aviation (because aviation is stuck in the age of sail, and measures distance in boat miles and speeds in boat miles per hour)
All Aviation literature will tell you to never spell it lowercase, and this is why. There's a lot of physics in aviation, and it's too easy to misread things. Always get your units right.
"nmi" is also common
Alternatively, we could start providing real geopolitical consequences for the Russians doing the trampling.
"The Russians" is a copout, though, if you can buy a GPS jammer for 50 bucks. It's commonly used e.g. by truckers who'd prefer their corporate liege lord don't track them every second they exist.
You'll have to make GPS more secure with or without geopolitical consequences for Russia, so why don't we focus on the actual topic of the article.
You'll have to make GPS more secure with or without geopolitical consequences for Russia, so why don't we focus on the actual topic of the article.
Truckers have been doing that for a while. It's become a serious threat to the safety of those using GPS only for the last few years when the Russians started doing it for entire regions.
There will always be holes in technology that exist to be exploited for nefarious purposes. The best way to deal with it is to present strong consequences for those who would exploit them.
There will always be holes in technology that exist to be exploited for nefarious purposes. The best way to deal with it is to present strong consequences for those who would exploit them.
As always, Zoidberg says “why not both?”
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Supposedly CRPAs are already due to come off the ITAR list later this year, so that's good news.
https://insidegnss.com/crpas-to-be-removed-from-itar-list-op...
https://insidegnss.com/crpas-to-be-removed-from-itar-list-op...
> Scott said of the rule change. “You’re not going to be able to buy them at Walmart or on Amazon, they’ll still be export controlled, but not on the munitions list.”
Why not? I have a FLIR which is under export restrictions and you can buy from them, shit like this will have a card inside saying you can't sell to unfriendly nationals: https://www.amazon.com/FLIR-One-Thermal-Imager-Android/dp/B0...
Why not? I have a FLIR which is under export restrictions and you can buy from them, shit like this will have a card inside saying you can't sell to unfriendly nationals: https://www.amazon.com/FLIR-One-Thermal-Imager-Android/dp/B0...
> Goward says Todd Humphreys of the University of Texas Radionavigation Laboratory suspects that China’s Beidou can mimic and spoof both GPS and Galileo signals.
Galileo has optional cryptographic signatures of its navigational data. They embed the data into their broadcast. Can be used for free.
Galileo has optional cryptographic signatures of its navigational data. They embed the data into their broadcast. Can be used for free.
Galileo’s open service (civil-access) E1 signal incorporates public/private key encryption to digitally sign and authentify data. False Galileo signals from malicious forces are easily detected and rejected by GNSS receivers because they lack encryption watermarks. The feature, called Open Service-Navigation Message Authentication (OS-NMA), has been fully operational since August 2023.
It's still vulnerable to replay attacks, even with signed navigation data.
Wouldn't that require them to match the timestamp somehow?
The receiver derives the time from the signal itself.
Right, so if the timecode in the signal doesn't match the receiving device's internal clock it should know the signal is invalid shouldn't it?
The time in the device isn’t independent of the received signal. The device typically has a clock that is much less accurate than the timesignal that gets set based on the gps signal. There aren’t many devices that can rival a gps satellite for time accuracy. A spoofed gps signal would not differ enough in time from a real one to tip you off.
Further, a big part of the working of GPS is that your location is trilaterated from discrepancies in time from the various signals due to time of flight.
The only way to accurately detect a spoofed signal is if you already know your location. (You can infer spoofing using IMUs, or signal analysis, etc… but that is a rare capability at this point)
Further, a big part of the working of GPS is that your location is trilaterated from discrepancies in time from the various signals due to time of flight.
The only way to accurately detect a spoofed signal is if you already know your location. (You can infer spoofing using IMUs, or signal analysis, etc… but that is a rare capability at this point)
If the receiver has no other even-slightly-plausible clock, then yeah, but let's assume that RTC chips and coin-cell batteries exist.
>One of the deadliest GPS L1 civil signal interference events occurred on Dec. 25. On that date, Azerbaijan Airlines Flight 8243, an Embraer 190, was lured off course while enroute from Baku, Azerbaijan, to Grozny, Russia.
I am not seeing anything about that in the Wikipedia article:
* https://en.wikipedia.org/wiki/Azerbaijan_Airlines_Flight_824...
It sounds like the GPS was jammed, not spoofed. The aircraft had already shot some missed approaches at the destination airport before the event that caused the loss of the aircraft.
I am not seeing anything about that in the Wikipedia article:
* https://en.wikipedia.org/wiki/Azerbaijan_Airlines_Flight_824...
It sounds like the GPS was jammed, not spoofed. The aircraft had already shot some missed approaches at the destination airport before the event that caused the loss of the aircraft.
Not surprising that a layperson (i.e. a reporter or Wikipedia editor) would not understand the difference between jamming and spoofing.
"GPS is falling behind Galileo and Beidou as the preeminent GNSS"
I remember, that Galileo went offline a few years ago for some days - and the joke was, no one noticed. So possible that today there are more regular users and possible that there are some advanced features of Galileo like the mentioned
"Galileo’s open service (civil-access) E1 signal incorporates public/private key encryption to digitally sign and authentify data"
But I think GPS falling behind Galileo would imply a bit more Galileo users, compared to GPS. Which would surprise me.
I remember, that Galileo went offline a few years ago for some days - and the joke was, no one noticed. So possible that today there are more regular users and possible that there are some advanced features of Galileo like the mentioned
"Galileo’s open service (civil-access) E1 signal incorporates public/private key encryption to digitally sign and authentify data"
But I think GPS falling behind Galileo would imply a bit more Galileo users, compared to GPS. Which would surprise me.
They introduced a few useful features that are unique and decided to offer them for free.
Like HAS (30cm precision after some integration time. Without additional correction data) and cryptographic verification of the transmitted GNSS data.
Like HAS (30cm precision after some integration time. Without additional correction data) and cryptographic verification of the transmitted GNSS data.
A number of "GPS" receives also received Galileo and Beidou. They then combine all the data to figure out the correct position. Likely the GPS chip in your phone will do more than one system. Any one system alone can provide a position (sort of - Japan has a system that only covers the area around Japan) so the loss of one isn't a problem.
> Galileo’s open service (civil-access) E1 signal incorporates public/private key encryption to digitally sign and authentify data
Which is fairly useless. The spoofed data can be legit data just selectively delayed by a couple of milliseconds and the receiver has no way to know.
Which is fairly useless. The spoofed data can be legit data just selectively delayed by a couple of milliseconds and the receiver has no way to know.
Is that actually true here? Satellite constellations move in complicated ways, so a receiver should be able to detect "impossible" configurations if the stream from only one satellite is delayed. If they are all delayed, then wouldn't that also cause the receiver's position to fail to resolve?
An attacker can receive all streams, delay the data from each satellite a variable amount, then retransmit them all again to appear to be in a different location.
Then also delay signals from other gnss providers to match.
I have witnessed this done in Iraq, so someone has already built the capability.
Then also delay signals from other gnss providers to match.
I have witnessed this done in Iraq, so someone has already built the capability.
A variable amount is what I was missing. That makes sense now, thanks.
Is that some sort of a replay attack? If so why isn't the timestamp embedded in the encrypted payload
It is.
It relies on the fact the clients clock will have a few milliseconds of error so they'll be unable to detect it.
If the client had an atomic clock, this attack wouldn't be possible.
It relies on the fact the clients clock will have a few milliseconds of error so they'll be unable to detect it.
If the client had an atomic clock, this attack wouldn't be possible.
The fundamental weakness of GPS and similar is that they are a set of beacons from which a position may be calculated. This has simplified the navigation task but also made that task more fragile.
Navigation itself must "toughen up" and the seeds for that are being deployed to autonomous systems as simultaneous localization and mapping (SLAM). Instead of being dependent on a single data source, a toughened system would infer location from many sources: magnetometers, photogrammetry, inertial measurement, and other sources of radiation (ex star trackers). The article does cover some developments in these areas as a second line after advocating for breaking changes to the current radio-time system.
GPS jamming and spoofing will not abate anytime soon. The first line of defense is to crosscheck GPS PNT against inputs from other sensors. Parkinson advocates “deep integration,” or close coupling, of GPS sensors and inertial reference platforms, such as laser, fiberoptic gyros and microelectromechanical gyros and accelerometers, to flag obvious GPS signal interference.
Navigation itself must "toughen up" and the seeds for that are being deployed to autonomous systems as simultaneous localization and mapping (SLAM). Instead of being dependent on a single data source, a toughened system would infer location from many sources: magnetometers, photogrammetry, inertial measurement, and other sources of radiation (ex star trackers). The article does cover some developments in these areas as a second line after advocating for breaking changes to the current radio-time system.
GPS jamming and spoofing will not abate anytime soon. The first line of defense is to crosscheck GPS PNT against inputs from other sensors. Parkinson advocates “deep integration,” or close coupling, of GPS sensors and inertial reference platforms, such as laser, fiberoptic gyros and microelectromechanical gyros and accelerometers, to flag obvious GPS signal interference.
It does seem that if next-gen GPS tech isn't already being tested/deployed then we've managed to already begin falling behind. GPS III just isn't anywhere near as useful in a non-permissive environment
Also, I read something on ITAR being relaxed specifically for CRPAs, this year, so maybe some of this is improving? ->
https://rntfnd.org/2025/02/20/first-fix-freeing-crpas-gps-wo...
Not directly related, but I also think its impressive that a major airliner could take a SAM hit, from what was likely a Pantsir-S1 (20KG of HE moving at Mach 2 is not something airlines usually design for) and still land with half the souls surviving. While not great, that is certainly far better than I expected and shows some excellent airmanship.
Also, I read something on ITAR being relaxed specifically for CRPAs, this year, so maybe some of this is improving? ->
https://rntfnd.org/2025/02/20/first-fix-freeing-crpas-gps-wo...
Not directly related, but I also think its impressive that a major airliner could take a SAM hit, from what was likely a Pantsir-S1 (20KG of HE moving at Mach 2 is not something airlines usually design for) and still land with half the souls surviving. While not great, that is certainly far better than I expected and shows some excellent airmanship.
We’ve been falling behind. I wish this was taken more seriously.
> […] launch an initiative to regain U.S. PNT leadership and ensure resilient, reliable PNT for critical infrastructure and the larger economy.
> GPS’s capabilities are now substantially inferior to those of China’s BeiDou. https://www.gps.gov/governance/advisory/recommendations/2023...
> […] launch an initiative to regain U.S. PNT leadership and ensure resilient, reliable PNT for critical infrastructure and the larger economy.
> GPS’s capabilities are now substantially inferior to those of China’s BeiDou. https://www.gps.gov/governance/advisory/recommendations/2023...
Here is an example of how GPS jamming/spoofing affects Strava tracks in Russia.
https://www.strava.com/activities/14539835271
I did a Ctrl+F and it doesn't mention once Inertial Navigation Systems (INS)[1]?
As long as an external signal for navigation is used, the problems of external signals will remain. INS doesn't suffer from this issue and is already used in planes, ships, cars and phones for years. Actually I miss INS in cycling computers, it could fix so many issues.
[1] https://en.wikipedia.org/wiki/Inertial_navigation_system
As long as an external signal for navigation is used, the problems of external signals will remain. INS doesn't suffer from this issue and is already used in planes, ships, cars and phones for years. Actually I miss INS in cycling computers, it could fix so many issues.
[1] https://en.wikipedia.org/wiki/Inertial_navigation_system
INS accumulates error over time, all of such systems require absolute position fixes (often via GPS) at regular intervals to remain accurate.
Yes. INS loses precision over time.
But not that much, the wiki states 650 meters in an hour. Is that enough for crossing the Atlantic Ocean with an airliner? Cheap car navigation can bring you through long tunnels (kilometers).
INS Navigation is old. It was used in V2 rockets. Primitive civilian systems were available in the B707, better in the 747 (70ies). Now we have them for many years in Integrated Circuits (I don’t know about their precision). The things modern cruises missiles like Taurus do are impressive. IF GNSS is not useable they use INS. INS loses precision. But they add a radar altimeter and compare that to locally stored map data or an image recognition (IR-Sensors looks for specific items on waypoints) to recalibrate in flight.
One problem seems that we rely on GNSS correcting the INS. That’s fine if the signal is lost, INS takes over. That’s bad if the signal is spoofed, GNSS lies to INS and INS copies the error. That’s what happened over the Middle East and East Europe. I’m not sure if pilots can turn that auto-correction off. I hope so.
PS: Please don’t remember what I mentioned when you watch Top Gun 2. The movie would be short.
But not that much, the wiki states 650 meters in an hour. Is that enough for crossing the Atlantic Ocean with an airliner? Cheap car navigation can bring you through long tunnels (kilometers).
INS Navigation is old. It was used in V2 rockets. Primitive civilian systems were available in the B707, better in the 747 (70ies). Now we have them for many years in Integrated Circuits (I don’t know about their precision). The things modern cruises missiles like Taurus do are impressive. IF GNSS is not useable they use INS. INS loses precision. But they add a radar altimeter and compare that to locally stored map data or an image recognition (IR-Sensors looks for specific items on waypoints) to recalibrate in flight.
One problem seems that we rely on GNSS correcting the INS. That’s fine if the signal is lost, INS takes over. That’s bad if the signal is spoofed, GNSS lies to INS and INS copies the error. That’s what happened over the Middle East and East Europe. I’m not sure if pilots can turn that auto-correction off. I hope so.
PS: Please don’t remember what I mentioned when you watch Top Gun 2. The movie would be short.
There is also Xona (https://spacenews.com/u-s-air-force-to-explore-xona-spaces-c...), a privately funded LEO constellation for PNT
Don't phased array antennas and similar need to be on a somewhat stable platform to be able to track a satellite? I can't imagine that would work too well in a mobile phone
'stable' on the timescale of radio waves is like claiming the statue of liberty isn't on a stable platform because one day continental drift will move it about...
For sending yes depending on what you mean as stable. For slow moving objects or fast moving objects with a steady heading (low changes in direction of the velocity, or acceleration) it isn't that much of a challenge anymore. For fighter aircraft or some of the faster drones it still presents a challenge that is expensive, but solvable with today's technology (at least from my understanding, the best of these systems are still highly classified).
For receiving however, you can simply use a phased array antenna to gain directional information in addition to your magnitude. This allows you to ignore interferance that is coming from the ground (though not any from a jammer located above the device, or any reflections from the atmosphere). The effect of this is somewhat like a shotgun microphone.
For receiving however, you can simply use a phased array antenna to gain directional information in addition to your magnitude. This allows you to ignore interferance that is coming from the ground (though not any from a jammer located above the device, or any reflections from the atmosphere). The effect of this is somewhat like a shotgun microphone.
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The MagNav tech, using maps of magnetic anomalies as a global reference, and getting
accuracy down to 3 meters sounds interesting.
Should use CDMA, better resistance from jamming
What do you suppose the GPS PRNs are?
(I'll save you a click: They're Gold codes, long pseudorandom sequences with carefully chosen autocorrelation and cross-correlation properties. In CDMA parlance, chipping sequences. The exact same thing.)
It's almost like the designers thought of this.
(I'll save you a click: They're Gold codes, long pseudorandom sequences with carefully chosen autocorrelation and cross-correlation properties. In CDMA parlance, chipping sequences. The exact same thing.)
It's almost like the designers thought of this.
But how wide is the signal? How much of spectrum should one jam?
Now that the US is no longer cooperative with other nations who are "taking advantage" of us, we should probably not expect to see the same level of international cooperation on GNSS as we have seen to date.