[HN Gopher] Study asks: Can cell phone signals help land a plane?
___________________________________________________________________
Study asks: Can cell phone signals help land a plane?
Author : gnabgib
Score : 24 points
Date : 2024-11-25 18:31 UTC (3 days ago)
(HTM) web link (newsreleases.sandia.gov)
(TXT) w3m dump (newsreleases.sandia.gov)
| amluto wrote:
| Perhaps they should also ask: if GPS is down in an area, do the
| cell towers continue to operate?
| thanksgiving wrote:
| You make me wonder, are these systems programmed to fall back
| to Galileo EU, Russian Or Chinese (mainland) GNSS at all?
| Should we fall back to systems controlled by other countries?
| throw0101a wrote:
| > _You make me wonder, are these systems programmed to fall
| back to Galileo EU, Russian Or Chinese (mainland) GNSS at
| all?_
|
| In the US, per FCC rules, it is not officially allowed to
| listen to other GNSS frequencies as they are not licensed:
|
| > _The Federal Communications Commission (FCC) rules require
| licensing of non-federal receive-only equipment operating
| with foreign satellite systems, including receive-only earth
| stations operating with non-U.S. licensed radionavigation-
| satellite service (RNSS) satellites._
|
| * https://www.gps.gov/spectrum/foreign/
|
| The FCC allowed Galileo use in 2018:
|
| * https://www.fcc.gov/document/fcc-approves-galileo-global-
| nav...
|
| I think the reasoning is that if it is not "officially
| sanctioned" then if there's interference with those signals
| it's not the FCC's problem. By allowing it they'll take noise
| on those frequencies more seriously in rules and enforcement.
| nradov wrote:
| FAA certified avionics won't fall back from GPS to foreign
| GNSS constellations for authorized flight operations. If GPS
| is degraded then pilots have to fall back to older navigation
| methods. Those foreign constellations mostly all operate on
| similar frequency bands so if GPS is being jammed in a
| certain area then the other systems will likely also be
| impacted.
| red0point wrote:
| Often they rely heavily on GPS for time and frequency
| synchronization (think 5G TDD, where all operators need to be
| aligned in time or they jam eatch other's uplink). The GPS
| antenna is also often quite visible from the outside of a base
| station.
|
| Still, what's also possible is to use PTP as backup (e.g., over
| eCPRI) and use the fiber / microwave backhaul to some master
| clock with, say, a ribidium time source as a backup, so I think
| it's not entirely unreasonable to assume that cell phone
| signals will remain available in the presence of a GPS outage.
| throw0101a wrote:
| > _Perhaps they should also ask: if GPS is down in an area, do
| the cell towers continue to operate?_
|
| If the towers are uniquely identified, and are geo-located
| accurately, it could be possible to triangulate your position
| even if they are not operational from a make-a-phonecal
| perspective. They just have to perhaps keeps shouting " _I 'm
| here!_".
|
| Perhaps they'd at least need a semi-accurate time source? (Like
| a local rubidium clock, or at least NTP/PTP over a fibre
| backhaul.) On the other hand smartphones can geolocate
| themselves decently from Wifi AP signals, and those tend to not
| have timestamps with-in the broadcasts.
| nradov wrote:
| What do you mean by GPS being "down" in an area? The
| constellation is in medium orbit so no satellite is area
| specific. WAAS is area specific so if one of those transmitters
| fails then that can prevent certain aviation uses of GPS.
| Jamming can also impact a limited area.
| throw0101a wrote:
| > _What do you mean by GPS being "down" in an area? [...]
| Jamming can also impact a limited area._
|
| Jamming can impact much more than just a limited area. Just
| ask anyone near a border with Russian:
|
| * https://gpsjam.org
|
| Like Estonia:
|
| * https://www.wingsmagazine.com/estonia-gps-interference-2/
| nradov wrote:
| Each Russian jammer is only effective within a limited
| area. Russia. Russia has deployed multiple jammers.
| throw0101a wrote:
| Each jammer can cost as little US$ 10:
|
| * https://hackaday.com/2020/09/08/teardown-mini-gps-
| jammer/
|
| And a single one can mess up an entire airport until its
| found:
|
| * https://trans.info/en/gps-jammer-that-brought-
| disruption-to-...
|
| * https://insidegnss.com/fcc-fines-operator-of-gps-
| jammer-that...
|
| Very cheap/easy to flood an area with noise.
| p_l wrote:
| Russian jammers regularly impact other countries
| teraflop wrote:
| > Another problem, she said, is spoofing, which involves using a
| fake signal to mislead receivers into believing they are in a
| different location. The technique is no secret, as gaming
| communities use it to cheat in location-based games like Pokemon
| Go.
|
| > "There are actual apps you can download that allow you to spoof
| your location, and entire subreddits dedicated to showing you how
| to use it for various games," Sanderson said.
|
| Not judging the research itself, but this is kind of a dumb
| statement. The type of "spoofing" that you can do by just
| installing an app, which merely causes the OS to return fake
| coordinates, has virtually nothing in common with the type of
| "spoofing" that would threaten an aircraft by actually
| transmitting fake radio signals.
| aeonik wrote:
| It's easy to add an authentication packet to weed out pirate
| signals, but all wireless systems are still susceptible to
| jamming.
| Retric wrote:
| You cannot jam signals the aircraft has already received from
| an earlier point on the flight. Inertial navigation + cell
| towers hundreds of miles away could be useful, essentially
| requiring a state actor to really render such a system
| useless.
| throw0101a wrote:
| Loran-C used to be available until it got shutdown in the 2010s
| because GPS was thought to be ubiquitous enough that other
| systems weren't needed:
|
| * https://en.wikipedia.org/wiki/Loran-C
|
| Turns out having a more resilient backup is useful.
|
| China has built out an eLoran system (as well as a fibre-based
| precise-timing infrastructure):
|
| * https://www.gpsworld.com/china-completes-national-eloran-net...
|
| * https://www.mdpi.com/2076-3417/13/23/12703
|
| * https://www.gpsworld.com/china-finishing-high-precision-grou...
|
| I don't think Loran-c gives enough accuracy to _land_ a plane all
| by itself, but it should get you to the airport, after which
| local beacons (VOR) will align you with the runway, and ILS will
| get you safely on the ground in IFR conditions.
| mmaunder wrote:
| This seems hand wavy. Nothing that demonstrates that they have
| any understanding of how aircraft currently navigate with GPS,
| WAAS, levels of accuracy that enable or rule out certain
| procedures. It's like they decided to just co-opt aviation
| because it's mission critical and has money. "Like one day maybe
| we'll be able to do the fancy airplane stuff with the radio stuff
| and math stuff."
| akira2501 wrote:
| I agree. This has "secondary military goal" written all over
| it. For commercial flight these are just weird ideas.
| akira2501 wrote:
| > pioneering a backup system to keep an airplane on course when
| it cannot rely on global positioning system satellites.
|
| So like the already existing VOR/DME network?
|
| > The idea is to use these alternative signals to calculate a
| vehicle's position and velocity.
|
| All commercial planes have an IMU/ADIRU in them. Most are doubly
| if not triply redundant.
|
| > There is no question GPS is still the gold standard for
| navigation
|
| Not for flight. There are plenty of areas in Europe where it is
| compromised to the point of being useless.
|
| > Scientists refer to it as "signals of opportunity"
|
| Way back in the day pilots would use FM radio stations in the
| same way. If you were really lost out somewhere over a dark
| patch.
|
| > If these signals are clean enough for navigation,
|
| The bigger problem you have is while these are "fixed location"
| services our database of the locations isn't exactly awesome or
| well maintained in the face of maintenance or physical changes.
|
| "Signals of opportunity" for flight is a bizarre regime to even
| consider.
| touisteur wrote:
| That and radar... mode S can transmit data packets, uplink and
| downlink. Never seen it in use but it's in the European Mode S
| standard so any compliant radar has tested and qualified its
| use... data rate is very low but enough for some chat.
| sokoloff wrote:
| > Way back in the day pilots would use FM radio stations in the
| same way.
|
| Assuming you're taking about ADF, that would use AM radio
| stations as a pseudo-NDB (or to listen to a ballgame).
| Animats wrote:
| Before commenting on this, please read "Final Report of the GPS
| Spoofing Group", from Ops Group.[1] This is a group for
| international pilots and flight planners who have to deal with
| GPS spoofing routinely. They are not happy about it, for multiple
| reasons. Newer avionics trusts GPS too much. Bad GPS data can
| affect other flight systems, mis-calibrate the inertial reference
| systems, and even change the aircraft clock.
|
| GPS spoofing confuses the Ground Collision Avoidance System,
| which uses GPS position and elevation maps to report nearness to
| the ground. The false alarm rate is now so high that such systems
| are useless in parts of the world.
|
| There's a lot of this spoofing going on. Look at the maps in the
| report.
|
| [1] https://ops.group/blog/gps-spoofing-final-report/
| codethief wrote:
| The link to the report doesn't work for me, and everything else
| seems to be behind a login wall. :\
| Animats wrote:
| Strange. Nothing special about it. Here's the raw PDF file.
|
| [1] https://ops.group/dashboard/wp-
| content/uploads/2024/09/GPS-S...
___________________________________________________________________
(page generated 2024-11-28 23:01 UTC)