5 ms·

So what would break if GPS went down for 4 days? Sat nav obviously, Amazon package tracking, Grindr? (I assume that falls back to cell tower triangulation???).

So what would break if GPS went down for 4 days? Sat nav obviously, Amazon package tracking, Grindr? (I assume that falls back to cell tower triangulation???). I guess theres some more serious things, any examples?

systemtest 7y ago
Shutting down GPS would be a good way to avert the upcoming attack on Area 51.
- benj111 7y ago
  I'm guessing this is a reference that's going over my head?
  - msavelyev 7y ago
    https://www.facebook.com/events/area-51/storm-area-51-they-cant-stop-all-of-us/448435052621047/ https://www.facebook.com/events/area-51/storm-area-51-they-c...
  - JamesCoyne 7y ago
    Yes. https://old.reddit.com/r/OutOfTheLoop/comments/cc3qnt/whats_up_with_all_these_area_51_memes/ https://old.reddit.com/r/OutOfTheLoop/comments/cc3qnt/whats_...
  - crysin 7y ago
    https://www.independent.co.uk/news/world/americas/storm-area-51-latest-aliens-sighting-us-military-ready-nevada-a9004086.html https://www.independent.co.uk/news/world/americas/storm-area... https://www.cnn.com/2019/07/13/us/area-51-raid-memes-trnd/index.html https://www.cnn.com/2019/07/13/us/area-51-raid-memes-trnd/in... https://deadline.com/2019/07/area-51-storming-may-be-countered-with-force-says-us-air-force-1202646103/ https://deadline.com/2019/07/area-51-storming-may-be-counter... https://www.washingtonpost.com/national-security/2019/07/13/half-million-people-signed-up-storm-area-what-happens-if-they-actually-show-up/?utm_term=.2b6da3a97b39 https://www.washingtonpost.com/national-security/2019/07/13/...
  - blaser-waffle 7y ago
    Internet meme turned (potential) real life flash mob. "Everyone go to Area 51 -- they can't stop all of us" essentially. As to if it's just internet cranks, the US military shifting views, or aggressive, foreign AGI-PROP is debatable. My money says it's a distraction, but I don't know what it's a distraction from. Can you imagine if these people decided to, say, storm immigrant detention centers, or abusive corporations... or anything that productive in a meaningful sense?
    - Fins 7y ago
      Didn't some "anti-fascist" try to attack a detention center recently? It did not end well.
    - deleted 7y ago
      [deleted]
galangalalgol 7y ago
this will be a fun thread! high frequency trading relies on gps disciplined osscilators for the precise timing needed (ntp isn't good enough, ptp isn't even good enough, though White rabbit should be). so hft would cease or go wonky trucking companies rely on it to enforce rest periods. so more truck accidents? turn by turn direction on phones would go out. wi fi is enough for nav, unless your phone and the wifi are on different ntp networks maybe I had a phone with broken gps and I didn't really notice.
- a3n 7y ago
  American trucker here. Occasionally I will lose the GPS signal in my truck, but my hours of service still counts down. The electronic logs are kept onboard, and transmitted at some point to headquarters. I suppose the Qualcomm unit might eventually be off by a second or three. But I don't know if its clock is updated by GPS, phone or wifi. I'm guessing phone. We're also required to carry paper log sheets in case of Qualcomm outage. So then it would be paper, watch and honesty. The honesty can be sanity checked by speed an distance.
  - sethhochberg 7y ago
    I don't know much about Qualcomm's gear for truckers, but FWIW even if the machine does pull its time data over the cellular network (possible on CDMA, less likely - impossible? - on GSM), the cell tower itself likely relies on GPS for its own time sync. Its very common for GPS to be used as a globally-accurate source of time data even in applications that have nothing to do with location.
    - toast0 7y ago
      GSM also provides a time reference. I seem to recall connecting to some networks that didn't provide it though. Base stations should be using GPS (and others) to discipline a local oscilator that should be ok enough for a while in absence of signal. They can probably also get a timing signal from their backhaul. It works better with precise timing, but I think it's workable with best efforts.
- 7y ago
alecmg 7y ago
Some devices supposedly can fall back to Galileo (now also down, nobody noticed), russian GLONASS and chinese... BeiDou. How could I test that?
- _pmf_ 7y ago
  If you have 60000 EUR+: https://www.rohde-schwarz.com/de/produkt/smbv100a-produkt-startseite_63493-10220.html https://www.rohde-schwarz.com/de/produkt/smbv100a-produkt-st... Something similar is used to test German Toll Collect On-Board Units (OBUs) before refurbishment.
- M2Ys4U 7y ago
  >Galileo (now also down, nobody noticed) Galileo hasn't reached full operating capability yet, so that's probably why few people have noticed (as why would you depend on an incomplete system?)
Cynddl 7y ago
Not sure why you were downvoted. Our infrastructure worldwide relies a lot on location data, incl. GPS data. There is actually an article from the New Yorker answering your question: much less traffic, all planes grounded, no train, etc. [1] > The U.S. Department of Homeland Security classifies sixteen infrastructure sectors—including dams, agriculture, health care, emergency services, and information technology—as critical, and therefore particularly vulnerable to sabotage. All but three require G.P.S. for essential functions. [1] https://www.newyorker.com/tech/annals-of-technology/what-would-happen-if-gps-failed https://www.newyorker.com/tech/annals-of-technology/what-wou...
- dmitrygr 7y ago
  At least the plane stuff is wrong. Planes do not need to be grounded and will not be, but the capacity of the system will be reduced as we once again crowd into the rigidly-defined airways between the VORs. Approaches will use ILS as many do already and it will be all ok. Airplanes were ok for decades before GPS and even now can function without it.
davidf560 7y ago
All modern digital radio networks (cellular, police/fire, etc.) rely on GPS signals to discipline high-stability frequency oscillators. If you look at any cellular antenna you can always see the white mushroom-shaped GPS antennas, usually lower on the tower or sometimes just sticking up off the equipment building. Those oscillators are used as references to generate the transmit/receive frequencies and also for very tight timing between separate transmit locations (many digital networks actually broadcast the same signal on the same frequency from multiple places at the same time). Without GPS, these reference oscillators can free-run for a while but they will eventually drift out of tolerance. Basically, without GPS, most/all cellular/digital radio networks will fail in some manner after a while. Precise failure modes will depend on a lot of things including exactly what is wrong with GPS and the type of emission, how the base station software is written, etc.
- tzs 7y ago
  Do they discipline by essentially being a full GPS receiver that decodes the timing information from multiple satellites, derives the time, and then adjusts the local oscillator so it is running at the right rate based on that time? Or do they do something simpler, and just derive a frequency reference from the frequency of the carrier signals and sync the local to some fixed ratio of the carrier frequency? The former would be more accurate, but would break if something went wrong with the data. The latter would probably not be as accurate, due to Doppler effect (I'm getting +/-0.00041% shift from Doppler effect), but would keep working as long as the carrier is being broadcast. You could probably correct for a good part of the Doppler effect just from the last known orbital parameters of the satellite--even if the data updates have been broken for a long time that should work.
  - makomk 7y ago
    GPS-disciplined oscillators are based around full GPS receivers that decode the GPS signals and compute time from them in the usual way, then use that to steer the local oscillator. I think the better ones have a fixed-position mode which makes use of the fact the ground station doesn't move to get slightly more accurate timing, but otherwise they're basically the same as any other GPS receiver.

systemtest 7y ago

Shutting down GPS would be a good way to avert the upcoming attack on Area 51.

benj111 7y ago
I'm guessing this is a reference that's going over my head?
- msavelyev 7y ago
  https://www.facebook.com/events/area-51/storm-area-51-they-cant-stop-all-of-us/448435052621047/ https://www.facebook.com/events/area-51/storm-area-51-they-c...
- JamesCoyne 7y ago
  Yes. https://old.reddit.com/r/OutOfTheLoop/comments/cc3qnt/whats_up_with_all_these_area_51_memes/ https://old.reddit.com/r/OutOfTheLoop/comments/cc3qnt/whats_...
- crysin 7y ago
  https://www.independent.co.uk/news/world/americas/storm-area-51-latest-aliens-sighting-us-military-ready-nevada-a9004086.html https://www.independent.co.uk/news/world/americas/storm-area... https://www.cnn.com/2019/07/13/us/area-51-raid-memes-trnd/index.html https://www.cnn.com/2019/07/13/us/area-51-raid-memes-trnd/in... https://deadline.com/2019/07/area-51-storming-may-be-countered-with-force-says-us-air-force-1202646103/ https://deadline.com/2019/07/area-51-storming-may-be-counter... https://www.washingtonpost.com/national-security/2019/07/13/half-million-people-signed-up-storm-area-what-happens-if-they-actually-show-up/?utm_term=.2b6da3a97b39 https://www.washingtonpost.com/national-security/2019/07/13/...
- blaser-waffle 7y ago
  Internet meme turned (potential) real life flash mob. "Everyone go to Area 51 -- they can't stop all of us" essentially. As to if it's just internet cranks, the US military shifting views, or aggressive, foreign AGI-PROP is debatable. My money says it's a distraction, but I don't know what it's a distraction from. Can you imagine if these people decided to, say, storm immigrant detention centers, or abusive corporations... or anything that productive in a meaningful sense?
  - Fins 7y ago
    Didn't some "anti-fascist" try to attack a detention center recently? It did not end well.
  - deleted 7y ago
    [deleted]

galangalalgol 7y ago

this will be a fun thread! high frequency trading relies on gps disciplined osscilators for the precise timing needed (ntp isn't good enough, ptp isn't even good enough, though White rabbit should be). so hft would cease or go wonky trucking companies rely on it to enforce rest periods. so more truck accidents? turn by turn direction on phones would go out. wi fi is enough for nav, unless your phone and the wifi are on different ntp networks maybe I had a phone with broken gps and I didn't really notice.

a3n 7y ago
American trucker here. Occasionally I will lose the GPS signal in my truck, but my hours of service still counts down. The electronic logs are kept onboard, and transmitted at some point to headquarters. I suppose the Qualcomm unit might eventually be off by a second or three. But I don't know if its clock is updated by GPS, phone or wifi. I'm guessing phone. We're also required to carry paper log sheets in case of Qualcomm outage. So then it would be paper, watch and honesty. The honesty can be sanity checked by speed an distance.
- sethhochberg 7y ago
  I don't know much about Qualcomm's gear for truckers, but FWIW even if the machine does pull its time data over the cellular network (possible on CDMA, less likely - impossible? - on GSM), the cell tower itself likely relies on GPS for its own time sync. Its very common for GPS to be used as a globally-accurate source of time data even in applications that have nothing to do with location.
  - toast0 7y ago
    GSM also provides a time reference. I seem to recall connecting to some networks that didn't provide it though. Base stations should be using GPS (and others) to discipline a local oscilator that should be ok enough for a while in absence of signal. They can probably also get a timing signal from their backhaul. It works better with precise timing, but I think it's workable with best efforts.
7y ago

alecmg 7y ago

Some devices supposedly can fall back to Galileo (now also down, nobody noticed), russian GLONASS and chinese... BeiDou. How could I test that?

_pmf_ 7y ago
If you have 60000 EUR+: https://www.rohde-schwarz.com/de/produkt/smbv100a-produkt-startseite_63493-10220.html https://www.rohde-schwarz.com/de/produkt/smbv100a-produkt-st... Something similar is used to test German Toll Collect On-Board Units (OBUs) before refurbishment.
M2Ys4U 7y ago
>Galileo (now also down, nobody noticed) Galileo hasn't reached full operating capability yet, so that's probably why few people have noticed (as why would you depend on an incomplete system?)

Cynddl 7y ago

Not sure why you were downvoted. Our infrastructure worldwide relies a lot on location data, incl. GPS data. There is actually an article from the New Yorker answering your question: much less traffic, all planes grounded, no train, etc. [1] > The U.S. Department of Homeland Security classifies sixteen infrastructure sectors—including dams, agriculture, health care, emergency services, and information technology—as critical, and therefore particularly vulnerable to sabotage. All but three require G.P.S. for essential functions. [1] https://www.newyorker.com/tech/annals-of-technology/what-would-happen-if-gps-failed https://www.newyorker.com/tech/annals-of-technology/what-wou...

dmitrygr 7y ago
At least the plane stuff is wrong. Planes do not need to be grounded and will not be, but the capacity of the system will be reduced as we once again crowd into the rigidly-defined airways between the VORs. Approaches will use ILS as many do already and it will be all ok. Airplanes were ok for decades before GPS and even now can function without it.

davidf560 7y ago

All modern digital radio networks (cellular, police/fire, etc.) rely on GPS signals to discipline high-stability frequency oscillators. If you look at any cellular antenna you can always see the white mushroom-shaped GPS antennas, usually lower on the tower or sometimes just sticking up off the equipment building. Those oscillators are used as references to generate the transmit/receive frequencies and also for very tight timing between separate transmit locations (many digital networks actually broadcast the same signal on the same frequency from multiple places at the same time). Without GPS, these reference oscillators can free-run for a while but they will eventually drift out of tolerance. Basically, without GPS, most/all cellular/digital radio networks will fail in some manner after a while. Precise failure modes will depend on a lot of things including exactly what is wrong with GPS and the type of emission, how the base station software is written, etc.

tzs 7y ago
Do they discipline by essentially being a full GPS receiver that decodes the timing information from multiple satellites, derives the time, and then adjusts the local oscillator so it is running at the right rate based on that time? Or do they do something simpler, and just derive a frequency reference from the frequency of the carrier signals and sync the local to some fixed ratio of the carrier frequency? The former would be more accurate, but would break if something went wrong with the data. The latter would probably not be as accurate, due to Doppler effect (I'm getting +/-0.00041% shift from Doppler effect), but would keep working as long as the carrier is being broadcast. You could probably correct for a good part of the Doppler effect just from the last known orbital parameters of the satellite--even if the data updates have been broken for a long time that should work.
- makomk 7y ago
  GPS-disciplined oscillators are based around full GPS receivers that decode the GPS signals and compute time from them in the usual way, then use that to steer the local oscillator. I think the better ones have a fixed-position mode which makes use of the fact the ground station doesn't move to get slightly more accurate timing, but otherwise they're basically the same as any other GPS receiver.