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So my phone can use these satellite navigation systems: U.S. GPS, Russian GLONASS, European Galileo, Chinese BeiDou and Japanese QZSS. I guess one more doesn't

So my phone can use these satellite navigation systems: U.S. GPS, Russian GLONASS, European Galileo, Chinese BeiDou and Japanese QZSS. I guess one more doesn't hurt, huh? It's curious how major powers all want to have their own satellite navigation systems. Edit: QZSS is a regional system, and not due to start until November 2018, yet my phone detected one of those satellites earlier about 2-3 weeks ago. Interesting, especially considering I'm nowhere near Japan. Unless, of course, it was a bug or some weird error case. Or maybe QZSS was doing some early testing?

215163831328308 9y ago
If you build your missiles to work using gps (as another poster pointed out), then you also want those to work if the US decides to not let you use the gps system.
orf 9y ago
How can you tell which nav systems your phone can see?
- vardump 9y ago
  Android API provides this: https://developer.android.com/reference/android/location/GnssStatus.Callback.html https://developer.android.com/reference/android/location/Gns... https://developer.android.com/reference/android/location/GnssStatus.html https://developer.android.com/reference/android/location/Gns... You can also use apps like GPS Test [0], etc. They can tell it as well. QZSS is represented by square icon(s) in that app. [0]: https://play.google.com/store/apps/details?id=com.chartcross.gpstest&hl=en https://play.google.com/store/apps/details?id=com.chartcross... (not affiliated with them in any way)
azernik 9y ago
These are essential national security assets, used for military purposes, and which a hostile (or even neutral) owner could turn off in case of war. The civilian use-case is a handy side benefit.
- nradov 9y ago
  I've listened to interviews with the creators of GPS and they were very clear that it was always intended as a dual use military / civilian system.
  - walrus01 9y ago
    It's always been that way, I mean, the master gps control station is a very highly guarded USAF base in Colorado.
- andygates 9y ago
  Was a handy side-benefit, then GPS got so cheap and ubiquitous people tag their dogs and hire bikes. Now, location services are an essential civilian service.
  - azernik 9y ago
    But that's not the reason why all these countries feel the need to launch their own. If that was what India cared about they'd happily stick to GPS.
  - pc86 9y ago
    Just because someone tags their dog doesn't make it an essential civilian service.
  - heneryville 9y ago
    A number of devices are theorized to use GPS for cryptographic randomness, such as ATMs. In 2007 the US navy accidentally jammed San Diego's GPS signal, but the effect wasn't too huge. https://fieldlogix.com/news/navy-accidentally-jammed-gps-system-in-san-diego/ https://fieldlogix.com/news/navy-accidentally-jammed-gps-sys...
jessriedel 9y ago
> ...my phone detected one of those satellites earlier about 2-3 weeks ago. Interesting, especially considering I'm nowhere near Japan. Could be an error, but you could just be in Australia or just about anywhere on the Eastern hemisphere. The orbits are geosynchronous and thus very high. https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#/media/File:Qzss-45-0.09.jpg https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#...
- robocat 9y ago
  Definitely not geosynchronous. It is a Quasi-Zenith Satellite System as per your link. A lovely animation of three satellites: https://upload.wikimedia.org/wikipedia/commons/b/ba/Qzss-01-120s2.gif https://upload.wikimedia.org/wikipedia/commons/b/ba/Qzss-01-...
  - vardump 9y ago
    https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#Orbit https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#... "QZSS uses three satellites, each 120° apart, in highly inclined, slightly elliptical, geosynchronous orbits. Because of this inclination, they are not geostationary; they do not remain in the same place in the sky. Instead, their ground traces are asymmetrical figure-8 patterns (analemmas), designed to ensure that one is almost directly overhead (elevation 60° or more) over Japan at all times."
    - robocat 9y ago
      Ahhhh: geosynchronous versus geostationary. I hope I wasn't the only confused muppet!
  - samnardoni 9y ago
    That animation clearly shows they are geosynchronous?
jhayward 9y ago
QZSS has been in test phase since 2010, and has had a full constellation of 4 satellites since last year.
fellellor 9y ago
I don't think IRNSS covers regions outside South Asia.

215163831328308 9y ago

If you build your missiles to work using gps (as another poster pointed out), then you also want those to work if the US decides to not let you use the gps system.

orf 9y ago

How can you tell which nav systems your phone can see?

vardump 9y ago
Android API provides this: https://developer.android.com/reference/android/location/GnssStatus.Callback.html https://developer.android.com/reference/android/location/Gns... https://developer.android.com/reference/android/location/GnssStatus.html https://developer.android.com/reference/android/location/Gns... You can also use apps like GPS Test [0], etc. They can tell it as well. QZSS is represented by square icon(s) in that app. [0]: https://play.google.com/store/apps/details?id=com.chartcross.gpstest&hl=en https://play.google.com/store/apps/details?id=com.chartcross... (not affiliated with them in any way)

azernik 9y ago

These are essential national security assets, used for military purposes, and which a hostile (or even neutral) owner could turn off in case of war. The civilian use-case is a handy side benefit.

nradov 9y ago
I've listened to interviews with the creators of GPS and they were very clear that it was always intended as a dual use military / civilian system.
- walrus01 9y ago
  It's always been that way, I mean, the master gps control station is a very highly guarded USAF base in Colorado.
andygates 9y ago
Was a handy side-benefit, then GPS got so cheap and ubiquitous people tag their dogs and hire bikes. Now, location services are an essential civilian service.
- azernik 9y ago
  But that's not the reason why all these countries feel the need to launch their own. If that was what India cared about they'd happily stick to GPS.
- pc86 9y ago
  Just because someone tags their dog doesn't make it an essential civilian service.
- heneryville 9y ago
  A number of devices are theorized to use GPS for cryptographic randomness, such as ATMs. In 2007 the US navy accidentally jammed San Diego's GPS signal, but the effect wasn't too huge. https://fieldlogix.com/news/navy-accidentally-jammed-gps-system-in-san-diego/ https://fieldlogix.com/news/navy-accidentally-jammed-gps-sys...

jessriedel 9y ago

> ...my phone detected one of those satellites earlier about 2-3 weeks ago. Interesting, especially considering I'm nowhere near Japan. Could be an error, but you could just be in Australia or just about anywhere on the Eastern hemisphere. The orbits are geosynchronous and thus very high. https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#/media/File:Qzss-45-0.09.jpg https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#...

robocat 9y ago
Definitely not geosynchronous. It is a Quasi-Zenith Satellite System as per your link. A lovely animation of three satellites: https://upload.wikimedia.org/wikipedia/commons/b/ba/Qzss-01-120s2.gif https://upload.wikimedia.org/wikipedia/commons/b/ba/Qzss-01-...
- vardump 9y ago
  https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#Orbit https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System#... "QZSS uses three satellites, each 120° apart, in highly inclined, slightly elliptical, geosynchronous orbits. Because of this inclination, they are not geostationary; they do not remain in the same place in the sky. Instead, their ground traces are asymmetrical figure-8 patterns (analemmas), designed to ensure that one is almost directly overhead (elevation 60° or more) over Japan at all times."
  - robocat 9y ago
    Ahhhh: geosynchronous versus geostationary. I hope I wasn't the only confused muppet!
- samnardoni 9y ago
  That animation clearly shows they are geosynchronous?

jhayward 9y ago

QZSS has been in test phase since 2010, and has had a full constellation of 4 satellites since last year.

fellellor 9y ago

I don't think IRNSS covers regions outside South Asia.