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author here - if anyone has any questions or remarks, let me know!
by ahubert 7y ago
author here - if anyone has any questions or remarks, let me know!
- bobviolier 7y agoNo question, but thanks for the research and article!
- ahubert 7y agothanks!
- efm 7y agoThanks for writing this. The title doesn't mention that Galileo is a Global Navigation System (GPS).
- deleted 7y ago[deleted]
- 9nGQluzmnq3M 7y agoGPS refers specifically to the US system.
- pacaro 7y agoIndeed, the second paragraph spells out that this is a Global Navigation Satellite System (GNSS) and places it in context with GPS, GLONASS, and BeiDou
- michaelt 7y agoUnfortunately, anyone who knows what the acronym GNSS stands for probably also already knows Galileo is such a system. So changing the title to 'Galileo GNSS outage' probably wouldn't clarify matters :(
- marcosdumay 7y ago"Galileo" can stand for a lot of things.
- myself248 7y agoWhich is funny, because I've heard it both ways. For a while, as new systems were coming online, GPS was being used as a generic term, and the US system was being referred to by its original name, NAVSTAR. But only purists would do that, and everyone else kept saying GPS to refer to the US system, so the new term GNSS was invented as the generic. I try to say NAVSTAR and GNSS to avoid the ambiguous GPS, just like I say "gridiron" and "soccer" to avoid "football".
- reaperducer 7y agoBut only purists would do that Perhaps the same sort of space nerds who still call Dish Network "Echostar." /Waves hand.
- myself248 7y agoOr track the ISS as Zarya. /waves a trusty Omnipoint phone
- heydabop 7y agoThat's because Galileo is a Global Navigation Satellite System (GNSS). Saying Galileo is a GPS is like saying Target is a Walmart.
- michaelt 7y agoI gather the US GPS system has "Autonav mode" where each satellite has long-term ephemerides, allowing 60 days of reduced-precision operation if the ground segment fails. Does Galileo have no such thing, or had the errors propagated into such data by the time someone sounded the alarm?
- makomk 7y agoThe 60 day long-term ephemerides were the older sytem. Autonav on the current GPS satellites is considerably fancier - basically, the satellites carry out ranging measurements between each other and compute their own updated clock and ephemeris solutions on the satellites themselves in a distributed fashion. Specced to provide essentially full accuracy for something like six months, minus ionosphere estimates which can only be measured from the ground. As far as I can tell, Galileo has nothing like this. They have a small buffer of future ephemeris data, but the ground segment failure here was so long that it completely ran out. Their approach seems to be full accuracy or why even bother.
- toomuchtodo 7y agoAny chance we'll see WAAS reference stations with more autonomy for uploading ionsphere correction data directly to the constellation, instead of having to aggregate at master stations, which then forwards to ground uplinks?
- londons_explore 7y agoWhy would you want that? For slightly more accuracy in a severe ground station outage? Seems only marginally worth it...
- toomuchtodo 7y agoMore redundancy, less single points of failure.
- DuskStar 7y ago
- cyanoacry 7y agoNice article! I used to work in this space (was formerly in charge of GNSS hardware at my company), and it's neat to see Galileo being put through its paces. I see now that the US gets to take GPS (and the fact that the Air Force pretty much runs it single-handedly) for granted. We are seeing _some_ problems (like the GPS III block upgrade and OCX, ahah), but the org chart seems to be considerably simpler than what Galileo's got to deal with.
- Aloha 7y agoThe operational and management aspects strike me as what happens when you have too many cooks in the kitchen - if everyone is responsible for everything, no one is responsible for anything