3 ms·
The rumour I saw was that the entire ground segment is dependent on a single Precise Timing Facility in Italy, which went down and took everything with it. Not
by makomk 7y ago
The rumour I saw was that the entire ground segment is dependent on a single Precise Timing Facility in Italy, which went down and took everything with it. Not sure what the holdover capability is like without the ground stations, but I'd venture a guess it's not great,
- michaelt 7y agoAccording to a report from 2009 [1] "The Galileo ground segment has two GCCs, each with a Precise Timing Facility (PTF) providing a very stable reference GST to all elements in the GCC. The two PTFs are developed by separate companies; this diversification is applied to reduce the possibility of common failures in this important element." I suppose it's possible the second GCC hadn't been fully commissioned? Or the switchover failed in some very hard to recover way? [1] https://reports.nlr.nl/xmlui/bitstream/handle/10921/210/TP-2009-082.pdf?sequence=1&isAllowed=y https://reports.nlr.nl/xmlui/bitstream/handle/10921/210/TP-2...
- antpls 7y agoIf the two GCCs don't agree on the Time, which one is correct ?
- michaelt 7y agoAccording to the document linked, each GCC has its own PTF comprised of four Caesium atomic clocks. So between the two sites, they have eight atomic clocks. Presumably if one atomic clock seems suspect, they simply look to their other seven?