
Investigating the Galileo Satellite Navigation System Outage with a LimeSDR - lysp
https://destevez.net/2019/07/galileo-constellation-outage/
======
tick_tock_tick
How often has GPS, excluding intentional military operations, been
unavailable?

Edit: Went looking around and it seem GPS has never suffered an outage. They
have had issues with some satellites, even two days ago it seem, but never a
true outage.
[http://navigationservices.agi.com/SatelliteOutageCalendar/GP...](http://navigationservices.agi.com/SatelliteOutageCalendar/GPSHistoricalOutages.aspx)

~~~
lorenzhs
Galileo has not declared Full Operational Capability (scheduled for 2020),
it's still in the Initial Services stage. It's a bit like complaining that a
beta has bugs.

~~~
makomk
The testing phase ended in 2016 - Galileo is a live GNSS network intended for
actual use in navigation. The reason they haven't declared Full Operational
Capacity is that they still haven't managed to deploy a full constellation of
satellites. All of the official announcements and navigation messages from the
satellites say that it's meant to be providing actual service, just with
slightly degraded accuracy due to the missing satellites.

Not only that, the EU's controversial eCall initiative, which requires cars
that go on the market after April 2018 to automatically call the emergency
services with their locations and a live mic to the interior if they detect a
crash, mandates the use of Galileo for positioning. Manufacturers can (anbd
probably will) use other GNSS systems in parallel, but Galileo is the only one
that's guaranteed to be supported by cars. This is for a system whose life-
saving benefits are supposedly so important as to outweigh the privacy issues.

------
Lowkeyloki
The author mentions how they're _not_ going to talk about rumors several times
over the course of the article. I'd love to hear what the rumor mill is saying
about the possible causes of the outage.

------
wrkronmiller
I'm no expert but according to this site, linked in the article, it appears
the system has started to come back online and that the issue was limited to
the ephemerides:
[http://www.navsas.eu/node/611](http://www.navsas.eu/node/611)

~~~
lorenzhs
Service was restored yesterday shortly before 9pm UTC: [https://www.gsc-
europa.eu/notice-advisory-to-galileo-users-n...](https://www.gsc-
europa.eu/notice-advisory-to-galileo-users-nagu-2019027)

------
londons_explore
It is a massive oversight that the satellites don't mark their own data as bad
if not commanded to from earth.

There are lots of reasons ground stations could go offline, and having the
satellites broadcast no data is far far better than broadcasting incorrect
data.

------
jcims
Anyone in here have a LimeSDR? They look great on paper but I get a sense from
what I’ve read that they can be a bit finicky to run.

Also I’m curious about the 1-bit recording. Is that a thing?

~~~
patrickyeon
1-bit recording is in fact a common thing for very noisy signals. You're
actually aggressively over-sampling and using correlations over many samples
(in time) to get the signal out from under the noise. I've only glanced over
it, but this looks like a fun related article, but driving the opposite way
(oversampling to get more effective bits)
[https://thecavepearlproject.org/2017/02/27/enhancing-
arduino...](https://thecavepearlproject.org/2017/02/27/enhancing-arduinos-adc-
resolution-by-dithering-oversampling/)

~~~
acqq
Thanks! There is a lot on the site, I really liked:

[https://thecavepearlproject.org/2015/01/29/a-simple-diy-
unde...](https://thecavepearlproject.org/2015/01/29/a-simple-diy-underwater-
connector-system/)

