But the vertical accuracy should reflect that.
That’s not very reliable too.
8 days without GPS use for HW renewed devices (*marked)
High accuracy GPS setting (all devices)
Only half sky view (out the window, house behind me), clear sky
Now:
GPS Fix for devices 1* - 2* - 3 - 4:
58 sec. - 145 sec. - 223 sec. - 66 sec.
GPS used yesterday on device 3
Before:
Dev. 1 fix time before HW renewal: 5 and 15 minutes
Dev. 2 fix time before HW renewal: 10 and infinite time
note:
Tested with no wifi, no data, time not adjusted since 8 days for dev. 1 and 2
Jolla Positioning package installed on all devices.
* = HW renewed
The fix time is greatly improved after a HW renewal.
These results tend to show that hardware can be an issue, at least in some cases.
However, GPS settings still act strangely. “High accuracy” seems to work better although no online help is provided.
Indeed, on the daily used device 3, no gps fix was possible without this setting since /home was restored.
EDIT: The following is nothing. I tried to switch again and again. No changes.
/EDIT
If you guys could try to switch from
GPS settings > custom > On On Off
to
GPS settings > High accuracy
and make some tests, this would be interesting.
For GNSS satelite ids.
1-32 is GPS
65-96 is GLONASS
2xx is Beidou
3xx is Galileo
2 Likes
Yeah, i did it. Same XA2 but with LOS 18.1 : After the first cold start (6 minutes), GPS works outside in the same city in a few seconds. Indoor after about 2 minutes.
Settings : Without WLAN support and without Bluetooth support. AGPS does not exist. Ready to go in a few seconds. That answers for me the question, is it hardware or software?
It looks like cheese, it smells like cheese, it must be a cockroach.
I also always thought it could be due to different hardware revisions or changed board layouts because the messages here in the forum are different. Currently I find that other OS can solve a possibly existing problem better.
Ok, this thread can be closed.
I have to admit that if WH repair increased the reception quality, not everything is solved.
After having HW fixed my devices, they had a rapid fixes during some 5 -10 day.
Although The SAT reception signal is much better than before the HW repair,
My daily one needed > 20 minutes to get a fix yesterday.
Now that HW cannot be in cause,
this shows that there is also a real software issue with GPS in SailfishOS.
(Sky was clear, no buildings, last use < 24h, at least 10 green bars, custom settings On On Off.)
2 Likes
GPS altitude is, by the design of the system, less accurate than the horizontal position.
In addition, it is worth remembering what the GPS altitude is.
GPS 101: The earth is not a perfect sphere. Some people call it an ‘oblate spheroid’ - it is fatter round the equator. If you measure the Earth’s circumference around the equator, and do the same around the poles, the distance around the equator is longer.
In the GPS model of the Earth, the earth is described by a mathematical shape called a geoid, which is not a sphere. This simplified object does not correspond precisely with the actual surface of the Earth. In some places it is lower, in other places it is higher. It is smooth (basically Mean Sea Level, to within a bit)
The GPS altitude is referenced to this mathematical model of the Earth’s shape.
As GPS is a system designed for use in the USA, the mathematical shape (geoid) used corresponds most closely with the shape of the Earth in the area of the North American continent. This means GPS altitudes, on average, will be closest to the true altitudes in North America. Everywhere else they can be way off.
Relative altitudes will be pretty OK, within the accuracy of the system, so if you know the actual altitude of where you start, then go straight up, for every metre of actual altitude gained you will gain a metre of GPS altitude. Of course, if you move horizontally while doing this, the GPS altitude will vary according to the shape of the geoid, which complicates things.
Further reading:
http://gpsinformation.net/main/altitude.htm
GLOBAL POSITIONING SYSTEM
STANDARD POSITIONING SERVICE
PERFORMANCE STANDARD
4th Edition
2008
For example, with current (2007) Signal-in-Space (SIS) accuracy, well designed GPS receivers have been achieving horizontal accuracy of 3 meters or better and vertical accuracy of 5 meters or better 95% of the time.
Note, the geoid used by GPS is the WGS84 ellipsoid, which is not particularly close to the actual shape of the Earth’s surface. The 2004 definition gives a resolution of about 100 km, which is basically the mean sea level averaged over that area. It’s good enough for a rough match, and can be augmented by D-GPS.
So, your GPS altitude can be way off, depending on how well the WGS84 ellipsoid describes the Earth in your vicinity. Relative altitudes should be OK-ish, remembering that the vertical accuracy is less then the horizontal accuracy as well.
Hope that helps.
Edit to add: Explainer for Ephemerides and Almanacs
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Useful background reading on Time To First Fix (Cold Start, Warm Start, Hot Start):
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More on Ephemerides and the Almanac:
The entire set of lessons (1-10) are worth going through if you want to learn more about GPS.
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With latest release, but at least with 4.4., GPS is working! Seconds instead of minutes!
Sadly, not for me on either of my XA2’s, both with 4.4. Its no faster getting a fix than before.
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Idem for me with my XA2 plus
Under open sky, over half an hour and still no fix this morning. Basically unuseable for anything practical and has been so for many, many, releases on the XA2 at least.
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Xperia 10 ii, 30 seconds to fix indoors with lot of glass around.
Its great that you have no issues on your 10ii, but that doesn’t really help us poor XA2 owners …
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HW fixed Xa2 freshly 4.4.0.64 flashed (maybe this is the reason):
1st fix: 13 minutes
second fix 12h later: 115 seconds
Not enoug for conclusins tho
Just for hope !
@Steve_Everett, @phklrz, did you HW clean/fix your devices?
When testing the GPS, does the update process for almanac/ephemeris starts as soon as the GPS sensor is activated, or is there a need to have a client app (e.g. GPSinfo or OSM scout) running?
I have an Xperia X2A ultra. For me, removing the top cover completely solved the GPS problem. The cap is slightly stuck on. It is made of aluminum and cannot break when lifted off. I get a GPS connection within a minute (7 satellites connected, 40 sighted). Before that it was absolute dead silence. The cap obviously shielded the signal in the malfunction. When I put the cap back on, however, the signal remains good. Now the shielding doesn’t seem to work anymore ?!
That speaks for a hardware problem after all.
My other settings are: Location - Individual Settings - GPS Positioning.
Battery - no power save mode.
Translated with www.DeepL.com/Translator (free version)
Hi,
Thanks for reporting.
Yes, the top cap seems to be a part of the antennas. When bad positionned with bad contacts with the underlying contact blades, it seems to act like a shield, avoiding good GNSS reception.
In this situation, it works better without the cap.
But if one sticks it back correctly, it should work even better.
I believe there should be a demand from a positionning app.
People generally use GpsInfo to make tests.