Strange GPS signal losses even though plenty of sats are in view

joeloc shared this problem 5 years ago
Closed

Something really strange is going on with GPS lately. Locus tends to lose the GPS signal even under perfect conditions and never gets it back. Have a look at the screen shot. The last fix is 15 minutes old, plenty of sats are in view, yet Locus says 0/16.


This happened to me about two or three times per week on my last trip. The GPS simply goes away without any reason and does not come back. Waiting does not help. Turning GPS off and on does not help.


The only thing that helps is (force)quit and restart Locus. After that, the GPS fix is back within seconds.


I know this sounds strange and at first I thought it to be a once-in-a-lifetime glitch. The Galaxy Note II has excellent GPS hardware after all. But it now happens too regularly to be ignored. I cant really tell with which Locus version this behaviour started, but it seems to happen with latest Pro as well as with latest beta.


Maybe it`s a driver problem instead of a Locus problem? Although I havent really updated my ROM in ages (still running 4.1). Anyway... the problem is annoying enough to be looked at more thoroughly (= posted). Because it simply means that you lose track recording until you notice.

Comments (35)

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I had this several times too :-(


GPS off/on helped sometimes, two times I had to reboot.


LG-P970 ICS 4.0.4 ROM IZS2.0


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guys, such problem is really hard to solve.


In android works very simple system.


1. application asks system for GPS locations


2. SYSTEM turn on GPS and periodically sends data to app


3. app say to system that it do not need location anymore


4. SYSTEM turn off GPS


I really suggest, when this happen, start for example guiding (to keep GPS on in Locus) and then try some other app. I`m almost sure, same problem will be also there ...

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That is quite possible... but it would not help :).

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yes, but it will help me, not to have bad dreams, due to too much unsolved tickets ;)

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just an idea... do you maybe use a special case? or a huge extended battery?

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Well... the problem appears without any other software in use besides Locus. And sometimes it goes away by quitting & restarting Locus. That much is clear.


I just thought maybe you could remember a recent (last six months?) change in your code talking to the driver. I cant exactly remember when this problem started, but I think I had no such issues in 2012. GPS always was rock solid.


I agree its rather impossible to debug though. Screenshots like mine above shouldnt happen should they? I mean... plenty of good (yellow) satellites but the text still says 0/16.

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Hmm and you had in 2012 same device?


Suggest to use (when this happen) menu > settings > GPS & Location > Reset A-GPS data. For this is needed internet connection, so count with it.


But of A-GPS data (if you don`t know) is:


GPS device received ephemeris (messages from satellites) and from these information compute necessary parameters and in the end - your location. Anyway in these computations is a lot of additional parameters that aren`t included in emphemeris. If GPS know these parameters (A-GPS data!), computation is much faster. If GPS don`t know them, it have to compute them manually (usually with iteration method) and getting a fix took much longer.


A-GPS data are usually valid one week, so if you`re out of internet connection for longer time, GPS fix may take a longer ...

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I cant see this has anything to do with A-GPS. It happens while recording a track and having had a perfect fix for many hours. Then suddenly the fix simply goes away and never comes back. All this is still with track recording turned on and without any user interaction. You only notice if you watch the locus screen or the status bar and find the gps icon blinking.


But I will try everything you suggest to get back 100%-reliable track recording :-).

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Menion, you write "A-GPS data are usually valid one week". Is this also true if your locations changs heavily during this week?


E.g. Request A-GPS in Munich, wait for fix. Disable GPS. Enter a plane to let`s say Rio de Janeiro, switch on GPS on there again.

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ah sorry, I thought that problem is only at start of GPS, my mistake.


Hmm are you using GPS Auto-off? Because it`s only one feature that may slightly affect this. It anyway just more often send requests 1. and 3.


1. application asks system for GPS locations


3. app say to system that it do not need location anymore

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I`m almost sure that these "ephemeris" contain orbital parameters of all satellites and precise prediction of their trajectories, so it doesn`t matter where you are ... you always need information about all satellites, not just few of them.

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no gps-auto-off. i record points every 10 seconds / 10 meters.


anyway... i will watch this more closely from now on, maybe i can find out exactly when it happens. i will also turn on the gps-signal-lost alert, although i normally find it majorly annoying. it keeps screaming at me when i enter shops or bars :).

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I have same issue with gps and only in Locus.

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I had a weird thing happen in Tallinn. The GPS was at least 500 meters off.


I restarted the phone and Locus, but then the GPS was stuck.


The GPS screen showed several (9?) satellites, but all were bunched up at the top of the 2D display.


Then I switched to GPS test - app, it got a fix within two seconds and after this Locus started working fine, too!


Samsung Xcover2 (A4.1)

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here too:


no gps-auto-off. i record points every 3 seconds / 10 meter

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stebu: The GPS screen showed several (9?) satellites, but all were bunched up at the top of the 2D display.


Last week I had this several times too but I must admit the same with GPS Test Plus :-(

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if the satellites are all on one place at top, this means, that Android know about them, receive some data, but not enough to even know their approximate location. So they have 0 azimuth, 0 elevation angle. Hmm should be better not to display them at all ...


Anyway, I have absolutely no idea what may I do here. I`m almost (95%) sure, that such problems aren`t related to any application, because apps generally do not have any methods to has direct influence on GPS connection.


I also many times read on Czech Android forum something like - "In this app, I cannot connect to GPS, but then I started Locus and all works". I`m always smiling, because here also, Locus is absolutely no effect on this. It just probably another request on GPS refreshed something in system logic and GPS started to work ...

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Menion (Official Rep) 6 minutes ago


if the satellites are all on one place at top, this means, that Android know about them, receive some data, but not enough to even know their approximate location. So they have 0 azimuth, 0 elevation angle.


Interesting that other users had the same problems on different smartphones.


Last week I made two screenshots within some minutes with GPS Test Plus (Locus showed the same): with the same satellites one time all sats on one place over 10 minutes, after a reboot they were all ok.


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Fishing in the dark... :)


I thought maybe it was a problem with my external battery ( http://www.zerolemon.com/details.php/... ). It`s quite a monster and covers much of the phones backside and might very well produce some unusual reflections(?) that irritate the driver.


But apparently it happens on other phones, on other ROMs, with different Locus versions, with other software... no luck here.

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I experienced exactly the same problem which started this thread yesterday :-(


It looks like only a full restart of my device (Gigabyte G1355 DualSim, Android 2.3.4) did help in the end.


I have some suspicion whether the behaviour has something in common with switching internet connection between WiFi and mobile data: I started Locus navigation within the reach of a WiFi network, Locus succesfully found its route and then I switched WiFi off (so the mobile data were expected to take over Internet connectivity) and started driving. Maybe the GPS did not like this switchover. But this is just a theory ....

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Surely no

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not related to wifi or network in general here either.

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I reported this problem in the forum 10 days ago. The same behavior was, when I tried to use Locus in a flying plane over Danmark. Full view of over 15 sats and no connection to Locus. Somebody thought it was due the high speed of the plain.

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And I still think so. Not every GPS problem has the same reason.

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I have the same situation from time to time on my old Samsung Galaxy S (GT-I9000). Always I thought it was not Locus but GPS hardware or driver. I just ask a bit of Menion`s time to think on this issue:


It seems there is some filter in Android, which "says" not to use some satellites if there signal is weaker than some threshold. When I am in the bus or train I see 9 or 10 sats in view but 0 in use. I put phone near window and after couple of seconds there are 6 or 7 sats in use. The difference in signal strength is not very big, but it is enough.


I understand that probably Locus can`t do anything with this. Just asking for an advice of an experienced Android developer: maybe there is some way to reduce this threshold, if it exists at all?


And by the way, personally for Menion: I plan to buy Galaxy Note 2 for my birthday. As I know, you have one. Is it really good? Does it worth it`s price? Are there some shortcomings in it?

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thanks, at least someone confirmed that it`s not just Locus problem, uff :)

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I had first flight in live last year and of course I tested Locus. But after around 15 minutes of flight, in few thousands metres above ground, locus also lost signal and get it again a while before landing. So I also think that these mobile devices aren`t capable to compute correct location in high heights ...

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I want to point out that the problem discussed here has NOTHING to do with difficult receiving conditions. Not in a bus, not behind a window, not in an airplane, not in a canyon, not in a thunderstorm, not in a rain forest. not in a building. Maybe we should concentrate on this in this thread?


I am simply losing a perfectly good gps fix in a wide open field, probably even while stopped for lunch break. And the fix will never come back by itself, regardless of how long I wait. It will also not come back if I turn the gps off and on.


Mostly, the fix will be back in a few seconds when I quit and restart Locus. But sometimes, not even this helps and I have to reboot my phone. That always helps.

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The old Galaxy-S has absolutely miserable GPS reception, the internet is full of that. More recent Galaxys are lightyears ahead. You will not regret updating.

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When using Locus with its gps function, I normaly use an external gps-mouse.


It has its own battery and last for around 10 hours and more and dosn`t draw power from the mobile.


In my flight I didn`t use the external gps, but the internal gps from the s3 mini.


Maybe external gps would work in flight? Next time I will test it.

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Perhaps those of us who have this problem ("Strange GPS signal losses even though plenty of sats are in view") should test (after a reboot to be sure) if they will see this with other apps too.


So we can exclude Locus to be the culprit.


But it will be difficult because I see this problem perhaps one time in one or two weeks :-(

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But Locus showed this just two minutes before :-)

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UPDATED:


I should add, that I use Samsung Note 2 (rooted)..and yes I was reluctant with "blaming" Locus not only because I use ENDOMONDO in parallel on the Note 2, but I usually use 2 devices when on the trail, the 2nd one is a Sony Arco S...and yes this had absolutly NO issues so far (but only running Locus, with NO other app in background), while the Note 2 had always these strange behaviour since the last 3 rides I did.


Hello, I face the same issues. I`m pretty sure it started with the most recent build. Even reboot did not always help.


I did not mention it here earlier, for I always use ENDOMONDO in parllel. So I am /wasn`t quite sure which causes the issue. But interesting though, once Locus (?) lost GPS fix or set position km-away from the actual location, ENDOMONDO did so as well. It seems that the hole Android GPS is confused.

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Exact my observations.

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Hello guys,


quite old topic. I believe it is still valid and such problems still happen rarely (I had same experience few weeks ago). Unfortunately even after years, I have absolutely no idea how may I help here. Simple search show ( https://www.google.cz/search?q=android+gps+lost+fix ), that it is quite common problem on almost all devices ( seems mainly on Note series ). So unfortunately ... I may only hope that this problem happen as less as possible to you all.