GPS Auto-Off & Track recording

GPS Auto-Off should be ignored if one of these functions are running: Track recording, Navigation, Guiding. Did I forget other functions which do not work correctly if GPS is temporarily disabled?

Hello Ryan,

Strange situation... I assume that your path uphill and downhill was the same (in case of GPS-auto off), am I right?

Could you check that the accuracy of track points is lower than 20m, please ?

Tap on the track > press Point info from left panel

You can also export wrong path to the GPX file and send this file to our support email locus@asamm.com

Actually, does it happen every time when you use GPS –auto off? Is track recorded so wrong?

Petr

@Petr:

To my knowledge Locus simply ignores conditions where GPS Auto-Off disturbs the actually wanted function (Navigation, Guiding, Track recording, ...?).

Up to now I don`t see this as occasional buggy behaviour but intention.

However I think it should be improved as described in my previous comment.

Hi Tommi,

I cannot agree! GPS Auto-off feature has highest priority because it`s primary function that save your battery. I personally use it even during a track record or guiding. Together with option "Keep auto-off enabled" - disabled, it`s really usable in all these actions.

Anyway as Peter wrote - question is whether points have really accuracy lower then 20m. I think that at points will be correct value. This will mean that Locus works correctly, so it store really points with reported accuracy better then 20m and internal GPS give really incorrect values. This is expected result ...

Hi Ryan, welcome and thank you for your report.

I`m not sure if both situations have the same setting.

So you can not compare the two records and it`s very difficult to say what happend.

And when you are sure the settings in

http://docs.locusmap.eu/doku.php/manu...

and in

http://docs.locusmap.eu/doku.php/manu...

was the same in both records (regardless of "GPS Auto-Off")

How good was the GPS Signal - same on both trip?

Sorry Ryan, but you have to make this trip again. One way with - and than back without "GPS auto off" to compare.. ;) ok ok a bad joke...

anyway

20m min accuracy means: record only(!) if the signal was better.

In the mountain with a bad gps signal this can be a too small radius.

Make some outdoor tests (also with other rec and gps options) and find out your best settings.

Have more nice hiking trips and excuse my english :)

Menion, I really like GPS Auto-off - but only for maybe visiting a town and have a look on the map from time to time. In such a situation it`s really useful to save battery. "Keep auto-off enabled"-enabled if screen is on doesn`t save a lot of battery compared to what is drained by the display. For me this switch is more or less useless, only "Keep auto-off enabled"-disabled is useful.

Ok, for Guiding (Notify when too far away from track) or guiding to waypoint it might give acceptable results depending on your expectations regarding accuracy of these warnings compared to off time for GPS.

But navigation and guiding (Notify when switching to another point) works only reasonable if display is on (and again "Keep auto-off enabled"-disabled). If display is off, these functions don`t work anymore reasonable.

Regarding track recording: Ok, I can fiddle around with GPS auto-off times, accuracy and on the other hand with the profile for track recording. Maybe I can get some usable results. But it is really complicated. I personally deleted those tracks if it happened that I forgot to switch GPS auto-off of because from the defined profile I expected a very accurate track.

Proposal (if you don`t like to change the settings for GPS auto-off in the GUI: A switch in the config file which allows priority for GPS Auto-off lower than Navigation, Guiding, track recording.

Hi Menion,

could you answer on this one again, please?

I`m not yet happy with the minimum consensus we achieved

Hi Tommi,

... I firstly wrote that this is not possible, but after short thinking, I think it`s possible. Auto-off feature is connected directly on GPS but it`s of course possible to disable it in some circumstances.

I`ll have to think about it more, because I really do not want to add some more settings into Locus settings. because I`m trying to make things simplier now, another settings like you want, make things only complicated (even if they make sense). Config file is also alternative, I know, but best is to find a settings that do not need any configuration, then creating tens and tens of possible settings for everything

Hi Menion.

Thanks for taking time to think about this again.

I fully agree that a setting which is not needed because everything`s working as a user would expect is much better than entries in a config file. The config file should only be a loophole for things which most users are happy with the default but where a minority has a different use case or like it to behave differently.

In my experience, you cant really trust the accuracy setting to prevent the GPS from delivering major rubbish. I have seen positions "run away" hundreds of kilometers, even though accuracy was set to 20m. Especially the first few points after enabling GPS can be quite bogus, which makes recording tracks with GPS-Auto-Off sort of a gamble. It might be a flaw in GPS hardware or in Android drivers or somewhere inbetween. Some phones are better, some are worse, but none are 100% reliable (at neast none I`ve had).

I dont really know if Locus can do anything about this. Maybe it could improve things to treat "the first few fixes after enabling" somehow with "greater care"? Locus could e.g. always start up the GPS with 1-second intervals and collect a few quick "throwaway-fixes" before settling into the user-specified recording rate. Would that make sense?

In the end, it`s not Locus fault and I understand that working around faulty hardware or drivers and wrong fixes is a sucky thing. But what can you do...

On a related note: I dont know how it works internally, but I assume Locus uses the first few gps fixes to calibrate the altitude sensor? That can (and does) lead to very bogus results.

I tried today a track recording with GPS Auto-off checked without expecting a usable record: I got no single point during the first 20 minutes and switched therefore back to the normal behavior.

You can see on my screen shot that GPS is really switched on and off but unexpectedly for me the battery drain is almost the same as with GPS always on.

hmm from your screen, it looks that more power was consumed during "auto-off" then after :). Anyway what about mobile signal? There seems that device searched for mobile signal during auto-off.

also you wrote you had no single point ... it depend on your settings and on terrain (trees, buildings etc...)

Anyway as joeloc wrote above, on quality of GPS signal (and on location of auto-off) has effect many circumstances. Because it takes some time till location has some better quality (after fix), "Min accuracy" parameter comes in play. This should prevent from storing some incorrect values. Unfortunately some devices reports much better accuracy then usually has and screenshots from Ryan are results.

I was able to increase recording time to almost double value during a testing thanks to "GPS update interval" set to 60s and quite good terrain (mainly flat cyclo roads). But it really depend ...

Sorry for the late reply! The path was slightly different on the downhill. My accuracy is actually 25m.

I almost always use the gps auto-off to save battery. Sometimes the track accuracy is okay, and other times its pretty messy.

I`ve sent that GPX file. Thanks!

Hello Ryan,

thank you for the email with track. As I expected, accuracy values are quite precise. One point has around 65m but rest is less then 20m (this 65 depend on accuracy you have set for track record)

anyway after some thinking, I added to locus very simple checker. I`ll give here part of code for ilustration

if (location.getAccuracy() <= SettingValues.GPS_SLEEP_MIN_ACCURACY) {

loadedAutoOffFixes++;

if (loadedAutoOffFixes > 2) {

// disable GPS

disableGps(false);

// valid accuracy, put to sleep

setAutoOffTimerSleeping();

// reset counter

loadedAutoOffFixes = 0;

}

}

which say, that Locus will wait for third precise GPS fix, till it turn off GPS. This mean that if you set accuracy on 20m, then third point that will come will be used, two before will be completely ignored (only for gps-auto off enabled).

So I suggest to do some more tests with next version and we`ll see if this helps eliminate worst points. Side-effect is that GPS will be turned on usually for additional 2 secs, till these two new locations will be computed (one per second).

Thanks menion...sounds great!

I`m testing it from window and it`s still not best, but don`t know better solution now.

Imagine points with this accuracy

enabled GPS, 150, 100, 80, 30, 40, 20, 10, 20

you`ll set min accuracy for auto-off to 20m, so location with 150, 100, 80, 30, 40 will be normally visible on map. Then 3 seconds nothing, then last location with 20m accuracy and then will be GPS turned off. It`s possible that last location will be best, but on this is visible, that for correctly recorded track, you need to set max. accuracy for track record to same value as auto-off, otherwise you`ll get recorded also points with worst accuracy, because points with 150, 100, 80, 30, 40 will be normally used by Locus.

I`m not sure if this is clear, probably not :) anyway just suggestion - set "Max accuracy" in track record to same value as "Min accuracy" in auto-off