Pressure Sensor

jtkorken shared this problem 4 years ago
Solved

Hello,

working with 2.8.0 and Samsung Note 2, Android 4.1.

Pressure sensor is been detected and accepted, activated, me happy, starting tour, stopping, me unhappy, for the track summary only gave 50 m up/down hill. Later in the graph then the explanation, pressure sensor only gave a "reslution" of 10 m in altitude (and tour had a rather flat profile but correctly measured about 300 m uphill).

Is this Samsung of locus?

Comments (34)

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Hm, with my S3 I see a pretty nice resolution:http://db.tt/zWKmAeSP

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jtkorken ... damn, I again forget on this. it`s already reported issue by "jusc" on older Locus forum. I promised to check it, but forget ...

it`s not problem of your device, can`t be. It`s some issue in my filtering algorithm. I`ll check it as soon as possible and get back some results.

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jtkorken and jusc, are you willing to test a version?

I was checking it quite a lot and found only one small issue, that cause bigger then wanted filtering of altitude. I`m not sure it will help, but some testing is needed

version is here https://dl.dropbox.com/u/8015949/Locu...

best is probably record any track with pressure sensor. export is as gpx or just save a screenshot of chart and values and then fill altitude for this track to check differences.

If there still be a problem, and this is possible, I`ll create version that will store all received and computed data to some file, so later analysis. Thank you

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Menion, there was also another strange behaviour reported some months ago here:

http://forum.locusmap.eu/viewtopic.ph...

Maybe you could reread and think if there could be another problem with the pressure sensor?

If you need some test data tell me.

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@menion

This has nothing to do with adding SRTM altitude later on.

The pressure sensor works as wanted.

But if you record a track in (phones) Offline Mode only using the pressure sensor for getting altitude you get different altitudes between manualy added waypoints and automaticly measured trackpoints by Locus

1. Calibrate the pressure sensor

2. Switch to offline Mode (Phone)

3. Start track recording .

4. Climb a bit and add a waypoint (the proposed point name and the altitude measured by the pressure sensor will be shown)

5. walk a bit down and add another waypoint.

6. Stop and store the track.

7. Compare waypoints and nearest track points altitude.

It looks as if Locus adds correct altitude only if the display is switched on and a waypoint will be added. So if you only record a track the pressure sensor seems not to be used or at least not to be used correctly.

At the moment I can ́t test it unfortunately.

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nothing changed. start alti set at 189, real alti at end about 250.

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I can confirm this. For me it seems, that the pressure sensor is only correctly used if the Display is on or you set a waypoint?

BTW: The diagram could be bigger in landscape mode

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I can confirm-confirm Jusc statement, too. While moving (e.g. by car), altitude displays/changes fine on the Satelite View screen.

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jtkorken, I have really a huge problem

jusc, what device you use?

I`m also using note 2 with 4.1 and have exactly same results

here are probably same problems ....

Anyway, I was playing quite a lot with is and here is result

- usually sensors report values few times per second (this can be +/- defined)

- when you minimize app to background, no problem. It still work normally

- if you turn screen off, device reduce frequency to once per 40 seconds!!!

I have tested it really a lot, tried set various frequency (which is only what I can do) and no difference, still only once per 40 seconds ..

This is probably some protection from Samsung in it`s ROM. It drive me crazy, but even if I found this for example http://nosemaj.org/android-persistent..., it cause no difference ...

Isn`t here anyone with Note 2 and some alternative ROM? Some CM or other? To check if it`s really based on Samsung improvements or is this new special feature of ICS

EDIT: ok, we`ll see http://developer.samsung.com/forum/bo...~

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@menion,

I ́m using stock rom delivered with Note 2. I loaded the version 2.8.1.4 for test tomorow just 5 miutes before.

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Also "only" stock rom, but rooted.

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Unfortunately Locus version 2.8.1.4 doesn ́t change it. It works as before without correct pressure sensor data.

@Tommy,

I wonder if you tested it with the S3 as I described. Do you really get proper altitude results with display off?

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wait, I was writing somewhere that it`s changed in 2.8.1.4??

if you check link on samsung support http://developer.samsung.com/forum/bo...

you may read where is problem and confirmation from Samsung side.

I tried update app so it should at least correctly handle small data that comes (so in worst case 40 sec old pressure value)

You may check it here https://dl.dropbox.com/u/8015949/Locu... . Anyway seems that there is not much I can do with it.

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Hi jusc,

just today I recorded a track while skiing with Locus Pro 2.8.1.

I used the pressure sensor and medium altitude filter and the track is really smooth and has many more different altitude values than one every 40 seconds.

But I fear that my S3 will be a victim of this "feature" with the next sw update from Samsung, too.

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Hi Menion,

maybe it could help if you tell Sam devs that S3 with baseband version I9300XXDLID doesn`t show this unwanted behaviour.

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problem is that this is not unwanted, it`s intent. In most cases, using sensors when screen is off, is a problem of application developer that incorrectly handle with these sensors. So they decide, then rather disable (change refresh rate to cca 40 secs) of sensors, then leave whole responsibility on developers

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I tested the version 2.8.1.5, but unfortunately I forgot to record the track. I saw a very strange behaviour on the sat screen: If display is on, it seems to be as before, but if the display is of for short time (5 min), the altitude climbs up to over 11.000!! meters, and falls down to correct altitude in the next seconds. I fear it would be recorded in the same way?

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hmm this means that frequency of pressure values on your device (when screen is off) is even higher then expected 40 seconds. Ok, thanks for report, I`ll try to improve it a little bit more

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I don ́t know if I explained it correctly

today in the flying train ;)

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Understand ...

Anyway, bad. Hmm maybe worst, news.

I did some improvements yesterday and today, during whole day, I did quite a lot of testing.

Did you read part of discussion on Samsung support page?

This is best result I can obtain from these devices

Pressure values comes in best, once per 40 seconds, so you always have 40 seconds flat altitude and then jump to new value ... useless.

So sorry, but I really can do anything with it. Some Samsung device just have this improvements, so they reduce frequency of sensors to these crazy values when screen is off

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Is it possible to go back to the start szenario? Because I only got these extreme values with version 2.8.1.5.

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I wrote "hmm this means that frequency of pressure values on your device (when screen is off) is even higher then expected 40 seconds. Ok, thanks for report, I`ll try to improve it a little bit more " ... so this will not happen in next version. In 2.8.1.5 was one new issue, that is fixed.

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Hmm, don`t know which changes were made to Locus but nevertheless the pressure sensor still works ok with screen off on SGS3 now with Android 4.1.2

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I updated my Note 2 to Android 4.1.2 (Jelly Bean) - latest official Samsung N7100XXDLL7 firmware with Android Revolution HD 8.0 from http://forum.xda-developers.com/showt....

But still NOT works correctly

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I`m not sure if you understand what I wanted to say before, but

1) it`s not working now

2) it will not work in future!!

It`s system that Samsung created in their devices, so till you`ll use ROM based on Samsung ROM, it will not work!

EDIT: and why this works for tommi, it`s really mystery for me :)

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I hoped, that Samsung has acknowledged this as bug and corrected it in the latest N7100XXDLL7_N7100OXADLL4_XEF firmware, the custom rom works with.

But maybe you are right...

Tommi is using another device.

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nono. After discussion with Samsung above http://developer.samsung.com/forum/bo... , they explain that it`s not bug, but intent. Many developer do not care a lot about battery life, so they keep sensors enabled even if they`re not required. So they created this solution and disable sensors always by their own

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So I have to think about another phone in the future :-)

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Menion, I cannot read in the link that they commented that this is implemented for all phones with pressure sensor in the same way and who knows if they really have the same software for S3 and Note2.

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@jusc: Do you still have the problem?

I recently switched with my SGS3 to CM10.1 and there is no problem with the sensor.

Maybe this could also be a solution for you?

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yes, I`m sure this will help. Every ROM based on raw android (like CM) should works correctly, because it`s "problem" only in Samsung ROM, not generally in the Android

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a few months later..., sorry I forgot this topic. As tommi wrote, with a custom rom based on CM 10.1 it works with the note 2 too.

But as far as I can see the GPS altitude differs about 40 meters to map elavation.

Strange...

But that is not a problem of Locus. :-)

Thanks for help

jusc

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jusc, do you something about distance between ellipsoid (optimized shere for GPS) and Geoid (real Earth)?

For this is tab "Offset" in altitude manager. Enable "automatic" correction and all should be fine ;) (or set there manually 40m)

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I was to fast. Today i made another test. I calibrated the pressure sensor and started the treck recording. Then I switched the display of. At the end of the track I had to switch the display on and to stop recording. Track was about 7,7 km but altidude track stopped at a few hundred meters.

But the altitude wasn ́t correct ́, but set to zero and doesn ́t come back to the awaited altitude. Stays at zero.

I compared the altidude with a second app (with display switche on) and it is correct in this case.

Files: alti.jpg