search

fmierlo / mytracks

Automatically exported from code.google.com/p/mytracks
1 stars 0 forks source link

timestamp not continuous / not accurate #1395

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
What steps will reproduce the problem?
1.record a track
2.move (within a certain, reasonable speed)
3.look at kml track data

What is the expected output? What do you see instead?
expected output: reasonable data (monotonically increasing timestamps, speed 
(calculated with location delta by time delta)

seen output: 
1st defect: timestamps earlier than previous one
excerpt from attached file:
...
<when>2013-08-29T10:44:01.132Z</when>
<gx:coord>9.091367 47.072913 1384.5999755859375</gx:coord>
<when>2013-08-29T10:44:02.132Z</when>
<gx:coord>9.09138 47.07298 1381.300048828125</gx:coord>
<when>2013-08-29T10:44:01.773Z</when>
<gx:coord>9.091401 47.07302 1382.699951171875</gx:coord>
<when>2013-08-29T10:44:03.543Z</when>
<gx:coord>9.091433 47.073125 1379.199951171875</gx:coord>
...
=> look at third timestamp => will cause an error in other software importing 
the track...

2nd defect: timestamps very close to last one, which imply unreasonable speed
excerpt from attached file:
...
<when>2013-08-29T10:48:38.145Z</when>
<gx:coord>9.080331 47.08601 880.5999755859375</gx:coord>
<when>2013-08-29T10:48:40.532Z</when>
<gx:coord>9.080326 47.086128 878.7000122070313</gx:coord>
<when>2013-08-29T10:48:40.580Z</when>
<gx:coord>9.080267 47.086161 875.7000122070313</gx:coord>
<when>2013-08-29T10:48:41.161Z</when>
...
=> look at 2nd & 3rd timestamp (10:48:40.532Z & 10:48:40.580Z)
=> time delta is only 0.048 seconds!
=> distance is roughly (!) 3.75 meters
=> speed would be roughly (!) 78 m/s
=> with a paraglider it's virtually impossible to accelerate from 2 m/s to 78 
m/s within 2s and then decelerate from 78 m/s to 10 m/s within another 0.5 s....

What version of MyTracks are you using? On what version of Android? On what 
phone?
MyTracks 2.0.5
Android 2.3.3
Phone HTC Desire Z A7272
Kernel 2.6.35.10-g53a84f9
Software version 2.42.405.4 CL192788

If possible please provide a log by uploading here.
Detailed instructions can be found here:
http://code.google.com/p/mytracks/wiki/HowToReportErrors

Please provide any additional information here:
I did see similar problems in other tracks I captured. I did not have log 
collector installed until now. will post log collector data the next time i 
record a track and see the same result.

attached is the kml file and a rough analysis in excel...

Original issue reported on code.google.com by matt.fas...@gmail.com on 18 Sep 2013 at 6:16

Attachments:

GoogleCodeExporter commented 9 years ago 
Sorry, here the same 'analysis' on a google spreadsheet...
https://docs.google.com/spreadsheet/ccc?key=0AgBgLoInVAdBdGZIYW9BMnBYcktYUmpxQnN
tQ3l0dHc#gid=3

for 1st issue look at line 38
for 2nd issue look at line 315

Original comment by matt.fas...@gmail.com on 18 Sep 2013 at 7:43

GoogleCodeExporter commented 9 years ago 
Thanks for the analysis. My Tracks uses the timestamp as reported from the GPS 
chip on your phone. Asking My Tracks to compensate or change the timestamp will 
probably leads to more issues.

Original comment by jshih@google.com on 17 Jan 2014 at 10:04