Issue 1169 in mytracks: Time stamp inaccuracies between Mytracks and bulk GPS logger
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mytr...@googlecode.com
Oct 11, 2012, 2:18:09 AM10/11/12
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Status: New
Owner: ----
Labels: Type-Defect Priority-Medium Reported-Site
New issue 1169 by jori.ham...@gmail.com: Time stamp inaccuracies between
Mytracks and bulk GPS logger
http://code.google.com/p/mytracks/issues/detail?id=1169
What steps will reproduce the problem?
1. use MyTracks and bulk GPS logger (or Garmin GPS device) simultaneously
log a track
2. export to GPX and load tracks in GPS Action Replay (sailing analysis),
GPSAR333bis is "free version". Use timestamp-mode in GPSAR
3. press track play at GPSAR and see how MyTracks and GPS logger has
timestamp difference.
What is the expected output? What do you see instead?
When logging a track I'd expect trackpoints to use GPS-based (better
stratum than Android OS) timestamps on trackpoints. Instead it seems that
logging uses Android-system timestamp which could be off many seconds.
Android system timestamps usually comes from operator network updates. And
operator usually gets time from..... GPS. But lag and not efficient system
causes network time to be inaccurate.
Expected output is that MyTracks & GPS logger trackpoints should be with-in
accuracy at same point at same time. For example yesterday I did a test and
Galaxy S3 clock was 3 seconds ahead so on GPS Action Replay the Galaxy
was "ahead of time" compared to GPS logger which operates on GPS clock. As
on GPS logger you don't set any clock, it just stores trackpoint with clock
value which is visible at NMEA-sentences.
What version of MyTracks are you using? 2.0.2
On what version of Android? ICS 4.0.4
On what phone? Samsung Galaxy S3
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:
How I see it, MyTracks should use GPS clock as a timestamp reference and
calculate difference of systemtime to GPS-time. This way all sensordata
timestamps could be fixed to GPS-time and have all GPS-based equipment
synchronized.
Owner: ----
Labels: Type-Defect Priority-Medium Reported-Site
New issue 1169 by jori.ham...@gmail.com: Time stamp inaccuracies between
Mytracks and bulk GPS logger
http://code.google.com/p/mytracks/issues/detail?id=1169
What steps will reproduce the problem?
1. use MyTracks and bulk GPS logger (or Garmin GPS device) simultaneously
log a track
2. export to GPX and load tracks in GPS Action Replay (sailing analysis),
GPSAR333bis is "free version". Use timestamp-mode in GPSAR
3. press track play at GPSAR and see how MyTracks and GPS logger has
timestamp difference.
What is the expected output? What do you see instead?
When logging a track I'd expect trackpoints to use GPS-based (better
stratum than Android OS) timestamps on trackpoints. Instead it seems that
logging uses Android-system timestamp which could be off many seconds.
Android system timestamps usually comes from operator network updates. And
operator usually gets time from..... GPS. But lag and not efficient system
causes network time to be inaccurate.
Expected output is that MyTracks & GPS logger trackpoints should be with-in
accuracy at same point at same time. For example yesterday I did a test and
Galaxy S3 clock was 3 seconds ahead so on GPS Action Replay the Galaxy
was "ahead of time" compared to GPS logger which operates on GPS clock. As
on GPS logger you don't set any clock, it just stores trackpoint with clock
value which is visible at NMEA-sentences.
What version of MyTracks are you using? 2.0.2
On what version of Android? ICS 4.0.4
On what phone? Samsung Galaxy S3
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:
How I see it, MyTracks should use GPS clock as a timestamp reference and
calculate difference of systemtime to GPS-time. This way all sensordata
timestamps could be fixed to GPS-time and have all GPS-based equipment
synchronized.
mytr...@googlecode.com
Oct 12, 2012, 9:05:25 AM10/12/12
to mytrac...@googlegroups.com
Comment #1 on issue 1169 by jori.ham...@gmail.com: Time stamp inaccuracies
Naturally GPS time should be fixed with leap seconds to get real world
UTC-time. Also it would be nice to have "export to GPX" with selectable
items for timestamp, like second resolution or millisecond resolution.
mytr...@googlecode.com
Nov 10, 2012, 1:57:44 PM11/10/12
to mytrac...@googlegroups.com
Updates:
Status: Intended
Comment #2 on issue 1169 by js...@google.com: Time stamp inaccuracies
For each track point, My Tracks does use the timestamp from the GPS data.
Status: Intended
Comment #2 on issue 1169 by js...@google.com: Time stamp inaccuracies
For each track point, My Tracks does use the timestamp from the GPS data.
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