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Tigge / antfs-cli

Extracts FIT files from ANT-FS based sport watches such as Garmin Forerunner 60, 405CX, 310XT, 610 and 910XT.
MIT License
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Daylight saving time breaks detection of new activities? #165

Open msitms opened 7 years ago

msitms commented 7 years ago

I'm using antfs-cli with my Forerunner 310XT. From time to time, it tries to download not only the new files, but all activities on the device. This is particularly painful when you're affected by the problems described in #132 and #145 -- in this case such a download might run for the whole night. (There is also no convenient way to delete all activities on the device except for the last few that have not yet been transmitted...)

Now it occurred to me that the last time this happend was after the daylight saving spring change. Both devices (my computer and my Forerunner) use the same local time zone and automatically adjust to daylight savings time, but depending on how activity time stamps are stored in Forerunner internally, and how the antfs-cli sync operation compares these time stamps to local file system time stamps, this might cause all activities to be recognized as new.

Maybe it helps to convert all time stamps to UTC before comparing?

henningspruth commented 6 years ago

I'm observing the same issue (downloading all "old" activities), and this only starts to happen after the DST changeover.

jklaise commented 6 years ago

@henningspruth same here, would not have realized it is DST related! It seems that all my old activities have somehow got new timestamps on the watch (as in all on the day first day of attempted upload after DST), hence the re-download, so it is possible that it's fundamentally a firmware issue (I'm assuming here antfs-cli cannot alter the activity timestamps on the watch itself).