Time off since DST

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mattleach2114
Posts: 8
Joined: Mon Feb 05, 2018 3:54 am
Dive Computer: Garmin Descent MK1

Time off since DST

Post by mattleach2114 » Mon Apr 12, 2021 10:49 pm

Diving with a Descent MK1. Since Daylight Savings time last month, all dives i've imported since the are an hour ahead.

Dove Sat and on my Descent it shows dive time is 9:24, uploaded to MacDive and shows 10:24. Not a huge deal as i manually changed but wanted to report. I can provide and FIT file if needed.

Thanks

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nick
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Re: Time off since DST

Post by nick » Thu Apr 22, 2021 3:54 am

Yeah could you please send me a couple of fit files - one that is correct and one that is not?

Will take a look.

mattleach2114
Posts: 8
Joined: Mon Feb 05, 2018 3:54 am
Dive Computer: Garmin Descent MK1

Re: Time off since DST

Post by mattleach2114 » Mon Apr 26, 2021 11:46 pm

I've attached a zip file containing 2 fit files, One labeled Good and the other Bad.

Thanks!
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Archive.zip
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nick
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Re: Time off since DST

Post by nick » Tue Apr 27, 2021 7:29 am

I think I have a fix. Can you drop me an email, I'll send you a beta version. Can you also clarify from those two files exactly what the dates are supposed to be?

morton
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Joined: Fri Jan 03, 2020 11:36 pm
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Re: Time off since DST

Post by morton » Tue May 18, 2021 10:42 am

Hey Nick,

if you still need files or details let me know, I was just troubleshooting this issue for a Descent Mk2i. What I'm seeing (being in America/Los Angeles TZ which currently has daylight savings time and is UTC-07:00)

Dive Start (MacDive) 2021-05-16 09:25:28
Dive Start (Actual) 2021-05-16 08:25:28

Raw timestamp .FIT file: 990121120 seconds
Raw time offset in .FIT file: 0 seconds

According to my understanding of the file format this means that the time was stored in UTC within the .FIT file.
Using the Garmin reference time 1989-12-31 00:00:00, adding the 990121120 seconds and converting the resulting UTC timestamp to the local timezone seems to yield the right results.

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nick
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Re: Time off since DST

Post by nick » Tue May 18, 2021 11:02 am

No data needed - the issue was fixed. Thanks though.

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