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Old 21-04-2019, 07:15   #1
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Time Data Source for Logbook and VDR

I've been struggling with a bum system clock, discussed here:


Use GPS Time on PC - Cruisers & Sailing Forums


But time data source is an issue for people with good system clocks as well -- without internet or network access, these all drift off, at best. This seems ridiculous that we can't be sure about the accuracy of the time stamps in VDR and logbook, when we have atomic clock precision time in the system anyway


So could we possibly have a choice to use GPS time for this plug-ins?


The logbook anyway gives a choice of "UTC", "Local = UTC =/-" and "GPS Auto" -- but does "GPS Auto" take the time from GPS, or just the time zone?


Please clarify.
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Old 21-04-2019, 10:54   #2
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Re: Time Data Source for Logbook and VDR

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Originally Posted by Dockhead View Post
I've been struggling with a bum system clock, discussed here:

The logbook anyway gives a choice of "GPS", "Local = UTC =/-" and "GPS Auto" -- but does "GPS Auto" take the time from GPS, or just the time zone?


Please clarify.
The "GPS Auto" option will take the UTC time from NMEA0183 message ZDA and RMC and update the time according the Timezone which is calculated through the longitude of the boat position.

Peter
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Old 21-04-2019, 11:12   #3
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Re: Time Data Source for Logbook and VDR

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Originally Posted by ptulp View Post
The "GPS Auto" option will take the UTC time from NMEA0183 message ZDA and RMC and update the time according the Timezone which is calculated through the longitude of the boat position.

Peter

OK, so, if I understand this correctly:


The other two settings are using the local machine's system time, correct?


And this third setting uses a different source -- the GPS time taken from the 0183 data stream, correct?


Except that you don't have a choice to use UTC -- the app calculates local time via longitude.


Is this all correct?


If this is correct -- then it would be really great if we could get a fourth option -- using time data from the 0183 data stream according to some time offset WE choose, and I think most of us would chose plain UTC.


This little option would solve a lot of problems for a lot of people, I think.


Or do I misunderstand this? Last summer using a different version of OpenCPN, the logbook (also a previous version) was definitely using local machine system time.
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Old 21-04-2019, 11:20   #4
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Re: Time Data Source for Logbook and VDR

There are 3 options which all use the GPS UTC time from the NMEA stream.
1. UTC. This is the UTC time straight from the NMEA stream.
2. Local This takes the UTC time from the NMEA stream and adds the timezone you select.
3. GPS Auto. This takes the UTC time from the NMEA stream and deducts the timezone from the longitude of the boat and adapt s the time accordingly.

If there is no NMEA stream to deduct the time it will take the system time.
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Old 21-04-2019, 11:23   #5
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Re: Time Data Source for Logbook and VDR

Quote:
Originally Posted by ptulp View Post
There are 3 options which all use the GPS UTC time from the NMEA stream.
1. UTC. This is the UTC time straight from the NMEA stream.
2. Local This takes the UTC time from the NMEA stream and adds the timezone you select.
3. GPS Auto. This takes the UTC time from the NMEA stream and deducts the timezone from the longitude of the boat and adapt s the time accordingly.

OK, that's great news!


So this is a change from the previous version, right?
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Old 21-04-2019, 11:27   #6
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Re: Time Data Source for Logbook and VDR

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OK, that's great news!


So this is a change from the previous version, right?
No it was always like this. No changes made here in some time.
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Old 21-04-2019, 12:17   #7
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Re: Time Data Source for Logbook and VDR

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No it was always like this. No changes made here in some time.

That's weird! I wonder what the problem was with my logbook, then!
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Old 21-04-2019, 16:10   #8
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Re: Time Data Source for Logbook and VDR

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That's weird! I wonder what the problem was with my logbook, then!
Why not use one of the utilities that correct the pc's system clock from the GPS clock?
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Old 21-04-2019, 16:13   #9
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Re: Time Data Source for Logbook and VDR

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Why not use one of the utilities that correct the pc's system clock from the GPS clock?
Such as https://www.coaa.co.uk/gpstime.htm or any similar.

I don't remember which I have running
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