GPS Time for accurate Computer Time

[rgleason]

GPS Time for Accurate Computer Time
(This seems to keep coming up.)

rgleason summary post in Feature Request thread

Post #1539 Update PC Clock with GPS Clock. - Berthold

Post #1541 Information regarding GPS, UTC and Atomic TAI time -Viking
Very interesting post with good information.

Post #1542 Free Solutions - Pavel

If there weren't ready made free solution that can happily coexist with OpenCPN and do it, maybe. But I don't see any real reason why not use GPS clock freeware or gpstime - Script that sets system time through a GPS. - Google Project Hosting depending on the platform...
Post #1543 We have it but too little time - Bdcat

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I think this feature would be useful for several reasons.
1. Celestial Navigation Plugin - help with setting PC time.
2. Weatherfax Plugin - several weather fax programs use GPS time for timing the satellites. [accuracy is not as stringent]
4. Pavel has listed several free solutions, but it would be simpler if this could be done at some point....

Is it worth putting into Tracker -Feature requests? ..somewhere just above Low priority?

Post #1543 We have it but too little time - Bdcat

Pavel...

We have code in OCPN to do this. Very old cruft, untested in a long time.

chart1.cpp:7451

Code:
#ifdef ocpnUPDATE_SYSTEM_TIME // Use the fix time to update the local system clock, only once per session if( ( sfixtime.Len() ) && s_bSetSystemTime && ( m_bTimeIsSet == false ) ) {
Too many ideas, too little time....
Dave

Jelbert Post in another thread

Yes I use an Olimex A20. It has no RTC and there is an external module posible. Now I use NTP for the time. There is also a way to use the GPS time. I found the sources for that already. What I have not yet figured out is if this will occupy the gps and if it can still be shared with OpenCPN.
The A20 including a 4 port usb serial converter and an old gps dongle uses 3.6W if it is very busy.
I did try to get SDR running on it with a gui but that became too slow or too unstable. So for now I ditched that idea.

Pavel's Response just below:

Jelbert... Have a look at Synchronizing ntpd to a Garmin GPS 18 LVC via gpsd - You can connect NTP to GPSd, so no problems with possible race conditions.
Pavel

[mischa.mole]

Since I use the RPI do record my tracks, and during longer trips, I tend to "improve" my setup, which leads to several restarts of the pi, the times of my track points are kind of messed up. All the solutions I found for the Pi use gpsd, which does not work for me (and since OpenCPN does not need it, I don't want to install it). Anyone knows a solution to set the system time to GPS time WITHOUT gpsd? If anyone could tell me how to activate the "builtin" function in the chart1.cpp, I would try to compile opencpn for myself (before turning off the "more than 2 hours difference"-check :-))

Thanks and BR
mischa

[bdbcat]

mischa...

in chart1.cpp, look for "ocpnUPDATE_SYSTEM_TIME".

Read the code, define the variable "ocpnUPDATE_SYSTEM_TIME", rebuild OCPN, fix sudoers file, and it might just work.

Dave