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+--- Thread: How GPS time is synced up with realtime clock time? (/showthread.php?tid=2262)
How GPS time is synced up with realtime clock time? - mgrouch - 2020-01-25
How GPS time is synced up with realtime clock time?
Raspberry PI doesn't have realtime clock. It relies on time service daemons.
It case if network NTP time is unavailable will my computer with openplotter pick up time from GPS?
Which process is responsible for that and where is the code that does it?
Thanks,
--MG
RE: How GPS time is synced up with realtime clock time? - e-sailing - 2020-01-25
See Signal K Web Admin plugin config Set System Time
RE: How GPS time is synced up with realtime clock time? - olewsaa - 2020-02-03
You can set up NTP to use both NTP servers and GPS, I have a small NTP server installed at home.
See : https://sites.google.com/site/olewsaa/yacht-server-with-raspberry/ntp-server-using-gps
Nice to have a NTP server on board, can help keeping time on all devices on board.
Ole
RE: How GPS time is synced up with realtime clock time? - abarrow - 2020-02-16
Thanks Ole! Instead of hours of researching and testing, I used your instructions on setting up an NTP server using gpsd, and it worked first time.
RE: How GPS time is synced up with realtime clock time? - ddelorme - 2020-02-16
I was going to say the same. the clock on the gps is very precise. It uses that clock to compute the total trip time for the gps signal. In which has the time the signal left the satellite along with its position. So it can calculate the distance or radius from the satellite when you have 4 or more satellites you can calculate your 3D position. Since the signal travels close to the speed of sound you need a very accurate clock. That is my very condensed version of how GPS works.