[time-nuts] Re: Suggestions solicited for Pi/GPSDO ntp server

[Hal Murray]

> I think it's about time to retire my old former cell site GPSDO.
> Technology has improved and I'm thinking of setting up a Raspberry Pi based
> ntp server for the local devices. (I also have some spare Pi's, so...)

> Does anyone have any suggestions for a good solid Pi/GPSDO setup and code for
> such a purpose? Something like Leo's device but, of course, much cheaper? 

How nutty of a NTP server do you want?

How much of a Linux hacker are you?  Do you need a detailed step-by-step guide 
or are rough hints good enough?

There are several varieties of GPS HAT available.  Ballpark $50.  I think most 
of them come with good setup directions.

There are several/many web pages describing how to set things up.  This is the 
classic.

The Raspberry Pi as a Stratum-1 NTP Server
  https://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html

Google for >Raspberry Pi GPS NTP setup< will find many others.

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That's GPS, no DO.  If you have a GPSDO that you like you will have to convert 
to 3V logic and wire it up: RX, TX, PPS.

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Pis up to 3 have their Ethernet connected over USB so there is 125 
microseconds of fuzz on the timing.  You would have to put your time-nut hat 
on to notice that.  The Ethernet on the Pi 4 has a direct connection.

The Pi 3 and Pi 4 come with BlueTooth on the serial port.  You have to disable 
that or setup another serial port.

You can use either chrony or ntpsec.  You can use GPSD, or go direct with most 
GPS devices.

Pi IO pins are 3V only.

Linux changes.  Some of the setup descriptions may be old enough to be out of 
date.

There are also minor differences between distros.


-- 
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