[time-nuts] Raspberry Pi NTP server

[David J Taylor]

David,

I've seen your comparison in the list archives. However, none of the
approaches I have seen published so far (including yours) exploit all the
possibilities I mentioned.

The Raspi having better community support doesn't help if the platform 
itself
is unfit for the purpose. It might be OK as a general purpose NTP server if
you don't have any special requirements to accuracy, but for a PTPv2
grandmaster, having the ethernet behind a USB interface is a no-go.

Regarding the RF interference - I'm running a Ublox M8T module directly
mounted on the BBB via my custom GPSDO cape. It is working just fine.
Disabling the onboard HDMI encoder might be the "secret sauce" for success.

BR,
Matthias
===================================

Matthias, my feeling is that if you want a precision source, neither BB not 
the RPi is a good solution.  Maybe with all the tweak you mentioned the BB 
approaches precision (for some values of precision).  I see the RPi as 
something which can provide far better NTP than simply using an Internet 
source, something which will be adequate for the majority of users (for some 
types of user!).

The RPi 4 doesn't have E/net over USB hence my comment on seeing a 
comparison.  The RF interference is to other parts of the spectrum - not 
specifically 1.5 GHz GPS - and has been documented.  I noticed it on either 
145 or 435 MHz bands when testing.  [Jim] Whether anyone has bothered to do 
proper measurements I doubt.

Cheers,
David
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