[time-nuts] NTP server using an OCXO, GPS chip and Raspberry Pi

[Hal Murray]

> Is this a reasonable setup for an affordable NTP server?

How/where are you going to connect up the OCXO?

> I want to build an affordable quality time source for my computer club. 

Assuming "time source" means NTP server, the CPU is where you want to connect 
up a good clock.  You will probably want to unsolder the current crystal and 
feed the input pad with the same frequency.  If you have troubles finding an 
OSCO at the right frequency, you can get a small board with one of the magic 
PLL chips.  I think TAPR has one.  If not, try eBay.

Another approach is to use the CPU as a heater.  It's not as good as a real 
OCXO, but much better than a bare crystal.  Cheaper and easier too.
  https://github.com/ntpsec/ntpsec/blob/master/contrib/ntpheat
  https://blog.ntpsec.org/2017/02/01/heat-it-up.html

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> I use Garmin 18 for this purpose.

It's quite old by now.  Newer modules are usually better.


There are several GPS HATs that plug into a Raspberry Pi.

This is for Linux, but it may provide interesting ideas and it has links to a 
couple of GPS HATs.
  https://www.ntpsec.org/white-papers/stratum-1-microserver-howto/

Here is David Taylor's HOWTO:
  https://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html


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