More than a year ago I read the site of David Taylor on using a Raspberry Pi as a Stratum-1 time-server. Ever since I have wanted to have that for myself too. So a few months ago I aquired the pieces and after some hacking and soldering I got a Proof of Concept working.
This was my first attempt at a Raspberry Pi NTPD and it works! video
Here it is in production on the border of my attic window:
Used there is a Raspberry Pi with a separate uBlox GPS module that I manually soldered a wire to the PPS pin of the chip to.
Looking for a good (easy and clean) shield I found this one from Keyestudio. It has everything you need (GPS, antenna and PPS signal) integrated in a nice board and it does not cost too much.
So I put it all together using the screws provided by Keyestudio and this is what it looks like:
Of course that Raspberry Pi needs a good and stable power supply, especially with the GPS head on top of it so I have to find one that works. For now my Anker Powerport5 with Anker USB cables works fine even for 3 Raspberry Pi's (2x 2B, 1x3B+), a charging Samsung Galaxy S7 edge and a charging Logitech Performance MX. It does not even get hot!