Hello, NTP server…
It’s ugly, but it works, finally.
Do I need it? Hell no, but it was an interesting little project that made use of some hardware I had laying around that I wasn’t doing anything with. For instance it’s been over 3 years now since Avi sent me the GPS receiver… it’s high time I did something with it.
I spent most of the afternoon and into the evening on it, and finally got it to work, so I thought it best to document the process since the documentation out there is fairly scattered.
Oh, and I will replace the jumper wire for the PPS signal with something a little nicer later on, I’m sure I have some spare jumper wire with an end on it elsewhere but if not I’ll have to buy some.
Updated 2020-07-03: I managed to get NanoBSD working on it. I did a piss-poor job of documenting it, so I just threw up the notes I had including my NanoBSD configuration for the APU1C. However it does work now, and I’m using ntpd to speak directly to the GPS via NMEA, so I avoid gpsd. Not because it’s bad or anything, but I do have objections to ESR as a human being, so I thought it best not to use anything he’s touched if it’s avoidable. I’m also using FreeBSD’s kernel PPS code, which from what I can tell gets me almost as close as Linux’s does.
I’ve only been tracking the jitter/offset for about a day or so, but it looks like lately it swings periodically in a band about 200μSec wide, which is pretty good considering the dogshit hardware I’m working with, and the incredibly bad placement of my antenna (I’m fairly convinced that most of the jitter is the poor antenna reception). I reason that when we buy a place and I can drill holes, I’ll put an active antenna on the roof and do it right.
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