I just built one of these. It's fun to have a little computer that can synchronize highly accurate time without an internet connection by listening to things in outer space!<p>I built an auto-install script that anyone here is welcome to use or reference[1]. If you know what you're doing, just change the GPIO pin to your PPS input and fire away.<p>Unlike the author I used Chrony instead of NTP. It's lighter-weight and much easier to configure with a PPS/GPS reference clock.<p>The GPS chip I used was an ATGM336H, which can be had for less than $8 on ebay. I'm able to lock consistently 11 satellites from my desk[2]<p>Keep in mind the Pi has no hw RTC. If you're doing this for fun spend a few more bucks and buy an rtc chip from ebay so you don't drift considerably between being powered off.<p>1. <a href="https://github.com/stephen-mw/raspberrypi/blob/master/roles/stratum_1_timeserver/install" rel="nofollow">https://github.com/stephen-mw/raspberrypi/blob/master/roles/...</a><p>2. <a href="https://www.ebay.com/sch/i.html?_from=R40&_nkw=ATGM336H&_sacat=0&LH_TitleDesc=0&LH_BIN=1&_sop=15" rel="nofollow">https://www.ebay.com/sch/i.html?_from=R40&_nkw=ATGM336H&_sac...</a>
I had one of these running with a 10 meter cable to the window so the receiver could get enough satellites. After 24/7 for about a year it just died and I haven't had time to figure out what's wrong. Lights blink but it's not reachable via ping, ssh or scp. HDMI output shows nothing. I had to move on to other projects, so I gave up and assumed I either got hacked or I hit the cheap-SD-card problem of corruption that seems to plague other users running their Pi continuously for longer periods.<p>I've started buying SanDisk's "High Endurance" microSD cards hoping it will mitigate any such issues in the future, but I haven't had time to get the NTP set up again... I really should have cloned the image.<p>I think the hardest part was finding a case with space for the GPS hat[0] with an open end for the coax connector. The hat sits a bit crooked because of something bulbous on top (condensator?).<p>[0]: <a href="https://store.uputronics.com/index.php?route=product/product&product_id=81&search=GPS+Expansion+Board+" rel="nofollow">https://store.uputronics.com/index.php?route=product/product...</a>
Off topic: I love this couples website. If you click through to the homepage they've got lots of stuff to browse.<p>Yes, it maybe old-style, but it's these sort of sites that the internet was originally built on. It's a real shame that they are becoming a dying breed.
> Configuring Wi-Fi<p>That alone will negate <i>any</i> benefit of running a stratum 1. You lose the precision and accuracy over wifi. Jitter on intranet with the pi as a timesource would be magnitudes greater than the GPS link.
this is pretty cool. i was looking at your case, could you tell me the exact model case you were using? i couldn't find the exact model on modmypi.<p>also, here's a writeup i did on my experiences creating something with an rpi 3 model b+:<p><a href="https://github.com/stephenhu/written/blob/master/raspberrypi.md" rel="nofollow">https://github.com/stephenhu/written/blob/master/raspberrypi...</a>