Open-sourcing a more precise time appliance
What&#x27;s interesting to me is how the form factor of timing GPS modules has stayed constant over the years.  I started my GNSS timing journey with a used Trimble GPS from the 2000s, and it has the same form factor and pinout as the modern multi-constellation timing GPSes from uBlox.<p>I&#x27;ve had a GPS clock going for several years at this point, and without an atomic clock or really any fanciness (just LinuxPPS and Chrony), I see about +&#x2F;- 380ns, which is pretty good.  NTP to the Internet gives me jitter in the range of about 20ms-70ms, about 5 orders of magnitude worse.<p>(The version a few iterations ago looked like this: <a href="https:&#x2F;&#x2F;github.com&#x2F;jrockway&#x2F;beaglebone-gps-clock" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;jrockway&#x2F;beaglebone-gps-clock</a>.  But I now have a uBlox multi-constellation GPS, which is much more accurate with my limited view of the sky from my Brooklyn apartment.  And I 3D printed the case, so it actually looks presentable instead of like some crazed madman that attacked a plastic case with a hacksaw -- which is exactly how I made the first case.  As for the DS3231 RTC that I added... that seems to be stable within about 1.5us, which is pretty impressive.  I tuned it a little bit with the trim register, though.)<p>My takeaway from this article is that the project seems quite compelling, but a lot of cost is added to support PTP.  I see why Facebook needs that, but to sync time precisely throughout my lab, all I need is a coaxial cable with 10MHz on it.  I don&#x27;t mind if my workstation is 20ms off UTC.