https://dougal.gunters.org/blog/2015/03/26/gpsd-time-service-howto/
GPSD Time Service HOWTO - Dougal Campbell's geek ramblings
Mar 26, 2015 - I don't know if I'll ever need this, but here's how to use a GPS unit with 1PPS (pulse-per-second) capability as an accurate time source feeding the ntpd time...
gpsd time service howtodougalcampbellgeekramblings