Comment by rwg

At ${PREVIOUS_JOB}, I ran a stratum-1 NTP server that got a timecode and PPS signal from a GPS clock. I could tell if someone had left the door to the lab open by what PLL frequency "ntpdc -c kerninfo" reported on that server — the various oscillators in the server would drift above/below their ideal frequencies depending on how hot/cold they were, and the room would get a few degrees colder with the door open.