Today I listened to FLOSS Weekly Episode 350 on the Network Time Protocol (NTP) while Lincoln was pass out on me for his afternoon nap. I still have this massive frustration with time. I don't feel like I know enough to be able to write software that reasonable logs time for scientific applications; I don't understand how to really specify time correctly, I don't know the issues that I should be aware of, and I really don't know how to specify the error that is involved. Having a properly setup NTP network configuration on a device is a great start (see www.pool.ntp.org), but that really isn't a very good. Most people have 1 to 3 hard coded ntp services, which is a pretty crummy initial setup. And to top it off, after the recent security issues with ntp, my two primary machines won't let me run "ntpq -p -n" to see how ntp is doing. It seems like any good text on geophysical data analysis should have precision timing near the beginning of the discussion. But if I were to write such a text, I know enough to know that I couldn't do a decent job of writing that section. Very frustrating. Listening to FLOSS Weekly, there were a bunch of topics that I don't remember ever hearing before.
International Atomic Time (TIA) - I think this is what the USCG RDC meant when they said that UTC was 32 seconds off from GMT back when I visited them in 2007 (32 is from memory. YMMV).
General Timestamp API Project - I should really look into what this project says before saying anything more about how time should be logged. Should it be in TIA?
DFC77 The German radio broadcasts of time, which is the same basic concept as WWV broadcasts of time in the US, NPL from England, and TDL from France.
http://www.leapsecond.com/ apparently has tons of time information.
I know just a little about Precision Time Protocol (PTP V2 / IEEE 1588-2008), but not enough to be useful and have never had a chance to try it.
It would be a great project to do an open data logging computer that integrated the ability to use NTP network time if nothing else worked well, GNSS/GPS time(s), PTP, radio times and/or anything else that was available and was designed to accurately (as possible) record data coming into the device from sensors.
BTW, I took a quick peek at the NTP github repo and sad to see that the NTP bug list is hidden behind a login in a bugzilla database. Not very accessible. I don't see a continuous integration testing setup. And to top it off, changes show up as from "unknown."