WWVB Observatory

A lot of my play coding lately has been related to WWVB, a 60kHz radio time signal broadcast from near Fort Collins, Colorado, USA.

I'm calling my latest work the "WWVB Observatory": I'm capturing the amplitude signal from an inexpensive "MAS6180C" receiver connected to a Raspberry Pi 50 times a second, and uploading the result to github hourly. The Pi is well-synchronized to the accurate time using NTP, and while it's not running as real-time software, the 20ms sample rate doesn't seem to pose any practical problems.

I'm mostly interested in using the data "ex post facto" to develop and measure the performance of different decoder algorithms, though I haven't started on that part yet. Others may have their own ideas.

In principle, this software infrastructure can also be used with other clock signals compatible with the MAS6180C: DCF77, HGB, MSF, JJY and BPC.

The code and data are on github. Right now I'm hoping to operate it for at least months, and if there's ever another leap second I fully intend to un-mothball it to try to record that very special moment that happens only rarely in the past few years.

One sub-part of the WWVB Observatory is an independent library for working with the leap second database known as "leap-seconds.list". I've uploaded it to github & pypi.

I still need to break out my "advanced Linux timekeeping APIs" library, erroneously called "clock_nanosleep.py". It wraps clock_nanosleep, clock_gettime, clock_settime and ntp_adjtime. clock_nanosleep is interesting because you can sleep until a particular deadline specified against a particular timesource (UTC, TAI, or monotonic being the useful options). Sleeping until a deadline is a fundamental building block of "realtime-ish" code like the WWVB Observatory.

Entry first conceived on 21 October 2021, 0:23 UTC, last modified on 25 October 2021, 2:49 UTC
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