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radioclk

Disciplines the system clock from an MSF, WWVB or DCF77 time signal

What it does

Decodes the low-frequency time-signal broadcasts -- MSF from Anthorn, WWVB from Colorado, DCF77 from Mainflingen -- from a receiver module attached to a serial port, and presents the result to ntpd as a reference clock.

Why you would want it

Time that does not come from the internet. For a station that must work disconnected -- emergency communications, a remote site, anything where the network is the thing that failed -- a radio clock is an independent source, and FT8 and other timed modes stop working within a couple of seconds of drift.

Before it will work

An LF time-signal receiver module wired to a serial port's data carrier detect line, and to be within range of a transmitter: MSF covers Britain and nearby, DCF77 much of Europe, WWVB much of North America. ntpd configured to accept a reference clock.

How it installs

  • apt: radioclk

Known problems

LF reception indoors is poor and switch-mode power supplies, LED lighting and computer monitors all interfere badly -- the receiver usually has to be away from the equipment it is timing. Decoding takes a full minute per frame and several frames to trust, so it is not a fast fix for a wrong clock. A GPS-disciplined source is more accurate and easier where the sky is visible; this is for where it is not.

Keeping it current

  • probe: apt policy
  • strategy: apt_upgrade

Where to get help with the software itself

Jonathan Buzzard's page above is the reference. Long stable rather than actively developed.

Source: catalog/packages/radioclk.yaml