[time-nuts] DCF77 signal change

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Mar 28 13:35:35 EDT 2007


I happened to notice this morning that my old "Conrad" DCF77 wall
clock had not changed to summertime and indicated "no lock" even
though the pulses looked good to my eye.

After about I minute I noticed that the first 14 pulses were no longer
uniform '0' bits, and a bit of googleing turned up the interesting news
that there is now weather information embedded in the first 14 bits.

http://www.meteotime.com/web/de/System/Default.aspx

        0         1         2         3         4         5
	012345678901234567890123456789012345678901234567890123456789
	-#--#---#--####--#--#--#--#--#--##-#---#-###-##---###-----#
	--#----#--####---#--##-#--#-##--##-#---#-###-##---###-----#
	-##--#-#-##-#----#--#-##--#-##--##-#---#-###-##---###-----#
	--###-##-##-#----#--####--#--#--##-#---#-###-##---###-----#
	---#-----#-#-#---#--#---#-#--#--##-#---#-###-##---###-----#
	-#------#--#-##--#--##--#-#-##--##-#---#-###-##---###-----#
	-#-----#--##-#---#--#----##--#--##-#---#-###-##---###-----#
	--#--#----#####--#--##---##-##--##-#---#-###-##---###-----#
         ^^^^^^^^^^^^^^

Obviously, my clock is so old that it was writte for the older "if
you see any of these bits, the transmitter has problems" signal spec.

Anyone know the encoding of the weather info ?  I wonder if they
use the minute bits to designate regions to save bits ?

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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