[GreenKeys] Western Union Time

[Brooke Clarke]

Hi Lar:

I have a couple of web pages on the WU clocks:
http://www.prc68.com/I/SWCC.shtml
http://www.prc68.com/I/SWCC2.shtml

It turns out the Teletype technology is used to do the hourly setting.  
That's to say it's a 200 Volt loop that uses a power resistor in order 
to get the time constant (L/R) down so that the setting pulse is fast.  
As far as I know there's no HV hourly setting system.  The modern 
equipment that's offered used LV solid state technology and so can only 
be used for a single clock, unlike the HV system where a series string 
of say 20 clocks can be set.

"Atomic Clocks" is a term used to describe self setting clocks that 
listen to WWVB on 60 kHz.
http://www.prc68.com/I/Shadow-Clock.shtml#WT5360U
There are stations in Colorado and Hawaii.
If you're in the US you should be able to receive the signal at least 
once per day around local midnight.  There are low cost small PCB 
receivers available, see:
http://www.prc68.com/I/Loop.shtml#CMMR6P60
I'm in N. California and the LED on the newest one I have seems to show 
solid copy 24/7.

Recently I recapped a Heathkit GC1000 Most Accurate Clock and every 
night after sunset it's going into "Hi Spec" mode using the built-in 
whip antenna (an inside antenna) where the 3.6 MHz crystal oscillator 
gets auto tuned to about 1 Hz accuracy.  The neat thing is that because 
of the auto tuning the time remains accurate to 0.1 Seconds and the 
display shows the 0.1 seconds.
http://www.prc68.com/I/HeathkitGC1000.shtml#Video

Note that in order to use any of the commonly available radio time 
signals (GPS, WWV, WWVB) you will need to decode the top of the hour.  
There is no unique hourly signal.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com