[time-nuts] Synchronizing to WWV

[Hal Murray]

tvb at LeapSecond.com said:
> Your ears are correct; the 100 Hz code began in 1960. See:
> http://tf.boulder.nist.gov/general/pdf/1670.pdf
> http://tf.boulder.nist.gov/general/pdf/1681.pdf
> http://tf.nist.gov/stations/wwvhistory.htm
> http://tf.boulder.nist.gov/general/pdf/1731.pdf

Fun reading.  Thanks.

I think I found a better one:
  http://tf.nist.gov/general/pdf/1969.pdf
NIST Special Publication 250-67
NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB
January 2005

Here is a chunk from page 14:
  (postscript page 14, document page 5)

An experimental time code containing year, month, day, and precise 
time-of-day began in April 1960 [14] and was made part of the regular 
broadcast in January 1961 [15]. This time code, known as the NASA 36-bit 
code, was produced at a 100 Hz rate using 1000 Hz modulation. Believed to be 
the first digital time code broadcast in the United States, it made it 
possible for the first time for self-setting, radio controlled clocks to 
appear. Earlier radio controlled clocks required human interaction to 
initially synchronize. The current time code format (modified slightly over 
the years) was a modified version of the IRIG-H code format. It was initiated 
on July 1, 1971 using a 1 Hz rate and 100 Hz modulation. The new code 
included a daylight saving time (DST) indicator [16]. The telegraphic time 
code was also permanently removed on this date.

So the 100 Hz subcarrier (that I didn't remember) didn't start until 1971.  
That was long after I was listening to WWV as a kid.



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