[time-nuts] Synchronizing to WWV

Rob Kimberley rk at timing-consultants.com
Tue Dec 22 10:17:44 UTC 2009


Download OK in UK.

Rob Kimberley 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Neville Michie
Sent: 22 December 2009 09:14
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Synchronizing to WWV

Hi
none of these nist references will download to me in Australia,
is it some sort of national security issue?

cheers,
Neville Michie



On 21/12/2009, at 11:01 PM, Hal Murray wrote:

>
> 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.
>
>
>
> -- 
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
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