[time-nuts] Synchronizing to WWV

[Bruce Griffiths]

Neville Michie wrote:
> Hi
> none of these nist references will download to me in Australia,
> is it some sort of national security issue?
>
> cheers,
> Neville Michie
>
They download fine across the ditch.
Probably a problem with your ISP.

Bruce
>
>
> 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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>
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