Download OK in UK. Rob Kimberley
-----Original Message----- From: [email protected] [mailto:[email protected]] 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: > > [email protected] 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. > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ > time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
