Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!tjk
From: tjk@csd4.milw.wisc.edu (Thomas Krueger)
Newsgroups: sci.electronics
Subject: Re: NBS time broadcast
Message-ID: <3572@csd4.milw.wisc.edu>
Date: 27 Jul 89 14:30:39 GMT
References: <8720@kean.mun.ca>
Sender: news@csd4.milw.wisc.edu
Reply-To: tjk@csd4.milw.wisc.edu (Thomas Krueger)
Distribution: na
Organization: College of Engineering Electronics Shop, UW Milwaukee
Lines: 43

In article <8720@kean.mun.ca> andrew@kean.mun.ca writes:
>Now, a few years ago, I remember seeing a Heathkit (read:expensive) project for
>"the world's most accurate clock".  Apparantly the thing picked up a broadcast 
>from the NBS and decoded it.
>
>What a lovely thing for my PC... "this file created on 22-Jul-89 10:59:03.4 
>_EXACTLY_"   :-)
>
>So the question... anyone know how this works and how/where it is broadcast?

We have two of them here at UWM. There are two shortwave radio stations, WWV
in Fort Collins, CO, and WWVH in Honolulu. They both broadcast on 2.5, 5, 10,
15 and 20 MHz. The signal has two subcarriers, one at 100 Hz, and another at
1000 Hz, that contain data the clock decodes.

The clock itself is the Heathkit GC-1000 "Most Accurate Clock". It receives
on 5, 10 and 15 MHz, and will hunt for the strongest signal. When it
receives two time frames that are the same (except for the obvious
difference) the clock will update and be accurate to the nearest .1s.
Supposedly the local oscillator will adjust itself up and down to agree with
WWV. The clock has switches for GMT/local time, daylight savings (I think),
delay propogation, channel lockout, and timezone.

The RS-232 board is an "option" so better order it with the clock. 

Caveat: Don't connect this sucker to an external antenna that lightning
likes to strike since you will blow the living piss out of the front end. In
a house, the supplied whip antenna should be all you need. After blowing up
both of these clocks many times, we connected the antenna to building
ground... works fine.

If you REALLY want to see the data stream, call 414-229-5955 at 1200 baud
and when the PACX switch asks you what system, type "clock" then return (of
course).

Hope this helps.

							- Tom
--
                 "A Veteran of the Psychic Wars"

Thomas Krueger, Univ WI Milwaukee College of Engineering Electronics Shop
tjk@csd4.milw.wisc.edu    [moderator, info-high-audio]    +1 414 229 5172