> However the world has moved to using GPS to globally
> distribute accurate time. It is just FARRRRR more reliable.

Is it cheaper?

Thanks,
Tony


----- Original Message -----
From: "Robert Rolf" <Robert.Rolf@UALBERTA.CA>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Tuesday, December 17, 2002 1:45 PM
Subject: Re: [PIC]: How to obtain the official US time clock?


> CHU does have a computer readable output
> http://inms-ienm.nrc-cnrc.gc.ca/time/chuhistory.html
>
> "The warble tone at seconds 31 to 39 allow any computer with a
> Bell 103 compatible 300 bps modem to receive and decode an
> accurate source of time."
>
> Germany also has a standard time broadcast as does Japan.
>
> However the world has moved to using GPS to globally
> distribute accurate time. It is just FARRRRR more reliable.
>
> Olin Lathrop wrote:
> >
> > > I really need to design a product that knows the official U.S. time,
> > aside
> > > from other features. Can someone tell me what is required for the
> > hardware
> > > and software to acquire the official time? And what kind of
connections
> > are
> > > required?
> >
> > There are several ways to do this, but you need to first decide what
> > accuracy you require.  If the gizmo already has an internet connection,
> > then the contacting a NNTP server requires no additional hardware.
There
> > are other options:
> >
> > 1  -  Have the user set it occasionally and use a real time clock in
> > between.
> >
> > 2  -  Decode the WWVL long wave broadcasts.  These are designed for this
>
> WWVB is the 60kHz station
> WWVH is HF station in Hawaii
> http://www.boulder.nist.gov/timefreq/stations/wwvb.html
>
> > purpose, but your hardware is susceptable to antenna orientation and
> > distance from Boulder.  Here in MA we are 2000 miles from Boulder and
> > placement and orientation of automatic clocks makes a big difference.  I
> > have two automatic clocks, and they only seem to pick up the signal at
> > night, sometimes.
>
> I'm up here in Edmonton (53N 113W), and my OSI clock picks up the signal
> at all appointed check times (day and night). Antenna placement and
> orientation is CRITICAL to reliable reception (no nearby fluorescent
> lights or light dimmers)
>
> > 3  -  Decode WWV broadcast.  These are at several shortwave frequencies.
> > I know 10MHz is one of them, and I think there are also broadcasts at
> > 2.5MHz, 5MHz, and 15MHz, but I'm not sure.  These may be more difficult
to
>
> & 20Mhz
> http://www.boulder.nist.gov/timefreq/stations/wwv.html
> 10,000 W on 5, 10, and 15 MHz; and 2500 W on 2.5 and 20 MHz
>
> > decode, but the coverage should be wider.  I'm not totally sure they
even
> > have encoded data on them.
>
> They do.
> "The modulation level is 50 percent for the steady tones,
> 50 percent for the BCD time code, ..."
>
> >
> > 4  -  Canada also broadcasts a time standard.  The radio station is
called
> > CHU if I remember right.  I don't know whether it contains coded
> > information that a micro can use.
>
> It does. See opening paragraph
>
> Robert
>
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