WWV DST

[rrennard]

Mark - you are correct... I am just to used to working with the superior system described at

http://www.navcen.uscg.gov/pubs/gps/sigspec/gpssps1.pdf

that is only good to about 100 nanoseconds anywhere on the planet, but it has no clue about DST.   The starting and ending dates for DST are easy to determine if you can figure out which day of the month it is, and what day of the week it is.

N7WY



---- Mark Bayern <[hidden email]> wrote:

> Yes, WWV does encode the DST bit. See
> http://tf.nist.gov/stations/wwvtimecode.htm for more info on the
> format.
>
> Mark  AD5SS
>
>
>
> On 4/3/06, [hidden email] <[hidden email]> wrote:
> > Did WWV ever send any DST coding?  I'll bet not.  Setting DST is not rocket science, just a simple algorithm.
> >
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[Mark Bayern-2]

Thanks for the reference. However, the idea that this system is
'superior' would depend upon why one is looking for a time reference.
If all you want is a relatively high accuracy clock the WWV signal is
superior IMO. It certainly is easier to decode! As an added benefit it
includes the DST bit -- you never know when the govt will decide to
change the DST rules.

If you need to know where you are and have a clear view of the sky
your system works well.  (As long as I don't have to code the
algorithms.)

Mark

On 4/3/06, [hidden email] <[hidden email]> wrote:
> Mark - you are correct... I am just to used to working with the superior system described at
>
> http://www.navcen.uscg.gov/pubs/gps/sigspec/gpssps1.pdf
>
> that is only good to about 100 nanoseconds anywhere on the planet, but it has no clue about DST.   The starting and ending dates for DST are easy to determine if you can figure out which day of the month it is, and what day of the week it is.
>
> N7WY
>
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[John Magliacane]

Hi Mark.

> Thanks for the reference. However, the idea that this system is
> 'superior' would depend upon why one is looking for a time reference.
> If all you want is a relatively high accuracy clock the WWV signal is
> superior IMO. It certainly is easier to decode! As an added benefit it
> includes the DST bit -- you never know when the govt will decide to
> change the DST rules.

Very true, but compared against WWVB and GPS, WWV/WWVH/CHU reception achieves
the poorest accuracy as a time and frequency reference due to the inherent
variability of ionospheric propagation.

NIST claims WWV/WWVH time reception to be accurate to within 1 to 20 ms.
WWVB reception is accurate to within 0.1 to 15 ms.

NIST's Frequency Measurement and Analysis Service, which is GPS-based, is
accurate to within 20 nanoseconds.  This precision is due in part to the fact
that NIST itself monitors the GPS signals while FMAS measurements are made, and
so the readings taken are, in fact, traceable to NIST's atomic standards.

Obviously, this is well beyond the accuracy most hams need in their shacks, but
modern soundcard based weak signal and SSTV modes are demonstrating very
clearly the increasing importance of being able to send and receive highly
accurate, stable, and well timed signals.  I suspect that trend will continue.


73, de John, KD2BD


Visit John on the Web at:

        http://kd2bd.ham.org/
.
.
.
.

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