T&T: Atomic watch

[KevinR]

> -----Original Message-----
> AT the power levels WWV puts out, you should be able to receive
> anywhere in the world

While the WWV time signals may be picked up on a shortwave receiver with
enough clarity for the human ear to decipher a usable time signal, for an
automated clock/watch to use the signal, it must be crystal clear so that
the automated receiver gets little static.

Many years ago, Radio Shack had a desktop clock that would auto-sync to the
WWV time signals. It turned out that the WWV signals were so weak on the US
east coast, that none of the clocks would work more than a few hundred miles
from Boulder. Radio Shack ended up dropping the product since it would not
work far from the WWV transmitters.

I did a project in 1992 where I needed to use the WWV time signals for
synchronizing the clocks for a large computer network in the New York City
area. While WWV continuously transmits time on five different frequencies
(2.5 MHz, 5.0 MHz, 10.0 MHz, 15.0 MHz and 20.0 MHz), none of these can be
heard on the east coast throughout the entire day. As the ionospheres'
conditions change as the sun goes across the sky, different HF banks come in
or go out. The system required an expensive five channel voting receiver
that could measure reception conditions and switch HF bands during the
day/night as propagation conditions changed.

As a test of present conditions tonight, I just tuned in WWV on my Icom
IC-746 to see how WWV was coming into northern New Jersey at 9 PM local
time. The test results were:

   2.5 MHz  -  Total static, could just barely hear WWV time ticks, could
not understand
               time announcements - signal unusable
   5.0 MHz  -  Heavy static. Human ear could understand time announcements,
but I doubt 
               an automated receiver could decode them
  10.0 MHz  -  Mostly clean, useful signal
  15.0 MHz  -  No signal heard
  20.0 MHz   - No signal heard

A single frequency receiver built into a wrist watch is pretty much a toy
that is only useful close to the WWV transmitters in Colorado (or the WWVH
transmitters in Hawaii). If you really want a reliable source of accurate
time, you can't beat the atomic clocks flying in the GPS satellites, as
monitored by a GPS receiver. 

Regards,
Kevin
www.BoatMoves.com