On Thu, 11 Oct 2007 11:26:03 -0700, K7ITM wrote:
On Oct 11, 5:12 am, Frnak McKenney
wrote:
On Wed, 10 Oct 2007 10:19:49 -0700, Richard Clark wrote:
On Tue, 09 Oct 2007 02:16:37 -0000, Frnak McKenney
wrote:

Am I asking too much?

Hi Frnak,

Judging by the questions and responses, I would have to say "Yes."
--snip--

Gee, all this trouble you're having getting a good signal from WWV on
10MHz makes me wonder, "why??" I mean, why bother? It must be the
challenge! I'm a bit closer to Ft. Collins, but I wouldn't expect
things to be all that much different, and in any event, the same
antenna I've used for them has worked fine for signals from W1AW, for
frequency measuring tests. That antenna is just a short piece of
wire, maybe five feet long, connected to a signal analyzer's input
port. The signal analyzer's input doesn't even have a particularly
good noise figure. But with it, I get a good enough signal from WWV
to easily track the nocturnal/diurnal frequency shifts that happen as
the path length changes. (The analyzer may not have a great RF front
end, but it has a very stable frequency reference...) Similarly, I
have a portable short wave radio that has an awful front end, and with
just a 3 foot whip antenna, it gets WWV 10MHz fine most of the time.
Obviously, there are times of the day when propagation just doesn't do
it, but over the period of one day, and not during a geomagnetic
storm, the signal is usually available.

Hm. Sounds great.

All this makes me wonder if the receiver in your clock is OK. I'd
start by looking at that; or at very least, see if a known-working
radio receiver has as much trouble with the signal as the clock seems
to. Given that the clock has a single frequency receiver, even a
pretty simple receiver design should give decent performance.

The RF section is a one-transistor (J-FET) amplifier followed by a
TDA1072A "Integrated AM receiver" chip. I'm not sure how to go
about comparing that to your equipment.

It's also possible that you have some signal source on nominally 10MHz
nearby, and you hear than instead of WWV. There are soooo many
microprocessors around the average home these days that it's entirely
possible that the source of the trouble is very nearby--but could also
be in a neighbor's house (or car -- or garage -- or ??).

Highly possible, but the noise level "at the speaker" seems to have
fallen off appreciably in the past few days. Also, I think I'm
doing a better job of tuning the antenna; adjusting with no clearly
defined signal is a chicken-and-egg problem, but two days ago I
started hearing a deafening cackle. grin!

If you want an accurate clock and get tired of fooling with WWV-10MHz,
and don't want to use WWVB-60kHz, you might consider using a GPS. As
long as you can manage an antenna with a reasonably clear view of the
sky, you should be able to have a clock reliably set to within less
than a second accuracy practically all the time. Or, if you'd like to
be independent of external references, modify your MAC with an oven
oscillator. Oven stabilized crystal oscillators left on for a long
time will almost always settle out to very low drift rates---one part
in 10^8 over a year shouldn't be difficult, in my experience, and GPS
signals can be used to calibrate it occasionally. One part in 10^8 is
about 1/3 of a second per year.

Yup. GPS would eb the way to go for accuracy... or -- for the
billion-dollar-budget people -- your very own Cesium Clock. grin!


Frank
--
To learn is to change. Learning allows an animal child to
finish the long, slow process of evolution by changing in its
own lifetime. Tiger cubs, eaglets, or babies, nature brings
us all into existence with the ability to learn, and the rest
is up to us. -- Susan McCarthy / Becoming a Tiger
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)