Antenna for receiving WWV/10MHz: am I asking too much?
 

Frnak McKenney wrote:





Hm... I don't _think_ so. At least, I havent heard of any plans for
a High-Def upgrade to Usenet lately, but with Congress currently in
session I suppose anything is possible.

As for testing the clock's accuracy, you're right about needing a
second source ("Qui custodiet ipsos custodes?" or something like
that? grin). On the other hand, as long as the digits are
flashing by, I'm happy to "just trust them".


One needs three clocks.. if you have only two, you only know that they
differ. If you have three, you can detect the failed clock, because the
other two read the same time.

Of course, if the different clocks have different accuracies or
reliabilities, that's another story.

For a more detailed treatment of such things, you might want to check
out the "Byzantine General" problem.


Based on the feedback from other posters, it's likely a consequence
of 10MHz propagation. A VLF RF signal like 60KHz reportedly does a
much better job of getting a readable signal to a wide area.

Although in my house (southern California), the 60 kHz signal seems to
fade in and out on a daily basis.

Antenna for receiving WWV/10MHz: am I asking too much?
 

Jim Lux wrote:

Why not take the GPS disciplined oscillator (e.g. a Z8301) and use that
to synthesize a fake WWV signal (which you could program up in the AVR),
and radiate that to your MACII. You can easily divide down the 10 MHz
from the oscillator to generate all the needed modulations for WWV (the
tones, ticks, and 100 Hz timecode). Synthesizing the voice
announcements might be a bit more challenging grin "At the tone,
Coordinated Universal Time is...." You could even have a switch to
change back and forth between WWV and WWVH.

Talking clock programs have been around for a long time. All you need
is samples for 0 through 24, 30, 40, and 50 and a few words. You could
even play games with it, I'm sure the clock does not care, for
example "At the beep, the fake univeristy time is" and so on.

You really don't need to do much at all, since if I remember correctly,
it's an AM modulated signal, with no modulation also being no carrier.
Am modulation and on/off switching of a high power radio signal is
fairly complex, but at the microwatt level it should be easy.

It's fairly slow so even a reed relay connected to a GPIO line
would do. I'm sure there are all sorts of digitaly controlled
analog switch chips that will quickly and cleanly switch 10mHz.

As an aside, if I remember correctly, the 60kHz version is just
pulse code modulation of a carrier at a very slow baud rate,
so it would be really easy.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

Antenna for receiving WWV/10MHz: am I asking too much?
 

Frnak McKenney wrote:


Robert,

Thank you for joining in.

On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts wrote:
Frnak McKenney wrote:
I'm in Richmond, Virginia and I'm trying to noticeably improve my
reception of WWV's 10MHz signal from Fort Collins, Colorado. It all
seemed so simple, two weeks ago: wind some wire, solder a
connector, and Hey...presto! a clean WWV signal. grin!
--snip--

Frank, can't you erect anything outside at all? A 10 metre dipole,
is after all, only about 5 metres long. And if you can't do that,
what kind of attic do you have? If your house is oriented
correctly, you could even build a three element wire yagi pointed
west inside the attic.

Um... 10m? I was hoping for 10MHz/30m. Or have I missed
something? (Wouldn't surprise me -- my 1st Class ticket expired
several decades back.)

HMMMM. I was having a blonde moment, I think. Of course I meant 10 MHz and
not 10 Metres. The dimensions were correct, though for 10 MHz. Looks like
one of those days where the brain fades...

Okay... ARRL Antennas, Chapter 8: Multielement Arrays. We've got
an (approximately, given skip) vertically-polarized 10MHz signal, so
the E-field is moving up and down and the wavefront is a circular
ripple (nearly a straight line by the time it gets to Richmond)
travelling roughly west-to-east, that is, it's hitting my house
end-on.

Dimensions shouldn't be that critical for receive only, and space
the elements at about 2.5 metres. Basically one element at about 47
feet, one at about 49.3 feet, and one at about 45 feet. Split the
47 ft one into two, feed it directly with 50 ohm coax, one side to
the shield, one to the centre conductor, and you have a three
element wire beam pointed, hopefully, west. (Put the longest
element on the east side, the shortest on the west.)

Um... if I label them as A/47ft, B/49ft, and C/45ft, the picture I
come up with looks like this from overhead:

| | |
| | |
--- To Fort Collins | + |
| + |
| | |
| | |
(scale)
|............................................C.A.B


I definitely think I'm missing something, but then, I haven't really
made it that far into the Antenna Handbook.

Anyway, thanks for the suggestion.

You're welcome. Your characterisation of the antenna as above is correct,
and hopefully your attic is correctly oriented. Of course if you can put it
outside, fixed wire beams are often very useful.


Frank
--
"Our Constitution is in actual operation; everything appears to
promise that it will last; but in this world nothing is certain
but death and taxes." -- Benjamin Franklin
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)

Antenna for receiving WWV/10MHz: am I asking too much?
 

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."

To this point you haven't exactly demonstrated you have a problem,
just a complaint of a signal of poor quality to a human's perception.
For the clock itself, that complaint is arguably weak.

Let's just examine the evidence for the problem: There is none!

You have a clock that has 100mS resolution, and yet you have never
said how much it is off. 100mS? 1S? 10S? 1 minute? 1 Hour? All,
or any part of any of these metrics?

It's hard to tell exactly how much the clock is off by.

Every time the power hiccups, or I have to move the MAC-II, or power
down the outlet the display switches to something like this (best
viewed with a fixed-width font):

_ _
_ _ /_ /_ /_ /_
/ / /_/ /_ _/ /_ /_

and it stays that way for weeks. Or months.

As Reggie would have chimed in at this point "If you can't measure it
and express it with a quantifiable, then you don't know anything."

Given the extent of my ignorance concerning 'most everything, that
seems likely. grin!

Of course, your only source of accurate information is the one you are
suggesting has a problem. It probably doesn't have a problem, but
then how does one use this source's accuracy to check itself? You
would need a second clock to check it, and we would be hearing your
complaint in stereo.

Hm... I don't _think_ so. At least, I havent heard of any plans for
a High-Def upgrade to Usenet lately, but with Congress currently in
session I suppose anything is possible.

As for testing the clock's accuracy, you're right about needing a
second source ("Qui custodiet ipsos custodes?" or something like
that? grin). On the other hand, as long as the digits are
flashing by, I'm happy to "just trust them".

I've calibrated time standards to the nearest 100nS and it is
accomplished at one sitting, no need for total connectivity such as
you might imagine (unless the clock you have is especially crappy).

Your clock has a resolution of 0.1 second. There are roughly 1
million ticks of the display in a day. A simple XTAL oscillator at 10
MHz would exhibit 50ppm stability and in a day wander up to 0.5
second. The next day it might wander back, the day following it might
slip below by 0.5 second.

If I read the MAC-II manual correctly, each time it "connects to
WWV" (gets a recognizable signal) it calculates and saves an
adjustment value. The front panel has two LEDs labelled "TRIM UP"
and "TRIM DN" to indicate how well it's doing.

... You would be hard pressed to confirm this
with over the air matching to the strike of the WWV gong - except if
the clock is especially crappy (and it could be). The same XTAL might
also exhibit an absolute error of 50ppm and accumulate time error.
This would be far more noticeable over the course of a week (you could
confirm the error by listening to time announcements - but you have
been silent to this issue).

True. And, while I'm sure the _WWV_ announcer hasn't been silent,
_I_ haven't heard anything comprehendable from him/her/it out of my
MAC-II's speaker at any point in the past few weeks.

These worst case errors all presume that the internal circuitry cannot
over the course of 24 hours manage to pull out one of 1400
synchronizing opportunities to phase lock out the error. These
circuits are generally optimized to accomplish just this (they work
fine in watches with a 60KHz signal after all). Your clock may be
especially crappy (but that is unlikely).

Based on the feedback from other posters, it's likely a consequence
of 10MHz propagation. A VLF RF signal like 60KHz reportedly does a
much better job of getting a readable signal to a wide area.

The clock synchronizing circuits don't have to listen to the bandwidth
of noise you hear, the speaker is for your convenience, not the
clock's. I am sure that it works fine with only 1 LED lit - this is
not a case of "can you hear me now?"

No, but (assuming you're subbing for WWV grin!) it would be nice
to know I was going to get a readable message from "you" more than
once every couple of months. (Why do I hear the echo of my parents'
frustration during my colege days? grin!)

Thanks for the feedback. I admit I hadn't thought that much about
the accuracy of the MAC-II; I'm afraid I've been too caught up in
simply trying to get digits instead of "error text" on the display.

Frank
--
"A good traveller has no fixed plans and is not intent on
arriving." -- Lao Tzu (570-490 BC)
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)

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.

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.

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 ??).

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.

Cheers,
Tom

Antenna for receiving WWV/10MHz: am I asking too much?
 

Frnak McKenney wrote:
I'm in Richmond, Virginia and I'm trying to noticeably improve my
reception of WWV's 10MHz signal from Fort Collins, Colorado. It all
seemed so simple, two weeks ago: wind some wire, solder a
connector, and Hey...presto! a clean WWV signal. grin!

It wasn't so simple, and I'm afraid I've let it become an "ego
thing" (see also: resource sink). I've outlined the problem below
in the hope that someone can either suggest something I haven't
already tried, or even point out something really dumb that I've
been doing and shouldn't keep doing. grin!


Background
----------

Several years back I inherited a Heathkit GCW-1001 Most Accurate
Clock II from my father. This is an update to it's predecessor,
Heath's GC-1000 Most Accurate Clock; its circuit, built around a
Philips TDA1072A AM receiver IC and an 87C52 microprocessor,
monitors WWV's 10MHz signal and decodes the BCD-coded 100Hz
subcarrier (details at http://tf.nist.gov/stations/wwv.html) to keep
the MAC-II accurate.

This MAC-II worked fine for my father: he had a 30 meter dipole of
some kind in the attic, above the second floor of a house on a hill.
For him, WWV's 10MHz signal from Fort Collins came in regular as...
well, "clockwork". igg!

For me, in a one-story-plus-basement, in a low spot in a river
valley, it's a different story. The GCW-1001 has a stack-o-LEDs
signal strength indicator driven by the TDA1072's AGC output; it
would wander between 2 and 4 LEDs with my 40" indoor dangling wire
antenna, and it could take weeks or months for atmospheric
conditions to randomly improve the signal to where the GCW-1001
could "lock in" a time.

Two weeks ago, in a fit of madness, I decided to try building a
better antenna, one which would let the clock lock onto WWV at
least, say, once a week. The tuned-loop antenna I've built _has_
increased the signal -- I'm seeing 4-5 LEDs lit on a regular basis,
and 6 on occasion -- but the clock still isn't sync'ing to WWV's
time signal. The clock face remains at a cute(?) 7-segment "not
SEt" display. And what seems to be louder is the carrier -- or _a_
carrier, at any rate -- but not the tones or the human voice time
callout coming out of the GCW-1001's speaker.

I seem to be up to my assets in alligators, and the swamp doesn't
seem to be draining much.


Problem
-------

My main problem is that, although the GCW-1001's LED "Signal" stack
_says_ it's getting a stronger signal, what I hear through the
speaker monitor isn't _clearer_. There are long periods when I
cannot hear any WWV tones through the GC-1001's speaker, the
tones/ticks are faint even when there are 5-6 LEDs lit, and the
voice is almost never audible/distinguishable. The clock _seems_ to
be sync-ing a little more often (it's done it four times in the past
two weeks), but I had hoped it might happen a _little_ more
frequently.

Am I asking too much? Is WWV's 10MHz signal from (say) 2,000 miles
away, simply too weak to pick up solidly without an outdoor antenna?


What I've tried
---------------

My (second) attempt at a 30m indoor loop antenna:

Main loop (tuned): A 36" near-circle of #12 insulated house wire
with an AM/FM tuning capacitor across it.

Pickup loop: One (36") turn of #27 magnet wire taped to the #12
loop with electrical tapegrin!. The ends (scraped and tinned)
are tied to the GCW-1001's 50ohm antenna input with a couple of
12" clip leads and a 3' section of coax.

The loops are mounted on (and held in shape by) a 1'x4'x0.5"
"backboard" made of "blue foam" house insulation that I found in my
basement; the loops are held in place by small plastic cable ties.
The foam backing is resting against a (roughly) N-S wall, which
_should_ orient the loop plane across the WWV wavefront for maximum
pickup.

Does this sound like a reasonable attempt at a tuned 10MHz loop?

Is there any reason to believe that the foam backing would affect
the loop inductance? I'm assuming it's a good insulator and nothing
more, but that's an assumption.

Is it possible that I'm picking up a non-WWV dignal so strong that
it's masking WWV? I tried tuning around 10MHz with a shortwave
radio; it didn't find WWV -- not a particularly hopeful sign -- but
it did pick up a station called (IIRC) WWCR. WWCR's 'web site
(www.wwcr.com) lists its transmitter #4 as using 9.985MHz and
9.975MHz between 0900 and 2100 CST.

Any advice or suggestions will be appreciated, up to and including
"You can't power a hedge trimmer from two AAA cells!".

Thanks...

Frank -
I am up in Maryland, not too far from you.

WWV on 10MHz is only usable for about a third or less of the day for
locking an electronic clock. Generally the late afternoons and
evenings are great, early afternoons and mornings are a little more
variable.

Overnight 5MHz works best. During the mid-day 15MHz or when
propogation permits 20MHz rules for WWV. I don't think your Heath has
any frequency diversity capability, right? Well, 10MHz is a pretty
good choice if you only have a choice of one, it is usually coming in
strong in the evenings there. Over wintertime 5MHz gets pretty good at
night.

You will, especially in the early morning, occasionally hear WWVH on
10MHz or 5MHz or 15MHz. Sometimes I hear both WWV and WWVH at the same
time. You can recognize WWVH by the woman's voice reading the time.

My best antenna for 10MHz WWV is my 40-meter dipole strung between
two trees. Mine mostly points broadside to the NE/SW but if you could
arrange it, it would be slightly preferable to have it broadside to be
sensitive to the W.

A dipole optimized for 10MHz would be even shorter - the formulas
put a half wave dipole at 47 feet long.

Tim.

Antenna for receiving WWV/10MHz: am I asking too much?
 

On Thu, 11 Oct 2007 06:23:44 -0700, Roy Lewallen wrote:
Frnak McKenney wrote:
. . .
Okay... ARRL Antennas, Chapter 8: Multielement Arrays. We've got
an (approximately, given skip) vertically-polarized 10MHz signal, so
the E-field is moving up and down and the wavefront is a circular
ripple (nearly a straight line by the time it gets to Richmond)
travelling roughly west-to-east, that is, it's hitting my house
end-on.
. . .
--snip--
While you're looking at the ARRL Antenna Book, look over the chapter on
propagation. You'll find that when receiving a signal by ionospheric
skip (as you are), the polarization will be randomly oriented. So
there's no point in choosing your antenna orientation on the basis of
some supposed wave polarization. Its orientation will, however, have a
striking impact on its pattern, so you should choose the orientation to
get the most favorable pattern.

Ah. So even if it starts out in vertically polarized in Fort
Collins 'way out thataway (he says, gesturing faintly west-ish)
WWV's signal might be polarized north-north-west by the time it gets
ro Richmond.

The fading in and out of the WWV signal you described in an earlier
posting is very likely due largely or at least partially to polarization
shift -- the signal fades when the polarization rotates to be crosswise
to your antenna, and gets loud when the polarization lines up with your
antenna's. I've seen tens of dB difference switching between a
vertically and horizontally polarized antenna, with the change going the
other way after a minute or so when the polarization rotates. If your
receiver needs a constantly strong signal, you're going to have a hard
time getting it what it needs.

Hm. Wonder if anyone has built an antenna whose polarization shifts
to "best match" the incoming signal? (No, not _this_ weekend!
grin!)

I haven't followed the thread closely, so please pardon me if I've
missed something. Your initial description of the problem sounded like
receiver overload. A sharp preselector would help a lot, although it
sounded like you were using a tuned loop which, if carefully balanced,
should provide that function.

A minor update: It seems that I was _mis_tuning my antenna,
adjusting it for the strongest signal (highest stack of LEDs lit).
Over the past two days either I've finally tuned it _correctly_ or
I've done that _and_ the signal has improved. Whatever the
cause(s), I can now -- at times, in fact for an hour at a time --
hear the tocks fairly clearly and even understand the voice. (Who
knew the announcer's phrase for UTC "Coordinated Universal Time"?).

How good? Well, I've unplugged the clock to reset it and it has
then received an "acceptable" WWV signal (it started showing digits)
eight times in the past two days. It might have been more times,
but I don't watch it constantly, and I've noticed that twiddling the
tuning knob tends to make sync-ing a little harder. ("Ack! It's
fading! See if I can tune the antenna _just_ a little better!"
grin!)

I _do_ know that the point of best reception is much narrower that I
thought it when I was tuning in that "other" signal. Turning the
tuning capacitor's knob a "minor wiggle" either way can decrease the
signal strength by an LED or 2, and I need to compensate for the
effect of moving my hand near the antenna to tune it. grin!.

Oh, and the MAC-II seems to be a lot pickier about what it will and
will not accept than my ears are. The microprocessor is driven by a
9.216MHz crystal and it's an 87C52 (an 8051-alike) which (as I
recall) means it only gets around 0.768 MIPS (clk/12) to do all its
work, so I doubt it's doing much "DSP" itself; its interrupt lines
are tied to a 567 tone decoder IC for WWV's "start of minute" and
BCD data subcarrier tones (1000Hz and 100Hz).

The MAC-II seems to be very "picky". Part -- but not all -- of its
requirement for starting the clock digits running is that it receive
a recognizable 100Hz signal for a full minute, that is, between one
1000Hz tone and the next. In other words, if WWV's signal is fading
on a 5- or 30-second cycle, odds are good that at one point the
signal will be come "bad". I've seen it recognize the start of a
"frame" by lighting its CAPTURE LED, but then turn it out ten or
forty seconds later when part of the frame has faded a bit; my ears
can still recognize the tones, but the're better designed and have a
better processor than the MAC-IIgrin!. This pickiness I suspect
is part of the reason it takes to long for the clock to start
running.

... If a preselector isn't enough, the next
step is to add an attenuator -- I have to use one between my TV and its
antenna, in fact. You should consider the possibility that the 10 MHz
WWV signal itself is overloading the receiver, in which case an
attenuator is necessary, and the last thing you'd want to do is use a
better antenna. A directional antenna can be used to reduce the strength
of interfering signals if they're coming from directions different than
WWV. But making an antenna which has good rejection in the right
directions can be something of a project.

I do a lot of reading in comp.dsp (sometimes it's fun just watching
the phrases fly back and forth grin!), and one common topic there
is the difference between "noise" and "signal". For me, "signal" is
"what I want", "noise" is "everything else", and the fun(?) part is
figuring out how to get as much of the former as I can while
downplaying or being able to ignore the effects of the latter. My
next step is to add a "line out" jack to the MAC-II so I can capture
long stretches of the signal to disk; when reception goes bad again
I'll be able to use Scilab or Matlab or something to play "Beat the
Heathkit!" with my own algorithms.

And if I get tired of that, I can unsolder the 87C52 and wire in one
of Atmel's $20 Butterfly boards in its place, adding an LCD and my
own algorithms. And _then_ I can... and _then_ I can... grin!

Anyway, "It's feeling _much_ better now." grin!


Frank
--
The first Zen master in Japan to write extensively on good and
evil was Dogen Zenji... Dogen was one of the most adamant of
those who rejected the widespread use of Buddhism for social,
political, and material power; and he was driven out of the
capital area for his trouble.
-- Thomas Cleary / The Japanese Art of War
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)

Antenna for receiving WWV/10MHz: am I asking too much?
 

On Thu, 11 Oct 2007 07:51:55 -0700, Richard Clark wrote:
On Thu, 11 Oct 2007 12:12:14 -0000, Frnak McKenney
wrote:
_ _
_ _ /_ /_ /_ /_
/ / /_/ /_ _/ /_ /_

and it stays that way for weeks. Or months.

A whip antenna should be able to sort out WWV for at least one of 1400
synchronizing events in a day. This may be a problem of too much
antenna at one time - and a nearby lightning event at that same time.
Your front end got fried out.

If you're reading these posts in the same order I'm posting, you'll
have already read my good news:

It's Working!

(Oh. That's right -- this is Usenet. Y'all can't here the
"doooonb"-ing from down the hall. Well, take my word for it -- or
even the MAC-II's display! grin)

This doesn't prove that the MAC-II's J-FET RF amplifier hasn't been
degraded through an... er, "very wideband RF overload" grin!, but
I think it does say that "completely fried" is unlikely (which
pleases me greatly! grin).

My earlier MAC-I had a nice whip built in, and could select the
strongest signal among (IIRC) 5, 10, and 15MHz, but it had the same
problems getting an "acceptable" WWV signal most of the time.


Frank
--
"Whatever you can do, or dream you can, begin it.
Boldness has genius, power and magic in it" -- Goethe
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)

Antenna for receiving WWV/10MHz: am I asking too much?
 

On Thu, 11 Oct 2007 09:52:53 -0700, Jim Lux wrote:
Frnak McKenney wrote:
--snip--
As for testing the clock's accuracy, you're right about needing a
second source ("Qui custodiet ipsos custodes?" or something like
that? grin). On the other hand, as long as the digits are
flashing by, I'm happy to "just trust them".

One needs three clocks.. if you have only two, you only know that they
differ. If you have three, you can detect the failed clock, because the
other two read the same time.

Well, you have a reasonable _presumption_, anyway. grin

In _theory_, one could have two clocks in error and one on time. Or
even all three out of step with (say) the NIST's clock. But
two-out-of-three would be the place to put your money. grin

Of course, if the different clocks have different accuracies or
reliabilities, that's another story.

For a more detailed treatment of such things, you might want to check
out the "Byzantine General" problem.

Faint recollections... "unreliable communication on the
battlefield" category?

Based on the feedback from other posters, it's likely a consequence
of 10MHz propagation. A VLF RF signal like 60KHz reportedly does a
much better job of getting a readable signal to a wide area.

Although in my house (southern California), the 60 kHz signal seems to
fade in and out on a daily basis.

I can believe it. I've seen those LCD "clock and weather" stations
take days to synchronize the time (I assume they're using WWVB).
OTOH, I'm hardly one to talk, since I've let the MAC-II sit
liostening for months at a time without successfully locking-in on
WWV.

Frank
--
Hanlon's Razor: ÿNever attribute to malice that which can
be adequately explained by stupidity.ÿ
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)

Antenna for receiving WWV/10MHz: am I asking too much?
 

On Thu, 11 Oct 2007 11:21:29 -0700, Robert Smts wrote:
Frnak McKenney wrote:
--snip--
On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts wrote:
Frnak McKenney wrote:
I'm in Richmond, Virginia and I'm trying to noticeably improve my
reception of WWV's 10MHz signal from Fort Collins, Colorado.
--snip--

Frank, can't you erect anything outside at all? A 10 metre dipole,
is after all, only about 5 metres long. And if you can't do that,
what kind of attic do you have? If your house is oriented
correctly, you could even build a three element wire yagi pointed
west inside the attic.
--snip--
I definitely think I'm missing something, but then, I haven't really
made it that far into the Antenna Handbook.

Anyway, thanks for the suggestion.

You're welcome. Your characterisation of the antenna as above is correct,
and hopefully your attic is correctly oriented. Of course if you can put it
outside, fixed wire beams are often very useful.

If I'm following the ARRL handbook correctly, I want the elements
laid out _across_ the incoming wavefront. For Fort Collins to
Richmond, that is, going west to east, that would mean I'd want to
string the wires/elements north-south. Naturally (per Murphy, the
patron saint of Data Processing) my house is oriented E-W. Which
does still, as you point out, leave the possibility of building
something outdoors.

Still, my current indoor loop seems to be picking up a nice strong
signal. It was upright when I first started testing, but it wound up
being laid flat at some point in the past few days -- about the time
I discovered that I had been mis-tuining it. Wonder which had more
effect: my changes, or atmospherics? grin!

Anyway, thank you for your time and suggestions. I did some looking
around on the 'web for introductory material to help me understand
the ARRL Antenna Handbook and stumbled onto these:

Antenna Newcomers and the Language of Antennas
http://www.cebik.com/tales/nc.html

Antennas from the Ground Up
http://www.cebik.com/gup/groundup.html

Some really nice propagation plots. Now, if there were just some
simple way of figuring out which way the antenna is oriented
relative to the plots... "It's an imperfect universe" grin!


Frank
--
Anyone who is not genuinely addicted to the search for knowledge
is unlikely to have the psychological energy to be a true scholar
in any field. But in history this work clearly resembles more
that of a detective than that of a scientist -- a search for and
judgment of particular evidence rather than a repeatable
experiment. The detective side of historical research needs
skill, background, and intuition.
-- Robert Conquest, "The Dragons of Expectation"
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)

Antenna for receiving WWV/10MHz: am I asking too much?
 

Tim,

Thanks for joining in.

On Sat, 13 Oct 2007 17:27:01 -0700, Tim Shoppa wrote:
Frnak McKenney wrote:
I'm in Richmond, Virginia and I'm trying to noticeably improve my
reception of WWV's 10MHz signal from Fort Collins, Colorado. It all
seemed so simple, two weeks ago: wind some wire, solder a
connector, and Hey...presto! a clean WWV signal. grin!
--snip--

Frank -
I am up in Maryland, not too far from you.

WWV on 10MHz is only usable for about a third or less of the day for
locking an electronic clock. Generally the late afternoons and
evenings are great, early afternoons and mornings are a little more
variable.

Overnight 5MHz works best. During the mid-day 15MHz or when
propogation permits 20MHz rules for WWV. I don't think your Heath has
any frequency diversity capability, right? Well, 10MHz is a pretty
good choice if you only have a choice of one, it is usually coming in
strong in the evenings there. Over wintertime 5MHz gets pretty good at
night.

My current box, the MAC-II, only monitors 10MHz; its predecessor,
the GC-1000 MAC, monitored (IIRC) 5/10/15MHz and chose the
strongest.

You will, especially in the early morning, occasionally hear WWVH on
10MHz or 5MHz or 15MHz. Sometimes I hear both WWV and WWVH at the same
time. You can recognize WWVH by the woman's voice reading the time.

My best antenna for 10MHz WWV is my 40-meter dipole strung between
two trees. Mine mostly points broadside to the NE/SW but if you could
arrange it, it would be slightly preferable to have it broadside to be
sensitive to the W.

A dipole optimized for 10MHz would be even shorter - the formulas
put a half wave dipole at 47 feet long.

Thanks for your signal report and the antenna suggestion. I'll keep
it in mind.

On the other hand, my tuned (and currently horizontal) loop is
suddenly picking up WWV/10MHz remarkably reliably, and I didn't even
have to "sacrifice a goat at midnight"! grin

Has your reception improved lately as well (last few days)?


Frank
--
Writers listen for harmonies; civilians listen for melody alone.
For them the facades of ordinary situations are opaque, and they
see what is there to be seen. Writers are attracted to translucence.
We start with nothing but an idea, an agitation, a compulsion, an
irritation. That, plus a bumblebee's faith that it can fly.
-- Hal Ackerman / Write Screenplays That Sell
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)