Antenna for receiving WWV/10MHz: am I asking too much?
Frnak McKenney
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 tape<grin!>. 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 McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
Physics is mathematical not because we know so much about the
physical world, but because we know so little; it is only its
mathematical properties that we can discover.
-- Bertrand Russell
--
nm...@wt.net
<fr...@far.from.the.madding.crowd.com> wrote:
>
> 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.
Sounds like it's being masked by some type of noise,
but this could just be from the signal being very weak.
If you can hear other stations ok, it probably the propagation
more than anything. Being that you can barely hear it on a
regular receiver seems to bear this out.
Unless a noise is local, and you are trying to null it, I see no
real advantage to using a small loop vs whatever else.
I would make sure you don't have any local noise. IE:
powerline noise, etc. If you did, the loop would be a good
antenna to null that noise as long as you can turn it.
But if there is no local noise, and the noise you hear is
atmospheric, then it's not going to matter much what
you use.
I've got a hunch that the propagation is just the pits for
you right now.
I wouldn't be surprised if you tried it in a couple of months
and it worked ok.. If you hear it on the regular radio ok,
the clock should too. If you can't hear it on the regular
radio, the clock probably won't either, and there is
probably not much you can do about it.
There should be times that it comes in fairly decent though,
depending on time of day, etc..
I would use what you hear on the regular receiver as to
whether the signal is really there or not.
Propagation on most of the HF bands has been fairly
flaky the last few months. IE: I got on 40m in the daytime
the last time I was in OK, and it was like I was on 20m..
Band was real stretched out, and pretty long skip zones.
I'd miss the semi locals I'd usually talk to, and end up
hearing stations 1000 miles away instead.
MK
Denny
Even with my antennas on a 150 foot tower there are times of day when
WWV at 10 megacycles is not audible... This is just the way the daily
propagation cycle is at 30 meters.
My best advice is to put up a dipole for 30 meters, even if you have
to bend the ends to make it fit your space... A horizontal dipole
being balanced picks up less vertically polarized noise than vertical
antennas... Getting the wire outdoors will help also... You are
likely picking up lots of humm and buzz inside the building from
various electrical and electronic devices...
The other issue is whether your clock is actually able to synch with
the WWV signal... You may have a defect in the clock... It would seem
that 4 or 5 bars should have done the trick...
denny / k8do
Owen Duffy
22g2000hsm.googlegroups.com:
> The other issue is whether your clock is actually able to synch with
> the WWV signal... You may have a defect in the clock... It would seem
> that 4 or 5 bars should have done the trick...
Presumably the LED meter indicates recieved power, not signal to noise
ratio.
Owen
ecregger
"Owen Duffy" <no...@no.where> wrote in message
news:Xns99C53CAD89...@61.9.191.5...
--------
That's good!
Polarization was one of my thoughts.
Also, how is the synch tone derived by the receiver? Maybe that part of the
radio needs tweaking? One would think that seven segments out of ten should
be sufficient. I'm assuming there are ten segments total.
Ed, NM2K
keithm
probable that the receiver is just seeing mostly noise?
As mentioned by someone else, propagation is currently "very ordinary" (aka
poor) at present, so maybe he's just out of range.
KeithM
VK1ZKM
"ecregger" <ecre...@bellsouth.net> wrote in message
news:BzROi.3400$s8....@bignews3.bellsouth.net...
Rick
Virginia.
This morning, Tues, 10/9, I listened to WWV on 10 MHz with the 4 antennas I
have at my disposal to see what kind of signal level I get.
My antennas are 80 meter and 40 meter dipoles, a 20 meter yagi and a 30 meter
dipole, all at about 50 feet.
On the first 3 antennas WWV runs about S6-9, and on the 30 meter dipole it is
10-20 db over 9.
This evening, 6 pm, the first 3 antennas haul WWV in at S9 and the 30 m
dipole has it at a rock solid 30 over.
So I agree with the advice you got to string up some kind of dipole and throw
out that loop, there is plenty of signal, you just have to go get it.
Rick K2XT
PS may I throw in a little commercial for my pet peeve? As you read this did
you notice that I did not include any text from previous posts? Did you miss
it?
Dan Richardson
>PS may I throw in a little commercial for my pet peeve? As you read this did
>you notice that I did not include any text from previous posts? Did you miss
>it?
No, but someone reading the message from an archive at some later date
may be puzzled what you are commenting on.
My understanding is to include the portion of the message that you are
replying to (as I have done here) so some other person - who may not
have been following the thread - can better stand your comments.
73,
Danny, K6MHE
Rick
>
>My understanding is to include the portion of the message that you are
>replying to (as I have done here)
Danny, perfection. Absolute perfection.
You de Man.
Rick
Ed Cregger
-----------
Some of us include the previous post's text because we can't remember
what we're answering unless we can refer to it while writing.
You too will grow old someday, if you live so long. <G>
Ed Cregger, NM2K
Ed Cregger
Robert Smts
>
> 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!>
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. 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.)
Bob, VE7HS
Frnak McKenney
Hi. Thanks for taking the time to respond.
On Tue, 09 Oct 2007 03:06:18 -0700, nm...@wt.net <nm...@wt.net> wrote:
>On Oct 8, 9:16 pm, Frnak McKenney
<fr...@far.from.the.madding.crowd.com> wrote:
>
>> 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.
>Sounds like it's being masked by some type of noise,
>but this could just be from the signal being very weak.
>
>If you can hear other stations ok, it probably the propagation
>more than anything. Being that you can barely hear it on a
>regular receiver seems to bear this out.
Sigh. So... there isn't some kind of cubist-wire-sculpture shape I
can bend my antenna into and magically make WWV appear? <grin!>
>Unless a noise is local, and you are trying to null it, I see no
>real advantage to using a small loop vs whatever else.
I constrained the problem by insisting on "indoor" and "small".
From your feedback, and my experience, it looks like I won't get
much further unless/until I'm willing to relax one of my
constraints.
>I would make sure you don't have any local noise. IE:
>powerline noise, etc. If you did, the loop would be a good
>antenna to null that noise as long as you can turn it.
>But if there is no local noise, and the noise you hear is
>atmospheric, then it's not going to matter much what
>you use.
I built a long-wire "antenna" last evening and I _thought_ my signal
picked up a bit... for a little while, anyway. I took a 100'
extension cord and unreeled it from the west end of the house to the
east end where the MAC-II is set up. On the floor. (Hardly a
"phased array"<grin!>, but I wanted to try _something_.)
I put the (plastic) reel with the rest of the cord up about a foot
away from my "loop", and I did seem to get a stronger signal
(translation: on the fade-ins it sounded a bit louder). I could
hear the "notes" fairly well at times and I could _almost_ make out
what was being said in the the voice segment. On the other hand,
this was somewhere around 1800, give or take an hour, and the signal
was fading in and out... it could have simply been due to
atmospheric conditions.
One good thing I learned was that I may have been tuning my antenna
incorrectly. It seems that there is a "roaring" that peaks the
GCW-1001's LED stack, but when I can distinguish the WWV tones and
maximize their loudness through the speaker I'm slightly _below_
that "roaring". In other words, I _have_ been mis-tuning, and
inadvertently helping drown WWV's signal out. Ouch. Wish I had an
accurate 10MHz signal generator; what I have is intended for audio
work and limited to about 1.5MHz.
>I've got a hunch that the propagation is just the pits for
>you right now.
Well, that's certainly a true description of what I'm experiencing
<grin!>, but I've had the MAC-II since 2004 and suffered the same
poor lock-in, and a MAC-I (GC-1000) a decade (ack!) behaved
similarly. 'Course, I used its built-in whip (something the MAC-II
lacks); I didn't build _it_ an antenna of its very own. <grin!>
>I wouldn't be surprised if you tried it in a couple of months
>and it worked ok.. If you hear it on the regular radio ok,
>the clock should too. If you can't hear it on the regular
>radio, the clock probably won't either, and there is
>probably not much you can do about it.
I was afraid of that. I suppose I could build a battery-powered RF
amplifier and stick it on the antenna, but the trick (stop me if
you've heard this one <grin!>) is to make just-the-stuff-I-want
louder. Making _everything_ louder doesn't help me.
>There should be times that it comes in fairly decent though,
>depending on time of day, etc..
>I would use what you hear on the regular receiver as to
>whether the signal is really there or not.
You're probably right. Means I have to clear off some more lab
bench space next to the MAC-II, and I should probably re-tighten the
dial cord on the Mohican and dust off its tuning capacitor plates.
<grin!>
This may wind up being a classic example of the "DIY->DYI
Transformation": a "really neat" do-it-yourself idea which started
out simply enough, but which has somehow turned into a
must-complete, spare-no-expenses Do-Yourself-In Project. <grin?>
>Propagation on most of the HF bands has been fairly
>flaky the last few months. IE: I got on 40m in the daytime
>the last time I was in OK, and it was like I was on 20m..
>Band was real stretched out, and pretty long skip zones.
>I'd miss the semi locals I'd usually talk to, and end up
>hearing stations 1000 miles away instead.
So... if I ran this really long piece of coax out to Oklahoma, then
I could pick up Fort Collins really well via skip? I've got a bunch
of A/V 75ohm stuff, and some old T-Base2 Ethernet cables; that's a
start... (Riiiight! <grin!>)
I think it's time to step back and think about what I've discovered
and learn a bit more theory; my ARRL Antenna Handbook (1991ed)
arrived in yesterday's mail, so I'll be learning from The Source.
(I sent my brother Bruce an e-mail message a few days back
explaining why antenna length mattered; it made sense at the time,
but I may have to revise it after some more reading.)
And, if I decide I need a radio-based time source before I can get a
good WWV signal, I could always hack a WWVB clock -- as long as it
had a dead LCD panel or something: I have this weird reluctance to
tear apart anything that is still working. <grin!>
Assuming, of course, that I can pick up WWV_B_ here. <grin?>
Anyway, thanks for reassuring me that my poor WWV reception really
might not be due to a poor antenna design. If I ever come up with a
Really Good Solution I'll post back here.
Frank
--
Do not follow where the path may lead. Go instead where there is
no path and leave a trail. -- Ralph Waldo Emerson
--
Geoffrey S. Mendelson
> Anyway, thanks for reassuring me that my poor WWV reception really
> might not be due to a poor antenna design. If I ever come up with a
> Really Good Solution I'll post back here.
What would help you is an outdoor active antenna. For a start look at MFJ's.
It's a metal box with an amplifier in it, and a whip antenna. It uses a
small box at the receiver end to pass DC up the coax to power it.
Placing it outside would help. Placing it outside and away from noise
sources, or on the roof would help more. A whip antenna is used because
it's a cheap commerical off-the-shelf (COTS) item. It could be replaced
with a thin wire. The coax could be replaced with a run of (more expensive)
mini-coax. This would make it easier to hide and you may be able to use it.
If you are handy with building things, there are lots of designs for similar
devices, the easiest is a single MMIC type amplfier. It may be more difficult
to actually do as they are very sensitive to static.
If all you have is a window, a loop around it would do. If it has a metal frame,
and all 4 sides are connected to each other, you can try using it as a loop.
If not, thin wire held up by transparent tape, or that metal tape used by
alarm systems would work.
Geoff.
--
Geoffrey S. Mendelson, Jerusalem, Israel g...@mendelson.com N3OWJ/4X1GM
IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/
Richard Clark
<fr...@far.from.the.madding.crowd.com> 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?
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."
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.
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. 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).
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).
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?"
73's
Richard Clark, KB7QHC
Cecil Moore
> You too will grow old someday, ...
... and forget to click the send button only once? :-)
--
73, Cecil http://www.w5dxp.com
ecregger
genetics predispose me to lean in that direction. <G>
Ed, NM2K
"keithm" <vk1...@yahoo.com> wrote in message
news:470bf852$1...@dnews.tpgi.com.au...
ecregger
New computer, new software and fasciculations. What a combo!
Ed, NM2K
"Cecil Moore" <nos...@w5dxp.com> wrote in message
news:vc9Pi.2123$lE2...@newssvr22.news.prodigy.net...
Frnak McKenney
Thanks for joining in.
On Tue, 09 Oct 2007 12:00:44 -0700, Denny <k8...@mailblocks.com> wrote:
> On Oct 9, 6:06 am, n...@wt.net wrote:
>> On Oct 8, 9:16 pm, Frnak McKenney
>>
>> <fr...@far.from.the.madding.crowd.com> wrote:
>>
>> > 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 ...
--snip--
>> Sounds like it's being masked by some type of noise,
>> but this could just be from the signal being very weak.
>> If you can hear other stations ok, it probably the propagation
>> more than anything. Being that you can barely hear it on a
>> regular receiver seems to bear this out.
--snip--
>Even with my antennas on a 150 foot tower there are times of day
>when WWV at 10 megacycles is not audible... This is just the way
>the daily propagation cycle is at 30 meters.
Grumph! (but the 150' tower impresses me! <grin!>)
>My best advice is to put up a dipole for 30 meters, even if you have
>to bend the ends to make it fit your space...
Well, a halfwave 30m dipole comes out to... 49 feet?
I went back and checked the NIST "Time and Frequency Services" PDF
file. According to this, WWV-10MHz comes off "half-wave vertical
antennas that radiate omnidirectional patterns."
Maybe I can wind my two 24.5' wires into vertical-axis helices?
<grin!>
> ... A horizontal dipole
>being balanced picks up less vertically polarized noise than
>vertical antennas... Getting the wire outdoors will help also...
>You are likely picking up lots of humm and buzz inside the building
>from various electrical and electronic devices...
Not sure what you could be referring to... other than the three
computers, 25" monitor, printer, Atmel AVR development board (8MHz
clock), flourescent desk lamp, and overhead I-look-like-an-
incandescent flourescent helix... all within 3 feet of the antenna
and clock. <grin!>
>The other issue is whether your clock is actually able to synch with
>the WWV signal... You may have a defect in the clock... It would
>seem that 4 or 5 bars should have done the trick...
If it _never_ sync-ed I'd be strongly leaning toward your way of
thinking. In the past, with a "dangling wire" antenna, it has
occasionally taken months to get in sync; with my two loops I've
managed to get it in sync three times (IIRC) in the past two weeks.
(If I were still rational on the subject, I'd just admit that I
_have_ seen improvement -- all the way from "completely
undependable" to "approaching acceptable" -- even if it's not quite
as much as I'd hoped for.)
Thanks again.
Frank
--
The cure for boredom is curiosity. There is no cure for
curiosity. --Ellen Parr
--
Frnak McKenney
Thanks for the comments.
Exactly. It's an LED bargraph driven by pin 9 on the TDA1072A chip;
according to the data sheet that's the "Field strength indicator
output", a log-scale output driven by the internal AGC amplifier.
I got a clearer WWV signal the other day and was able to re-tune my
antenna. It turns out that the "loud signal" I was tuning to wasn't
WWV, just some random RF I was overloading my poor clock with. The
bargraph now sits down at 1-2 LEDs most of the time, although I did
see a "bursty" period this morning where it went up to 3-5 LEDs.
The WWV audio was coming and going on about a five-second interval:
louder (almost clear), then softer (almost to disappearing), then
louder again. "Wow", so to speak. <grin!>
Ah, well. Maybe in my Copious Free Time I'll replace the MAC-II's
87C52 with something I understand, like an AVR, and program it _my_
way. (Oh. Then _I_ get the support calls. ... Ack!)
Frank
--
"Curiosity is one of the permanent and certain characteristics
of a vigorous mind. -- Dr. Samuel Johnson
--
Frnak McKenney
On Tue, 09 Oct 2007 22:22:07 GMT, Rick <rick...@hotmail.com> wrote:
>I am in New Jersey. Propagation from Colorado to here is probably
>similar to Virginia.
>
>This morning, Tues, 10/9, I listened to WWV on 10 MHz with the 4
>antennas I have at my disposal to see what kind of signal level I
>get.
>
>My antennas are 80 meter and 40 meter dipoles, a 20 meter yagi and a
>30 meter dipole, all at about 50 feet.
>
>On the first 3 antennas WWV runs about S6-9, and on the 30 meter
>dipole it is 10-20 db over 9.
>
>This evening, 6 pm, the first 3 antennas haul WWV in at S9 and the
>30 m dipole has it at a rock solid 30 over.
>
>So I agree with the advice you got to string up some kind of dipole
>and throw out that loop, there is plenty of signal, you just have to
>go get it.
Okay, Rick, you've convinced me. The heck with Oklahoma! (Sorry,
MH.) I'm running my antenna line to New Jersey! <grin!>
If I've sounded reluctant to put an antenna up in the attic, it's
partly that I'm reluctant to drill holes through walls and ceilings
to run the antenna cable without at least _some_ assurance that the
results would be worth it... and partly that I'm just reluctant to
drill holes, spackle, and paint. I suppose I could run the line
through the attic hatch door rim and down the hallway ceiling...
>PS may I throw in a little commercial for my pet peeve? As you read
>this did you notice that I did not include any text from previous
>posts? Did you miss it?
Well, yes. The original post was a bit long and should have been
trimmed as appropriate, but a couple of lines (see above) would have
made things a little clearer to some poor soul who ran across the
post in isolation.
In any case, thanks for the feedback. Let's see... 300 miles of
10-Base2 cable...
Frank
--
"Our souls may lose their peace and even disturb other people's,
if we are always criticizing trivial actions -- which often are
not real defects at all, but we construe them wrongly through
our ignorance of their motives..." -- Teresa of Avila
--
Frnak McKenney
Robert,
Thank you for joining in.
On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts <b...@rsmits.ca> 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.)
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.
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
--
Geoffrey S. Mendelson
> Not sure what you could be referring to... other than the three
> computers, 25" monitor, printer, Atmel AVR development board (8MHz
> clock), flourescent desk lamp, and overhead I-look-like-an-
> incandescent flourescent helix... all within 3 feet of the antenna
> and clock. <grin!>
With all that hardware, wouldn't NTP (internet time) be a better option? Or if
you are not too deep into steel and concrete a GPS receiver?
Jon Kåre Hellan
> Frnak McKenney wrote:
>> Not sure what you could be referring to... other than the three
>> computers, 25" monitor, printer, Atmel AVR development board (8MHz
>> clock), flourescent desk lamp, and overhead I-look-like-an-
>> incandescent flourescent helix... all within 3 feet of the antenna
>> and clock. <grin!>
>
> With all that hardware, wouldn't NTP (internet time) be a better option? Or if
> you are not too deep into steel and concrete a GPS receiver?
Sounds like OP is really interested in bringing his father's WWV clock
to life.
But if correct time is the objective, ntp is easy. Over the internet
it is supposed to be accurate to tens of milliseconds. On our network,
1 - 5 ms is typical, but I suppose it is quite well behaved.
A GPS intended for timing gives better than 100 ms accuracy off the
cable. It can discipline ntp on a computer to typically 1 - 10 us
accuracy.
It looks like the Garmin GPS 18lvc us the timing GPS of choice for
hobbyists. You need a pulse per second (PPS) signal. There are other
GPS dongles which don't have PPS on the plug, but you can find the signal on
the circuit board.
More info at TAPR: "http://www.tapr.org". See also the timekeepers
mailing list archive:
"http://fortytwo.ch/mailman/pipermail/timekeepers/".
John Ackerman N8UR is an authority on timing and ham radio.
But again - this is probably not what you're really after :-)
73
LA4RT Jon
Frnak McKenney
Geoff.,
Thanks for adding your comments.
On Wed, 10 Oct 2007 12:34:08 +0000 (UTC), Geoffrey S. Mendelson <g...@mendelson.com> wrote:
> Frnak McKenney wrote:
>> Anyway, thanks for reassuring me that my poor WWV reception really
>> might not be due to a poor antenna design. If I ever come up with a
>> Really Good Solution I'll post back here.
>
>What would help you is an outdoor active antenna. For a start look at MFJ's.
>It's a metal box with an amplifier in it, and a whip antenna. It uses a
>small box at the receiver end to pass DC up the coax to power it.
I looked around and found http://www.mfjenterprises.com/
Their MFJ-1020C looks interesting.
For now, though, I think I want to concentrate on getting as much as
I can from "bare wire".
>Placing it outside would help. Placing it outside and away from noise
>sources, or on the roof would help more. A whip antenna is used because
>it's a cheap commerical off-the-shelf (COTS) item. It could be replaced
>with a thin wire. The coax could be replaced with a run of (more expensive)
>mini-coax. This would make it easier to hide and you may be able to use it.
The old GC-1000 had a built-in whip; the GCW-1001 doesn't even have
that... just a threaded 50ohm coax connector.
>If you are handy with building things, there are lots of designs for similar
>devices, the easiest is a single MMIC type amplfier. It may be more difficult
>to actually do as they are very sensitive to static.
I'll see what I can find. Thanks for the keyword.
>If all you have is a window, a loop around it would do. If it has a metal frame,
>and all 4 sides are connected to each other, you can try using it as a loop.
>If not, thin wire held up by transparent tape, or that metal tape used by
>alarm systems would work.
I like that -- there's a window/storm window about 4' away facing
east.
As to your other post...
On Thu, 11 Oct 2007 00:09:08 +0000 (UTC), Geoffrey S. Mendelson <g...@mendelson.com> wrote:
> Frnak McKenney wrote:
>> Not sure what you could be referring to... other than the three
>> computers, 25" monitor, printer, Atmel AVR development board (8MHz
>> clock), flourescent desk lamp, and overhead I-look-like-an-
>> incandescent flourescent helix... all within 3 feet of the antenna
>> and clock. <grin!>
>
> With all that hardware, wouldn't NTP (internet time) be a better option? Or if
> you are not too deep into steel and concrete a GPS receiver?
Both of these would be excellent ways of keeping an accurate time
source at hand, and it would be perfectly reasonable to assume that
that was what I was trying to accomplish. I apologize for the lack
of clarity; let me back up a bit.
When I started out, I simply wanted to learn about how antennas
worked, how an EM wave made it from point A to point B in a way that
would let me... how do I say it? "Fit all the pieces together"?
And, as part of that, I was trying to see how well I could take
basic principles and make-with-my-hands something that demonstrated
that (a) I had understood correctly and that (b) I could actually
build something that worked.
I'd had the MAC-II around for more than three years, sitting in the
background and mildly annoying me because every power hiccup reset
the display to its startup "not SEt" text and it could be months
before it was running again. Mildly annoying, but I didn't have a
serious need to know exactly what time it was.
It occurred to me (eventually <grin!>) that building An Antenna that
made the MAC-II a more dependable TOD source would be a Really Good
Test Of My Antenna Building Skills... sort of like learning to swim
by jumping off a dock. As silly as that may sound, when you're
venturing into unfamiliar territory (and as a consultant, I do a lot
of that) there's always a new kind of swimming to learn, and there
always seems to be a dock you eventually wind up jumping off if
you're going to learn very much.
So if it looks like my "stroke" is extremely poor at this point,
well, that's likely; on the other hand, I'm not exactly drowning,
either. I'm waving my hands in all directions, learning what seems
to make me move and what doesn't, and listening to helpful comments
from the Peanut Gallery on the dock. Youse guys. <grin!>
Throwing money at the prob... er, "adopting a pre-packaged
solution" <grin!> gets me the Time Of Day -- precise, reliable,
hopefully accurate -- but it doesn't help me learn how to swim...
er, build antennas. And, besides, my budget is a bit tight at this
point, which means no new test equipment... I don't suppose anyone
knows how to generate an accurate 10MHz alignment signal by rubbing
a 1.5MHz Function Generator and a Tek465 'scope together? <grin!>
Okay... I'm sure that's more than most (all?) of you wanted to
know. Please feel free to recycle this post in an environmentally
acceptable manner. <grin!>
Frank
--
"...in the end, it's simply about telling stories, in conditions
that allow me to do my best work. 'The exercise of vital powers
along lines of excellence in a life affording them scope,' to
quote the Greek definition of happiness."
-- J.M. Straczynski ("Babylon 5") on scriptwriting
Frnak McKenney
> On Tue, 09 Oct 2007 02:16:37 -0000, Frnak McKenney
><fr...@far.from.the.madding.crowd.com> 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)
--
Geoffrey S. Mendelson
> Sounds like OP is really interested in bringing his father's WWV clock
> to life.
A totaly different approach occured to me when I found that there
were no time signals readable here. WWV, CHU (if it is still around)
and their European equivalents never seem to be readable here.
The 60 kHz WWV coverage map puts me almost a 1000 miles beyond the edge
of their "weak but occasionaly useable" (my words) propigation. Someone
on another list claims his clock syncs about 30 miles north and at sea
level, but he never answered a question of too what and how often. :-(
What I thought of doing was sort of an radio to NTP interface. Access
the time information via NTP and then modulate a signal with it. 10 mHz
would be more difficult, you might be able to get 60kHz with a sound
card, or something like it. Obviously, you would not need or want
anything very strong and you may be able to couple it directly to the
antenna socket.
I know it would be cheating, but it seems like a fun hardware/software
project. You probably could get a magazine article published about it,
and maybe even sell enough boards to to offset the cost of making them.
Roy Lewallen
> . . .
> 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.
> I definitely think I'm missing something, but then, I haven't really
> made it that far into the Antenna Handbook.
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.
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.
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. 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.
Roy Lewallen, W7EL
Richard Clark
<fr...@far.from.the.madding.crowd.com> 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.
Jim Lux
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.
Jim Lux
>
> 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.
Geoffrey S. Mendelson
> 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.
Robert Smts
>
> Robert,
>
> Thank you for joining in.
>
> On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts <b...@rsmits.ca> 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.
K7ITM
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
Tim Shoppa
> 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!>
>
> 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!>
>
>
> ----------
>
> 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 tape<grin!>. 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
> 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.
>
> "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.
Jimmie D
"Tim Shoppa" <sho...@trailing-edge.com> wrote in message
news:1192321621.5...@q5g2000prf.googlegroups.com...
I work on a weather radar that used time data from a WWV rx. the rx was a
scanning receiver that would automaticaly switch frequencies when a lock was
lost. Sometimes it would go for days without syncing. This got to the point
where the WWV rx was replaced with a GPS rx. Problem solved.
Jimmie
Frnak McKenney
> 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.
>> . . .
> 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-II<grin!>. 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
Frnak McKenney
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
Frnak McKenney
> Frnak McKenney wrote:
--snip--
>> 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: ĸNever attribute to malice that which can
be adequately explained by stupidity.ĸ
Frnak McKenney
>> On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts <b...@rsmits.ca> 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.
>>
>>>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.
>> 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"
Frnak McKenney
Thanks for joining in.
On Sat, 13 Oct 2007 17:27:01 -0700, Tim Shoppa <sho...@trailing-edge.com> 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
Frnak McKenney
> On Oct 11, 5:12 am, Frnak McKenney
><fr...@far.from.the.madding.crowd.com> wrote:
>> On Wed, 10 Oct 2007 10:19:49 -0700, Richard Clark <kb7...@comcast.net> wrote:
>> > On Tue, 09 Oct 2007 02:16:37 -0000, Frnak McKenney
>> ><fr...@far.from.the.madding.crowd.com> wrote:
>>
>> >>Am I asking too much?
>>
>> >Hi Frnak,
>>
>> >Judging by the questions and responses, I would have to say "Yes."
> 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
Jimmie D
>
> 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!>)
Locking in 8 times in 2 days is probably pretty good
Not sure what you are tuning but best signal to noise ratio is not always
synchronous with greatest gain.
Jimmie
Roy Lewallen
>
> 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.
Not exactly. The wave will still be nearly planar, that is, the
orientation of the E field will be in a plane which is perpendicular to
a line between you and the effective point in the ionosphere where the
wave is coming from. But the E field can be rotated in any direction
within that plane. So you want your antenna to have substantial gain in
the direction of Fort Collins and at the elevation angle of the arriving
signal (the latter will vary somewhat). But the polarization is a crap
shoot.
>
> Hm. Wonder if anyone has built an antenna whose polarization shifts
> to "best match" the incoming signal? (No, not _this_ weekend!
> <grin>!)
Sure, many. Polarization diversity is an old idea. In a previous life I
worked on a phased array radar (cf.
http://www.globalsecurity.org/space/systems/an-fps-85.htm). The
transmitters have only horizontal dipole antennas so they transmit only
a horizontally polarized signal. But each of the 4660 receivers has two
dipole antennas, one vertical and one horizontal. This gives the
receiver information about whether an object is tumbling or rotating,
for example, by the way the polarization is shifted by the reflection.
Amateurs would have to use polarization diversity at both ends of a
contact, since there's no way to predict which polarization would be
best at a given moment for transmitting to a fixed polarization
receiving antenna.
>
> 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!>)
Be cautious in generalizing about your accomplishments. Day-to-day
propagation differences can be extreme. Unless you can do an immediate
A-B comparison or take many, many measurements over a very long period
of time, there's no way to distinguish between antenna and propagation
changes.
> . . .
> 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.
The whole objective to receiving system design is to maximize the
signal/noise ratio, where "noise" is "everything you don't want". Making
both larger by the same amount accomplishes nothing you can't do with a
simple amplifier.
>. . .
Roy Lewallen, W7EL
Roy Lewallen
>
> 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.
You're following it correctly only if you're using elements which are no
longer than about 5/4 wavelength. The direction of maximum gain isn't
longer perpendicular to the wire if the wire is longer. This is covered
very will in the _Antenna Book_.
>
> 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!>
As I mentioned in my other recent posting, there's no way for you to tell.
> 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!>
You can duplicate the plots for the kinds of simple antennas you're
dealing with, with the free demo version of EZNEC available from
http://eznec.com. In the View Antenna display, select View/Objects, then
check the "2D Display" box. Then you'll see a 2D plot superimposed on
the view of the antenna, to show how the two are related. When viewing a
3D plot, the View Antenna display rotates along with the 3D pattern, so
you can see how they're related if you keep both windows open.
Roy Lewallen, W7EL
Jimmie D
"Roy Lewallen" <w7...@eznec.com> wrote in message
news:13h5cif...@corp.supernews.com...
Normally WWV rxceivers have there antennas tilted at 45 degrees in an
attempt at polarity diversity. Im not sure if the department store clocks do
anything like this. The only one I have ever seen used a loopstic antenna.
The professional grade rx I am familar with that was used to set the time on
a computer used a contuously loaded dipole on an outside mount with 45
degree polarization.
Jimmie
Roy Lewallen
>
> Normally WWV rxceivers have there antennas tilted at 45 degrees in an
> attempt at polarity diversity. Im not sure if the department store clocks do
> anything like this. The only one I have ever seen used a loopstic antenna.
> The professional grade rx I am familar with that was used to set the time on
> a computer used a contuously loaded dipole on an outside mount with 45
> degree polarization.
*Chuckle*
Tilting would work fine if an incoming wave couldn't have any
polarization except vertical or horizontal. But it can -- it can be at
any angle. So it doesn't matter how you tilt the antenna, the
probability of the incoming wave's polarization being aligned with it,
at right angles to it, or having any other relationship to it, is the
same as for any other tilt. (For simplicity, I'm ignoring the fact that
the probability of a wave arriving with a particular polarization angle
varies with the elevation angle when ground reflection is involved --
which it virtually always is with HF skip propagation.)
A 45 degree tilt might be useful if you were receiving a line-of-sight
signal which might come from either a horizontally or vertically
polarized antenna. But even then, if the transmitter's antenna was
tilted 45 degrees the other way, you'd be cross polarized and in the
same boat as if one were horizontal and the other vertical.
One solution is a circularly polarized antenna, which responds equally
well to linearly polarized waves at any polarization angle. However,
there are a few problems involved with that. First, it's difficult to
get circular polarization from an antenna when ground reflections are
involved. Second, most of the simpler circularly polarized antennas like
a turnstile are circularly polarized in only one or two directions. For
that antenna, for example, the polarization is elliptical at other
azimuths and elevation angles, and linear to the side. And finally, it
seems to me possible that ionospheric propagation can cause a received
signal to be elliptically polarized even though it's linear when it's
transmitted. I don't know if this is the case, but if it is, it
guarantees that even a circularly polarized antenna would experience
fading from polarization shift. Of course, even if you completely
eliminate fading from polarization shift, you still have to deal with
multipath.
Roy Lewallen, W7EL
art
snip
Doesn't a circular polarized antenna lose 3 db when responding to
linearly polarised waves?
IF that is the case it doesn't "respond equally as well"
As far as 45 degrees goes that is not correct for maximum response,
more likely a 45 +- 11 degrees would supply the most gain.
Kraus refers to this empirical tilt action in his chaptor on helix
antennas
which I now see as the summation of all radiator vectors when
expanding Gauss.
Art
Jimmie D
> Jimmie D wrote:
>>
>> Normally WWV rxceivers have there antennas tilted at 45 degrees in an
>> attempt at polarity diversity. Im not sure if the department store clocks
>> do anything like this. The only one I have ever seen used a loopstic
>> antenna. The professional grade rx I am familar with that was used to set
>> the time on a computer used a contuously loaded dipole on an outside
>> mount with 45 degree polarization.
>
> *Chuckle*
>
> Tilting would work fine if an incoming wave couldn't have any polarization
> except vertical or horizontal. But it can -- it can be at any angle. So it
> doesn't matter how you tilt the antenna, the probability of the incoming
> wave's polarization being aligned with it, at right angles to it, or
> having any other relationship to it, is the same as for any other tilt.
> (For simplicity, I'm ignoring the fact that the probability of a wave
> arriving with a particular polarization angle varies with the elevation
> angle when ground reflection is involved --
> which it virtually always is with HF skip propagation.)
>
> A 45 degree tilt might be useful if you were receiving a line-of-sight
> signal which might come from either a horizontally or vertically polarized
> antenna. But even then, if the transmitter's antenna was tilted 45 degrees
> the other way, you'd be cross polarized and in the same boat as if one
> were horizontal and the other vertical.
Like I said it was an attempt, reccomended by the manufacturer of the rx no
less. I always got a chuckle out of it too, every time I saw it. A member of
our engineering staff went into a long spiel about why it should be mounted
at 45 degrees. Thats when I asked him what college he attended because I
didnt want my kids going there. A few days later he sent me an email
apologizing and admitted I was right that it really doesnt matter which way
its turned.
Jimmie
Jim Lux
>
>
> Hm. Wonder if anyone has built an antenna whose polarization shifts
> to "best match" the incoming signal? (No, not _this_ weekend!
> <grin>!)
Yes, such things have been built. There are some French researchers who
built an adaptive combiner that combined multiple polarizations, and
also did the processing to allow using both the ordinary and
extraordinary ray, and substantially improved link reliability on 1000km
skywave paths.
>
> 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"?).
UTC is not an acronym. It's a madeup identifier that matches neither
the English (Coordinated Universal Time) or the French (T U C.. I won't
even attempt to figure out what it is..).
These sorts of international metrology things have all sorts of such
negotiated compromises in them, stemming all the way back to the Prime
Meridian being in Greenwich, but measuring in meters.
Richard Clark
wrote:
>> hear the tocks fairly clearly and even understand the voice. (Who
>> knew the announcer's phrase for UTC "Coordinated Universal Time"?).
>
>UTC is not an acronym. It's a madeup identifier that matches neither
>the English (Coordinated Universal Time) or the French (T U C.. I won't
>even attempt to figure out what it is..).
Hi All,
In fact, UTC is an acronym (already anticipated by Frnak and
explicitly stated every minute). It is but one of several, this one
being rather genericized (because any longer would force a lot of
talking, and minute passes by pretty quickly). The others would
include: UTC(NIST), UT1; and the academic UT0, and UT2.
The reason for the initials order is that there is an hidden comma.
Universal Time, Coordinated. Wikipedia reports this as an erroneous
expansion, but Wikipedia wasn't there in my Metrology classes (a
couple dozen miles from NBS) where we worked with these NBS standards.
It wasn't there when (1974) I performed the second leap second on my
Cesium Beam Standard which was calibrated through WWVB (taking about
half an hour, part of which was waiting during the roughly 15 minute
intervals between TOCs). My antenna was so far away (on the fantail
of the ship in another "time zone"), that I had to slip the time by
100nS.
Knowing that Arthur only reads his own threads, I won't have to
anticipate his rejection of the following efficiency reports for a
non-gaussian antenna. From NIST (the people who know efficiency)
about their 60KHz antenna system:
"Each antenna is a top loaded monopole consisting of
four 122-m towers arranged in a diamond shape.
A system of cables, often called a capacitance hat or
top hat, is suspended between the four towers.
This top hat is electrically isolated from the towers,
and is electrically connected to a downlead suspended
from the center of the top hat. The downlead serves
as the radiating element.
"Ideally, an efficient antenna system requires a
radiating element that is at least one-quarter wavelength
long. At 60 kHz, this becomes difficult. The wavelength is
5000 m, so a one-quarter wavelength antenna would be
1250 m tall, or about 10 times the height of the WWVB
antenna towers. As a compromise, some of the missing
length was added horizontally to the top hats of this
vertical dipole, and the downlead of each antenna is
terminated at its own helix house under the top hats.
Each helix house contains a large inductor to cancel
the capacitance of the short antenna and a
variometer (variable inductor) to tune the antenna
system.
"Using two transmitters and two antennas allows the
station to be more efficient. As mentioned earlier, the
WWVB antennas are physically much smaller than
one quarter wavelength. As the length of a vertical
radiator becomes shorter compared to wavelength,
the efficiency of the antenna goes down. In other words,
it requires more and more transmitter power to increase
the effective radiated power. The north antenna system
at WWVB has an efficiency of about 50.6%, and the
south antenna has an efficiency of about 57.5%.
However, the combined efficiency of the two antennas
is about 65%. As a result, each transmitter only has to
produce a forward power of about 38 kW for WWVB to
produce its effective radiated power of 50 kW."
Gene Fuller
The NIST folks could probably increase the efficiency to greater than
90% if they dug a large pit to temporarily store the decaying electrons.
All of those dying electrons lying on the ground tend to discourage the
active electrons from working as hard as they could.
The efficiency could be raised to nearly 100% if the two helices were
wound in opposite directions. That would provide the best shot at
equilibrium.
73,
Gene
W4SZ
Tim Shoppa
Don't know about WWV in particular, but this past weekend on the ham
bands there was an obvious uptick in propogation conditions. The MUF
was up enough that I heard several pileups on 15 meters and 40 and 30
Meters were more hopping than usual in mid-day/early evening.
Tim.
Richard Clark
wrote:
>> However, the combined efficiency of the two antennas
>> is about 65%. As a result, each transmitter only has to
>> produce a forward power of about 38 kW for WWVB to
>> produce its effective radiated power of 50 kW."
>
>The NIST folks could probably increase the efficiency to greater than
>90% if they dug a large pit to temporarily store the decaying electrons.
>All of those dying electrons lying on the ground tend to discourage the
>active electrons from working as hard as they could.
>
>The efficiency could be raised to nearly 100% if the two helices were
>wound in opposite directions. That would provide the best shot at
>equilibrium.
Hi Gene,
You shave points too close. They could achieve 130% efficiency if
they simply tapped into the current return on the inside of the wire.
Arthur's 3dB here and 3dB there, if you use enough wire, then you are
beginning to talk about GAIN!
Also, Fort Collins is a higher altitude than Podunk Illinois, so
impedance is less than 377 Ohms too! High gain, maybe 129% efficient.
***** irony mode off ********
Load resistance seen by the transmitters is roughly 0.85 Ohm
transformed to 50 Ohms.
Jim Lux
> On Mon, 15 Oct 2007 09:06:49 -0700, Jim Lux <james...@jpl.nasa.gov>
> wrote:
>
>
>>>hear the tocks fairly clearly and even understand the voice. (Who
>>>knew the announcer's phrase for UTC "Coordinated Universal Time"?).
>>
>>UTC is not an acronym. It's a madeup identifier that matches neither
>>the English (Coordinated Universal Time) or the French (T U C.. I won't
>>even attempt to figure out what it is..).
>
>
> Hi All,
>
> In fact, UTC is an acronym (already anticipated by Frnak and
> explicitly stated every minute). It is but one of several, this one
> being rather genericized (because any longer would force a lot of
> talking, and minute passes by pretty quickly). The others would
> include: UTC(NIST), UT1; and the academic UT0, and UT2.
Au contraire...
while UT1, UT0, and UT2 are, in fact, acronyms of a sort, primarily
based on astronomical time, this is not the case for UTC..
the coordination has to do with matching up UT and TAI (atomic) time..
all those leap seconds, etc.
As one online source puts it:
The (Bureau Internationale de l'Heure) BIH was charged with the task of
monitoring and maintaining the program and introduced the term Temps
Universel Coordinné or Coordinated Universal Time for the coordinated
time scale in 1964.
BIH is the predecessor of the current BIPM (who seem to have a problem
with the standard kilo losing mass) http://www.bipm.org/
or, for more information:
http://syrte.obspm.fr/journees2004/PDF/Arias2.pdf
which says: The name of Coordinated Universal Time UTC appeared in CCIR
documents in the early 60s.
One might also seek a paper from 1964, by Guinot. (who was a time guy at
the BIH back then)
A paper by Dennis McCarthy at USNO on "Evolution of Time Scales"
mentions in Section 6 that: the term "Coordinated Universal Time" was
introduced in the 1950s to designate a time scale in which the
adjustments to quartz crystal clocks were coordinated among
participating laboratories in the US and UK.
A more recent paper by Guinot says:
"Until 1965, the more or less common scale for emission of signals,
which had received spontaneously the name of Coordinated Universal Time
(UTC), had not been strictly defined."
>
> The reason for the initials order is that there is an hidden comma.
> Universal Time, Coordinated.
Funny, thing, though, that if one searches the literature of the time
for that particular sequence of words, it never occurs..
Given that Coordinated Universal Time existed well before UTC, I suspect
that the comma thing is a post hoc creation.
Roy Lewallen
> Richard Clark wrote:
>>
>> The reason for the initials order is that there is an hidden comma.
>> Universal Time, Coordinated.
>
> Funny, thing, though, that if one searches the literature of the time
> for that particular sequence of words, it never occurs..
>
> Given that Coordinated Universal Time existed well before UTC, I suspect
> that the comma thing is a post hoc creation.
Not everything is English, folks. UTC is for Universale Temps
Coordinaire. No comma is implied or needed because in French, an
adjective follows the word it modifies, with very few exceptions.
Roy Lewallen, W7EL
Richard Clark
wrote:
>> The reason for the initials order is that there is an hidden comma.
>> Universal Time, Coordinated.
>
>Funny, thing, though, that if one searches the literature of the time
>for that particular sequence of words, it never occurs..
You are writing to one who read the literature - at that time. My
experience is not from arm chair history 101. UTC was arrived at as a
compromise between the French (naturally) and the "rest of the world"
(what else?). My bona fides are documented too: two diplomas from the
only Metrology school in the United States - at that time. Time in
service: with training in calibration and maintenance of the HP Cesium
Beam standard, and VLF subsystem - at that time. I also lived through
the great switch-over from cycles to hertz, and GMT to Zulu - at that
time (or slightly before... I wasn't looking at the clock that day).
I can flood this page with 250 references that employ the strict usage
of "Universal Time Coordinated" "Universal Time, Coordinated" or
"Universal Time (Coordinated)" and specifically 35 of them printed
before 1967. With google it takes more time to cut and paste than
actually find them. A short list includes:
Title 15 1971 Code of Federal Regulations By United States Office of
the Federal Register (1971)
"... the Universal Time Coordinated (UTC)
system' as recommended by the Bureau
International de l'Heure (bill).
The carrier offset currently is minus 300 ..."
Meteorological and Geoastrophysical Abstracts By American
Meteorological Society (1960)
International Aerospace Abstracts
By American Institute of Aeronautics and Astronautics Technical
Information Service, United States National Aeronautics and Space
Administration, Institute of the Aerospace Sciences Technical
Information Service (1961)
Proceedings of the IEEE. By Institute of Electrical and Electronics
Engineers (1963)
Scientific and Technical Aerospace Reports
By United States. National Aeronautics and Space Administration.
Scientific and Technical Information Division, United States National
Aeronautics and Space Administration. Scientific and Technical
Information Office, NASA Scientific and Technical Information
Facility, United States National Aeronautics and Space Administration.
Scientific and Technical Information Branch, NASA Center for AeroSpace
Information, United States. National Aeronautics and Space
Administration. Office of Scientific and Technical Information (1963)
Navigation Dictionary By United States Naval Oceanographic Office
(1969)
New Scientist By EBSCO Publishing (1971)
Basic Electronic Instrument Handbook By Clyde F. Coombs (1972)
Newer titles:
UPI Style Book & Guide to Newswriting By Harold Martin, Bruce Cook
Dictionnaire des sciences et techniques du pétrole By Magdeleine
Moureau, Gerald Brace
Acronyms, Initialisms & Abbreviations Dictionary By Ellen T. Crowley
GPS Satellite Surveying By Alfred Leick
All of 10 minutes (give or take).
Familiar with any service acronyms like BFD?
Jim Lux
> On Mon, 15 Oct 2007 16:43:53 -0700, Jim Lux <james...@jpl.nasa.gov>
> wrote:
>
>
>>>The reason for the initials order is that there is an hidden comma.
>>>Universal Time, Coordinated.
>>
>>Funny, thing, though, that if one searches the literature of the time
>>for that particular sequence of words, it never occurs..
>
>
> You are writing to one who read the literature - at that time. My
> experience is not from arm chair history 101. UTC was arrived at as a
> compromise between the French (naturally) and the "rest of the world"
> (what else?). My bona fides are documented too: two diplomas from the
> only Metrology school in the United States - at that time. Time in
> service: with training in calibration and maintenance of the HP Cesium
> Beam standard, and VLF subsystem - at that time. I also lived through
> the great switch-over from cycles to hertz, and GMT to Zulu - at that
> time (or slightly before... I wasn't looking at the clock that day).
>
> I can flood this page with 250 references that employ the strict usage
> of "Universal Time Coordinated" "Universal Time, Coordinated" or
> "Universal Time (Coordinated)" and specifically 35 of them printed
> before 1967. With google it takes more time to cut and paste than
> actually find them. A short list includes:
I defer to your googling skills..
I tried the search above, turned up nothing (other than obvious
derivative works like the wikipedia entry) in the first 10 pages of
hits, and took the references from BIH as definitive.
(I also tried WebOfScience, etc.)
I also didn't trust references from post, say, 1970, because by then,
you'd have seen definitions created by "back-formation" (i.e. finding
words that match the acronym.. which, when it comes right down to it, is
how lots of acronyms get created in the first place)
>
> Proceedings of the IEEE. By Institute of Electrical and Electronics
> Engineers (1963)
Looked for this one, and couldn't find it. Which month?
The oldest paper in Proceedings that has the term "universal time" in it
is Hudson's paper in June 1967, p815 ff
It refers to CCIR recommendation 374.1 and CCIR reports 365 (in 1965)
and 366 in connection with the discussion of UTC and SAT, but doesn't
actually define UTC, nor does it provide a reference to a defining
source. (other than a "in press" paper by Cord and Hudson, "Some trends
in UT")
Smith's paper in the Proceedings in May 1972, seems to provide a fairly
definitive history (page 481) citing the CCIR Study Group 7 Interim
meeting in 1962 and CCIR Xth Plenary Assembly in 1963 (Vol III, p193),
as well as an earlier recommendation of the IAU XIth General Assembly in
1961 ("Resolutions adopted by comm. 31" Trans IAU, Vol XI B(1961), p 329)
>
> Familiar with any service acronyms like BFD?
Sure.. but this is really a Tiny FD..
But, I really would like to find a definitive printed reference, as
opposed to the recollections of folks present at the birth. Think of it
as something akin to the citations in the OED. Once you have that
golden reference, discussions like this one end in a hurry.
It's also because I'm casually interested in the obscure history of
things like this. A co-worker asked the other day, "Why is wine in 750ml
bottles, and when did it change from whatever they used before the
metric system existed?"... turns out it's actually a fairly recent
change. Another interesting discussion had to do with the use of
"transfer standards" when building the pyramids in Egypt: failure to
calibrate your working cubit against the standard within the calibration
interval was punishable by death. No "For indication only, out of cal"
stickers there, apparently. {I'm also looking for a definitive source
for that story...presumably it would be in hieroglypics.. as one can
imagine, though, there's a lot of very odd stuff out there when you
bring up anything ancient Egypt related)
Jim, W6RMK
Owen Duffy
> Not everything is English, folks. UTC is for Universale Temps
> Coordinaire. No comma is implied or needed because in French, an
> adjective follows the word it modifies, with very few exceptions.
Then wouldn't it be Temps Universale Coordinaire?
Owen
Frnak McKenney
> Frnak McKenney wrote:
>>
>> 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.
>
> Not exactly. The wave will still be nearly planar, that is, the
> orientation of the E field will be in a plane which is perpendicular to
> a line between you and the effective point in the ionosphere where the
> wave is coming from. But the E field can be rotated in any direction
> within that plane. So you want your antenna to have substantial gain in
> the direction of Fort Collins and at the elevation angle of the arriving
> signal (the latter will vary somewhat). But the polarization is a crap
> shoot.
So... I'd need a really crappy antenna? I think I have one around
here... <grin!>
Seriously, thanks for the description.
>> Hm. Wonder if anyone has built an antenna whose polarization shifts
>> to "best match" the incoming signal? (No, not _this_ weekend!
>> <grin>!)
>
> Sure, many. Polarization diversity is an old idea. In a previous life I
> worked on a phased array radar (cf.
> http://www.globalsecurity.org/space/systems/an-fps-85.htm). The
> transmitters have only horizontal dipole antennas so they transmit only
> a horizontally polarized signal. But each of the 4660 receivers has two
> dipole antennas, one vertical and one horizontal. This gives the
> receiver information about whether an object is tumbling or rotating,
> for example, by the way the polarization is shifted by the reflection.
Sounds like a really neat setup... on the other hand, it may be a
bit much for my poor MAC-II clock. <Grin!>
--snip premature self-back-patting--
>> 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.
--snip--
> Be cautious in generalizing about your accomplishments. Day-to-day
> propagation differences can be extreme. Unless you can do an immediate
> A-B comparison or take many, many measurements over a very long period
> of time, there's no way to distinguish between antenna and propagation
> changes.
Um. I just noticed.
Yesterday I powered the clock off and added a "line out" jack so I
could record the received audio. I got distracted here and there,
and when I put it all back together I couldn't get WWV to save my
life. I finally ripped out my wiring, assuming I'd inadvertently run
a wore too close to the RF stuff... but even _that_ didn't help.
I'm now concluding that I reacted too rapidly, that the WWV signal
had simply faded into the background noise.
Seems to be true today as well. I re-added my wiring, and the
signal was unchanged (still rotten: bits and pieces of WWV tones
fading and returning a random-appearing basis). I can now record
long segments of bits of WWV... plus much louder bits of other
shortwave activity and assorted noise sources.
Ah, well. It'll be back some day. <grin!>
>> 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.
--snip--
> The whole objective to receiving system design is to maximize the
> signal/noise ratio, where "noise" is "everything you don't want". Making
> both larger by the same amount accomplishes nothing you can't do with a
> simple amplifier.
Yup.
Heath's algorithm, or at least my interpretation of it based on its
behavior, is to require clear reception -- from start to end -- of
complete TOD "frames", and to only statr the display running when
they're reallyREALLYsure they're locked in.
I have a feeling that one could do a more "statistical" approach and
get better results on poor signals. For example, it appears that
the MAC-II requires that, to be acceptable, a BCD TOD "bit" has to
have its start and end within certain time boundaries. On the other
hand, one could capture whatever bits of 100Hz tone were around and
attempt, over time, to fit them into a pattern and see if it matched
a valid WWV frame. You'd have to take into account that the
contentsof the frame (the TOD) would be changing during your
accumulation, but I think it makes more sense to strip and squeeze
every useful bit of information one can get out of what one _does_
receive rather than waiting for life (or propagation) to be nearly
perfect.
But that's for _next_ month. <grin!>
Frank
--
"We are taught you must blame your father, your sisters, your
brothers, the school, the teachers -- you can blame anyone but
never blame yourself. It's never your fault. But it's always
your fault, because if you wanted to change, you're the one
who has got to change. It's as simple as that, isn't it?"
--Katherine Hepburn
Frnak McKenney
> Frnak McKenney wrote:
--snip--
>> 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!>
>
> As I mentioned in my other recent posting, there's no way for you to tell.
I noticed. Yesterday all those really clear tones and voice
segments vanished while I wasn't paying attention. I can still hear
enough WWV on occasion to know it's still there, but it's not even
close to being strong enough to start the clock running.
>> 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!>
>
> You can duplicate the plots for the kinds of simple antennas you're
> dealing with, with the free demo version of EZNEC available from
> http://eznec.com. In the View Antenna display, select View/Objects, then
> check the "2D Display" box. Then you'll see a 2D plot superimposed on
> the view of the antenna, to show how the two are related. When viewing a
> 3D plot, the View Antenna display rotates along with the 3D pattern, so
> you can see how they're related if you keep both windows open.
Thanks for the pointer; I didn't knwo that there was a free version
available. I'll check it out when I get a chance
Frank
--
"Don't be afraid to take a big step if one is indicated.
You can't cross a chasm in two small jumps."
-- David Lloyd George, British Statesman
Frnak McKenney
> Frnak McKenney wrote:
>> Hm. Wonder if anyone has built an antenna whose polarization shifts
>> to "best match" the incoming signal? (No, not _this_ weekend!
>> <grin>!)
>
> Yes, such things have been built. There are some French researchers who
> built an adaptive combiner that combined multiple polarizations, and
> also did the processing to allow using both the ordinary and
> extraordinary ray, and substantially improved link reliability on 1000km
> skywave paths.
Neat!
>> 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"?).
>
> UTC is not an acronym. It's a madeup identifier that matches neither
> the English (Coordinated Universal Time) or the French (T U C.. I won't
> even attempt to figure out what it is..).
Thanks for the background. Mostly, I was just impressed to hear
_any_ recognizable voice coming out of the MAC-II's speaker after
all this time; the announcer could have said "Washington Standard
Time" and I'd have been impressed. <grin!>
> These sorts of international metrology things have all sorts of such
> negotiated compromises in them, stemming all the way back to the Prime
> Meridian being in Greenwich, but measuring in meters.
Um. That would be in... "chrono" meters, right? <grin!>
Frank
--
I find the great thing in this world is not so much where we
stand, as in what direction we are moving: To reach the port of
heaven, we must sail sometimes with the wind and sometimes against
it, -- but we must sail, and not drift, nor lie at anchor.
-- Oliver Wendell Holmes
Frnak McKenney
> On Oct 14, 12:34 pm, Frnak McKenney
><fr...@far.from.the.madding.crowd.com> wrote:
>> On Sat, 13 Oct 2007 17:27:01 -0700, Tim Shoppa <sho...@trailing-edge.com> 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--
>> 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)?
>
> Don't know about WWV in particular, but this past weekend on the ham
> bands there was an obvious uptick in propogation conditions. The MUF
> was up enough that I heard several pileups on 15 meters and 40 and 30
> Meters were more hopping than usual in mid-day/early evening.
Well, I hope it continued for everyone else, but for me the WWV
signal has faded back into obscurity. I can occasionally hear
small, dim fragments of its former glory, and that for only 10-20
seconds at a time.
I guess I really should have sacrificed that goat. <grin?>
Frank
--
"...each new generation born is in effect an invasion of
civilization by little barbarians, who must be civilized
before it is too late." -- Thomas Sowell
Roy Lewallen
Good point. This should be reported to the French language police!
Roy Lewallen, W7EL
Roy Lewallen
> . . .
> I guess I really should have sacrificed that goat. <grin?>
Hey, it looks like you're figuring out some of the secret techniques of
improving radio propagation!
Roy Lewallen, W7EL
Owen Duffy
Roy, I think that as others have posted, it is neither English nor
French, but a bastardisation that doesn't concede either language to be
the better for expressing the meaning. The diplomacy aspect of striking
standards no doubt!
Owen
Michael Coslo
But the goat finds it not at all satisfactory.
- 73 de Mike KB3EIA -