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Antenna for receiving WWV/10MHz: am I asking too much?
On Oct 8, 9:16 pm, 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. ... On Tue, 09 Oct 2007 22:22:07 GMT, Rick 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 -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
Robert, Thank you for joining in. On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts wrote: Frnak McKenney wrote: I'm in Richmond, Virginia and I'm trying to noticeably improve my reception of WWV's 10MHz signal from Fort Collins, Colorado. It all seemed so simple, two weeks ago: wind some wire, solder a connector, and Hey...presto! a clean WWV signal. grin! --snip-- Frank, can't you erect anything outside at all? A 10 metre dipole, is after all, only about 5 metres long. And if you can't do that, what kind of attic do you have? If your house is oriented correctly, you could even build a three element wire yagi pointed west inside the attic. Um... 10m? I was hoping for 10MHz/30m. Or have I missed something? (Wouldn't surprise me -- my 1st Class ticket expired several decades back.) 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 -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
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? Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838 Visit my 'blog at http://geoffstechno.livejournal.com/ |
Antenna for receiving WWV/10MHz: am I asking too much?
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Antenna for receiving WWV/10MHz: am I asking too much?
Geoff., Thanks for adding your comments. On Wed, 10 Oct 2007 12:34:08 +0000 (UTC), Geoffrey S. Mendelson 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 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 -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
On Wed, 10 Oct 2007 10:19:49 -0700, Richard Clark wrote:
On Tue, 09 Oct 2007 02:16:37 -0000, Frnak McKenney wrote: Am I asking too much? Hi Frnak, Judging by the questions and responses, I would have to say "Yes." To this point you haven't exactly demonstrated you have a problem, just a complaint of a signal of poor quality to a human's perception. For the clock itself, that complaint is arguably weak. Let's just examine the evidence for the problem: There is none! You have a clock that has 100mS resolution, and yet you have never said how much it is off. 100mS? 1S? 10S? 1 minute? 1 Hour? All, or any part of any of these metrics? It's hard to tell exactly how much the clock is off by. Every time the power hiccups, or I have to move the MAC-II, or power down the outlet the display switches to something like this (best viewed with a fixed-width font): _ _ _ _ /_ /_ /_ /_ / / /_/ /_ _/ /_ /_ and it stays that way for weeks. Or months. As Reggie would have chimed in at this point "If you can't measure it and express it with a quantifiable, then you don't know anything." Given the extent of my ignorance concerning 'most everything, that seems likely. grin! Of course, your only source of accurate information is the one you are suggesting has a problem. It probably doesn't have a problem, but then how does one use this source's accuracy to check itself? You would need a second clock to check it, and we would be hearing your complaint in stereo. Hm... I don't _think_ so. At least, I havent heard of any plans for a High-Def upgrade to Usenet lately, but with Congress currently in session I suppose anything is possible. As for testing the clock's accuracy, you're right about needing a second source ("Qui custodiet ipsos custodes?" or something like that? grin). On the other hand, as long as the digits are flashing by, I'm happy to "just trust them". I've calibrated time standards to the nearest 100nS and it is accomplished at one sitting, no need for total connectivity such as you might imagine (unless the clock you have is especially crappy). Your clock has a resolution of 0.1 second. There are roughly 1 million ticks of the display in a day. A simple XTAL oscillator at 10 MHz would exhibit 50ppm stability and in a day wander up to 0.5 second. The next day it might wander back, the day following it might slip below by 0.5 second. If I read the MAC-II manual correctly, each time it "connects to WWV" (gets a recognizable signal) it calculates and saves an adjustment value. The front panel has two LEDs labelled "TRIM UP" and "TRIM DN" to indicate how well it's doing. ... You would be hard pressed to confirm this with over the air matching to the strike of the WWV gong - except if the clock is especially crappy (and it could be). The same XTAL might also exhibit an absolute error of 50ppm and accumulate time error. This would be far more noticeable over the course of a week (you could confirm the error by listening to time announcements - but you have been silent to this issue). True. And, while I'm sure the _WWV_ announcer hasn't been silent, _I_ haven't heard anything comprehendable from him/her/it out of my MAC-II's speaker at any point in the past few weeks. These worst case errors all presume that the internal circuitry cannot over the course of 24 hours manage to pull out one of 1400 synchronizing opportunities to phase lock out the error. These circuits are generally optimized to accomplish just this (they work fine in watches with a 60KHz signal after all). Your clock may be especially crappy (but that is unlikely). Based on the feedback from other posters, it's likely a consequence of 10MHz propagation. A VLF RF signal like 60KHz reportedly does a much better job of getting a readable signal to a wide area. The clock synchronizing circuits don't have to listen to the bandwidth of noise you hear, the speaker is for your convenience, not the clock's. I am sure that it works fine with only 1 LED lit - this is not a case of "can you hear me now?" No, but (assuming you're subbing for WWV grin!) it would be nice to know I was going to get a readable message from "you" more than once every couple of months. (Why do I hear the echo of my parents' frustration during my colege days? grin!) Thanks for the feedback. I admit I hadn't thought that much about the accuracy of the MAC-II; I'm afraid I've been too caught up in simply trying to get digits instead of "error text" on the display. Frank -- "A good traveller has no fixed plans and is not intent on arriving." -- Lao Tzu (570-490 BC) -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
Jon Kåre Hellan wrote:
Sounds like OP is really interested in bringing his father's WWV clock to life. But again - this is probably not what you're really after :-) 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. Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838 Visit my 'blog at http://geoffstechno.livejournal.com/ |
Antenna for receiving WWV/10MHz: am I asking too much?
Frnak McKenney wrote:
. . . 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
On Thu, 11 Oct 2007 12:12:14 -0000, Frnak McKenney
wrote: _ _ _ _ /_ /_ /_ /_ / / /_/ /_ _/ /_ /_ and it stays that way for weeks. Or months. A whip antenna should be able to sort out WWV for at least one of 1400 synchronizing events in a day. This may be a problem of too much antenna at one time - and a nearby lightning event at that same time. Your front end got fried out. 73's Richard Clark, KB7QHC |
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