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Antenna for receiving WWV/10MHz: am I asking too much?
I'm in Richmond, Virginia and I'm trying to noticeably improve my reception of WWV's 10MHz signal from Fort Collins, Colorado. It all seemed so simple, two weeks ago: wind some wire, solder a connector, and Hey...presto! a clean WWV signal. grin! It wasn't so simple, and I'm afraid I've let it become an "ego thing" (see also: resource sink). I've outlined the problem below in the hope that someone can either suggest something I haven't already tried, or even point out something really dumb that I've been doing and shouldn't keep doing. grin! Background ---------- Several years back I inherited a Heathkit GCW-1001 Most Accurate Clock II from my father. This is an update to it's predecessor, Heath's GC-1000 Most Accurate Clock; its circuit, built around a Philips TDA1072A AM receiver IC and an 87C52 microprocessor, monitors WWV's 10MHz signal and decodes the BCD-coded 100Hz subcarrier (details at http://tf.nist.gov/stations/wwv.html) to keep the MAC-II accurate. This MAC-II worked fine for my father: he had a 30 meter dipole of some kind in the attic, above the second floor of a house on a hill. For him, WWV's 10MHz signal from Fort Collins came in regular as... well, "clockwork". igg! For me, in a one-story-plus-basement, in a low spot in a river valley, it's a different story. The GCW-1001 has a stack-o-LEDs signal strength indicator driven by the TDA1072's AGC output; it would wander between 2 and 4 LEDs with my 40" indoor dangling wire antenna, and it could take weeks or months for atmospheric conditions to randomly improve the signal to where the GCW-1001 could "lock in" a time. Two weeks ago, in a fit of madness, I decided to try building a better antenna, one which would let the clock lock onto WWV at least, say, once a week. The tuned-loop antenna I've built _has_ increased the signal -- I'm seeing 4-5 LEDs lit on a regular basis, and 6 on occasion -- but the clock still isn't sync'ing to WWV's time signal. The clock face remains at a cute(?) 7-segment "not SEt" display. And what seems to be louder is the carrier -- or _a_ carrier, at any rate -- but not the tones or the human voice time callout coming out of the GCW-1001's speaker. I seem to be up to my assets in alligators, and the swamp doesn't seem to be draining much. Problem ------- My main problem is that, although the GCW-1001's LED "Signal" stack _says_ it's getting a stronger signal, what I hear through the speaker monitor isn't _clearer_. There are long periods when I cannot hear any WWV tones through the GC-1001's speaker, the tones/ticks are faint even when there are 5-6 LEDs lit, and the voice is almost never audible/distinguishable. The clock _seems_ to be sync-ing a little more often (it's done it four times in the past two weeks), but I had hoped it might happen a _little_ more frequently. Am I asking too much? Is WWV's 10MHz signal from (say) 2,000 miles away, simply too weak to pick up solidly without an outdoor antenna? What I've tried --------------- My (second) attempt at a 30m indoor loop antenna: Main loop (tuned): A 36" near-circle of #12 insulated house wire with an AM/FM tuning capacitor across it. Pickup loop: One (36") turn of #27 magnet wire taped to the #12 loop with electrical tapegrin!. The ends (scraped and tinned) are tied to the GCW-1001's 50ohm antenna input with a couple of 12" clip leads and a 3' section of coax. The loops are mounted on (and held in shape by) a 1'x4'x0.5" "backboard" made of "blue foam" house insulation that I found in my basement; the loops are held in place by small plastic cable ties. The foam backing is resting against a (roughly) N-S wall, which _should_ orient the loop plane across the WWV wavefront for maximum pickup. Does this sound like a reasonable attempt at a tuned 10MHz loop? Is there any reason to believe that the foam backing would affect the loop inductance? I'm assuming it's a good insulator and nothing more, but that's an assumption. Is it possible that I'm picking up a non-WWV dignal so strong that it's masking WWV? I tried tuning around 10MHz with a shortwave radio; it didn't find WWV -- not a particularly hopeful sign -- but it did pick up a station called (IIRC) WWCR. WWCR's 'web site (www.wwcr.com) lists its transmitter #4 as using 9.985MHz and 9.975MHz between 0900 and 2100 CST. Any advice or suggestions will be appreciated, up to and including "You can't power a hedge trimmer from two AAA cells!". Thanks... Frank 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 -- |
Antenna for receiving WWV/10MHz: am I asking too much?
On Oct 8, 9:16 pm, Frnak McKenney
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 |
Antenna for receiving WWV/10MHz: am I asking too much?
On Oct 9, 6:06 am, wrote:
On Oct 8, 9:16 pm, Frnak McKenney 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 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
Denny wrote in news:1191956444.157030.11580@
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 |
Antenna for receiving WWV/10MHz: am I asking too much?
"Owen Duffy" wrote in message ... Denny wrote in news:1191956444.157030.11580@ 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 -------- 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
Since he said previously that he could hardly hear the tones/voice, isn't it
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" wrote in message ... "Owen Duffy" wrote in message ... Denny wrote in news:1191956444.157030.11580@ 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 -------- 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
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. 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? |
Antenna for receiving WWV/10MHz: am I asking too much?
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Antenna for receiving WWV/10MHz: am I asking too much?
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 |
Antenna for receiving WWV/10MHz: am I asking too much?
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. 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? ----------- 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
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. 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? ----------- 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
Frnak McKenney wrote:
I'm in Richmond, Virginia and I'm trying to noticeably improve my reception of WWV's 10MHz signal from Fort Collins, Colorado. It all seemed so simple, two weeks ago: wind some wire, solder a connector, and Hey...presto! a clean WWV signal. grin! It wasn't so simple, and I'm afraid I've let it become an "ego thing" (see also: resource sink). I've outlined the problem below in the hope that someone can either suggest something I haven't already tried, or even point out something really dumb that I've been doing and shouldn't keep doing. grin! 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
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. 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 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?
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? 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
Ed Cregger wrote:
You too will grow old someday, ... .... and forget to click the send button only once? :-) -- 73, Cecil http://www.w5dxp.com |
Antenna for receiving WWV/10MHz: am I asking too much?
I'm just trying to be helpful, not a wiseguy. Although it does seem that my
genetics predispose me to lean in that direction. G Ed, NM2K "keithm" wrote in message ... Since he said previously that he could hardly hear the tones/voice, isn't it 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" wrote in message ... "Owen Duffy" wrote in message ... Denny wrote in news:1191956444.157030.11580@ 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 -------- 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
G
New computer, new software and fasciculations. What a combo! Ed, NM2K "Cecil Moore" wrote in message ... Ed Cregger wrote: You too will grow old someday, ... ... and forget to click the send button only once? :-) -- 73, Cecil http://www.w5dxp.com |
Antenna for receiving WWV/10MHz: am I asking too much?
Denny,
Thanks for joining in. On Tue, 09 Oct 2007 12:00:44 -0700, Denny wrote: On Oct 9, 6:06 am, wrote: On Oct 8, 9:16 pm, Frnak McKenney 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 -- 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?
Owen,
Thanks for the comments. On Tue, 09 Oct 2007 19:58:10 GMT, Owen Duffy wrote: Denny wrote in news:1191956444.157030.11580@ 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. 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 -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
On Oct 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 |
Antenna for receiving WWV/10MHz: am I asking too much?
Jon Kåre Hellan wrote:
(Geoffrey S. Mendelson) writes: 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. 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. But again - this is probably not what you're really after :-) 73 LA4RT Jon |
Antenna for receiving WWV/10MHz: am I asking too much?
Frnak McKenney wrote:
Hm... I don't _think_ so. At least, I havent heard of any plans for a High-Def upgrade to Usenet lately, but with Congress currently in session I suppose anything is possible. As for testing the clock's accuracy, you're right about needing a second source ("Qui custodiet ipsos custodes?" or something like that? grin). On the other hand, as long as the digits are flashing by, I'm happy to "just trust them". One needs three clocks.. if you have only two, you only know that they differ. If you have three, you can detect the failed clock, because the other two read the same time. Of course, if the different clocks have different accuracies or reliabilities, that's another story. For a more detailed treatment of such things, you might want to check out the "Byzantine General" problem. Based on the feedback from other posters, it's likely a consequence of 10MHz propagation. A VLF RF signal like 60KHz reportedly does a much better job of getting a readable signal to a wide area. Although in my house (southern California), the 60 kHz signal seems to fade in and out on a daily basis. |
Antenna for receiving WWV/10MHz: am I asking too much?
Jim Lux wrote:
Why not take the GPS disciplined oscillator (e.g. a Z8301) and use that to synthesize a fake WWV signal (which you could program up in the AVR), and radiate that to your MACII. You can easily divide down the 10 MHz from the oscillator to generate all the needed modulations for WWV (the tones, ticks, and 100 Hz timecode). Synthesizing the voice announcements might be a bit more challenging grin "At the tone, Coordinated Universal Time is...." You could even have a switch to change back and forth between WWV and WWVH. Talking clock programs have been around for a long time. All you need is samples for 0 through 24, 30, 40, and 50 and a few words. You could even play games with it, I'm sure the clock does not care, for example "At the beep, the fake univeristy time is" and so on. You really don't need to do much at all, since if I remember correctly, it's an AM modulated signal, with no modulation also being no carrier. Am modulation and on/off switching of a high power radio signal is fairly complex, but at the microwatt level it should be easy. It's fairly slow so even a reed relay connected to a GPIO line would do. I'm sure there are all sorts of digitaly controlled analog switch chips that will quickly and cleanly switch 10mHz. As an aside, if I remember correctly, the 60kHz version is just pulse code modulation of a carrier at a very slow baud rate, so it would be really easy. Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838 Visit my 'blog at http://geoffstechno.livejournal.com/ |
Antenna for receiving WWV/10MHz: am I asking too much?
Frnak McKenney wrote:
Robert, Thank you for joining in. On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts wrote: Frnak McKenney wrote: I'm in Richmond, Virginia and I'm trying to noticeably improve my reception of WWV's 10MHz signal from Fort Collins, Colorado. It all seemed so simple, two weeks ago: wind some wire, solder a connector, and Hey...presto! a clean WWV signal. grin! --snip-- Frank, can't you erect anything outside at all? A 10 metre dipole, is after all, only about 5 metres long. And if you can't do that, what kind of attic do you have? If your house is oriented correctly, you could even build a three element wire yagi pointed west inside the attic. Um... 10m? I was hoping for 10MHz/30m. Or have I missed something? (Wouldn't surprise me -- my 1st Class ticket expired several decades back.) HMMMM. I was having a blonde moment, I think. Of course I meant 10 MHz and not 10 Metres. The dimensions were correct, though for 10 MHz. Looks like one of those days where the brain fades... Okay... ARRL Antennas, Chapter 8: Multielement Arrays. We've got an (approximately, given skip) vertically-polarized 10MHz signal, so the E-field is moving up and down and the wavefront is a circular ripple (nearly a straight line by the time it gets to Richmond) travelling roughly west-to-east, that is, it's hitting my house end-on. Dimensions shouldn't be that critical for receive only, and space the elements at about 2.5 metres. Basically one element at about 47 feet, one at about 49.3 feet, and one at about 45 feet. Split the 47 ft one into two, feed it directly with 50 ohm coax, one side to the shield, one to the centre conductor, and you have a three element wire beam pointed, hopefully, west. (Put the longest element on the east side, the shortest on the west.) Um... if I label them as A/47ft, B/49ft, and C/45ft, the picture I come up with looks like this from overhead: | | | | | | --- To Fort Collins | + | | + | | | | | | | (scale) |............................................C.A.B I definitely think I'm missing something, but then, I haven't really made it that far into the Antenna Handbook. Anyway, thanks for the suggestion. You're welcome. Your characterisation of the antenna as above is correct, and hopefully your attic is correctly oriented. Of course if you can put it outside, fixed wire beams are often very useful. Frank -- "Our Constitution is in actual operation; everything appears to promise that it will last; but in this world nothing is certain but death and taxes." -- Benjamin Franklin -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
On Oct 11, 5:12 am, Frnak McKenney
wrote: On Wed, 10 Oct 2007 10:19:49 -0700, Richard Clark wrote: On Tue, 09 Oct 2007 02:16:37 -0000, Frnak McKenney wrote: Am I asking too much? Hi Frnak, Judging by the questions and responses, I would have to say "Yes." To this point you haven't exactly demonstrated you have a problem, just a complaint of a signal of poor quality to a human's perception. For the clock itself, that complaint is arguably weak. Let's just examine the evidence for the problem: There is none! You have a clock that has 100mS resolution, and yet you have never said how much it is off. 100mS? 1S? 10S? 1 minute? 1 Hour? All, or any part of any of these metrics? It's hard to tell exactly how much the clock is off by. Every time the power hiccups, or I have to move the MAC-II, or power down the outlet the display switches to something like this (best viewed with a fixed-width font): _ _ _ _ /_ /_ /_ /_ / / /_/ /_ _/ /_ /_ and it stays that way for weeks. Or months. As Reggie would have chimed in at this point "If you can't measure it and express it with a quantifiable, then you don't know anything." Given the extent of my ignorance concerning 'most everything, that seems likely. grin! Of course, your only source of accurate information is the one you are suggesting has a problem. It probably doesn't have a problem, but then how does one use this source's accuracy to check itself? You would need a second clock to check it, and we would be hearing your complaint in stereo. Hm... I don't _think_ so. At least, I havent heard of any plans for a High-Def upgrade to Usenet lately, but with Congress currently in session I suppose anything is possible. As for testing the clock's accuracy, you're right about needing a second source ("Qui custodiet ipsos custodes?" or something like that? grin). On the other hand, as long as the digits are flashing by, I'm happy to "just trust them". I've calibrated time standards to the nearest 100nS and it is accomplished at one sitting, no need for total connectivity such as you might imagine (unless the clock you have is especially crappy). Your clock has a resolution of 0.1 second. There are roughly 1 million ticks of the display in a day. A simple XTAL oscillator at 10 MHz would exhibit 50ppm stability and in a day wander up to 0.5 second. The next day it might wander back, the day following it might slip below by 0.5 second. If I read the MAC-II manual correctly, each time it "connects to WWV" (gets a recognizable signal) it calculates and saves an adjustment value. The front panel has two LEDs labelled "TRIM UP" and "TRIM DN" to indicate how well it's doing. ... You would be hard pressed to confirm this with over the air matching to the strike of the WWV gong - except if the clock is especially crappy (and it could be). The same XTAL might also exhibit an absolute error of 50ppm and accumulate time error. This would be far more noticeable over the course of a week (you could confirm the error by listening to time announcements - but you have been silent to this issue). True. And, while I'm sure the _WWV_ announcer hasn't been silent, _I_ haven't heard anything comprehendable from him/her/it out of my MAC-II's speaker at any point in the past few weeks. These worst case errors all presume that the internal circuitry cannot over the course of 24 hours manage to pull out one of 1400 synchronizing opportunities to phase lock out the error. These circuits are generally optimized to accomplish just this (they work fine in watches with a 60KHz signal after all). Your clock may be especially crappy (but that is unlikely). Based on the feedback from other posters, it's likely a consequence of 10MHz propagation. A VLF RF signal like 60KHz reportedly does a much better job of getting a readable signal to a wide area. The clock synchronizing circuits don't have to listen to the bandwidth of noise you hear, the speaker is for your convenience, not the clock's. I am sure that it works fine with only 1 LED lit - this is not a case of "can you hear me now?" No, but (assuming you're subbing for WWV grin!) it would be nice to know I was going to get a readable message from "you" more than once every couple of months. (Why do I hear the echo of my parents' frustration during my colege days? grin!) Thanks for the feedback. I admit I hadn't thought that much about the accuracy of the MAC-II; I'm afraid I've been too caught up in simply trying to get digits instead of "error text" on the display. Frank -- "A good traveller has no fixed plans and is not intent on arriving." -- Lao Tzu (570-490 BC) -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) Gee, all this trouble you're having getting a good signal from WWV on 10MHz makes me wonder, "why??" I mean, why bother? It must be the challenge! I'm a bit closer to Ft. Collins, but I wouldn't expect things to be all that much different, and in any event, the same antenna I've used for them has worked fine for signals from W1AW, for frequency measuring tests. That antenna is just a short piece of wire, maybe five feet long, connected to a signal analyzer's input port. The signal analyzer's input doesn't even have a particularly good noise figure. But with it, I get a good enough signal from WWV to easily track the nocturnal/diurnal frequency shifts that happen as the path length changes. (The analyzer may not have a great RF front end, but it has a very stable frequency reference...) Similarly, I have a portable short wave radio that has an awful front end, and with just a 3 foot whip antenna, it gets WWV 10MHz fine most of the time. Obviously, there are times of the day when propagation just doesn't do it, but over the period of one day, and not during a geomagnetic storm, the signal is usually available. All this makes me wonder if the receiver in your clock is OK. I'd start by looking at that; or at very least, see if a known-working radio receiver has as much trouble with the signal as the clock seems to. Given that the clock has a single frequency receiver, even a pretty simple receiver design should give decent performance. It's also possible that you have some signal source on nominally 10MHz nearby, and you hear than instead of WWV. There are soooo many microprocessors around the average home these days that it's entirely possible that the source of the trouble is very nearby--but could also be in a neighbor's house (or car -- or garage -- or ??). If you want an accurate clock and get tired of fooling with WWV-10MHz, and don't want to use WWVB-60kHz, you might consider using a GPS. As long as you can manage an antenna with a reasonably clear view of the sky, you should be able to have a clock reliably set to within less than a second accuracy practically all the time. Or, if you'd like to be independent of external references, modify your MAC with an oven oscillator. Oven stabilized crystal oscillators left on for a long time will almost always settle out to very low drift rates---one part in 10^8 over a year shouldn't be difficult, in my experience, and GPS signals can be used to calibrate it occasionally. One part in 10^8 is about 1/3 of a second per year. Cheers, Tom |
Antenna for receiving WWV/10MHz: am I asking too much?
Frnak McKenney wrote:
I'm in Richmond, Virginia and I'm trying to noticeably improve my reception of WWV's 10MHz signal from Fort Collins, Colorado. It all seemed so simple, two weeks ago: wind some wire, solder a connector, and Hey...presto! a clean WWV signal. grin! It wasn't so simple, and I'm afraid I've let it become an "ego thing" (see also: resource sink). I've outlined the problem below in the hope that someone can either suggest something I haven't already tried, or even point out something really dumb that I've been doing and shouldn't keep doing. grin! Background ---------- Several years back I inherited a Heathkit GCW-1001 Most Accurate Clock II from my father. This is an update to it's predecessor, Heath's GC-1000 Most Accurate Clock; its circuit, built around a Philips TDA1072A AM receiver IC and an 87C52 microprocessor, monitors WWV's 10MHz signal and decodes the BCD-coded 100Hz subcarrier (details at http://tf.nist.gov/stations/wwv.html) to keep the MAC-II accurate. This MAC-II worked fine for my father: he had a 30 meter dipole of some kind in the attic, above the second floor of a house on a hill. For him, WWV's 10MHz signal from Fort Collins came in regular as... well, "clockwork". igg! For me, in a one-story-plus-basement, in a low spot in a river valley, it's a different story. The GCW-1001 has a stack-o-LEDs signal strength indicator driven by the TDA1072's AGC output; it would wander between 2 and 4 LEDs with my 40" indoor dangling wire antenna, and it could take weeks or months for atmospheric conditions to randomly improve the signal to where the GCW-1001 could "lock in" a time. Two weeks ago, in a fit of madness, I decided to try building a better antenna, one which would let the clock lock onto WWV at least, say, once a week. The tuned-loop antenna I've built _has_ increased the signal -- I'm seeing 4-5 LEDs lit on a regular basis, and 6 on occasion -- but the clock still isn't sync'ing to WWV's time signal. The clock face remains at a cute(?) 7-segment "not SEt" display. And what seems to be louder is the carrier -- or _a_ carrier, at any rate -- but not the tones or the human voice time callout coming out of the GCW-1001's speaker. I seem to be up to my assets in alligators, and the swamp doesn't seem to be draining much. Problem ------- My main problem is that, although the GCW-1001's LED "Signal" stack _says_ it's getting a stronger signal, what I hear through the speaker monitor isn't _clearer_. There are long periods when I cannot hear any WWV tones through the GC-1001's speaker, the tones/ticks are faint even when there are 5-6 LEDs lit, and the voice is almost never audible/distinguishable. The clock _seems_ to be sync-ing a little more often (it's done it four times in the past two weeks), but I had hoped it might happen a _little_ more frequently. Am I asking too much? Is WWV's 10MHz signal from (say) 2,000 miles away, simply too weak to pick up solidly without an outdoor antenna? What I've tried --------------- My (second) attempt at a 30m indoor loop antenna: Main loop (tuned): A 36" near-circle of #12 insulated house wire with an AM/FM tuning capacitor across it. Pickup loop: One (36") turn of #27 magnet wire taped to the #12 loop with electrical tapegrin!. The ends (scraped and tinned) are tied to the GCW-1001's 50ohm antenna input with a couple of 12" clip leads and a 3' section of coax. The loops are mounted on (and held in shape by) a 1'x4'x0.5" "backboard" made of "blue foam" house insulation that I found in my basement; the loops are held in place by small plastic cable ties. The foam backing is resting against a (roughly) N-S wall, which _should_ orient the loop plane across the WWV wavefront for maximum pickup. Does this sound like a reasonable attempt at a tuned 10MHz loop? Is there any reason to believe that the foam backing would affect the loop inductance? I'm assuming it's a good insulator and nothing more, but that's an assumption. Is it possible that I'm picking up a non-WWV dignal so strong that it's masking WWV? I tried tuning around 10MHz with a shortwave radio; it didn't find WWV -- not a particularly hopeful sign -- but it did pick up a station called (IIRC) WWCR. WWCR's 'web site (www.wwcr.com) lists its transmitter #4 as using 9.985MHz and 9.975MHz between 0900 and 2100 CST. Any advice or suggestions will be appreciated, up to and including "You can't power a hedge trimmer from two AAA cells!". Thanks... Frank - I am up in Maryland, not too far from you. WWV on 10MHz is only usable for about a third or less of the day for locking an electronic clock. Generally the late afternoons and evenings are great, early afternoons and mornings are a little more variable. Overnight 5MHz works best. During the mid-day 15MHz or when propogation permits 20MHz rules for WWV. I don't think your Heath has any frequency diversity capability, right? Well, 10MHz is a pretty good choice if you only have a choice of one, it is usually coming in strong in the evenings there. Over wintertime 5MHz gets pretty good at night. You will, especially in the early morning, occasionally hear WWVH on 10MHz or 5MHz or 15MHz. Sometimes I hear both WWV and WWVH at the same time. You can recognize WWVH by the woman's voice reading the time. My best antenna for 10MHz WWV is my 40-meter dipole strung between two trees. Mine mostly points broadside to the NE/SW but if you could arrange it, it would be slightly preferable to have it broadside to be sensitive to the W. A dipole optimized for 10MHz would be even shorter - the formulas put a half wave dipole at 47 feet long. Tim. |
Antenna for receiving WWV/10MHz: am I asking too much?
On Thu, 11 Oct 2007 06:23:44 -0700, Roy Lewallen wrote:
Frnak McKenney wrote: . . . Okay... ARRL Antennas, Chapter 8: Multielement Arrays. We've got an (approximately, given skip) vertically-polarized 10MHz signal, so the E-field is moving up and down and the wavefront is a circular ripple (nearly a straight line by the time it gets to Richmond) travelling roughly west-to-east, that is, it's hitting my house end-on. . . . --snip-- While you're looking at the ARRL Antenna Book, look over the chapter on propagation. You'll find that when receiving a signal by ionospheric skip (as you are), the polarization will be randomly oriented. So there's no point in choosing your antenna orientation on the basis of some supposed wave polarization. Its orientation will, however, have a striking impact on its pattern, so you should choose the orientation to get the most favorable pattern. Ah. So even if it starts out in vertically polarized in Fort Collins 'way out thataway (he says, gesturing faintly west-ish) WWV's signal might be polarized north-north-west by the time it gets ro Richmond. The fading in and out of the WWV signal you described in an earlier posting is very likely due largely or at least partially to polarization shift -- the signal fades when the polarization rotates to be crosswise to your antenna, and gets loud when the polarization lines up with your antenna's. I've seen tens of dB difference switching between a vertically and horizontally polarized antenna, with the change going the other way after a minute or so when the polarization rotates. If your receiver needs a constantly strong signal, you're going to have a hard time getting it what it needs. Hm. Wonder if anyone has built an antenna whose polarization shifts to "best match" the incoming signal? (No, not _this_ weekend! grin!) I haven't followed the thread closely, so please pardon me if I've missed something. Your initial description of the problem sounded like receiver overload. A sharp preselector would help a lot, although it sounded like you were using a tuned loop which, if carefully balanced, should provide that function. A minor update: It seems that I was _mis_tuning my antenna, adjusting it for the strongest signal (highest stack of LEDs lit). Over the past two days either I've finally tuned it _correctly_ or I've done that _and_ the signal has improved. Whatever the cause(s), I can now -- at times, in fact for an hour at a time -- hear the tocks fairly clearly and even understand the voice. (Who knew the announcer's phrase for UTC "Coordinated Universal Time"?). How good? Well, I've unplugged the clock to reset it and it has then received an "acceptable" WWV signal (it started showing digits) eight times in the past two days. It might have been more times, but I don't watch it constantly, and I've noticed that twiddling the tuning knob tends to make sync-ing a little harder. ("Ack! It's fading! See if I can tune the antenna _just_ a little better!" grin!) I _do_ know that the point of best reception is much narrower that I thought it when I was tuning in that "other" signal. Turning the tuning capacitor's knob a "minor wiggle" either way can decrease the signal strength by an LED or 2, and I need to compensate for the effect of moving my hand near the antenna to tune it. grin!. Oh, and the MAC-II seems to be a lot pickier about what it will and will not accept than my ears are. The microprocessor is driven by a 9.216MHz crystal and it's an 87C52 (an 8051-alike) which (as I recall) means it only gets around 0.768 MIPS (clk/12) to do all its work, so I doubt it's doing much "DSP" itself; its interrupt lines are tied to a 567 tone decoder IC for WWV's "start of minute" and BCD data subcarrier tones (1000Hz and 100Hz). The MAC-II seems to be very "picky". Part -- but not all -- of its requirement for starting the clock digits running is that it receive a recognizable 100Hz signal for a full minute, that is, between one 1000Hz tone and the next. In other words, if WWV's signal is fading on a 5- or 30-second cycle, odds are good that at one point the signal will be come "bad". I've seen it recognize the start of a "frame" by lighting its CAPTURE LED, but then turn it out ten or forty seconds later when part of the frame has faded a bit; my ears can still recognize the tones, but the're better designed and have a better processor than the MAC-IIgrin!. This pickiness I suspect is part of the reason it takes to long for the clock to start running. ... If a preselector isn't enough, the next step is to add an attenuator -- I have to use one between my TV and its antenna, in fact. You should consider the possibility that the 10 MHz WWV signal itself is overloading the receiver, in which case an attenuator is necessary, and the last thing you'd want to do is use a better antenna. A directional antenna can be used to reduce the strength of interfering signals if they're coming from directions different than WWV. But making an antenna which has good rejection in the right directions can be something of a project. I do a lot of reading in comp.dsp (sometimes it's fun just watching the phrases fly back and forth grin!), and one common topic there is the difference between "noise" and "signal". For me, "signal" is "what I want", "noise" is "everything else", and the fun(?) part is figuring out how to get as much of the former as I can while downplaying or being able to ignore the effects of the latter. My next step is to add a "line out" jack to the MAC-II so I can capture long stretches of the signal to disk; when reception goes bad again I'll be able to use Scilab or Matlab or something to play "Beat the Heathkit!" with my own algorithms. And if I get tired of that, I can unsolder the 87C52 and wire in one of Atmel's $20 Butterfly boards in its place, adding an LCD and my own algorithms. And _then_ I can... and _then_ I can... grin! Anyway, "It's feeling _much_ better now." grin! Frank -- The first Zen master in Japan to write extensively on good and evil was Dogen Zenji... Dogen was one of the most adamant of those who rejected the widespread use of Buddhism for social, political, and material power; and he was driven out of the capital area for his trouble. -- Thomas Cleary / The Japanese Art of War -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
On Thu, 11 Oct 2007 07:51:55 -0700, Richard Clark wrote:
On Thu, 11 Oct 2007 12:12:14 -0000, Frnak McKenney wrote: _ _ _ _ /_ /_ /_ /_ / / /_/ /_ _/ /_ /_ and it stays that way for weeks. Or months. A whip antenna should be able to sort out WWV for at least one of 1400 synchronizing events in a day. This may be a problem of too much antenna at one time - and a nearby lightning event at that same time. Your front end got fried out. If you're reading these posts in the same order I'm posting, you'll have already read my good news: It's Working! (Oh. That's right -- this is Usenet. Y'all can't here the "doooonb"-ing from down the hall. Well, take my word for it -- or even the MAC-II's display! grin) This doesn't prove that the MAC-II's J-FET RF amplifier hasn't been degraded through an... er, "very wideband RF overload" grin!, but I think it does say that "completely fried" is unlikely (which pleases me greatly! grin). My earlier MAC-I had a nice whip built in, and could select the strongest signal among (IIRC) 5, 10, and 15MHz, but it had the same problems getting an "acceptable" WWV signal most of the time. Frank -- "Whatever you can do, or dream you can, begin it. Boldness has genius, power and magic in it" -- Goethe -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
On Thu, 11 Oct 2007 09:52:53 -0700, Jim Lux wrote:
Frnak McKenney wrote: --snip-- As for testing the clock's accuracy, you're right about needing a second source ("Qui custodiet ipsos custodes?" or something like that? grin). On the other hand, as long as the digits are flashing by, I'm happy to "just trust them". One needs three clocks.. if you have only two, you only know that they differ. If you have three, you can detect the failed clock, because the other two read the same time. Well, you have a reasonable _presumption_, anyway. grin In _theory_, one could have two clocks in error and one on time. Or even all three out of step with (say) the NIST's clock. But two-out-of-three would be the place to put your money. grin Of course, if the different clocks have different accuracies or reliabilities, that's another story. For a more detailed treatment of such things, you might want to check out the "Byzantine General" problem. Faint recollections... "unreliable communication on the battlefield" category? Based on the feedback from other posters, it's likely a consequence of 10MHz propagation. A VLF RF signal like 60KHz reportedly does a much better job of getting a readable signal to a wide area. Although in my house (southern California), the 60 kHz signal seems to fade in and out on a daily basis. I can believe it. I've seen those LCD "clock and weather" stations take days to synchronize the time (I assume they're using WWVB). OTOH, I'm hardly one to talk, since I've let the MAC-II sit liostening for months at a time without successfully locking-in on WWV. Frank -- Hanlon's Razor: ˙Never attribute to malice that which can be adequately explained by stupidity.˙ -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
On Thu, 11 Oct 2007 11:21:29 -0700, Robert Smts wrote:
Frnak McKenney wrote: --snip-- On Tue, 09 Oct 2007 22:35:29 -0700, Robert Smts wrote: Frnak McKenney wrote: I'm in Richmond, Virginia and I'm trying to noticeably improve my reception of WWV's 10MHz signal from Fort Collins, Colorado. --snip-- Frank, can't you erect anything outside at all? A 10 metre dipole, is after all, only about 5 metres long. And if you can't do that, what kind of attic do you have? If your house is oriented correctly, you could even build a three element wire yagi pointed west inside the attic. --snip-- I definitely think I'm missing something, but then, I haven't really made it that far into the Antenna Handbook. Anyway, thanks for the suggestion. You're welcome. Your characterisation of the antenna as above is correct, and hopefully your attic is correctly oriented. Of course if you can put it outside, fixed wire beams are often very useful. If I'm following the ARRL handbook correctly, I want the elements laid out _across_ the incoming wavefront. For Fort Collins to Richmond, that is, going west to east, that would mean I'd want to string the wires/elements north-south. Naturally (per Murphy, the patron saint of Data Processing) my house is oriented E-W. Which does still, as you point out, leave the possibility of building something outdoors. Still, my current indoor loop seems to be picking up a nice strong signal. It was upright when I first started testing, but it wound up being laid flat at some point in the past few days -- about the time I discovered that I had been mis-tuining it. Wonder which had more effect: my changes, or atmospherics? grin! Anyway, thank you for your time and suggestions. I did some looking around on the 'web for introductory material to help me understand the ARRL Antenna Handbook and stumbled onto these: Antenna Newcomers and the Language of Antennas http://www.cebik.com/tales/nc.html Antennas from the Ground Up http://www.cebik.com/gup/groundup.html Some really nice propagation plots. Now, if there were just some simple way of figuring out which way the antenna is oriented relative to the plots... "It's an imperfect universe" grin! Frank -- Anyone who is not genuinely addicted to the search for knowledge is unlikely to have the psychological energy to be a true scholar in any field. But in history this work clearly resembles more that of a detective than that of a scientist -- a search for and judgment of particular evidence rather than a repeatable experiment. The detective side of historical research needs skill, background, and intuition. -- Robert Conquest, "The Dragons of Expectation" -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
Antenna for receiving WWV/10MHz: am I asking too much?
Tim,
Thanks for joining in. On Sat, 13 Oct 2007 17:27:01 -0700, Tim Shoppa wrote: Frnak McKenney wrote: I'm in Richmond, Virginia and I'm trying to noticeably improve my reception of WWV's 10MHz signal from Fort Collins, Colorado. It all seemed so simple, two weeks ago: wind some wire, solder a connector, and Hey...presto! a clean WWV signal. grin! --snip-- Frank - I am up in Maryland, not too far from you. WWV on 10MHz is only usable for about a third or less of the day for locking an electronic clock. Generally the late afternoons and evenings are great, early afternoons and mornings are a little more variable. Overnight 5MHz works best. During the mid-day 15MHz or when propogation permits 20MHz rules for WWV. I don't think your Heath has any frequency diversity capability, right? Well, 10MHz is a pretty good choice if you only have a choice of one, it is usually coming in strong in the evenings there. Over wintertime 5MHz gets pretty good at night. My current box, the MAC-II, only monitors 10MHz; its predecessor, the GC-1000 MAC, monitored (IIRC) 5/10/15MHz and chose the strongest. You will, especially in the early morning, occasionally hear WWVH on 10MHz or 5MHz or 15MHz. Sometimes I hear both WWV and WWVH at the same time. You can recognize WWVH by the woman's voice reading the time. My best antenna for 10MHz WWV is my 40-meter dipole strung between two trees. Mine mostly points broadside to the NE/SW but if you could arrange it, it would be slightly preferable to have it broadside to be sensitive to the W. A dipole optimized for 10MHz would be even shorter - the formulas put a half wave dipole at 47 feet long. Thanks for your signal report and the antenna suggestion. I'll keep it in mind. On the other hand, my tuned (and currently horizontal) loop is suddenly picking up WWV/10MHz remarkably reliably, and I didn't even have to "sacrifice a goat at midnight"! grin Has your reception improved lately as well (last few days)? Frank -- Writers listen for harmonies; civilians listen for melody alone. For them the facades of ordinary situations are opaque, and they see what is there to be seen. Writers are attracted to translucence. We start with nothing but an idea, an agitation, a compulsion, an irritation. That, plus a bumblebee's faith that it can fly. -- Hal Ackerman / Write Screenplays That Sell -- Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all) |
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