Atomic clock woes

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Atomic clock woes

Postposted on Sun Aug 04, 2013 6:21 pm

I have had several alarm clocks and just general clocks that are supposed to set themselves via the atomic clock signal. Not a single one of them works where I live here in Ohio. I live in a valley with several hills/ridges all around me. Any kind of signal has problems here, even cell phones will not work reliably unless you happen to have Sprint or one of the carriers that use Sprint towers. There is one Sprint tower about half a mile away on a hill top. Every one else is out of luck. :(

Any way I asked the phone tech that was here the other day if he knew why the atomic clock signal would not work here and he went off on a long explanation that ended up implying I did not have a clue what I was talking about since the atomic clock signal was supposed to be microwave and would work any where. I waited until he had fixed my internet issue then handed him a battery powered clock and some brand new batteries and asked him to get it to work. Twenty minutes later he handed me the clock and said he had to go. Of course the clock wasn't working. I did not press the issue but I had made my point. :evil:

So, any one have a clue why I can't get my clocks to work when everyone else says they should?
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 6:43 pm

Here in the Continental US, the National Bureau of Standards broadcasts clock synchro signals on the following frequencies/wavelengths:

Code: Select all
60 kHz          5 kilometers
2.5 mHz         120 meters
5.0 mHz         60 meters
10.0 mHz        30 meters
15.0 mHz        20 meters
20.0 mHz        15 meters


Even a quarter-wave antenna @ 20 mHz (quarter-wave being the last point of decent passive antenna efficiency compared to wavelength) needs to be a minimum of 3.75 meters long, and no wall clock has that. The clock signals are very long-wave and the tech talking about microwaves must have stuck his head into one. That said, long-wave signals usually propagate well over long distances regardless of terrain. Any chance your surrounding hills are iron mines or the like?
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 6:45 pm

Well, the tech was totally clueless, as it is not microwave at all. Microwaves are very directional, and are easily blocked (otherwise we'd all get irradiated by our microwave ovens). WWVB uses longwave radio, not microwave.

Based on the info at this page, I'd say you've probably got a local source of interference in the 60kHz band. Being inside a building with a metal roof and/or siding could also be an issue.

Edit: Per Ned, I imagine large deposits of iron ore in the surrounding hills could also be problematic.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 6:47 pm

You need something that can talk to your router and use netdate or something.

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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 7:02 pm

No metal walls or roof. As far as I know the hills are mostly just silt covered with dirt until you get down to water level and hit lime stone. The whole area was carved out by glaciers and the run off from glaciers thousands of years ago. The only iron around here is from abandoned farm equipment and cast off from two rail road tracks that are no longer there. Most of that stuff is slowly disappearing to the scrap yards in the area for some ready cash.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 8:28 pm

I remember buying an atomic clock years ago, and the manual stated that it would sometimes take up to a few hours to set itself, depending on signal strength. I would set it up and leave it for a while and come back later to see if it has made any progress.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 8:52 pm

I have a radio set watch, winch is able to set itself fine once a day (in Virginia) so antenna size apparently isn't an issue.

One thing to remember is that the signal will come though much, much stronger at night. (Radio clocks are often hardwired to try to set themselves to the radio signal on the hour for five hours after midnight to take advantage of this) In fact, the only time I've been able to get a synchronization signal in the middle of the day was in Colorado itself, where NIST broadcasts. So maybe it's a matter of when you're pressing the set button.

Local terrain and atmospherics will play a big role too, so you may just have bad geography. Another option might be a GPS clock, but you'll usually have to position an antenna so it gets sky coverage. For computers or anything net connected, yeah, just use ntp.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 9:04 pm

confusedpenguin wrote:I remember buying an atomic clock years ago, and the manual stated that it would sometimes take up to a few hours to set itself, depending on signal strength. I would set it up and leave it for a while and come back later to see if it has made any progress.


I have tried waiting it out with no luck. I have tried different rooms, floors, facing different directions, etc.

At this point it comes down to geography or interference of some type. Out side of some unknown iron ore vein it seems geography is not the likely culprit. Interference is possible but the only things I can think of that might cause it would be the cell tower or power lines in the area.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 9:17 pm

Khali wrote:At this point it comes down to geography or interference of some type. Out side of some unknown iron ore vein it seems geography is not the likely culprit. Interference is possible but the only things I can think of that might cause it would be the cell tower or power lines in the area.

Cell tower is a very unlikely culprit, because it operates at a much (many orders of magnitude) higher frequency.

Power lines operate at a much lower frequency. However, if these are high voltage transmission lines and there's any arcing I imagine the harmonics generated could conceivably interfere with the time signal. I know nearby power lines can sometimes mess with AM radio reception, so this may be your culprit... how close are these power lines, and are they high voltage transmission lines? If so, do you hear any buzzing coming from any of the the towers?

IMO it's also possible that you've just gotten very unlucky with the geometry of the valley you're in, and its orientation relative to the transmitter. Longwave is supposed to follow the contours of the Earth, but I wouldn't be surprised if there are some exceptions to this.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 9:43 pm

A bit of poking around (you got my curiosity going!) led me to this.

If you've got an attic, it sounds like it may be possible to put a cheap passive resonator up there which will improve reception of the 60 kHz WWVB signal for nearby atomic clocks. My knowledge of RF design is pretty limited, but there seem to be a couple of people on that thread who know what they're talking about.

Unfortunately, tuning the resonator properly is going to require some equipment you probably don't have (I'm guessing a signal generator and 'scope, at least). You wouldn't happen to be friends with a ham radio enthusiast or analog/RF engineer, would you?
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 10:11 pm

I've owned several of these things (still have one wall clock from LaCrosse left, mostly use it because of its exterior wireless temperature sensor), they are all pretty crappy in terms of build quality, reliability and susception to interference. I've seen some of them being unable to receive the signal at the same location where others worked fine, or (very often) stopping receiving the signal completely after few months. Just assemble your own table clock (there are few plans available online, some are using Nixie tubes to display digits) with an external GPS receiver or ask someone else to do it for you or buy one which can get time data over internet or something, you'll save a lot of time and frustration...
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 10:21 pm

Surely there are NTP-enabled clocks with WiFi for less than the $350 they're asking for the one PenGun linked? Crap, I can build an entire frikkin' PC for less than that! Nearly everyone has WiFi these days, it seems like this would be a no-brainer!
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 10:53 pm

just brew it! wrote:Surely there are NTP-enabled clocks with WiFi for less than the $350 they're asking for the one PenGun linked? Crap, I can build an entire frikkin' PC for less than that! Nearly everyone has WiFi these days, it seems like this would be a no-brainer!

That was the first on the google list. I'm sure there are cheaper ones.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 11:07 pm

Its not so much I want it to work. The problem is getting to be that any clock you look at while shopping has this as a feature and some you can't even set the time yourself. I see the day coming when a simple clocked will be dumbed down so people won't have to, or be able to, set the time.

New product designers focus on getting their products to work in high population area's like cities because that's where the most money is to be earned. Those of us that live in small towns and rural areas are a secondary thought, if we get thought about at all. It takes years for some things to make it out to these areas. The atomic clock signal is just a minor example.

I talked to a friend that lives in the closest town from here, two miles away in the same valley, and he can not get the signal either. I guess its a running joke in town that when the town wide garage sale day rolls around you can find one of these clocks for sale at about 75% of the garage sales.
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Re: Atomic clock woes

Postposted on Sun Aug 04, 2013 11:34 pm

PenGun wrote:
just brew it! wrote:Surely there are NTP-enabled clocks with WiFi for less than the $350 they're asking for the one PenGun linked? Crap, I can build an entire frikkin' PC for less than that! Nearly everyone has WiFi these days, it seems like this would be a no-brainer!

That was the first on the google list. I'm sure there are cheaper ones.

That wasn't really meant as a knock on your post; I was (at first) somewhat surprised that such a thing even existed, then taken aback when I saw the price. A simple alarm clock with NTP-over-WiFi capability would probably require about $20 in parts; granted this device does more than that, but still...

Khali wrote:Its not so much I want it to work. The problem is getting to be that any clock you look at while shopping has this as a feature and some you can't even set the time yourself. I see the day coming when a simple clocked will be dumbed down so people won't have to, or be able to, set the time.

New product designers focus on getting their products to work in high population area's like cities because that's where the most money is to be earned. Those of us that live in small towns and rural areas are a secondary thought, if we get thought about at all. It takes years for some things to make it out to these areas. The atomic clock signal is just a minor example.

Given that they are all driven by a single transmitter located in Colorado, I imagine coverage isn't much better in urban areas. If anything, there are more potential sources of interference and signal blockage. It's probably just a symptom of the race to the bottom in consumer electronics; they've done the bare minimum to ensure that the feature works as long as you're not in an area with weak signal.

And quite frankly, not letting you set the time manually is just brain-dead.

Khali wrote:I talked to a friend that lives in the closest town from here, two miles away in the same valley, and he can not get the signal either. I guess its a running joke in town that when the town wide garage sale day rolls around you can find one of these clocks for sale at about 75% of the garage sales.

Sounds like your valley is a WWVB dead zone.
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Re: Atomic clock woes

Postposted on Mon Aug 05, 2013 1:28 am

OK, for those interested I did some more research and finally found a answer. I talked to a cousin who is big into HAM radios and has been for years. From what I can tell by looking on the internet after talking to him, he has the right answer. He says that the atomic clock radio signal will only go about 1200 miles before weakening enough to lose the ground hugging feature. You can pick it up out to 2000 miles or so before it weakens to the point it would be useless. Past the 1200 mile point you would have to be on a flat plane or on a hill to pick it up reliably. The 1200 mile limit puts it right at the Illinois/Indiana state line. That puts me about 150 miles out side the reliable signal limit, living down in a valley is just the icing on the cake.

So if you live east of the Mississippi river chances are the signal will not be reliable. The farther east the worse it gets. If your close to one of the cities on the East coast your totally out of luck due to distance and interfering signals that come with high populated areas.

There were plans to build a second transmitter in the east at the Redstone Arsenal in Huntsville, Alabama, but it got quashed by the Marshall Space Flight Center objecting to having such a high power transmitter so near to their operations.
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Re: Atomic clock woes

Postposted on Mon Aug 05, 2013 2:04 am

Khali wrote:OK, for those interested I did some more research and finally found a answer. I talked to a cousin who is big into HAM radios and has been for years. From what I can tell by looking on the internet after talking to him, he has the right answer. He says that the atomic clock radio signal will only go about 1200 miles before weakening enough to lose the ground hugging feature. You can pick it up out to 2000 miles or so before it weakens to the point it would be useless. Past the 1200 mile point you would have to be on a flat plane or on a hill to pick it up reliably. The 1200 mile limit puts it right at the Illinois/Indiana state line. That puts me about 150 miles out side the reliable signal limit, living down in a valley is just the icing on the cake.

Looks like 1200 miles is actually more like the western edge of Ohio (not IL/IN state line), but yeah you're still gonna be borderline if 1200 miles is the limit for reliable reception.

Khali wrote:So if you live east of the Mississippi river chances are the signal will not be reliable. The farther east the worse it gets. If your close to one of the cities on the East coast your totally out of luck due to distance and interfering signals that come with high populated areas.

So basically they shouldn't be selling these things at all in the eastern part of the US. :roll:

Khali wrote:There were plans to build a second transmitter in the east at the Redstone Arsenal in Huntsville, Alabama, but it got quashed by the Marshall Space Flight Center objecting to having such a high power transmitter so near to their operations.

Seems to me you'd want it further east and north anyway. Better chance of cutting through all the interference on the east coast, and transmitting from Huntsville would still leave parts of Maine with marginal signal. Seems like somewhere in North Carolina or Virginia would be ideal.

Edit: If there's any signal at all at your house, the resonator/booster idea might still be feasible as a fix...
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Re: Atomic clock woes

Postposted on Mon Aug 05, 2013 8:39 am

My experience along the gulf coast is that these things will reset properly about one night in three. I prefer a Seiko quartz wall clock.
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Re: Atomic clock woes

Postposted on Mon Aug 05, 2013 8:52 am

Per Wackypedia:

WWVB's Colorado location makes the signal weakest on the U.S. east coast, where urban density also produces considerable interference. In 2009, NIST raised the possibility of adding a second time code transmitter, on the east coast, to improve signal reception there and provide a certain amount of robustness to the overall system should weather or other causes render one transmitter site inoperative. Such a transmitter would use the same time code, but a different frequency.

Use of 40 kHz would permit use of dual-frequency time code receivers already produced for the Japanese JJY transmitters. With the decommissioning of the Swiss longwave time station HBG at 75 kHz, that frequency is potentially also available.
Plans were made to install the transmitter on the grounds of the Redstone Arsenal in Huntsville, Alabama, but the Marshall Space Flight Center objected to having such a high power transmitter so near to their operations. Funding, which was allocated as part of the 2009 ARRA "stimulus bill", expired before the impasse could be resolved, and it is now unlikely to be built.

Two other possibilities were explored in 2012. One was to add a second transmission frequency at the current transmitter site. While it would not have helped signal strength, it would have reduced the incidence of interference and (frequency-dependent) multipath fading.

None of the ideas for a second transmitter were implemented.

Instead, WWVB added phase modulation to the WWVB carrier in 2012. This required no additional transmitters or antennas. The modulation scheme is broadly similar to that used by time signal station DCF77. A receiver that decodes the phase modulation can have greater processing gain, allowing usable reception at a lower received signal-to-noise ratio than the amplitude modulation time code. The scheme is more fully described in a later section in this article.


So maybe a newer receiver that groks this new phase modulation would get you a good enough signal.
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Re: Atomic clock woes

Postposted on Mon Aug 05, 2013 2:03 pm

Ya know when I had clocks they would keep pretty good time for years. I doubt any changed more than 5 minutes a year.

So why do you need the atomic clock accuracy? Your phone does netdate, or something very like, it and you could set any clocks that strayed quite easily.
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Re: Atomic clock woes

Postposted on Mon Aug 05, 2013 2:07 pm

For those in the US, direct access to the WWV broadcast is available by phone at 303-499-7111.
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Re: Atomic clock woes

Postposted on Tue Aug 06, 2013 12:25 pm

And in Canada the NRC holds Canada's official time with everything from web clocks to NTP to telephone to shortwave: http://www.nrc-cnrc.gc.ca/eng/services/ ... clock.html
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