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WWVB Celebrates 50 Years of Broadcasting Time

timothy posted about 10 months ago | from the signals-straight-to-my-watch dept.

Communications 97

First time accepted submitter doublebackslash writes "On July 5th, WWVB, NIST's timekeeping radio station transmitting near Fort Collins, will celebrate 50 years of continuous operation. Operating at 60kHz, the signal actually follows the curvature of the Earth via a trick of electromagnetics, allowing nearly the entire globe to receive an accurate time signal, which has in recent years reached an accuracy of 1 part in 70 trillion. Recent upgrades, which came in $15.9 million under budget will allow the station to be better received even in large buildings, giving it an edge on timekeeping that not even GPS can touch, with its need for open skies to receive a signal."

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97 comments

And (3, Informative)

ArchieBunker (132337) | about 10 months ago | (#44191165)

It also operates at 5MHz, 10MHz, 15MHz, and 20MHz.

Re:And (4, Informative)

Telecommando (513768) | about 10 months ago | (#44191195)

No, that's WWV on those frequencies.

Re:And (-1)

Anonymous Coward | about 10 months ago | (#44191239)

"Caves of steel... pickles are ants!" So... lately, you've been hearing a mysterious entity chant those words, but you're not sure where they're coming from? I've got bad news for you; that's a magical spell designed to tickle your ass! Major tickle on ass! Major tickle!

Re: And (4, Informative)

jrmcferren (935335) | about 10 months ago | (#44191659)

WWVH also operates on those frequencies. It is possible to hear both at the same time with good conditions and a good antenna. As a user of HF spectrum this is a valuable resource.

Re: And (1)

denelson83 (841254) | about 10 months ago | (#44192697)

WWVH doesn't operate on 20 MHz. WWV and WWVH also broadcast on 2.5 MHz, though.

Re: And (1)

RabidReindeer (2625839) | about 10 months ago | (#44194329)

WWVH doesn't operate on 20 MHz. WWV and WWVH also broadcast on 2.5 MHz, though.

Although the exact set of frequencies used has changed over the years.

TFA completely ignored that CHU Canada also broadcasts time signals. It's not a US monopoly, even if the NIST clocks are probably the world's most accurate. CHU broadcasts on 7.333 MHz, and I think on 14.666.

WWVB is unique, however, in that it is tailored for reception and decoding by automated time-tracking equipment. The WWV and CHU stations provide voice data.

TFA is also spouting nonsense about WWVB being something only good for toys. I have several bits of weather station gear that use it for time tracking. Which not only allows them to display a time-of-day clock, but also makes for better logging of weather events.

Re: And (1)

Muad'Dave (255648) | about 9 months ago | (#44217955)

I'm fairly certain that CHU [wikipedia.org] has moved from 7333 kHz to 7850 kHz. It also transmits on 3330 kHz and 14670 kHz.

WWV and WWVH also have digital-compatible subcarrier signal formats [wikipedia.org] , BTW.

Re: And (1)

RabidReindeer (2625839) | about 9 months ago | (#44223695)

I'm fairly certain that CHU [wikipedia.org] has moved from 7333 kHz to 7850 kHz. It also transmits on 3330 kHz and 14670 kHz.

WWV and WWVH also have digital-compatible subcarrier signal formats [wikipedia.org] , BTW.

As you might have guessed, I don't switch on the shortwave that often these days.

I think Japan also broadcasts time signals. Not sure what other countries do, though.

Re: And (1)

Muad'Dave (255648) | about 9 months ago | (#44224107)

Then this discussion might be the impetus for you to switch on and have a listen! There's still an awful lot of interesting-tending-to-weird stuff on HF these days. If you have an SSB-compatible receiver, you can listen in on amateur radio folks working the world. The US version of the bands we use are listed here [arrl.org] in several formats - they're mostly representative of ham usage worldwide.

Re: And (1)

RabidReindeer (2625839) | about 9 months ago | (#44226097)

Then this discussion might be the impetus for you to switch on and have a listen! There's still an awful lot of interesting-tending-to-weird stuff on HF these days. If you have an SSB-compatible receiver, you can listen in on amateur radio folks working the world. The US version of the bands we use are listed here [arrl.org] in several formats - they're mostly representative of ham usage worldwide.

I've got my own impetus. It's Hurricane season! WX4NHC 14.325Mhz.

Re:And (2, Funny)

Anonymous Coward | about 10 months ago | (#44192699)

.. and the programming seems way too predictable.

Not to mention the overuse of dead celebrities (0)

Anonymous Coward | about 10 months ago | (#44194133)

Both Mike Wallace and Jane Barbie are now long dead, but their voices will continue on the airwaves 24/7 until either the United States collapses, or world war 3 destroys the transmitters.

Re:And (1)

Anonymous Coward | about 10 months ago | (#44193581)

National Institute of Standards and Technology time: this is Radio Station WWV, Fort Collins Colorado, broadcasting on internationally allocated standard carrier frequencies of two-point-five, five, ten, fifteen, and twenty megahertz, providing time of day, standard time interval, and other related information. Inquiries regarding these transmissions may be directed to the National Institute of Standards and Technology, Radio Station WWV, 2000 East County Road 58, Fort Collins, Colorado, 80524.

Sometimes I tune my shortwave radio to 5 or 10 MHz just to listen to WWV click away. It's kind of relaxing, and makes me think about things. The electronic clock ticking. It just goes on forever and ever like the heartbeat of civilization.

I actually have kind of an obsession with WVV. I was at the transmitter site a couple years ago, nerding the fuck out and taking pictures like a giddy school girl.

You'd (5, Funny)

JustOK (667959) | about 10 months ago | (#44191209)

You'd think they'd be a bit more accurate than just "On July 5th"

Re:You'd (1)

AmiMoJo (196126) | about 10 months ago | (#44192885)

Speaking of accuracy their claims are somewhat misleading. Their reference atomic clock is that good but if you receive the signal you aren't going to get 1 part in 70 trillion.

It's a very useful service, don't get me wrong, but for accuracy GNS is the best option at the moment.

Re:You'd (0)

Anonymous Coward | about 10 months ago | (#44193185)

July 5th is accurate. You probably meant more precise.

I implemented a teensy WWCB transmitter once (5, Interesting)

Clueless Moron (548336) | about 10 months ago | (#44191261)

Some 15 years ago, when they were at their original low power, my area was so fringe that my fancy new WWVB wristwatch just wouldn't pick it up.

The protocol is really quite straightforward and well documented at their site. The 60kHz signal sends binary by sending either full power or a bit less (I forget how many dB). I used a computer synced with NTP and a plain old soundcard generating 60kHz from a sound card into an audio amp, and I just did either full on or full off. The output ran into a big coil that I had wound to be roughly resonant around 60kHz.

Much to my amazement, it worked. So I just kept the watch near that coil overnight and it synced perfectly, until WWVB cranked up their power at which point I retired the mess.

Re:I implemented a teensy WWCB transmitter once (2)

tjp (264994) | about 10 months ago | (#44191453)

How did you manage to have a "plain old soundcard" that could put out 60kHz? Since human hearing tops out at 20kHz, standard sound cards have a maximum sampling rate of 48kHz, so there's no way you could get more than 24kHz out of that. Perhaps whatever aliased frequency did come out happened to produce enough resonance at 60kHz to satisfy the receiver?

Re:I implemented a teensy WWCB transmitter once (1)

viperidaenz (2515578) | about 10 months ago | (#44191581)

Perhaps it was a 192khz sound card.

Re:I implemented a teensy WWCB transmitter once (1)

ArchieBunker (132337) | about 10 months ago | (#44191645)

192KHz sampling rate. Maybe the DAC is capable of outputting a 60KHz signal? Although the I/V converter stages usually do some low pass filtering.

Re:I implemented a teensy WWCB transmitter once (1)

Clueless Moron (548336) | about 10 months ago | (#44194723)

Whether it was low pass filtering or just the card being at its limits I don't know, but the output was really quite weak. That's why I needed an audio amp. A 40W amp, no less. Since the audio amp wasn't designed for 60kHz either, the output still wasn't all that strong, but it was good enough for the watch to pick it up sitting next to the coil.

Re:I implemented a teensy WWCB transmitter once (3, Interesting)

Clueless Moron (548336) | about 10 months ago | (#44191655)

This one could, and I don't claim to know why. But I saw it clearly on my oscilloscope: 60kHz.

Actually it wasn't exactly 60kHz, it was 59 point something because of quantization according to a frequency counter, but apparently it was close enough to keep the watch happy.

Re:I implemented a teensy WWCB transmitter once (1)

Anonymous Coward | about 10 months ago | (#44191897)

It's simple. People who say they did things that are demonstrably false, never did that thing, they just imagined they could, after some time has passed, they retell it as if they had.

Anyway it is possible with something like an M-Audio 192, which has a 192kHz sampling rate, but it would be much less expensive to drive an oscillator like a 555 from your parallel port. Not that I've tried.

Re:I implemented a teensy WWCB transmitter once (0)

Anonymous Coward | about 10 months ago | (#44192673)

I have customers who record 192 kHz audio, It is a very basic sample frequency these days.
I know one customer who records bats, another customer uses it for recording sound effect, both valid reasons to record at a high sample frequency.

Every observatory was tuned in. (0)

Anonymous Coward | about 10 months ago | (#44191305)

I remember listening to it echo around the domes back in the '70s when I was a kid first starting out in astronomy. A lot of modern observatory warmrooms have radios still tuned in, but often it's as much for nostalgia's sake as anything. But it will always evoke fond memories of long, cold, dark nights at the telescope for me.

Nearly the entire globe- except not really (4, Informative)

markdavis (642305) | about 10 months ago | (#44191311)

>"Operating at 60kHz, the signal actually follows the curvature of the Earth via a trick of electromagnetics, allowing nearly the entire globe to receive an accurate time signal"

Except it doesn't. It depends on time of day, weather, season, exact location, how much local interference, building construction, elevation, and many other factors.

I really WISH it were as strong and wonderful as implied in the summary, but it is not. I have used radio controlled, WWVB clocks for many years and one thing they are NOT is "reliable", at least not where I live. Of the dozens of clocks I have used over 20+ years, NONE of them could get a reliable signal anywhere I have lived in the Mid Atlantic coast of the USA.

I am lucky to have it sync several nights in a row and then go weeks without a signal (sometimes even a month). Unfortunately, none of the clocks I have seen will store a step adjustment, so they drift just like any other quartz clock- some are even worse than just a cheap $15 non-radio-controlled clock.

Having to constantly set and sync clocks on everything (except my computer equipment and SOME of the radio clocks) is really annoying in 2013. With all that freed up VHF TV, why couldn't the government have set aside just a tiny blip that could be used for another time sync that could penetrate buildings and work in the daytime and regardless of weather?

Oh well. WHEN it works, it is nice.

Re:Nearly the entire globe- except not really (2, Interesting)

Anonymous Coward | about 10 months ago | (#44191543)

The problem I have is there's no error correction/checksum -- the signal is binary-digit encoded, so it's possible to get a clock that think it's synced but is off by X hours or X minutes or X seconds while otherwise thinking that all is well. This isn't a big problem on smarter systems that continuously monitor the signal but most wall clocks/etc. only check from time to time so they can spend 12 hours thinking it's another time entirely. This isn't incredibly common because the signal is 1 bit per second, so it's pretty robust even at low strength, but it does happen.

The German version of radio timekeeping includes a checksum to avoid these issues. Then again, their version requires a lot more math to calculate the date, and only uniquely identifies dates within like a 200-year range (which sounds like a long time, but it short enough that you can get into trouble with hard-coded assumptions).

There is error checking now. (1)

Anonymous Coward | about 10 months ago | (#44194271)

Nist revised the WWVB format, it now carries two time signals on the same carrier. The enhanced time signal encodes the date/time as a 26 bit number with 5 parity bits. Absolutely foolproof, no, but there is now error checking for clocks that support this new format.

Re:Nearly the entire globe- except not really (1)

Anonymous Coward | about 10 months ago | (#44191593)

Let's see... 60kHz is Low Frequency: approximately a wavelength of 5km.

Very High Frequency: 30-300MHz: a wavelength between 10m and 1m.

NIST would have to set up transmitters for your VHF time source all over the freaking place.

Re:Nearly the entire globe- except not really (1)

markdavis (642305) | about 10 months ago | (#44192169)

Yes, I know. There would have to be a presence at nearly every TV station. Or they could use a tiny bit of UHF and get the TV stations to do it for them. At lest it would then get "everywhere" in each market.

Either that, or add an a single 60Hz east coast transmitter and alternate transmissions every minute between the two.

Re:Nearly the entire globe- except not really (1)

Anonymous Coward | about 10 months ago | (#44192307)

They do. They're called GPS satellites.

Re:Nearly the entire globe- except not really (4, Informative)

Trepidity (597) | about 10 months ago | (#44191623)

Indeed they don't even claim anything close to worldwide coverage themselves. Here are their estimated coverage maps [nist.gov] .

Re:Nearly the entire globe- except not really (0)

Anonymous Coward | about 10 months ago | (#44191763)

Yeah, I'm in south Florida (near Ft. Lauderdale), and it's dicey at best during the spring and summer.
IOW, my putative "atomic clock" doesn't display the icon signifying that it's re-synced in the previous 24h.

But, that's OK, I can just put my receiver on 5 or 10 MHz, depending on the time of day and the weather,
and get the real story from WWV.

In any case, I'm glad I can still rely on both WWV and WWVB to be there for us.

Re:Nearly the entire globe- except not really (2)

Jaruzel (804522) | about 10 months ago | (#44192661)

I'm pretty sure, that outside of the US, Joe Public doesn't even know WWVB exists, which is a shame as a single standard global time signal (back in the day) would have been kinda cool.

Here in the UK we have something similar (even runs on the same frequency):

http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-radio-time-signal [npl.co.uk]

http://en.wikipedia.org/wiki/Time_from_NPL [wikipedia.org]

It's referred to as the 'Rugby clock'.

-Jar

Re:Nearly the entire globe- except not really (1)

Anonymous Coward | about 10 months ago | (#44192971)

I see, "world" as in "World Series".

Re:Nearly the entire globe- except not really (0)

Anonymous Coward | about 10 months ago | (#44194193)

What -- you expected accuracy from "timothy"?!? N00B!

Re:Nearly the entire globe- except not really (0)

Anonymous Coward | about 10 months ago | (#44191919)

The problem is not setting aside spectrum. When you suggest VHF, you are pretty much requiring that they setup a nationwide network of relays to distribute this time signal and all the difficulties in maintaining and calibrating this system.

They use these low frequency carriers as it lends itself well to wide area regional broadcasts, being not line-of-sight and groundwave carried.

What you propose wouldn't solve the problems you have had with clocks that don't implement the complete WWVB protocol, nor would it solve your problems with lack of sync, which are most likely caused by poor grounds on your receivers. Moreover, it would be yet another time protocol that would continue to frustrate you as device manufacturers neglect to incorporate it, or implement it incorrectly.

Re:Nearly the entire globe- except not really (1)

dj245 (732906) | about 10 months ago | (#44192003)

I have used radio controlled, WWVB clocks for many years and one thing they are NOT is "reliable", at least not where I live.

It occurs to me that if the signals have almost no chance of reaching China according to the coverage maps, the factory making these things is probably just guessing if it works or not.

Even if they have some sort of signal generator mockup, it would seem to be difficult to replicate exact local conditions in the USA.

Re:Nearly the entire globe- except not really (4, Informative)

Ozoner (1406169) | about 10 months ago | (#44192167)

> It occurs to me that if the signals have almost no chance of reaching China

As you say it would be trivial for the manufacturer to build a WWVB test generator,

however there are multiple alternatives to WWVB around the world.
Many clock chips can switch to an alternative signal if WWVB isn't audible.
http://www.cl.cam.ac.uk/~mgk25/time/lf-clocks/ [cam.ac.uk]

FWIW, I can hear WWVB in Australia, although I do need an outside antenna.

Re:Nearly the entire globe- except not really (0)

Anonymous Coward | about 10 months ago | (#44192223)

Looking at http://www.nist.gov/pml/div688/grp40/vb-coverage.cfm I see it covering the Americas but not much else.

Captcha: teletype

Re:Nearly the entire globe- except not really (0)

Anonymous Coward | about 10 months ago | (#44192589)

The worst part of it is, even when getting signal, the clock will sometimes sync up incorrectly due to noise or interferance. I have several such clocks and it isn't surprising to see them all agree except for one which might be exactly 20 minutes off (or an hour, or any other one-digit error).

Which makes it completely unsuitable for use as an alarm clock. "Sorry I'm late, but I'm actually early according to my clock" doesn't go over well with most bosses.

But I mostly fault the clock makers for this problem. If a clock is otherwise keeping reasonable time and the receiver suddenly thinks the time is 8 hours different than what's on the display, the correct response should be "let's go retry that" instead of "load the grossly incorrect values and keep ticking".

Re:Nearly the entire globe- except not really (1)

markdavis (642305) | about 10 months ago | (#44193773)

Thank you for that wonderfully informative post! I thought I was crazy when one of my clocks syncs and it is exact 20 minutes TO THE SECOND off. It is probably a flipped bit and without any checksum, there you have it.

I agree with you also on the last part- it is not like it would be difficult to build a little smarts into a clock so it will reject something that seems wrong and try again. Also, if it would just store a step adjustment, it could, theoretically, "learn" to tell correct time to within one second per year, even without syncing for a year.

Re:Nearly the entire globe- except not really (1)

Phreakiture (547094) | about 10 months ago | (#44193763)

With all that freed up VHF TV

What freed up VHF TV? My area has more VHF channels post-digital than it did before. Locally, channels 6, 13, 23 and 51 are all on VHF (RF channels 6, 12, 7 and 13, respectively).

Re:Nearly the entire globe- except not really (1)

markdavis (642305) | about 10 months ago | (#44193791)

Most stations in most areas of the USA moved to UHF during digital conversion. Even in your area, you have only 4 stations on 13 VHF channels, leaving 9 free.

Re:Nearly the entire globe- except not really (2)

Phreakiture (547094) | about 10 months ago | (#44193833)

There are 12, actually (there is no channel 1) but you are right. There are 8 vacant. I suppose something could be done there, provided some care was taken to ensure that it also didn't interfere in adjoining markets.

One thought that I've been playing with lately is the idea of putting very narrowbanded signals into channel boundaries. WWVB's signal is extremely narrow banded, having a theoretical nyquist frequency of 0.5 Hz (though the reality is probably a bit broader due to modulating square waves onto the carrier). I suppose you could put something like this on the boundary between channels without it causing too much havoc.

Channels 2-4 are contiguous; 5 and 6 are adjacent, and channels 7-13 are contiguous. That looks like 9 inter-channel boundaries that could be used for this.

On a side-note, I am very tired of the misinformation being spread that all digital TV is UHF. It isn't even close. Some folks get this, but instead misunderstand that all digital TV is VHF-high or UHF. That's closer, but still wrong. The only part of the band that has been deprecated is the top of UHF (channels 52-69 were removed), which has been reallocated for two-way usage. That's kind of why I jumped in initially.

Re:Nearly the entire globe- except not really (1)

markdavis (642305) | about 10 months ago | (#44194269)

If you saw my other post, I think another suitable idea would be to have a second, east coast transmitter and then have it alternate transmission with the west coast transmitter every minute or so. That way we could retain compatibility with all existing equipment and yet have MUCH better coverage.

About TV- yeah, I know what you mean.

Accuracy... (4, Informative)

msauve (701917) | about 10 months ago | (#44191321)

WWVB time propagation isn't accurate to 1.4 e-14, as stated. The souce might be, but propagation delays and variability make it so you can get nowhere close to that upon reception. GPS is better in all respects, other than perhaps reception in some particular locations.

Re:Accuracy... (2, Interesting)

Anonymous Coward | about 10 months ago | (#44191579)

The broadcast signal is that accurate. And even the received signal is that precise, given a stationary receiver. So baring multi-path issues (which are detectable) you can do a one-time calibration for your local propagation delay to make your local accuracy match your precision.

Moreover, they also provide a frequency reference, in addition to the time signal, so you can do your time timekeeping just by counting peaks. Such references are immune to propagation delay (though not to Doppler effects, if your receiver is mobile) as they do not encode specific point-in-time data.

Re:Accuracy... (1)

whizbang77045 (1342005) | about 10 months ago | (#44193923)

Precise, yes. Accurate, no. Propagation varies all over the place. I doubt any two places on earth are ever able to get exactly the same time. Close enough for all practical purposes, yes. Exact, no.

Re:Accuracy... (3, Interesting)

ClickOnThis (137803) | about 10 months ago | (#44191595)

You do have a point.

Given that light travels about 0.3 m in one nanosecond, a variation in the signal path-length of about 300 m would induce a smudge on the arrival-times of about a microsecond. Realistic path-length variations could no doubt be larger, and could vary over a time-period of minutes or hours, depending on ionospheric conditions. This would of course be much larger than the inferred time-accuracy of 1.14e-14 s in the single second between each broadcast 'tick'.

However, GPS [wikipedia.org] is subject to the same vagaries of ionospheric conditions, as well as error in signal-interpretation. It has a theoretical accuracy of 14 ns, but more typically it is 100 ns.

No doubt the received accuracy of both WWVB and GPS could be improved by frequently collecting and applying the appropriate ephemera corrections for a given geographical location.

Re:Accuracy... (1)

ClickOnThis (137803) | about 10 months ago | (#44191649)

Whoops, sorry for responding to my own post, but I forgot to add that light travels only about 4 micrometres in 1.4e-14 s, and it's not hard to imagine that the signal-path varies by much more than that in a single second, even for a relatively quiet ionosphere. So yes, you can't get the full benefit of WWVB's accurate clock on a second-by-second basis.

Re:Accuracy... (4, Informative)

msauve (701917) | about 10 months ago | (#44191851)

The claim was "allowing nearly the entire globe to receive an accurate time signal..."

Even with no path length variation, good luck determining the path length to any specific location to micrometers in order to correct for the delay. Good luck doing so even within 15 meters (50 ns).

Using long term averaging, one might get frequency accuracy close to the claim, but not time (unless you have a hydrogen maser, I suppose). GPS is the best global time time distribution system available. If you look at BIPM Circular T [bipm.org] , even national time labs have a hard time tracking UTC within 100 ns over a month. So, if you get GPS time accurate to 50 ns, (which is base off UTC(USNO), you're doing well.

The other factor is that the time isn't actually known until after the fact - UTC is a weighted average. UTC(NIST) [bipm.org] , which is what's being broadcast, can differ by ~4e-8/s (~40 ns) from the actual time, a billion times worse than the claim.

Re:Accuracy... (0)

Anonymous Coward | about 10 months ago | (#44192725)

Exactly what keep GPS from having exactly the same issues you talk about here.

Also note that the ground waves from a 60 kHz signal has a pretty stable path, and accurately determining your path length is not entirely implausible. It's not trivial, but it's at least as easy as with GPS.

And of course having a stable frequency reference is as good as having a stable time signal, so long as you know what time it is when start hearing the signal.

Re:Accuracy... (0)

Anonymous Coward | about 10 months ago | (#44192313)

Actually, ground-wave path length doesn't change all that much. Ionospheric skipping (multipath) does, but at 60 Khz, you can receive a ground wave a pretty darn long way, and you can detect the multipath, too, and ignore it. That's what was done under LORAN (at 100 Khz), and it worked pretty darn well, and was generally more repeatable in its fixes than GPS.

Re:Accuracy... (3, Interesting)

pe1chl (90186) | about 10 months ago | (#44192857)

For some time I plotted the jitter of reception of DCF-77 (a similar transmitter in Germany) and I found there was a clear cycle of increase and
decrease of the jitter of the pulses output by my receiver (measured over one minute) over the day.
At daytime the jitter is around 20us, at nighttime it is more like 200us.
This is most likely explained by path length variations that apparently are depending on propagation.
(although texts about such transmitters often boast that there is no propagation effect like the one seen at shortware at those frequencies)

The claimed accuracy is of course at the source, and maybe when you started receiving WWVB years ago and perform some kind of averaging
over a long interval, you could eventually get an accuracy like that, but there is no way it can be achieved over short intervals, let alone for
individual second pulses.

Re:Accuracy... (0)

Anonymous Coward | about 10 months ago | (#44194241)

You corrected for temperature effects on your end?

Re:Accuracy... (1)

Shirley Marquez (1753714) | about 10 months ago | (#44199957)

One of the good things about WWVB is that propagation delays on LF (60 KHz) are much more predictable than propagation delays on the HF frequencies used by WWV. Once you correct for the speed-of-light delay for the distance between you and Fort Collins, WWVB results are highly accurate and repeatable. WWV timing is much more variable, as the signal can get to you by a variety of paths involving one or more bounces off the ionosphere, and the height of the ionosphere layer also changes.

Re:Accuracy... (1)

msauve (701917) | about 10 months ago | (#44200597)

"Once you correct for the speed-of-light delay for the distance between you and Fort Collins, WWVB results are highly accurate and repeatable. "

But the only way to do that is to have a better time source to begin with. And if you have that, why do you need WWVB?

Re:Accuracy... (1)

Shirley Marquez (1753714) | about 10 months ago | (#44208901)

You don't need a better time source. You just need to know the distance to Fort Collins. That can be easily calculated, and there are web sites that will do it for you. Terrain might cause slight variations in propagation but that is a very small effect; few users are likely to need a degree of precision high enough to require measurement of the exact path delay.

1 peak per... (0)

Anonymous Coward | about 10 months ago | (#44191387)

This is not a chemical solution. Accuracy of time or frequency is measured in peaks per million/billion/trillion, etc.

GPS Time (0)

Anonymous Coward | about 10 months ago | (#44191425)

And since GPS satellites carry their own atomic clocks, nearly all of today’s time and frequency needs are served from space. For proof, look no further than the phone in your pocket, delivering time beamed down from orbit.

Ah, no. The phone in my pocket, as with millions of others, gets its time from the teclo's network. Which is why it jumps forward an hour every year when daylight savings starts - despite our state not observing daylight savings. At least they get around to fixing it two or three days later. Every year, like clockwork. You'd think they'd learn. Good on you, Telstra! :P

Re:GPS Time (0)

Anonymous Coward | about 10 months ago | (#44191477)

Hahahaha, stupid Queenslanders.

Re:GPS Time (1)

GumphMaster (772693) | about 10 months ago | (#44191511)

Ah, no, it's the muppets at Telstra who clearly don't come from Queensland, Western Australia, or the Northern Territory.

Re:GPS Time (0)

Anonymous Coward | about 10 months ago | (#44191939)

Ironically if it is a UMTS or LTE handset, the network protocol includes a timecode which provides UTC at better resolution (not accuracy) than GPS L1, for syncing slot transmit times. Despite this being an accurate timebase (with no guarantee of accurate offset), I have not seen any handsets which use this received timebase for keeping the clock synchronised. This in spite of having to continuously receive this signal to receive incoming handshakes.

Software Defined Radio & WWVB? (2, Interesting)

Anonymous Coward | about 10 months ago | (#44191635)

So anyone here tried using a software defined radio setup to receive and decode the WWVB signal?

Re:Software Defined Radio & WWVB? (2)

dohzer (867770) | about 10 months ago | (#44191647)

Exactly what I was wondering. I think you'd need a special devices or add-on module capable of receiving such low frequency signals.

Quotation in summary come from.... (?) (1)

ebob (220513) | about 10 months ago | (#44191707)

Is it too much to expect the quotation in the summary to actually come from the linked article? In part it says "Recent upgrades, ... will allow the station to be better received even in large buildings." My curiosity was piqued. What were these upgrades? Not only was there no explanation in the Wired article, none of the text quoted in the summary seems to appear in the article. WTF?

Re:Quotation in summary come from.... (?) (2)

msauve (701917) | about 10 months ago | (#44191929)

NIST changed the broadcast format to include some phase modulation [nist.gov] .

Re:Quotation in summary come from.... (?) (1)

Agripa (139780) | about 10 months ago | (#44195641)

Besides the new format breaking existing receivers that use a phase locked loop to decode the signal, Xtendwave, who may have had prior inside information, has patents covering the new format.

accuracy (1)

manu0601 (2221348) | about 10 months ago | (#44191865)

I wonder how is it measured. Anyone knows?

Quite the understatement (3, Insightful)

nedlohs (1335013) | about 10 months ago | (#44191965)

" $15.9 million under budget"

Sure that'd be be a nice change for some billion dollar government project - to run a little under instead of doubling the budget,

But this was a budget of $16 million...

Re:Quite the understatement (0)

Anonymous Coward | about 10 months ago | (#44193943)

The project was not "Under budget" They were given a grant of 16 million to enhance the system and only used 100K. They were nice enough to save the taxpayer 15.9 million. Most government agencies would have used the entire amount then included that 16 million in their next years budget.

Re:Quite the understatement (1)

nedlohs (1335013) | about 10 months ago | (#44194939)

Using less than the grant is what "under budget" means.

They were given X dollars and told to do Y. Thus X is the "budget" for Y. In this case they did Y but spent less than X. That's what we call "under budget".

But yes, hopefully no one actually proposed what they did would cost $16 million. Or if they did, hopefully that person now has a job in which they do not do budget estimates.

New format of encoding (0)

Anonymous Coward | about 10 months ago | (#44191969)

From a posting on another list.

new WWVB phase modulation format:
        http://tf.boulder.nist.gov/general/publications.htm (search for Bin Number "2591")

Also of interest, a company contracted to help with the development will have silicon (and patents) at some point:
        http://www.xtendwave.com/xtendwave-awarded-grant-for-atomic-clock-enhancements.html
        http://www.xtendwave.com/atomictimekeeping.html

never heard of WWVB (-1)

Anonymous Coward | about 10 months ago | (#44191985)

not sure why i would use it. my cell phone gets the time from the cell tower, i think. and my netbook automatically gets its time from the internet. i have no need for WWVB. never heard of 60 khz before. guess that is near the AM broadcast band. my radio doesn't go below 530 KHz or so. I never listen below FM anyways.

but thanks for posting the article.

Re:never heard of WWVB (-1)

Anonymous Coward | about 10 months ago | (#44192599)

Hint, even less fucks are given about what you do or don't do. Pot calling kettle black?

Re:never heard of WWVB (0)

Anonymous Coward | about 10 months ago | (#44193615)

Why are you on /. then you fucktard? Go back to /b/

How Accurate? ... Right (1)

theshowmecanuck (703852) | about 10 months ago | (#44192197)

the signal actually follows the curvature of the Earth via a trick of electromagnetics, allowing nearly the entire globe to receive an accurate time signal, which has in recent years reached an accuracy of 1 part in 70 trillion.

An accuracy of 1 part in 70 trillion. Yeah. Maybe right at the clock they use. But people setting their clocks by it live a distance from the station. And the speed of the radio waves is finite. So the further from the station the less effectively accurate the signal is (people don't measure the exact distance they are from the source so they can't know the real time when they get the signal). The time to receive could be a second or two behind the real time for someone receiving on the far side of the earth. So how does touting their supreme accuracy reflect on actuality? Not well. I wonder if it is worth creating a super duper accurate time keeping service that can't be received accurately.

Re:How Accurate? ... Right (1)

tlhIngan (30335) | about 10 months ago | (#44192501)

So the further from the station the less effectively accurate the signal is (people don't measure the exact distance they are from the source so they can't know the real time when they get the signal). The time to receive could be a second or two behind the real time for someone receiving on the far side of the earth. So how does touting their supreme accuracy reflect on actuality? Not well. I wonder if it is worth creating a super duper accurate time keeping service that can't be received accurately.

You know, if you wanted, you could compensate for the propagation delays - given your location is fixed relatively to the station, you can just add or subtract the difference.

The famous Heathkit WWV (not WWVB) clock, the GC-1000, actually has dip-switches that sets propagation delays. Though, granted, when it's in "Hi-Spec" mode (meaning the internal oscillator and the receiver are in sync) you only get sub-100ms accuracy. (It tunes its internal oscillator around 3.6MHz until the CPU runs at precisely a multiple of the received signal, given a damn accurate 3.6MHz signal)

Re:How Accurate? ... Right (4, Insightful)

techno-vampire (666512) | about 10 months ago | (#44192739)

The time to receive could be a second or two behind the real time for someone receiving on the far side of the earth.

No, it can't. The Earth's circumference is about 25,000 miles, which means that nothing can be more than 12,500 miles away by the shortest route. Considering that the speed of light is roughly 186,000 miles/second, the maximum propagation delay is about 67.2 ms.

Re:How Accurate? ... Right (1)

expatriot (903070) | about 10 months ago | (#44193655)

If you want a frequency standard, instead of knowing what UTC is "now", you can use the chroma signal from broadcast TV. The big stations use atomic clocks as a reference.

I own a clock (0)

Anonymous Coward | about 10 months ago | (#44192289)

I own a clock that is tuned to one of those frequencies. I besides the broadcast signal that I can listen to on the shortwave radio, the clock receives and decodes the BCD encoded broadcast [nist.gov] which means that the little AA battery is all I need; that and telling the clock the year, and my time zone. Everything else, the day, date, day of the week, the hour, minutes and seconds it sets itself, and keeps itself set accurately to less than a second. All I need is to attach a little arduino to it with an NTP encoder and I can have a stratum 1 NTP server. The clock cost me twenty bucks (very cheap!)

Re:I own a clock (2)

jabuzz (182671) | about 10 months ago | (#44193723)

You don't even need that, you can just use an appropriate ferrite rod and decoder board with a handful of discrete components and hook it up to a serial port.

http://www.buzzard.me.uk/jonathan/radioclock.html [buzzard.me.uk]

It uses what I call the Woz method, aka minimal hardware, do it in software. You will actually get a better result using that method as well because the computer is capturing the timestamps of the signal edges directly without it going through some intermediate process.

One day I will get around to doing the super noise filtering version using Baysian statistics. Basically the more accurately you already know the time the more you can filter the noise out of the signal.

WWV and NSA crypto (2)

nsaspook (20301) | about 10 months ago | (#44192701)

We had several KWR-37 devices that needed time sync to under one second worldside with the transmitting station when changing daily key cards. WWW()x was great until you where some where past SE asia, then we used the Russia time sync RWM to lock devices,
http://en.wikipedia.org/wiki/RWM [wikipedia.org]
http://en.wikipedia.org/wiki/KW-37 [wikipedia.org]
http://www.nsa.gov/public_info/_files/uss_pueblo/Section_V_Cryptographic_Damage_Assessment.pdf [nsa.gov]

Syncing Seismographs (2)

mardigras (792150) | about 10 months ago | (#44195829)

Back in the early 1980's, my group used the Heathkit radios to synchronize portable seismographs. "At the tone, the time will be..."
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