"Atomic" setting clocks - work in Texas?

[MilDoc]

LOML wants a new alarm clock that projects on the ceiling. I'm a gadget freak and like the idea of the so-called "Atomic Set" clocks that are automatically set by time signal from Boulder, CO. But I wonder if we even receive the signal strong enough here? I have no idea.

Anyone have one? And how far are you from Boulder?

[Tom Slick]

mine works perfect in california

[Otter]

You should be fine, here is there coverage maps

http://tf.nist.gov/stations/wwvbcoverage.htm

These are the folks that run it.

[LinuxRandal]

While Colorado is the official location, I don't believe it is the only one. Empirical evidence, makes me believe between the time I bought my first one for home, and the ones I bought for work need to be reset from the eastern time zone, to the central time zone.

Location Independence MO


Some have problems inside of concrete and steel buildings, when not on an outside wall.

[Crash2510]

we have one that works in ohio can't see why texas would have a problem

[LCHIEN]

I have several here is Houston area, all work fine.
Some of them are "atomic" radio controlled analog-like clocks from Klock-It.com.

The radio frequencies used are long wave and travel long distances easily - broadcast from Colorado, I believe.

Every clock I've seen using the NIST radio transmission has to have the time zone told to it.
NIST I imagine only transmits GMT or as they call it now, UCT time.

[cabinetman]

We've got 'em here in South Florida, and they work fine...just a bit further than Texas. Ours says the signal is from Ft. Collins, Colorado.
.

[frumper64]

Works for me in Dallas

We have a couple of atomic clocks and they work just fine. Actually, I think I remember reading that the signal from Boulder is retransmitted on local radio frequencies around the country (public radio stations as I recall).

[LCHIEN]

here's probably mroe information than you want to know, describing how these clocks work:

http://tf.nist.gov/stations/radioclocks.htm

http://starbulletin.com/2005/08/21/news/kokualine.html

The're really radio controlled clocks, but the radio control is referenced to an atomic clock near Boulder, Colorado.
The data is transmitted on 60 KHz, which is way lower than the 600-1200 KHz for AM radio and the 88 Mhz to 108 MHz bands for AM and FM radio. They use enough power to cover the US lower 48... that band sends well over distances and skips well at night so its possible as noted, to receive it as far as south america, alaska and hawaii, at least once a day or two to keep your clock in sync within a second or so.

There are also a number of other ways to get NIST or Atomic referenced time.
One I used to use for DOS was a program that called a phone modem at NIST that sent time setting signals to your computer.
Local TV stations (usually PBS affiliated) send NIST time information over their broadcast channel and many later model VCRs were set up to receive and set this time to he VCR clock. (I suspect this is what Frumper was referring to).
The time is also broadcast over the internet and various private TCP/IP-based networks using what is called NTP - network time protocol. There are many programs to do this, many free or shareware. I have used Tardis 2000 (shareware), AboutTime (freeware) and others. If you have Windows XP, it already has an internet time protocol installed and made active by default, IIRC. You can point them at different time servers in the US and Europe maintained by different organizations and universities. Accuracy when Time setting this way depends upon your network delay variability as typically they measure delay and then use it to adjust the received time.

You can also set your time accurately to a GPS receiver, these clocks are atomic clocks in orbiting space satellites that are extremely accurate but still corrected to the NIST super accurate clock that is the national reference. Most GPS receivers have serial ports that allow connection to a PC and you can get the time set to your PC clock from this with appropriate software. These clocks are accurate to much better than 1 microsecond (about 50 nanoseconds is the value I seem to recall off the top of my head) and the time delay from the satellite to your GPS is part of the known values for GPS location so it can all be corrected out. In reality it takes your PC a few microseconds to receive and recognize the time synchronization so without special hardware it won't be that good.

[MilDoc]

Thanks again for the info folks!

Now, trying to decide which brand to get .....

[skipwill]

I have one that works just fine in central SC. Pretty far away from Ft. Collins Colorado, but never the less...it is 'on time'

Bought mine from Sams for around $25...It displays the Time, temp in and out, moon phase, and date. I am happy with it.

Skip

https://www.ShopFileR.com

[JR]

here's probably mroe information than you want to know, describing how these clocks work:

Loring, you've shown depth on a number of topics before, but this is the first time I've been surprised. This is a pretty esoteric field.

FWIW, and consistent the the theme of more than anyone wanted to know, the "atomic" in the atomic clock, or Primary Reference Source (PRS), at NIST uses Cesium (Cs) to achieve its accuracy. Cs, when heated, forms a gas. When light is passed though that gas in a vacuum chamber, only the portion operating at a specific frequency can be passed to detectors on the other side of the chamber. A local oscillator, connected via feedback loop to the Cs chamber for accuracy, provides the frequency which is then delivered using the variety of mechanisms (and others) described in Loring's post.

Loring, you may be interested to know that the delivery mechanisms may get another vehicle soon. PTP (IEEE-1588), heretofore used to coordinate robotics in MAP applictions, is going through a rev to make it appropriate for telcom applictions. in principle it should provide frequency translation in packet networks similar to the performance of GPS.

JR