is the atomic clock off by 1 hr now because of the early time change?

[flashy bazook]

I have a hand watch that checks the signal from the atomic clock in Colorado every night and re-sets itself if it is off.

For some reason, it couldn't get the signal for a couple of nights around the early change of clocks to the summertime schedule. So I manually put the time 1 hr ahead.

All of a sudden (last night and the night before) the watch manages to catch the signal.

And, what happens? It sets itself at the wrong time - 1 hr earlier!!

So does this mean the early change in the summertime changeover in the time schedule has messed up the atomic clock in Colorado?

(or is there something happening to cause my own watch to misinterpret the signal!).

 

[jtice]

I had one computer here at work switch back also,
I was thinking it might have been the Atomic time doing that.
You would think they would be on top of things.

~John

 

[Starlight]

All 3 of my clocks reset on Sunday morning. One clock then switched back the next day, and reset again the following day. All 3 are correct now. I have had one of them do the same type thing a few times before. I think they just get a poor quality signal sometimes and then you get discrepancies.

 

[JohnK]

Mine advanced perfectly for the change.

 

[matrixshaman]

I think your atomic clock is having a reception problem or otherwise. My atomic clock had already changed to Daylight time by itself on Sunday evening - several hours ahead of the official change. And it is still correct now for the new daylight savings time.

 

[jch79]

I think all they had to do was speed up the atoms one hour with a particle accelerator.

 

[Empath]

I have a dozen or more clocks and watches that set themselves by the atomic clock's WWVB radio signal. All set themselves without incident, except one I have in the garage. It caught the signal the next night.

The WWVB signal broadcasts at 60khz with one bit of data every second, with the data indicated by the bit placement in the 60 second minute, telling the year, day of year, hour, minute, second, and flags that indicate the status of Daylight Saving Time, leap years, and leap seconds. All time is UTC. A clock using an algorithm basing the DST on the date rather than the state of the DST bits would be unusual programming.

Here's the format of the time code signal

A good reference site.

 

[flashy bazook]

thanks for the responses - very illuminating!

I just checked my watch and it has the DST flag set on off. So I manually reset the watch to DST flag on ON, and reset the time back one hr.

It may be something about how my watch uses the DST flag from the atomic clock signal - maybe it doesn't use it? Or maybe it uses all of the atomic clock signal except for the DST flag, which is keyed to a date?

We'll see next time it catches the signal from the atomic clock if it resets, or if it stays OK given the DST flag manual change I made.

Still, it is somewhat puzzling.

 

[iced_theater]

My Casio Wave Ceptor changed over at about 2:03 am to 3:03 am. So worked good Too bad my Seiko Coutura doesn't account for DST.

 

[2xTrinity]

Everything of mine with a radio in it -- cell phone, alarm clock on my bedside stand etc. all switched itself over. Also, computers that were connected to the internet all switched themselves over as well. An much older laptop of mine though I had to set manually.

 

[Bob_G]

I've only got two atomic clocks, same brand, and they always take two days to get the change correct. I think they change, then change back, then change back again. Whatever, I've learned to just have faith and wait.

 

[Joe Talmadge]

I think all they had to do was speed up the atoms one hour with a particle accelerator.

Technically, doesn't that actually make time slow down?

 

[TedTheLed]

my mac is still an hour behind, even after I 'synched' it with the network time. . .?

 

[Minjin]

Supposedly, they increase their signal strength for a few days after the daylight savings change and this can cause some sensitive atomic clocks to have difficulty interpretting the signal. Give it a few more days.

 

[LowBat]

I have a travel atomic clock and I placed it outside just after the time change took effect and set it to scan for the new time. It received properly arrording to the icon, but the time didn't go forward one hour. This tells me the signal out of Colorado wasn't updated right away. The next day I tried again and this time the WWVB was correct.

 

[LowBat]

my mac is still an hour behind, even after I 'synched' it with the network time. . .?

For windows you have to download a patch to correct for the new DST; maybe your apple needs something similar.

EDIT: BTW, are you joining us this Saturday? I'm coming from Oxnard if you need a ride.

 

[ACMarina]

I've got a Sharp Atomic clock (analog) that's still not right. Seems they hard-coded it to interpret the time itself, and it's set to change in April with the old time change schedule. So it gets the basic time for the world, sets to it in the eastern time zone, and it's set the way it thinks it should be. No patch to download to fix it, though - I've been checking to see if the manufacturer is going to do anything or if I'm gonna have to get a new clock..

 

[ChopperCFI]

The atomic clock signal is always sending Universal Coordinated Time (UTC). It does not change for daylight saving time. Not everyone in the US or the world switches to DST for various reasons.

The actual time source is an ensemble of several different atomic clocks from around the world. The US provides two of the inputs; NIST and USNO. The ensemble function is done in France (that's why the UTC acronym doesn't match the way we say it in the US). These clocks are cesium beam/fountain and hydrogen masers.

The frequency never changes. It is accurate to better than one part in 10^12. That is roughly equivalent to measuring the equator of the earth to an accuracy of one millimeter. What does change is the time encoding of the signal. It only changes to correct time in leap seconds. WWV and GPS include this corrected time encoding.

A descriptive technical paper by Dr. Levine at NIST is here. A lot of good trivia about time and frequency can be found at the NIST website.

 

[DavidD]

I have a casio waveceptor watch that did the change perfectly. We have 2 wall clocks by SkyScan? that have yet to make the change. Now we are in Indiana, which never participated in DST before. So, those clocks had the DST deactivated. But, I followed the directions on the instruction sheet to reactivate the DST, but with no luck. Even tried removing the battery (twice, once for 2-3 minutes, once for about 6 hours) which I thought would reset it (comes with DST ON as default). Still no luck. They get the signal and set themselves. Just an hour off.

David

 

[ACMarina]

DavidD, I found after some research that my Skyscan-branded clock wasn't actually an atomic clock. It was preset at the factory with a coin-cell to hold the time, but nothing actually sets it to the atomic clock. YMMV, of course, but I had to manually reset the time..