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



## flashy bazook (Mar 14, 2007)

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!).


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## jtice (Mar 14, 2007)

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


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## Starlight (Mar 14, 2007)

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.


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## JohnK (Mar 14, 2007)

Mine advanced perfectly for the change.


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## matrixshaman (Mar 14, 2007)

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.


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## jch79 (Mar 14, 2007)

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


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## Empath (Mar 14, 2007)

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.


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## flashy bazook (Mar 14, 2007)

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.


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## iced_theater (Mar 14, 2007)

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.


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## 2xTrinity (Mar 14, 2007)

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.


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## Bob_G (Mar 14, 2007)

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.


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## Joe Talmadge (Mar 14, 2007)

jch79 said:


> 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?


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## TedTheLed (Mar 14, 2007)

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


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## Minjin (Mar 14, 2007)

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.


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## LowBat (Mar 14, 2007)

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.


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## LowBat (Mar 14, 2007)

TedTheLed said:


> 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.


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## ACMarina (Mar 14, 2007)

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..


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## ChopperCFI (Mar 14, 2007)

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.


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## DavidD (Mar 15, 2007)

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


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## ACMarina (Mar 15, 2007)

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..


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## matrixshaman (Mar 15, 2007)

LowBat said:


> 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.


I'm in CO. and mine changed over fine - early a few hours in fact. Maybe you're not getting the signal that well on the West Coast. Isn't there a closer signal for there?


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## flashy bazook (Mar 16, 2007)

I can now report that my "atomic" watch managed to catch the atomic clock signal last night, and stayed on the right time.

I guess I won't know for sure whether it was my manually fixing the DST flag in the watch that did it or not.

Will see what happens when DST elapses in the fall of '07, and again next year when the DST comes around again!

This was the first time I ever had trouble, and that's why I wondered if the change in the timing of the DST change had something to do with it.

But I sure learned a lot about the topic, thanks for the many very useful posts.


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## cave dave (Mar 16, 2007)

2 Oregon scientific and an analog casio waveceptor watch all were correct Sunday morning with no effort on my part.


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## geepondy (Mar 16, 2007)

Thanks Empath, very interesting links. What I don't understand is why only one bit per second of transmission data? Hear in the northeast, I sometimes have a tough time picking up the signal and I can easily see that in a minute's time, the signal might fade so that the data is lost.



Empath said:


> 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.
> 
> ...


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## gadget_lover (Mar 16, 2007)

I wonder if it's so that people can decode it manually just like they do morse code. I imagine that one could actually differentiate the tones as if they were dash-dot.

Daniel

It would be nice if it was transmitted faster and more frequently.

Daniel


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## Empath (Mar 16, 2007)

The 60 khz signal is a ground wave. It can travel for thousands of miles, but it competes with a lot of noise. It's a range of frequencies that's even capable of reaching subs and such. Longwaves that low are generally military utility signals.

Most clocks making use of the signal don't try to get the whole picture on one minute's worth of data. It will watch the signal for several minutes until it's verification algorithms are satisfied.


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## DieselDave (Mar 17, 2007)

My Garmin GPS clock is wrong and I thought it set itself via signal.


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## geepondy (Mar 17, 2007)

Thanks Empath. That explains why that when I had to manually initiate the atomic clock setting for my watch and after I found the perfect spot where the signal would come in, I had to stand still for a full four minutes before it synchronized. 

How do you know all of this?


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## Wyeast (Mar 17, 2007)

My cheapie digital Waveceptor set itself correctly. The nav in the car, however, is still an hour back, and like DieselDave, I think it's supposed to set itself via signal... I guess someone forgot to reprogram the GPS satellites for the early DST too.


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## flashy bazook (Mar 17, 2007)

my own atomic watch also behaves the same way, it says it needs between 2-6 minutes to acquire the signal and reset the time as appropriate.

you can try to initiate the signal acquisition manually, and then kind of sit around and wait, but I generally find I am too impatient (and would in any case need to set the watch down as it needs to be immobile).

Also, the best reception time is very late at night/very early in the morning when signal interference is minimized.

It all seems very primitive (very low bits/signal), but I guess there are good reasons for it, including the thousands of miles signal range and ability to penetrate ground/sea.


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## Retrotech (Mar 24, 2015)

I have a theory that I can test on March 29. When I put my German made RC clock in a West window it sets properly to US DST but when it is on the East side of the house it sets back an hour. My theory is that it gets a European time signal there. If so, it will read correctly after March 29th when Europe goes to DST. I'll keep you posted.


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## Kestrel (Mar 24, 2015)

Retrotech said:


> I have a theory that I can test on March 29. When I put my German made RC clock in a West window it sets properly to US DST but when it is on the East side of the house it sets back an hour. My theory is that it gets a European time signal there. If so, it will read correctly after March 29th when Europe goes to DST. I'll keep you posted.


It sounds like there has been a blockade, my suggestion would be an airlift undertaken by the West to resupply your clock, lol.

*The Berlin Airlift*


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## Greta (Mar 24, 2015)

I have a similar type thing happen with my cell phone. Where I live is right on the border of AZ and CA. During DST, CA is one hour behind AZ. So sometimes the time on my phone will be AZ time and sometimes it is CA time - depending on which room in the house I am in. It's a bit annoying... :ironic:


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## PhotoJim (Mar 26, 2015)

Greta said:


> I have a similar type thing happen with my cell phone. Where I live is right on the border of AZ and CA. During DST, CA is one hour behind AZ. So sometimes the time on my phone will be AZ time and sometimes it is CA time - depending on which room in the house I am in. It's a bit annoying... :ironic:



Sounds like you're right between two cellsites, one in each state, and your phone uses both depending on where in your house you are.

That'd be possible in my province too (Saskatchewan). We're on CST year-round; Manitoba flip-flops CST/CDT; Alberta does MST/MDT. Could be fun on the border.


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