# Radio Atomic Clock Wrong Hours **URL:** \ **Category:** Factual Questions\ **Created:** [November 26, 2014, 5:25pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696 "2014-11-26T17:25:39Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![JHB1492](https://avatars.discourse-cdn.com/v4/letter/j/7feea3/32.png) [@JHB1492](https://boards.straightdope.com/u/JHB1492)\ **Post date:** [November 26, 2014, 5:25pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/1 "2014-11-26T17:25:39Z")
When the time changed, my radio atomic clock has been keeping time erratically. One days it h displays the correct time, then the next day, it is off a couple of hours, then the next day, it is off six (6) hours, then the next day, it displays the correct time, then the next day it is off four (4) hours, etc., etc. What gives??? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 26, 2014, 5:41pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/2 "2014-11-26T17:41:46Z")
In the old days you could say “Even a broken clock is right twice a day.” With modern clocks with more sophisticated failure modes, you can have one which isn’t even that good; it’s never right. Old joke: “What time is it when your clock is doing what it’s doing? Time to get a new clock.” Serious answers: You could try unplugging it and removing any backup battery it may have. Then after a few minutes, plug it back in. Also sometimes these smarter clocks go bonkers if the backup battery is nearly dead. So you might try replacing that battery; that’s sure to be cheaper than buying a whole new clock. ---
**Author:** ![JHB1492](https://avatars.discourse-cdn.com/v4/letter/j/7feea3/32.png) [@JHB1492](https://boards.straightdope.com/u/JHB1492)\ **Post date:** [November 26, 2014, 6:54pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/3 "2014-11-26T18:54:51Z")
Don all that ---
**Author:** ![JHB1492](https://avatars.discourse-cdn.com/v4/letter/j/7feea3/32.png) [@JHB1492](https://boards.straightdope.com/u/JHB1492)\ **Post date:** [November 26, 2014, 8:27pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/4 "2014-11-26T20:27:08Z")
Done all that. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 26, 2014, 8:27pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/5 "2014-11-26T20:27:33Z")
Then this > [@LSLGuy](#): > > … Old joke: “What time is it when your clock is doing what it’s doing? Time to get a new clock.” … is no longer a joke. ---
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [November 26, 2014, 8:32pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/6 "2014-11-26T20:32:28Z")
Both my clock and DVR have clocks that set automatically and they have always been 25 minutes off. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [November 26, 2014, 10:17pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/7 "2014-11-26T22:17:43Z")
you have power, radio receiver and clock systems to go bad. if you’ve replaced thew backup battery with a known good battery (and made sure the contacts were clean and tight) and also powered down for a bit (10 minutes or longer is sometimes needed for bad memory or functions to disappear) then test the clock further. clocks allow manual setting of the time (to allow use in a bad radio signal area or that it becomes useful before the day or two for it to get a signal). set it and watch it. check frequently. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [November 26, 2014, 10:24pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/8 "2014-11-26T22:24:32Z")
> [@JHB1492](#): > > When the time changed, my radio atomic clock has been keeping time erratically. One days it h displays the correct time, then the next day, it is off a couple of hours, then the next day, it is off six (6) hours, then the next day, it displays the correct time, then the next day it is off four (4) hours, etc., etc. > What gives??? Well is something changing your time zone ? Also, “atomic clock” wasn’t a full description of your system… perhaps if you could be less ambiguous. Maybe you are in some wild orbit of a large black hole. ---
**Author:** ![Rain\_Soaked](https://avatars.discourse-cdn.com/v4/letter/r/e19adc/32.png) [@Rain\_Soaked](https://boards.straightdope.com/u/Rain_Soaked)\ **Post date:** [November 26, 2014, 11:17pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/9 "2014-11-26T23:17:55Z")
Is it a La Crosse clock? Mine do that as well whenever we switch to and from Daylight Saving. I have seen them get the proper time and the next day switch back. Then later switch to the proper time. After a day or so, it is correct. La Crosse says it is due to radio reception issues. These are clocks that have a radio receiver inside that receive an over the air time signal to automatically set the time. ---
**Author:** ![DataX](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@DataX](https://boards.straightdope.com/u/DataX)\ **Post date:** [November 26, 2014, 11:49pm UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/10 "2014-11-26T23:49:58Z")
I have found keeping my clock(a) near a window for a few hours seems to help. As Rain soaked mention - this is a known problem after DST - and some manufacture say it can take five days to resolve itself. Here is a 68 page best practices manual from NIST that has some good info: > **[2422.pdf](https://tf.nist.gov/general/pdf/2422.pdf)** > > 4.31 MB It appears to me that the pre 2012 version of the signal (and presumably what exists in all devices prior to that date or before the spec was announced) is that the signal is sent once a minute - and takes the full minute. There doesn’t appear to be (that I could tell) error checking in it - and they recommend that the manufacture require two sequential frames before starting the time, but apparently during DST - you need more than 2 minutes to sync up: > [@](#): > > Each change in the DST bits will first be received in the mainland United States between 16:00 (PST) and 20:00 (EDT), depending on the local time zone and on whether DST is about to begin or end. A receiver in the Eastern time zone (UTC−5) must therefore correctly receive the “DST is changing” indication within a seven-hour period before DST begins, and six hours before DST ends, if it is to change the local time display at the correct time. Receivers in the Central, Mountain, and Pacific time zones have one, two, and three more hours of advance notice, respectively. > **[WWVB](https://en.m.wikipedia.org/wiki/WWVB)** > > WWVB is a longwave time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST). Most radio-controlled clocks in North America use WWVB's transmissions to set the correct time. > The normal signal transmitted from WWVB is 70 kW ERP and uses a 60 kHz carrier wave yielding a frequency uncertainty of less than 1 part in 1012. The time code signal is derived from a set of atomic clocks located at the site, and transmitted using th... Anyway - I don’t know exactly what is going on, but I don’t recall any of my atomic clock based instruments being quick. If you live far away from Colorado - it appears to me that sometimes - you need to put it by a window - sometimes even overnight. Why exactly - I don’t know - but I’m guessing it is something similar to what I posted above. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [November 27, 2014, 12:50am UTC](https://boards.straightdope.com/t/radio-atomic-clock-wrong-hours/705696/11 "2014-11-27T00:50:07Z")
I recently changed the battery in my radio clock and it wouldn’t pick up the time at all. I finally found the manufacturer’s web site and it clearly said that after you change the battery, you have to press the reset button. Which I did and it has worked perfectly ever since. I probably know that once but those batteries must last five years.