Talk:Radio clock

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—Yamara ✉  18:09, 14 March 2008 (UTC)

Discussion
''News radio: The easiest method to access standard time is to listen to the news on radio. National radio news programs set their clocks to the transmissions from the standards departments of their respective countries.'' - This is an Opinion 70.251.161.12 17:01, 5 May 2006 (UTC)

Name of this article
Aren't these usually called clock radios? Evertype 18:17, 17 April 2006 (UTC) - No
 * On a somewhat related matter, wouldn't the appropriate name for this article be "Radio-controlled clock"? I have never seen or heard of these devices refered to simply as "radio clock"--Kevin586 20:35, 22 January 2007 (UTC)
 * yes, these refer to radio controlled clocks. Clocks that update their time based on radio signals received. A clock radio is just a regular clock, with a radio attached.crd721
 * Actually, most radio clocks are sold as "atomic clocks". I check out the clocks in Target and WalMart, so I see that this is what they actually use to label these clocks.  (See also the last paragraph in the introduction of atomic clock.)  But I think that "radio clock" is acceptable. Val42 23:00, 9 March 2007 (UTC)

Interoperability
I'm missing a clear statement whether or not a simple radio clock purchased in one country will work in the other. From reading the text I'd say rather not, but it doesn't say so. Else it is written quite understandable - thinks Steffen.
 * I would say you are correct: simpler radio clocks I have seen (in north america) have options that only account for the four time zones that run through it. I have seen some radio clocks and wrist watches that claim to adjust themselves for any time zone one might travel to. —The preceding unsigned comment was added by Kevin586 (talk • contribs) 23:45, 24 January 2007 (UTC).


 * I have a radio clock that I can (manually) set to any time zone, and then -- if it can detect WWVB -- it will automatically adjust the minutes and seconds appropriately.
 * So it will work in any country (as long as I manually set the time zone appropriately), as long as I bring it back to somewhere where it can detect WWVB once a week or so for it to re-synchronize.
 * But the article needs to answer the following question:
 * Will a clock designed to listen to WWVB work if I leave it in Germany where it can only hear the DCF77 broadcast? is the DCF77 broadcast "compatible enough" with the WWVB protocol (at least the "minutes" and "seconds" parts) so that clock will continue to work? --68.0.124.33 (talk) 00:11, 2 March 2008 (UTC)


 * The answer is no, but not due to the fact that the DCF77 broadcast isn't "compatible enough". The real problem is that a WWVB radio clock can't "hear" the DCF77 broadcast since it uses a different frequency and a normal WWVB clock can't receIve broadcasts at 77.5 kHz. There are, however, multiband radio clocks and watches. (Multiband watches are more common, of cause.) 95.89.154.162 (talk) 11:42, 15 July 2009 (UTC)

Performance
The "Performance" section seems to bring up a few relevant issues (for example, the need to orient a clock in a window properly, and the necessity of setting the time zone) and many irrelevant ones (like the supposed unavailability of tech support for these clocks), but uses a very sarcastic tone:

"A typical radio clock will be accurate to the millisecond but may be off by an hour or two, because the user failed to understand the manual. These range from a single sheet of paper, folded twice, to a booklet the size of a business card and 100 pages (50 leaves) long, in both English and Spanish. In most cases, the timepiece was designed by highly-skilled engiteers using specifications published by the NIST, then manufactured in the Far East, usually China. Design parameters are highly subject to cost constraints, which limit the number of chips and the number of switches, or buttons: in general, it is cheaper to have five buttons and 5! (30) modes than to have 30 buttons and one mode. The resulting state-machine diagrams are so complex that the engineers can barely understand them. The engineers then pass on their specifications to technical writers, who may or may not be fluent in English, and are not allowed to replicate the engineers' diagrams, lest the user understand the complexity of the clock's design. A user who doesn't understand may try to cotact the manufacturer, but they will never reach a person who can answer the question: the engineer speaks only Mandarin and never answers the phone, and there is 'no' Technical Support department."

This ought to be rolled back, or heavily edited. I will roll it back if no one steps up to edit it. ThinkingInBinary 01:14, 22 August 2007 (UTC)

oscillator
The article currently correctly points out that "No GPS receiver directly computes time or frequency, rather they use GPS to discipline an oscillator".

However, my understanding is that *every* radio clock (and NTP) does the same thing, so it is misleading to imply that *only* GPS receivers do this.

All radio clocks including GPS (and also NTP) use a local oscillator to maintain an approximate time, then use the received signal to either (a) adjust the oscillator clock frequency (directly, or indirectly by adjusting the clock divider), or (b) force the counter to the correct time, then continue to use the oscillator to increment the time, or (c) both.

Or is there some subtlety that I am missing, or some other kind of clock that somehow works differently? --68.0.124.33 (talk) 00:11, 2 March 2008 (UTC)
 * No, you didn't miss a subtlety. Practical radio clocks have a local oscillator that's synchronized against the radio signal. Battery operated clocks (and watches) usually synchronize once per day to preserve the battery. And yes, NTP software has a local oscillator too (usually the PC clock). Note that NTP is an internet time sync protocol, not directly related to radio clocks. Jaho (talk) 23:38, 1 February 2010 (UTC)

Relative accuracy of cheap radio clocks during periods of non-reception
Editor ParaGreen13 maintains that inexpensive radio clocks are "reasonably accurate" between syncs, claiming that ordinary quartz clocks, watches, etc., are good to a half a second a day "at worst."

This page on crystal accuracy disagrees: He cites 20 ppm, which is 5x better than a typical crystal.. and allows for almost 2 seconds a day worth of wrong.

A half second a day would be about 6 ppm, and that would be a very special crystal indeed. If there is a source (other than watch makers' sales literature) for this "half a second per day" figure, I would ask ParaGreen13 to please provide it.

ParaGreen13 also claims "Oftentimes it's closer to 1.8 sec. or less/week" and "Usually not +/- by more than 1-2 sec/week". 1.8 sec/week is just about at three ppm and 1 sec/week, better than two ppm. These figures are flatly unachievable without a crystal oven (and then you get much much better, in the range of one part per billion).

It is true that it is possible to find individual watches (usually not the cheapest) that perform that well or even better, but that does not say anything about the quality of components in a $20 radio clock.

The watch benefits not only from a crystal but also from the constant temperature that's achieved by you wearing it on your wrist. And many higher-end watches "discipline" their oscillator, making fine adjustments if you reset them by small increments - after doing a few corrections "to the second" you will likely not have to do it again, or at least not as much.

The inexpensive circuits in $20 radio clocks do not have top-quality watch crystals, nor any constant-temperature mechanism, nor a disciplining mechanism.

Even at half a second a day, after a few days of no signal (not uncommon depending on where you live WRT the time standard transmitter) you can be off by several seconds. To the person who bought the radio clock for "atomic clock" accuracy I doubt this would be considered "quite reasonably accurate." Jeh (talk) 07:34, 29 December 2009 (UTC)

broken link
Under external link "NPL list of Standard Time and Frequency Transmissions" pointing to http://www.npl.co.uk/time/measurement_time/time_trans.html is broken. — Preceding unsigned comment added by ThePianoGuy (talk • contribs) 11:38, 13 February 2011 (UTC)

loran
The US loran system has been shut down.

http://www.navcen.uscg.gov/?pageName=loranMain — Preceding unsigned comment added by 76.90.10.240 (talk) 03:13, 13 October 2011 (UTC)

UK signal
There cannot be two different signals both broadcast on the same frequency from the same location, so one of the lines in this table must be wrong. 212.159.69.4 (talk) 17:02, 31 December 2011 (UTC)
 * Looks like GBZ was the name for a standby transmitter on 16 kHz, and was never a 60 kHz transmitter. NPL's Web site and some googling indicate that the GBZ call sign is no longer used. I took it out. --Wtshymanski (talk) 19:39, 31 December 2011 (UTC)

"They are suitable for scientific or other work which does not require higher accuracy than they can provide"
I noticed this sentence in the article (section 1.1.2 as of this writing, 2016-01-31 1208.19 UTC) and I was struck by the fact that it is not only true of "Modern radio clocks" that are "referenced to atomic clocks" and which "provide access to high-quality atomic-derived time over a wide area using inexpensive equipment" but that it is also true of all timepieces which exist anywhere on earth as of right now or indeed at any point in the past, and, I say with unusual certainty, any timepiece which may be manufactured at any point in the future.

I am relatively inexperienced with Wikipedian issues beyond grammar, spelling, and blatant factual inaccuracies, but do basic tautologies like "x is suitable for any purpose which does not require higher accuracy than x can provide" really have a place here? If your scientific "or other" work only requires a timepiece that's accurate twice a day, an old saying suggests that even a broken clock would be suitable. Mattman00000 (talk) 12:18, 31 January 2016 (UTC


 * That seems like a fair point to me. The sentence looks frankly like padding. If you don't feel comfortable deleting it I will. In fact I think its entire paragraph can go as it's redundant with the rest of that section. It think it's a "leftover" from an earlier version of the article that lacked the rest of that section. Jeh (talk) 21:21, 31 January 2016 (UTC)

Missetting
It has been my experience based on a half-dozen or more WWVB radio controlled clocks, that many of them will sometimes misset themselves (say by 10 minutes or more), probably when the signal is weak and/or there is interference. I use triac lamp dimmers which are notorious for causing AM radio noise. I always advise never using them directly as alarm clocks, but instead using them to check non-radio-controlled alarm clocks. A digital shortwave radio that can get a standard time signal, such as WWV 10.000 MHz, can help find goofy missettings. Note that when comparing an audio signal with a visual signal, that there are possibly two different personal equations involved. agb — Preceding unsigned comment added by 173.233.167.63 (talk) 22:55, 8 May 2017 (UTC) Same here. Mine went screwy around midnight and woke me up!!

SKYNET
Hi, apparently there is a classified uplink/downlink frequency which uses FHSS but with a long duration low noise setup the signals can be decoded into the encrypted payload and time signal. Perhaps this should be added as it can be used as a reference similar to GPS/GNSS/Galileo ? same with

BBC Radio 4
I've noticed Radio 4 is on the list for the UK, but I can't seem to find very much proof this is used by radio clocks as a time signal. Most radio clocks in the UK seem to be set to MSF (I couldn't find an example of any using 198Khz), and MSF covers the whole country. The reference in the URL is a deadlink, and web archive just shows it as a list of stations. The closest evidence I could find was https://www.nxp.com/docs/en/application-note/AN1597.pdf Should it be removed? I couldn't find much evidence on NPL's website apart from this http://web.archive.org/web/20180422095850/https://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/droitwich-bulletins


 * I was under the (possibly incorrect) impression that the BBC sent a Time signal over Radio 4's frequency via RDS to supported Car Stereo sets in order for them to set their own time. Shielder95 (talk) 23:45, 27 June 2020 (UTC)

I didn't time to dig into it, but here is the original BBC technical doc referenced by the NXP application note; hope this can help:

L.F. RADIO-DATA: Specification of BBC  phase-modulated transmissions on  long-wave -  Strangerpete (talk) 00:33, 27 June 2020 (UTC)


 * The Radio 4 long wave is used primarily for radio teleswitching of electricity supplies. See Radio teleswitch and Economy 7 articles. Philedmondsuk (talk) 08:30, 4 July 2020 (UTC)

The above is correct, Radio 4 is used for the setting of electricity meters, not for consumer radio clocks. Should it still be on this list? Jayflux (talk) 19:05, 2 May 2021 (UTC)

WWV on 25 MHz now broadcasts with 2.5 kW
WWV on 25 MHz is broadcasting with a power of 2.5 kW

Could we move the list of stations to its own article?
Having the station list on this page is a bit misleading in some cases, as radio clocks aren't run off of all of them. For example, WWVB, rather than WWV, is the source for USA radio clocks. A list of time stations would be very useful on its own, though, as they're used for research and the BIPM list sometimes misses details. Thoughts on moving the table to a "time standard station" page? Vannevarmorgan (talk) 01:36, 30 March 2021 (UTC)
 * There is a related article, "Time signal" which discusses both the kind of stations covered by this article, as well as voice announcements. By the way, WWV can be used for automated time reception, although other services are usually preferred. Jc3s5h (talk) 16:51, 30 March 2021 (UTC)