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Mydesign
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Self-Timing Clock
Mydesign   9/3/2013 7:15:47 AM
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"it should keep all the readings and just coast along on the internal crystal-controlled clock until the next time it gets a good calibration signal. It doesn't do that. It changes the date to some random number. Designed by Monkeys!"

Michael, is it good or bad? I think it's better to fix it permanently near to door or window, so that the signal reception is great

Rob Spiegel
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Re: Self-Timing Clock
Rob Spiegel   9/3/2013 10:44:37 AM
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Good point, MyDesign, but my goodness, do we really have to add signal reception into the equation as to where to place our clocks? 

JimT@Future-Product-Innovations
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Re: Self-Timing Clock
JimT@Future-Product-Innovations   9/3/2013 11:54:23 AM
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I got an Indoor/Outdoor digital thermometer with an integrated clock.  The only TIME setting available on this device was to "Select Time Zone".  Leafing thru the directions, trying to discover how to set the clock time, I read that the signal is transmitted from the US Atomic Clock in Denver, CO.  Not only does it take hours to detect this (unknown bandwidth) weak signal, but it only shows/reads Mountain-Time, so its chronically 2 hours slow -- but to the Nano-second!!  No Value Added for this technology.

tekochip
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Platinum
Re: Self-Timing Clock
tekochip   9/3/2013 3:49:14 PM
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There was a cheap chipset that was released for WWV reception a number of years ago.  Some of the white goods guys wanted to put it into appliances.  The reception was terrible and the chipset manufacturer calmly stated that you had to find the right positioning for good reception, perhaps by a window.  I laughed and told him that nobody was going to run around their kitchen with a double oven and try to find the best reception for the clock.


ab3a
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Platinum
Re: Self-Timing Clock
ab3a   9/3/2013 8:23:40 PM
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It isn't just the "reception."  Decades ago, we used to use a Heathkit WWV clock.  It used to jump all around in time. Sometimes it would be off by an hour. Sometimes it would be off by several minutes.

The problem wasn't just the clock. They were receiving a subcarrier from WWV/WWVH  (NOT WWVB). The subcarrier would transmit either short or long pulses each second in a BCD code to indicate the time. However, selective fading would often shorten a pulse here or there. The detection circuits, even though they had a strong signal, would decode these pulses incorrectly.

Our solution was to have the vendor add a sanity check to the circuitry to reject time changes of more than one minute.

In retrospect, a real WWVB clock would have been a better idea. You don't get selective fading at 60 kHz.

Perhaps NIST would be willing to reconsider the 100 Hz subcarrier format and use something more reliable on WWV and WWVH, such as a very slow fsk signal with error detection codes.

Jake Brodsky

Rob Spiegel
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Blogger
Re: Self-Timing Clock
Rob Spiegel   9/3/2013 8:48:20 PM
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That's terrible, JimT. But the mind will adjust. If that's the only clock you look at, in time you'll make the two-hour adjustment without thinking.

Wireless geek
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Iron
Re: Self-Timing Clock
Wireless geek   9/6/2013 12:31:43 AM
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2 hours slow?! If your radio-controlled clock shows MST instead of your time zone, it is becuase you selected the wrong time zone (and/or also got the daylight-saving time enable/disable switch in the wrong position).   The time broadcast from Colorado is not MST but UTC and the products are all capable of calculating the time offset to your time-zone (at least between EST and PST). 

These low-cost products may have pathetic performance in terms of reception reliability (at least until receivers for the new broadcast replace the old ones), but there shouldn't be a problem with the time zone.  

 

 

 

jcj
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Iron
Re: Self-Timing Clock
jcj   9/4/2013 9:21:43 AM
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Most of the clock like this that I've seen work like "normal" digital clocks when they don't see an adequate signal. Holding the current time makes a lot more sense than randomly setting the time. I've had experiences where I'll move a clock from one room to another and find out that it does not have enough signal to reset. In fact, I have a friend that can't get decent reception on one of these clocks so she gives it to me, it sets properly at my house and I bring it back to her.

Mydesign
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Re: Self-Timing Clock
Mydesign   9/6/2013 4:15:22 AM
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"Most of the clock like this that I've seen work like "normal" digital clocks when they don't see an adequate signal. Holding the current time makes a lot more sense than randomly setting the time."

Jcj, most of the clocks works either on single or dual power sources. If there is no solar power, it will get feed by the battery power.

Cadman-LT
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Platinum
Re: Self-Timing Clock
Cadman-LT   9/8/2013 2:54:52 AM
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I agree, just because it loses signal shouldn't make it freak out and randomly guess. You at least should be able to set it manually...even though that defeats the point, but still.

tucsonics
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Silver
Re: Self-Timing Clock
tucsonics   9/6/2013 12:22:40 AM
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Thanks for all the comments! It's nice to know that I wasn't alone. The most obvious solution to my problem was to move the clock to a different wall, but it was a case of the tail wagging the dog! I wanted the clock where I could see it conveniently. I don't know if the low frequency signal would be impeded by the wire mesh they apply to the exterior stucco walls. I do know that leaving the clock by the window overnight effects the reset. As a designer of phase-lock loops for electronic warfare applications, it was standard procedure to enable the local clock to coast in both frequency and phase at the last known correction when the reference was lost. I guess the clock designers didn't have the fail-safe idea in mind.

Wireless geek
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Iron
Re: Self-Timing Clock
Wireless geek   9/6/2013 12:42:53 AM
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Yes, of course it should coast until it is sure about the reception quality.  "Monkeys" you're saying?!   This should be obvious enough to monkeys too...

I made the same observation on a radio-controlled clock in my office -  in 2012 it suddenly became '92 for a few days...  I thought that it took me 20 years back in time, but it was acutally 80 years into the future...  Isn't time-traveling exciting? 

But don't worry!  NIST realized that these problems are common and introduced a new broadcast format last year (check out their website), so we should expect that new products will be better behaved.   

Mydesign
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Platinum
Re: Self-Timing Clock
Mydesign   9/6/2013 4:19:36 AM
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"But don't worry!  NIST realized that these problems are common and introduced a new broadcast format last year (check out their website), so we should expect that new products will be better behaved.   "

Wireless geek, hope for the best and there is no doubt that it can get much improved by new technologies.

AnandY
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Gold
Re : Made my monkeys
AnandY   9/4/2013 2:30:54 AM
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Now that that Atomic-Digital clock of yours was really designed by monkeys; glad you pointed that out yourself. There are simply too many unpredictable things that can happen during the day and most of these unpredictables will render the clock unreliable and, at times, grossly inaccurate. You might just as well peek outside the window and guess the time.

johnmoran
User Rank
Iron
Re: Re : Made my monkeys
johnmoran   9/4/2013 9:25:27 AM
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Afternoon

All the clocks in my house are radio controlled (7, I think). They are in all sorts of positions, next to all sorts of electronics (two in my electronics lab), and some on the inside of 24" thick stone walls. They all tell the same time and all change with Summer and Winter changes. Some are connected to the UK time standatrd, some to the German one.

I have gone through all that to point out that yes, THAT clock was designed my a monkey, but not ALL radio clocks are. Mine are all different makes, by the way - some digital, some analog.

Maybe the American atoms are different to the European ones ... :))

Kind regards - John

Orin Laney
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Silver
clock signal reception
Orin Laney   9/4/2013 1:16:08 PM
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Yours is a WWVB clock (60 KHz) and uses a ferrite loop antenna, usually parallel to the display face.  The loop has two nulls in the reception pattern.  Orientation of the loop is more important than the absolute position of the clock.  Find the vector from your location to Fort Collins, Colorado.  Assuming the clock is flat like a wall clock, place it so that a line normal to the display face (for a circular clock like a wall clock it would be the axis of the circle) points toward the Colorado transmitter.  You can be off by 20 or 30 degrees without problems.  However, if a line parallel to the face of the display points to the transmitter, you are in the null and moving the clock without rotating it won't help much.  For instance, if you are due east or west of the transmitter, placing the clock flat against a wall with north-south orientation will work, but placement on an east-west wall will not.

tekochip
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Platinum
Re: clock signal reception
tekochip   9/4/2013 2:05:46 PM
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Now imagine following that process with a double oven.

William K.
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Platinum
Re: clock signal reception
William K.   9/4/2013 2:18:41 PM
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Like several have commented, it is quite possible to get a burst of noise that causes an error in the years part of the data. Of course, there are workarounds that could be added to the code in the clock, but that adds cost. So possibly a better antenna to hve a stronger signal, or something like that. But the year is seldom my concern, it is almost always the minutes thyat I need to be correct about.

Orin Laney
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Silver
Re: clock signal reception
Orin Laney   9/4/2013 4:09:20 PM
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All it would take is an accessible screw adjustment to rotate the antenna independently of the oven orientation.  Possibly that's too complicated for appliance designers.

Colorado Native
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Silver
WWV clocks
Colorado Native   9/5/2013 3:03:44 PM
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I've owned several La Crosse Technology clocks over the last ten years, my first was (and is) a wrist watch which has kept time quite well, the only 'bug' is that the battery only lasts about 11 months and every time you change it, it takes most of the night to regain the correct time and date.  Sometimes, if it takes a bit too long to change the battery, you may have to tell it what zone you are in, which is easy enough.  It has been able to hold the signal even driving through the Rockies.

I also have two different wall clock models, both of which act a bit differently when the batteries are changed.  One only needs the time zone reset afterwards but the other one sometimes requires more than the time zone to be reset for some reason but sooner or later, sometimes a day, it 'catches up' and always maintains time until the next battery change.  I have also given a La Cross to my Mother-in-Law which is on a wall (East-West) and it does not have a problem with the signal either.

It would appear that the design of the antenna/front end of these troublesome clocks is lacking a bit and needs improvement.  The only drawback I've seen in my 'atomic' clocks is that they take several hours to resync when the signal is interrupted.

I've also monitored WWV Fort Collins for years without any trouble receiving their time signals and I've got 250 miles of mountains between us.

Wireless geek
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Iron
Re: WWV clocks
Wireless geek   9/6/2013 12:34:16 AM
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Colorado Native, didn't you know that the WWVB broadcast also comes from Fort Collins, where the WWV signal comes from?   If so, why are you so surprised to recieve it well in the Rockies?   You are practically in the station's back yard there...   Now let me know how you're receiving it in NY...   Good luck!    

Colorado Native
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Silver
Re: WWV clocks
Colorado Native   9/6/2013 10:25:00 AM
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Wireless Geek:

Of course I know the WWVB (and all of their time signals) is broadcast from Fort Collins, I do not recall saying (or indicating) I was "surprised to receive it so well".  For that matter I have received their signal from Hawaii as well as Fort Collins (shortwave radio of course, transmitted on several frequencies).  While there well may be possible reception problems in N.Y., you obviously do not know how the Rockies can interfere with signal reception, even if it is in the "backyard".

Depending on atmospheric conditions, the signal, even relatively close to the transmitter, can be difficult to reliably receive, add in other intereference and you may not be able to receive the signal reliably at all.  Poor antenna design in some of these clocks certainly do not help, a cheap stick antenna will often not be up to the task.  Do not blame the source in all cases, as mentioned in another comment, steps have been taken to try to improve the 'clarity' of the signal content in weak reception areas.

My wristwatch has not had any problems syncing with WWVB anywhere I have traveled as yet but I haven't been out of the USA with it yet.

Wireless geek
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Iron
Re: WWV clocks
Wireless geek   9/6/2013 10:47:14 AM
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Generally speaking, I have a feeling that almost everywhere outdoors, and far from strong interferers, reception is usually successful.   It is interesting to hear about your experience with your wristwatch.  I have a Casio "Waveceptor" and it works well only as long as I am not staying at one of those larger hotels (tall buildings, based on concrete/steel frames). The small Holiday Inns are ok.   The losses in penetrating large buildings appear to be more challenging than the propagation losses for this 60kHz signal.   Anyway, with the new system being a few orders of magnitude better, everything should work in buildings too.   By the way, I recently went hiking in the beautiful Rockies (you lucky Colorado native!) and was in Fort Collins as well.  My experience with a small WWVB alarm clock was that it didn't work in Fort Collins itself!   That's probably because the AM receiver was saturated.  Once shielded/distanced, it worked ok.  It's interesting that these products fail at both ends of the signal-level range that can be found within the USA.  The newer ones should not. 

 

Colorado Native
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Silver
Re: WWV clocks
Colorado Native   9/6/2013 11:17:40 AM
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Wireless Geek:

 It is interesting how various structures can restrict reception of a given signal.  For instance, inside my house, we have problems with weak signal areas from my Ethernet router even though it has a strong transceiver in it, the same goes for Wi-Fi, there are spots in which it is all but useless.

Your experience with your time clock in Fort Collins is not unusual, being 'close' to the transmitter will often overload the receiver's front end, this happens with most other types of transmissions as well, AM, TV, ect.  I've worked at TV stations where houses located near the transmitter could not receive the signal, too much signal!  A tuned attenuator inserted in the antenna line at the receiver fixed the problem. 

It is difficult to design an RF front end that can cope with most all signal conditions but a significantly wide range should be achievable at little additional cost.  I've noticed that some receivers have come equipped with a local/distant switch to help with the problem.

Glad to hear you enjoyed our State.

Wireless geek
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Iron
Re: WWV clocks
Wireless geek   9/6/2013 11:29:01 AM
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Yes, I certainly did enjoy your state very much!  :-)

Did you see the "local/distant" switch on WWVB receivers, or are you saying this in general?  It is indeed difficult to design a receiver with a very wide dynamic range, but it is easier when the modulation scheme is phase-based (as is the new WWVB scheme) rather than AM, so I'm expecting new products to work well both outdoors in Fort Collins and inside buildings in NY. 

Colorado Native
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Silver
Re: WWV clocks
Colorado Native   9/6/2013 11:48:50 AM
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Hello, Wireless:

None of the WWVB clocks I have has such a switch, the clock we gave to my Mother-in-Law is fairly large, I'll have to check it and see if it does.  At least the wall mount or smaller desk size WWVB clocks are large enough to have such a switch.  I have seen the switch on better multi-wave radios, it has been around for many years on some radios, particularly the multi-band receivers.  I have one from the mid-sixties with the switch and I've seen the switch on even older radios.  I guess it fell out of favor perhaps, for various reasons, like being cheap with the design.  I'll check that clock for the switch later today and let you know.

Wireless geek
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Iron
Re: WWV clocks
Wireless geek   9/8/2013 3:20:21 PM
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Thanks for looking into this.   I never saw such switch on modern products and I doubt that you will.  They have an AGC, but it can't go all the way up to the strong levels experienced near the station. 

bobjengr
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Platinum
SELF-TIMING CLOCK
bobjengr   9/5/2013 5:42:54 PM
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Very interesting post Michael.   Our house was build in 1953 and was designed for ceil heat.  With that being the case, we have electrical conductors in the floors and ceiling of each room.   I have long since "cut this system loose" and installed a central heating and air conditioning system.  In other words, no ceil heat although I still have the wires embedded.  With that being the case, I have also experienced difficulties with "self-timing" clocks and with cell phone reception.  The best reception for my cell phone comes when I'm in the front yard.  I was told by an EE friend of mine the previous heating system was the cause.  Can anyone comment on that one? 

Tool_maker
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Platinum
3 clocks - 3 times
Tool_maker   9/9/2013 12:54:07 PM
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  I have three such clocks in my house and they all plug into wall sockets, so batteries only enter in the equation when the power goes out and all three return to what they think the correct time is. My problem is none of them ever show the same time. They are all within a couple minutes, all change on and off daylight savings when necessary and all project the time and temp on the ceiling. I like all three, but they never have the same time.

  What do I care if things vary by 2-3 minutes, come January I will be retired and will not really care what the clock says unless they cause me to miss a Cardinal's, Ram's or Blue's telecast. All else will depend on whether or not the fish are biting, and they do not use any clock, but depend on the weather. Life is good.

johnmoran
User Rank
Iron
Re: 3 clocks - 3 times
johnmoran   9/11/2013 6:04:51 PM
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Tool_maker - as I said a while ago, I have 7 radio clocks around the house, and I forgot about my Casio Waveceptor wrist-watch.

Wherever I can see a pair at the same time, they all change in perfect step, including my watch.

If yours don't change in step, then they aren't synchronised to the radio signal and are probably free-running for short periods when they lose the radio signal.

The only problem I have ever had with a radio clock was when the supplier delivered a pure German version by mistake and it insisted in working to their time, which is always an hour ahead of us and the Summer time changes were different. However, pulling it apart showed a link on the PCB - UK/DE - changing it over made my clock a UK one, but still receiving the German time signals.

So, all the problems people seem to be having here appear to be just lousy reception, and maybe a few lousy clocks.

Sorry to repeat it, but I think it may be your system over there.

Regards - John

AnandY
User Rank
Gold
Re : Self-Timing Clock Makes Up Its Own Time
AnandY   10/3/2013 2:33:26 PM
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@ Mydesign, placing the clock near window or door may fix the problem of signal reception for good, but it doesn't answer the question posed in the paragraph posted by you. It should keep the date received during last better signal reception period. It makes no sense if it changes the date to some random number when it is not getting enough signals.

AnandY
User Rank
Gold
Re : Self-Timing Clock Makes Up Its Own Time
AnandY   10/3/2013 2:33:29 PM
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@ tekochip, LOL, of course nobody is going to take such pains for just getting their clock right. Similarly, no one would like to compromise the interior look of his/her room by putting his/her clock where it doesn't look good in the quest for good signal reception. I would immediately throw that clock out of the window and place a traditional cell powered clock where it looks good.

Cabe Atwell
User Rank
Blogger
Re: Re : Self-Timing Clock Makes Up Its Own Time
Cabe Atwell   10/23/2013 6:16:11 PM
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I have a watch that adjusts itself when passing through different time zones and updates itself using the signal from atomic clocks. It also uses solar power to recharge the battery, which should last for 10 years before needing to be changed. 



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