OT Clock synchronization

[Metspitzer]

I really have no need to know the exact second of time. I do, however, often wish electronic clocks could automatically set themselves to an accuracy of a minute or so. I am sure I am not the first to be unconvinced by having to reset the clock on my answering machine or coffee maker after a power outage. I would also be nice if my new camera could get the correct time/date from it's initial charge.

Because it is not already being done, there must be more to it than meets the eye. It seems like it would be trivial to just transmit the time/date code over the power lines. Anything plugged in should become automatically set. Can someone enlighten me on why this doesn't already happen?

Ok.........I know the answer. Cost. It is always about money, isn't it?

[Don Phillipson]

Dollars and cents explain why this does not happen automatically and without charge. Standard time laboratories all over the world broadcast the time free via Internet, so your PC's internal clock can reset itself accurately to a few seconds. The same laboratories broadcast fee-paid time service capable of recalibrating laboratory instruments etc. accurately to microseconds. No economic market has yet emerged that will reset your mains-fed microwave or your battery-operated camera at a price you are willing to pay.

[Jim Elbrecht]

-snip-

You're just buying the wrong stuff. I have clocks that are set by the atomic clock via satellite [though because of where we live the clocks have to sit in a west facing window to be set]-- my DVR sets itself through the cable- I suspect that's where my VCR figured out what time it was- my InfoGlobe sets itself through the telephone lines.

My $20 clock radio [one of the 'would-set-itself-if-I-left-it-in-the-window-at-the--end-of-the-house-clocks] has a battery so I only need to set it once every few years. I hope I didn't pay much for the unhandy feature of being able to set itself.

Jim

[George]

Its a pretty common feature in devices anymore. Even my 5 year old low end weather station has a receiver that listens to WWVB and gets very accurate time and additional stuff like automatic DST changes since they set a flag when we transition to DST.

[trader4]

Same here. I have one of the Crosse Technologies wireless outdoor/ indoor temp displays and it sets the clock via WWVB. Works great. I agree they should put this in more appliances or at least a battery so that it will keep time for a few hours if the power goes out. Around here, the power loss isn't frequent and when it does, 90% of the time it's for less than a minute. I suspect the reason they don't put the radio link in appliances is that unlike the wireless thermostat, a lot of time you don't have much control over where to put it. And it might not get pickup, then people would be complaining.

As for why not transmit it over the powerline, I think it comes down to who would pay for it? You can't just have one transmitter at the power plant. There would have to be eqpt installed closer to the distribution endpoints and there is no incentive for the power company to shell out the $$$.

[Edward Reid]

Actually it's set by direct transmission from a ground station. Same idea though. These clocks are often, amusingly, labeled "atomic clock". Just a minor elision there ...

It's already so cheap to pick up this signal that investing in another one would be mostly redundant -- not always but usually.

GPS receivers get the time from the GPS birds, and that's an extremely precise time. But a GPS receiver chip, even a very low end one, would be considerably more expensive and would usually fail indoors.

Edward

[Ed Pawlowski]

"Metspitzer" wrote

See, you know the answer. The old motor driven analog clocks were very accurate with the 60 cycle electricity. Digital are timed differently and drift. They use a crystal oscillator that is not a perfect cycle of 60. I'm sure someone can explain it better.

[Wayne Boatwright]

On Tue 14 Dec 2010 03:06:48p, Don Phillipson told us...

Our very inexpensive clock radios automatically sync themselves, presumably from satellite, and also adjust for DST. There are no fees involved.

[Peter]

What brand and model#? I'm interested in getting one.

[willshak]

My tall case grandfather clock always keeps the time during a power outage. The pendulum just keeps on a-swinging. :-)

[Wayne Boatwright]

On Wed 15 Dec 2010 09:37:37a, Peter told us...

Emerson Research #CKS2023. I bought two of them at Big Lots! about 4 years ago.

[Robert Green]

Are you sure those are time-radio based? The ones I bought just have a huge coin cell battery to "remember" the time and a super-accurate clock mechanism. That's what they call "SmartSet" - The giveaway is that when the power returns, they spend a few seconds running through the numbers on he display. CKS1862 is the model I have and IIRC, the box was quite deceptive about whether it was a "radio set" clock. I was going to take it back (to Wal-mart) but after setting it up, I decided "what the heck" and kept it. Glad I did. It's a very good clock.

I actually prefer a non-radio clock because updating inside the house is a spotty procedure at best because of plaster lath making some rooms a Faraday cage. I believe the Emersons come set to the proper "zulu" time when you buy the clock (battery is good for 5 years - it's the biggest coin cell battery I've ever seen) and you just set the time zone you're in. I believe if that battery goes dead or you remove it, you'll have to reset the time manually. That test is up to you because mine's been holding time as well as my PC that gets the time from the Naval Observatory so I can't complain. The clock also allows you to reset the onset/end of DST if Congress decides to muck with it *again.*

So radio set or not, I'd still recommend them. Mine's been going over two years without dropping a minute and has big blue numbers I can read without my glasses - mostly.

-- Bobby G.

[JIMMIE]

This technology has been on the gonna happen shelf for a long time. It may be getting a lot closer. Power companies are begining to charge by "net metering" Cost per KWH will depend on the time of day you use it. Your power meter will be in relatively constant communication with the PoCo so the data will be on the the powerlines. When this happens added circuitry in a device to set clocks should only cost a few cents. The chip in your clock that does the main work probably isnt a dedicated clock chip. More than likely it is in fact a microprocessor so most of the hardware to do this job is already there.

Jimmie

[Wayne Boatwright]

On Thu 16 Dec 2010 01:46:35p, Robert Green told us...

No, I'm not positive that they are time-radio based. However, the two we bought came with the coin cell batteries uninstalled. The instructions said to first install the batter, then plug into the AC. At that point the display had blinking dashes for about a minute, then displayed the time in the Eastern Standard Zone. The last instruction was to set the actual Time Zone you lived in, which then changed to the correct time. If the AC is off or the clock is ujplugged, when the power is back on the display immediately appears with no running through the numbers to reach the time.

The only downside for us is that it doesn't have a setting for "Arizona Time" or a switch to disable adjusting for daylight savings time. I compensate by shifting the time zone that gives us the correct time one way or the other.

Ours seems to be automatic. We've not yet had occasion to remove/replace the battery either, but I assume it will do the same thing it did when originally installed by us.

We're happy with the clocks and I would also reocmmend them. Our display is also blue and large enough to read without glasses. BTW, our model looks virtually identical to yours based on the drawing in your manual.

[Stephen Furley]

I haven't seen new clocks which use the mains frequency for a long time. Quartz c*ck movements had be had for a couple of pounds now.

Here in the UK we used to have a radio time signal transmitted from Rugby. A few years ago BT lost the contract for it, and it's now transmitted by a different company from a transmitter in Cumbria. The frequency is very low, so the old Rugby transmitter needed a large tuning coil, this large:-

Ed Pawlowski wrote: