[time-nuts] Another "atomic" clock question

[Bob Camp]

Hi

These clocks (and their wrist watch cousins) work fairly simply. They decide on a time of day (maybe midnight) and try to pick up WWVB. If they succeed in getting a time signal, they sync up to it and turn off the receiver. If they do not succeed, they try again later (maybe 15 minutes, maybe an hour). If after several tries they don’t get anything, they go back to sleep (radio wise) and try again the next day. 

This is a great approach if you want to save battery power. It’s all integrated in a single IC deep in the clock or watch along with all the drivers for what ever sort of display the thing has. They don’t make this kind of stuff out of bits and pieces anymore. 

The bottom line is that there is only a “signal” present for a very brief period each day. If they get +/- 0.1 seconds, they are doing amazingly well. Turning that into a frequency measurement device - not so easy. 

The simple approach: Run a wall clock off of your DUT and compare it to the second hand on the WWVB clock. In a few weeks / months you will have a pretty good idea what’s going on. You probably will know it to as good as the Atomic Clock is capable of reporting.

Bob

On Feb 23, 2014, at 4:33 PM, Bob Albert <bob91343 at yahoo.com> wrote:

> Steve,
> 
> Now that you have brought up this subject, do you know of any way to use these LaCrosse clocks to calibrate frequency standards?  It seems to me that since we can buy a cheap device that receives and decodes the WWVB signal, it shouldn't be a big step to use it as a basis for frequency measurement.
> 
> Bob
> 
> 
> 
> 
> On Sunday, February 23, 2014 1:21 PM, Bob Camp <lists at rtty.us> wrote:
> 
> Hi
> 
> From what I’ve seen, if you are after a large wall clock with mechanical hands on it, you already have the top of the line. There are others out there. The ones I’ve seen or tried are no better than what you already have. Many of them are worse...
> 
> Yes, that’s sad. They are designed to hit a price point.
> 
> Bob
> 
> On Feb 23, 2014, at 3:56 PM, Steve <steve65 at suddenlink.net> wrote:
> 
>> I have several "atomic" clocks in my home -- the consumer type which syncs up with WWVB. The ones I have happen to be manufactured by LaCrosse. They are analog clocks with hour, minute and second hands. They can be erratic.
>> 
>> Last year I had to remove the face from one of them and manually reset the second hand. Now another one's battery ran down and I replaced it, but after replacing the battery the second hand won't sync up. And once in a while the second hand will stop and go one second backward! And another clock would not run at all with a new battery, so I hooked it up to the bench power supply and it worked as expected. Put a battery in it and it took off and is still going!
>> 
>> I see other brands on the internet. Do other brands exhibit the occasional goofy behavior? Anyone have experience with these clocks to suggest which manufacturers produce less flaky clocks? I think I'd pay more money for a better clock to get away from the vagaries of LaCrosse.
>> 
>> Thanks.
>> 
>> Steve, K8JQ
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