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Re: Two Wave-Ceptor watches differ by 5 seconds
From: Lu Abel
Date: 2015 Sep 8, 15:34 -0700
From: Lu Abel
Date: 2015 Sep 8, 15:34 -0700
I know nothing about these watches, but please all me some
observations:
There are three (and "a half") ways to synchronize to highly accurate time signals.
1. Via GPS -- GPS requires time accurate to the nanosecond to work properly.
2. Via WWVB, low-frequency time signals broadcast by the US's National Bureau of Standards.
3. Via the Internet. There is a specific protocol that is used to broadcast highly accurate time signals on the Internet.
"and a half" -- cellphones sometimes display time with high accuracy. Cellphone towers need accurate time to interlink and work properly with our phones, carriers may or may not bleed that over to the handsets themselves.
In my ignorance, I will speculate these watches use WWVB for synchronization. Embedding GPS in a watch is likely impractical and/or too expensive.
And therein lies a rub -- the quality of the WWVB receiver.
I have on my desk an "atomic clock" that I got as a giveaway at a large electronics chain and it works great. It keeps accurate time over a 24-hour period and inevitably syncs itself via WWVB every night.
On the other hand, I do some volunteer work at a local non-profit school. Somebody got the bright idea of having accurate clocks in the classrooms and bought a bunch of classroom-size "atomic clocks" off the Internet.
Fully half of these clocks, located in the San Francisco Bay area, failed to synchronize to WWVB.
I even took several of them out-of-doors and did everything I could to try to get the best signal, even trying the clocks in several different orientations in case they had a directionally-dependent antenna. NO LUCK. I don't think it was an issue of interference because half of the clocks did synchronize, it just seems to be an issue of receiver quality, especially signal sensitivity.
Unfortunately, I know of no simple way (short of an electronics laboratory filled with very expensive gear) to test the sensitivity of an"atomic clock" to the WWVB signal.
There are three (and "a half") ways to synchronize to highly accurate time signals.
1. Via GPS -- GPS requires time accurate to the nanosecond to work properly.
2. Via WWVB, low-frequency time signals broadcast by the US's National Bureau of Standards.
3. Via the Internet. There is a specific protocol that is used to broadcast highly accurate time signals on the Internet.
"and a half" -- cellphones sometimes display time with high accuracy. Cellphone towers need accurate time to interlink and work properly with our phones, carriers may or may not bleed that over to the handsets themselves.
In my ignorance, I will speculate these watches use WWVB for synchronization. Embedding GPS in a watch is likely impractical and/or too expensive.
And therein lies a rub -- the quality of the WWVB receiver.
I have on my desk an "atomic clock" that I got as a giveaway at a large electronics chain and it works great. It keeps accurate time over a 24-hour period and inevitably syncs itself via WWVB every night.
On the other hand, I do some volunteer work at a local non-profit school. Somebody got the bright idea of having accurate clocks in the classrooms and bought a bunch of classroom-size "atomic clocks" off the Internet.
Fully half of these clocks, located in the San Francisco Bay area, failed to synchronize to WWVB.
I even took several of them out-of-doors and did everything I could to try to get the best signal, even trying the clocks in several different orientations in case they had a directionally-dependent antenna. NO LUCK. I don't think it was an issue of interference because half of the clocks did synchronize, it just seems to be an issue of receiver quality, especially signal sensitivity.
Unfortunately, I know of no simple way (short of an electronics laboratory filled with very expensive gear) to test the sensitivity of an"atomic clock" to the WWVB signal.
On 9/8/2015 12:47 PM, Bill B wrote:
On 9/7/2015 6:52 PM, Randall Morrow wrote: > My assumtion was that these "atomic" watches always reset themselves > with radio signals nightly. They *try* to reset on a nightly basis if that function is turned on. Occasionally any number of conditions can interfere and they do not reset although they try several times. On my Wave Ceptor a push of the lower-right-hand button displays a "get" screen. It will tell you the last date and time the watch successfully reset.
