Electronic – Why pick 262144 Hz oscillator frequency

clockcrystaloscillatorrtc

Some Bulova watches (for example the Precisionist collection) use 262144 Hz crystal oscillators instead of the usual 32768 Hz. What are the true advantages of this higher frequency, if they even exist?

The usual quartz clock frequency is 32768 Hz because that's the lowest power of two above 20 kHz. This means the usual frequency is above human hearing range, but still allows ticking at one second intervals by simply dividing with 2^15.

Bulova claims their ~262 kHz watches are an order of magnitude more precise (~10 seconds per year vs the ~15 seconds per month of standard quartz watches). Do higher frequencies really help with precision or is it just marketing?

Their ~262 kHz watches also tick eight times per second. Many people enjoy this smoother motion, and it feels a bit more like a mechanical watch. But couldn't they achieve exactly the same effect by just dividing the usual ~32 kHz by 2^12? It seems like they chose to maintain the 2^15 divisor, for some reason.

Best Answer

As already commented, the accuracy doesn't depend on frequency.
It does significantly depend on temperature.

What Is ‘High Accuracy Quartz’? Most watches rocking a quartz movement are guaranteed accurate to around 15 seconds a month or so. This is still much better than even the best mechanical watches, but there’s a breed of quartz watches out there that can do even better: the High Accuracy Quartz (HAQ). HAQ’s still operate under the same principals as standard quartz movements, but they take into account the one major threat to quartz accuracy: changes in temperature. HAQ’s are, thus, thermo-compensated and can detect these changes and adjust themselves accordingly, which typically results in a guaranteed accuracy rate of around 10 seconds per year.

Source: https://gearpatrol.com/2018/08/20/your-complete-guide-to-quartz-watches/

It's quite likely they used thermo-compensation, which has nothing to do with frequency.

A drawback of a higher frequency is a higher power consumption.
Their manual suggests the battery should be replaced each year which sounds frequent to me (I havent replaced the battery of my cheap watch the last 3 years).

Related Topic