[time-nuts] How to get 32.768KHz from 10MHz.

[Bruce Griffiths]

Rick Karlquist wrote:
> A more practical offshoot of this concept is to subsample the
> 32 kHz oscillator at 128 Hz (ie a sampling phase detector) and use a slow
> loop to tune the 32768 kHz oscillator.  The biggest problem here is that
> you have to have a tunable oscillator.  Attempting to get around
> this by injection locking a non-tunable oscillator is probably not
> going to work very well, since the frequency tolerance is likely
> to be larger than the small amount of frequency pulling you can
> get with injection locking.  Basically, if the oscillator tolerance
> is 0.01%, and it has a Q of >>10,000, it will be hit or miss depending
> on luck.
>
> Rick N6RK
>   
The drawback of all injection locked oscillator schemes is that the 
injection locked oscillator needs to be tunable.
However a simple trimmer cap may suffice if the temperature excursion of 
the oscillator isnt too large and the occasional readjustment to 
compensate for aging is acceptable.

Bruce