[time-nuts] WWVB PM Time Questions

[Mark Haun]

On 23-Jul-20 4:35 AM, Detlef Schuecker via time-nuts wrote:
> Hi,
>
>> principles.  The STM32L4 series which I often use has a pretty decent
>> ADC: fast (5 MSPS), with about 11 good bits in differential mode, and
>> "proper" hardware downsampling (called the DFSDM in the manual).  If the
> Yes, the STM32 series also have built-in OPAmps, so one could hook up a 
> loop or a ferrite directly to the uC without too much external components. 
> Sampling at 160ks/s should suffice to get the phase and DCF77 is in reach 
> as well. At this rate you have ~500-1000 processor ticks per sample which 
> should be enough to do real time demodulation.

Are there any examples (schematics) out there for the front-end
electronics?  I haven't found much by googling except the KD2BD design
which is more involved than I would like.  The integrated designs used
in "atomic" clocks seem very simple, but I am unsure how to duplicate
them.  I would like to use a crystal filer, but I'm at a bit of a loss
to start.  For example, would one choose series or parallel resonance? 
I believe the impedance of these tuning forks is quite high at series
resonance---tens of kohms.  I didn't make much progress the last time I
tried doodling op-amp circuits to use one.

My general impression of this list is that a lot of folks are pretty
comfortable with analog and discrete digital design, but find DSP and
algorithms "hard."  I'm exactly the opposite so maybe I am in the right
place ;)

Mark