[time-nuts] Re: Fixing PN degradation via ADEV measurement

[Lux, Jim]

On 6/20/22 2:39 AM, Magnus Danielson via time-nuts wrote:
>
>
> So, a counter is really like an ADC for phase, with wide bandwidth 
> input and a sub-sampling mechanism (trigger/time-base). Through 
> processing frequency estimates can be provided. Aliasing occurrs in 
> the sub-sampling. Modern counters can provided estimation filters than 
> goes from a higher sub-sampling rate to a lower, which to some degree 
> removes aliasing, but not fully. These frequency estimation methods 
> form a form of decimation filter.
>
> Cheers,
> Magnus 

An intruiging thought as I drink my first cup of coffee (meaning it's 
not well thought out)..

jumping off from "counter is similar to an ADC for phase" - is there a 
time domain equivalent for Nyquist criterion?   Certainly there's the 
cycle ambiguity.. you know when the zerocrossing occurred, but not how 
many are in between (although a counter usually does). For everything 
else there is a frequency/time duality, so I suspect there is.  The 
criterion is usually explained in terms of information - so there should 
be an equivalent "has all the information" statement for counters/gate 
widths/precisions.