[time-nuts] OCXO and fluctuations after EFC adjustment

[jimlux]

On 4/10/20 2:31 PM, Richard (Rick) Karlquist wrote:
> 
> 
<snip>
> 
> At this time, I will give my usual speech about IMHO the fact that
> since the invention of the DDS on a chip, EFC should no longer be used 
> for high performance oscillators.
> 
> Rick N6RK

Yes..

The only case I can think of is where the oscillator is being directly 
multiplied up and one cannot tolerate the spurs from a DDS.  There are 
folks who believe that this is the case for generating the downlink 
carrier in a deep space transponder.

However, I believe that even in that incredibly niche application, one 
can design a DDS to have minimal spurs in the area close to the carrier. 
In fact, just today, a transponder on Bepi Colombo makes a close 
approach to Earth on its way to Mercury that implements just such a scheme.

I can conceive that there might be an application where the "move the 
spurs around" approach wouldn't work or would be too complex.