[time-nuts] Question about SA.33 Rb clock

[Hal Murray]

kb8tq at n1k.org said:
> The gotcha is that the spur spec’s are not always met. As you might guess,
> doing  testing over really wide DDS ranges is impractical. Some designs use
> cleanup loops. The gotcha then becomes a spur (say at 0.053 Hz) that is
> inside the cleanup loop bandwidth …. 

How narrow can I make the loop bandwidth with a traditional analog filter 
using reasonable parts?  Do people build GPSDO style digital filters?

Is there a reasonable formula for the spurs from a DDS?  That sounds like a 
place where guaranteed-by-design would be appropriate.



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