[time-nuts] Distribution amps and slew rate

Magnus Danielson magnus at rubidium.dyndns.org
Sat Nov 3 18:27:48 EDT 2012


David,

On 11/03/2012 10:44 PM, David Hooke wrote:
> Folks,
>
> Given that slew rate is so critical, why do we distribute sine waves and
> perform the zero-crossing detection at every target instrument?

... or rather, why do we design our input stages so they are so 
slew-rate sensitive?

Sine isn't necessary a bad choice, the benefit of a sine is that you 
would not have to be as wide-band as to handle a whole number of 
overtones. That translates into lower amount of noise.

There isn't really one right way of doing it, you can go about it in 
several ways, but you need to do it consistently.

I've modified my TADD-2:s such that I use the input treatment to drive 
one of the outputs, so that they will square up sines for me. For some 
signals this have lowered my trigger jitter and hence improved my 
ability to see more of the actual signal I want to see.

Just as much as you can get a counter with very high single shot 
resolution, it doesn't help if you do not treat your signals properly to 
get the most of that counter.

When doing DMTD tricks, the mixer is the easy part, squaring the signal 
up to get good trigger jitter for the total is what takes a lot of effort.

Cheers,
Magnus




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