[time-nuts] DMTD Question1

John Miles jmiles at pop.net
Wed Jan 27 00:53:20 UTC 2010


> > So why even talk about TC phase shifts at the ps / deg level?   Who
> > cares and who needs it?

A picosecond is 1000 femtoseconds.  When you're spending $100/ea. on parts
rated for 60-70 fs jitter, a picosecond starts to look like a long time
indeed.

> > Does not sound like you are doing the Nuts any service to address
> > things that are orders of Magnitude below usefulness.

When designing something like this, it's useful to understand where, and
why, your efforts fall short of the state of the art.  That way you can be
sure that the compromises you're making are the right ones.  The idea is not
to leave any obvious low-hanging fruit for optimization.  You want to get
the most out of the money you're spending, whether it's $200 or $20,000,
right?

I do think there's a lot of room between "state of the art" timing
performance and conventional TIC-grade performance where corners can be cut
and costs can be saved.  It's helpful (and more interesting) if you can make
those calls rationally, instead of just adopting circuits from papers and
hoping for the best.

-- john, KE5FX




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