Re: Time Domain Reflectometer (was Re: internet outages)
On Sun, 23 Dec 2018 22:54:20 -0600
John Hasler <jhasler@newsguy.com> wrote:
> rhkramer writes:
> > Yeah, but I wasn't thinking about actually using a CRT to display
> > the signal in real time, but, instead, collect samples (at maybe 4
> > GHz??), store them, and then display them as a static display.
>
> At that sort of frequency sampling scopes (including the old crt ones)
> sample at far below the signal repitition rate.
Yes, they rely on the signal being repetitive. To see a single
transient, you want at least five samples in the relevant period,
preferably more.
There is normally a real Nyquist bandwidth quoted somewhere in the
small print. I used to repair and calibrate Hitachi scopes for a while,
until everyone stopped using them.
--
Joe
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