Tom Henry Tunable Noise Source

Don Tillman don at till.com
Wed Nov 17 16:40:30 CET 1999


   From: "Grant Richter" <grichter at execpc.com>
   Date: Tue, 16 Nov 1999 22:20:54 -0600

   > (3) How is the pattern (distribution ?) of a Sample and Hold
   > changed when you're sampling a white-noise-FMed VCO instead of
   > sampling the noise directly ?

   White noise has a gaussian (bell shaped) probability distribution
   relative to amplitude.  The further from zero volts the lower the
   probability of getting a sample.

Isn't it true that "white noise" describes the spectral distribution
and not the probability distribution?

Sure, most analog noise white sources have gaussian probability
distributions.  But consider two popular digital white noise sources;
a sequence of random numbers is considered fine white noise as is the
low-pass-filtered single-bit output of a psuedo random shift register.
They both have flat probability distribution.

  -- Don



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