One more pseudo-random trick

[Don Tillman]

   Date: Sat Sep 20 01:10:54 -0700 1997
   From: Don Tillman <don at till.com>

   I just noticed that there's one very cool feature of feedback shift
   register noise generators...

   Given that the pattern always shifts over one bit for every clock
   pulse, you can filter the noise simply by tapping off each stage with
   a resistor and summing.  (I mean choosing Z-transform-based resistor
   values, and both positive and negative summing.)

   So that's a great way to make pink (or whatever) noise.

[Later I noticed that someone else already suggested this.  I'm
clearly getting lost in my email.]

Here's another idea:  

One obvious problem with pseudo random feedback shift registers is
that the noise has absolutely no value distribution; it's binary.

To fix this you could tap off the stages like before, but use the
Z-transform of an all-pass filter.

  -- Don