[sdiy] Digital noise generation

[Fredrik Carlqvist]

All M-sequences produce every number between 1 and 2^N-1, but the tap
positions and number will change the ordering. For some combinations, there
will be several distinct pops or even brief tones somewhere in the cycle,
others are smooth. If you listen to an unprocessed LFSR output you will soon
be able to determine it's length by ear, at least if it's shorter than a
minute.

It's not so much a matter of the number of taps, a 2-tap LFSR can be as
smooth as a 12-tap. 

Using more than one bit from the LFSR output (while increasing the shifting
speed accordingly) will not change the distribution, but probably remove som
pops. 


Fredrik C