Re: Noise Source with Limiter ?

From: Mike Monett (no_at_spam.com)
Date: 10/16/04 

Date: Sat, 16 Oct 2004 16:45:37 -0400

Hi Phil,

  Phil wrote:

> A good limiter produces flat-topped pulses of uniform height, with
> slightly sloping sides. This produces a histogram that has two
> huge peaks at the positive and negative clip levels, plus a low,
> flattish region in between corresponding to the nearly-straight
> sloping sides.

> - ^ ^
> / \ | | | |
> _______/ \_____ vs ______| +--------+ |_______

> Not very close at all.

  Actually, I'm not sure what you are describing. A limiter has only
  two output levels: one and zero. There are no "two huge peaks at the
  positive and negative clip levels" and no "low, flattish region in
  between".

> If you stick the clipped noise through a narrow bandpass filter,
> it will get more Gaussian-looking, and (IIRC) it will become
> Gaussian as the bandwidth goes to zero.

  Every signal is a collection of narrowband noise signals. Getting
  the bandwidth to zero is the dream of anyone who tried designing
  stable oscillators. The output would be the purest sine wave
  imaginable!

> Cheers,

> Phil Hobbs

Regards,

Mike Monett