[AH] Red noize

[Harry Bissell]

If I follow this the 2^(n-1) frequencies is where n is the number of stages in the
register.
I have a 31 stage shift register so that would be 2^30. Thats enough frequencies for
my hearing... I have never had a hole in even the most agressive bandpass filter...

OTOH this was a replacement for the National Semi 5831 (?) 17 stage noise source,
which had good enough frequency distribution (of energy) but a cycle time of less
than 2 seconds... which I COULD hear the envelope of...
woosh...woosh...woosh...woosh...
(you get the picture).

Why not take two (or more) shift register noise sources and sum their outputs
together in an analog fashion.  use different clocks... that would make it WAY more
random !!!

H^)

Magnus Danielson wrote:

> From: Martin Czech <martin.czech at intermetall.de>
> Subject: Re: [AH] Red noize
> Date: Fri, 4 Feb 2000 13:01:32 +0100 (MET)
>
> > Idea : (may be stupid)
> >
> > Shift register noise has the advantage to be really white in the interesting
> > bandwidth, but it is not really random. How about using a junction avalanche
> > (that may not be white noise, depends on current, surface effects i.e. devices
> > etc.) to xor some of the shift registers inputs? I guess the shift register
> > will scramble (modulate) the avalanche pulses to something white,
> > but the sequence will be more random, there may be some correlation in it,
> > but it will never be the same, i.e. no cycles.
>
> The trouble with the shift register is that it produces 2**N-1 number of
> frequencies (at most). These are single frequencies evenly spread appart.
> XORing with noise will not do very well since the modulation would have a DC
> term which would let too much of the original waveform thru.
>
> Use more steps instead, then it will be dense enougth.
>
> > 2nd Idea:
> >
> > I've read about mathematical theory about poles with rational order,
> > or in general network transfer functions with non integer order.
> >
> > There is no reason why math should prefer x**2 instead of x**2.18973,
> > we do this every day using the pocket calculator.
> > Has anything useable grown out of this roots since 1970??
>
> Actuall, there are good reasons for some restrictions of that sort. It is
> still a mystery how the Columbs law of fources between two round objects
> being electrically charged could be so accurate on r**2. It was simple
> reasoning behind that and the conclusion has hold for remearsurements to the
> 16thies digit without disturbance in the force.
>
> Cheers,
> Magnus