# [sdiy] Uniformly distributed noise generator?

Steven Cook stevenpaulcook at tiscali.co.uk
Mon Jun 10 18:00:20 CEST 2013

```I've had some more coffee now but I still don't get this. (:

> Hi Steven,
> "white" refers to the frequency domain distribution, "gaussian" to the
> time domain distribution. Both are independent, however gaussian white
> noise is the most common by far. Any other kind is very rare.

Are you saying that analogue (noisy transistor junction) 'white noise' has a
Gaussian amplitude distribution?

Best Regards,

Steven Cook.
support at spcplugins.com
http://www.spcplugins.com/

> Below is what Wikipedia says.
>
> Cheers,
> D.
>
> ----------------
>
> Being uncorrelated in time does not restrict the values a signal can
> take. Any distribution of values is possible (although it must have
> zero DC component). Even a binary signal which can only take on the
> values 1 or -1 will be white if the sequence is statistically
> uncorrelated. Noise having a continuous distribution, such as a normal
> distribution, can of course be white.
>
> It is often incorrectly assumed that Gaussian noise (i.e., noise with
> a Gaussian amplitude distribution — see normal distribution)
> necessarily refers to white noise, yet neither property implies the
> other. Gaussianity refers to the probability distribution with respect
> to the value, in this context the probability of the signal falling
> within any particular range of amplitudes, while the term 'white'
> refers to the way the signal power is distributed (i.e.,
> independently) over time or among frequencies.
>
> We can therefore find Gaussian white noise, but also Poisson, Cauchy,
> etc. white noises. Thus, the two words "Gaussian" and "white" are
> often both specified in mathematical models of systems. Gaussian white
> noise is a good approximation of many real-world situations and
> generates mathematically tractable models. These models are used so
> frequently that the term additive white Gaussian noise has a standard
> abbreviation: AWGN.
>
> White noise is the generalized mean-square derivative of the Wiener
> process or Brownian motion.
>
> A generalization to random elements on infinite dimensional spaces,
> such as random fields, is the white noise measure.
>
> On Mon, Jun 10, 2013 at 1:55 PM, Steven Cook
> <stevenpaulcook at tiscali.co.uk> wrote:
>> Hi,
>>
>>
>>> gaussian (like normal noise circuits)
>>
>>
>> Maybe I've not had enough coffee today, but isn't ordinary white noise
>> uniformly distributed rather than gaussian?
>>
>> Steven Cook.
>> support at spcplugins.com
>> http://www.spcplugins.com/
>>
>> --------------------------------------------------
>> From: "cheater00 ." <cheater00 at gmail.com>
>> Sent: Monday, June 10, 2013 9:43 AM
>> To: "synth-diy" <synth-diy at dropmix.xs4all.nl>
>> Subject: [sdiy] Uniformly distributed noise generator?
>>
>>> Hi guys,
>>> I was wondering if anyone has seen a noise circuit that is not
>>> gaussian (like normal noise circuits) but instead uniformly
>>> distributed.
>>>
>>> If you look at gaussian noise on a scope then it looks like a blurry
>>> line, which has the most intensity at 0V and becomes darker and darker
>>> as you move away from 0V.
>>>
>>> I'm looking for something that has exactly the same brightness from
>>> e.g. -5V to +5V.
>>>
>>> Cheers,
>>> D.
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>
>>
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