[sdiy] Uniformly distributed noise generator?

Scott Gravenhorst music.maker at gte.net
Mon Jun 10 17:39:48 CEST 2013


Martin Klang <mars at pingdynasty.com> wrote:
>
>On 10 Jun 2013, at 15:06, cheater00 . wrote:
>
>> On Mon, Jun 10, 2013 at 3:15 PM, Scott Gravenhorst <music.maker at gte.net> wrote:
>>> 
>>> It has been sooo long since the implementation of the chuff chuff LFSR with only a
>>> few bits and low clock rate that it is truly a ridiculous comparison to analog noise
>> 
>> That's not really good enough in my application. This is for a
>> measurement fixture. I need true, never-repeating randomness.
>
>Never-repeating, for realz?

Of course not...  and yes, I should have written "within the timespan of measurement given the
clock rate".  So yes, any bit length LFSR will repeat, regardless of clock rate _sometime_, they
all do.  However there are practical limits are there not?

Are there applications that can exhaust that capacity.  Sure.  It's a real world and the math is
the math.

But, my question then is - Does Damian's application exhaust that and actually give him repeated
lies?  I suggest that it is an exercise for him to compute.

>If you don't need more than 1/ms for the next 4 billion years 
>then a Mersenne Twister PRNG [1] will do just fine. 
>
>There are some nice implementations out there [2]. I developed a 
>solution for the STM32F mcu's which will be published at some 
>point. Of course the STM32F2 and F4 have built-in true RNG, 
>making the twister a bit superfluous. 
>
>If you are very, very particular about the randomness of your 
>values then verify with the diehard (or dieharder) test suites 
>[3]. 
>
>hth,
>
>/m
>
>[1] http://en.wikipedia.org/wiki/Mersenne_twister
>[2] http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
>[3] http://code.google.com/p/dieharder/
>

-- ScottG
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