[sdiy] converting white noise to pink noise

Tom Wiltshire tom at electricdruid.net
Tue Mar 4 19:28:52 CET 2008


On 4 Mar 2008, at 15:53, Eric Brombaugh wrote:

> How about programming a PIC12C50x part with a nice 32-bit LFSR  
> algorithm? Those will run at 4MHz, so the repeat rate would be  
> something on the order of 12 hours assuming a 100kHz sample rate  
> (not unreasonable for a PIC). The parts cost ~$2. The program would  
> be maybe 20 - 30 instructions long. Noise would be white out to  
> ~50kHz - well beyond human range.
>
> Eric

I second this approach! But then, I would, wouldn't I?!

You could easily program a LFSR onto a 8 pin DIP 12F/12C series PIC.  
I recently did a 64-bit LFSR algorithm that doesn't repeat for  
200,000 years at 20KHz, so don't worry about repetitive noise.
Eric is right - the parts (all one of them) are cheap, the program is  
simple, and you can have noise which is pure white to pretty much any  
measure of accuracy if you care to.

The article Colin F posted (below) really does cover it. I learned  
quite a bit about noise/random numbers from this page when I was  
looking into the topic.

http://www.edn.com/article/CA313057.html

Regards,
Tom






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