[sdiy] converting white noise to pink noise

Dave Manley dlmanley at sonic.net
Wed Mar 5 18:21:33 CET 2008

Tom Wiltshire wrote:
> On 5 Mar 2008, at 14:41, Scott Gravenhorst wrote:
>> I will add that sometimes the bit labeling is a bit weird.  I'm very 
>> much used to a
>> zero based numbering system for anything with "N bits" where N > 0, 
>> but some LFSR bit
>> taps I've seen, including the Xilinx link I posted, use a 1 based 
>> system.  From this
>> confusion an error can easily arise.
> Yes, I've been caught out like this too. Finished up writing a LFSR that 
> wasn't anywhere near as good as it was supposed to be. It was only when 
> I really went back over it and checked everything that I spotted the 
> numbering difference and the error.
> Being a longtime computer programmer, I obviously count "0, 1, 2, 3" 
> rather than "1, 2, 3" but for some reason LFSR taps seem to mostly start 
> with bit 1. Weird. Maybe they were designed by normal people or something.

Pretty sure the blame for this lies with the mathematicians.  If you 
ever do any crypto stuff you'll find similar numbering, and an annoying 
habit of numbering the MSB "one".


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