[sdiy] Digital noise sources
ebrombaugh at earthlink.net
Fri Mar 28 15:52:46 CET 2008
Tom Wiltshire wrote:
> Sorry to go back to this again, but I wonder if someone could clear
> something up for me. There's something I don't understand:
> What's the difference between outputting a random stream of bits at high
> frequency (1-bit digital noise) and outputting a series of random bytes
> to a DAC (8-bit digital noise)?
> Are they equivalent? Is one better than the other?
> If someone who understands digital better than I could explain this, I'd
> be very grateful.
That's a good question and one that's often occurred to me as well. I
built up some Octave code to investigate this and what I found was that
there really is no spectral difference between 1-bit and 8-bit random
noise. The only noticeable difference is that if the max values of the
8-bit noise line up with the max values of the 1-bit noise then the
overall power in the 8-bit noise will be a few dB lower.
The most critical aspect of your noise generator is ensuring that it has
a long period and uniform distribution.
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