Why is noise introduced when using Open Music Labs original code?
I can't think of any reason that using analogRead(), as opposed to the hardware-clock-triggered free-running ADC, would improve the results of the FFT. analogRead() triggers each conversion in software, and it's therefore vulnerable to latency while some ISR finishes executing. At best, it won't have as accurate a timebase as the ADC's hardware clock. The FFT needs a series of samples very evenly-spaced in time in order to provide accurate results.I'm still waiting for something quantitative to support that assertion. Like, some input data and output data, showing a noisy result for a clean input.
A lot of people seem to get noise.