Locating ADC sample accuracy analysis post

Somewhere on this forum is a post dealing with the sample speed vs. accuracy of the Uno ADC. It has a graph of sine waves that were measured and analysed for distortion. It was quite a long post in a long thread. I'm trying the same thing but for the life of me I can't find it again. Can anyone locate it please?

I'll not be happy if someone suggests using the search box :stuck_out_tongue:

http://www.openmusiclabs.com/learning/digital/atmega-adc/ http://www.openmusiclabs.com/learning/digital/atmega-adc/in-depth/index.html

Thank you.

Slightly disappointing now that I've reviewed it. For someone with the resources to use a spectrum analyser, I would have expected a picture of the sampled wave forms. We only have indirect evidence of success. And even that isn't clear. Their results show distortion around a test frequency of 1 kHz. That's a bit low when testing a sample rate of 200 kSa/s. And the max distortion is only -36 dB below signal and approaches the window boundary which might mean that it's an analysis aberration.