Actually that's not true. It seems like it should be, but its not. Also, a 20kHz tone, by definition, is a sine wave.

Nothing personal Matt.

EDIT:

OK - here are some ways to think of it that don't involve numbers and letters dancing together in some sort of unholy rite:

- The simple 'connect the dots' shape is the stored data, not the waveform. The information about the shape of the waveform is spread over many samples and is no longer stored in a single sample.

- The simple 'connect the dots' shape contains frequencies higher than the Nyquist frequency. Or we could say the D/A step produced these frequencies, however we want to look at it. In any case, they will be removed in the next step.

- One really cool 'high level' way of looking at it is this - the dots are not the waveform they are just data, and the only waveform that can connect the dots and not contain elements over the Nyquist frequency is the original waveform.

[This message has been edited by charlie (edited October 07, 2002).]