> I also don't completely understand about their being only one possible solution. It makes sense if you know that the signal is a single sine wave, but since i

> I also don't completely understand about their being only one possible solution. It makes sense if you know that the signal is a single sine wave, but since in general the signal is a summation of an unknown number of sine waves, it's not clear. I guess this is something he didn't have time to get into more depth for the quick overview :) I'll give this a stab. Assume you're connecting the dots (samples) with a pencil. You can see that the high frequency filter would not let the pencil go up or down several times between 2 adjacent dots because any movement at that rate would be too high a frequency right? Now extend that thinking: Any movement not along a specific path (the one possible solution) would produce frequencies above the limit of the filter. Even a teeny tiny little bend in that line would result in a tiny few decibels of sound at a frequency above the filter and hence are not allowed. Make sense? Experts: is that accurate?