Compressive Sampling is a new field of sensing theory that sidesteps the traditional Nyquist sampling limit. The Nyquist limit is an information theory result that says to perfectly capture a signal which is bandwidth limited at a certain frequency, X, you must take 2 times X samples per second.  So for example, if you want to perfectly detect a 20Hz sine wave, you must take 40 samples a second. To perfectly represent audio that humans can hear (typically understood to be sounds in the 20-20,000Hz range) we must use 40,000 samples per second (40kHz). CD audio uses 44.1kHz, and professional audio systems typically sample at 48kHz a second.  [Note that the number of samples per second has nothing to do with the quantization, or accuracy of the samples, so audio that is sampled at 20 bits per sample has more information (and less noise) than audio sampled at 16 bits per sample.] Continue reading →