The technique is refered to as "under-sampling" while it is a signal processing technique it is not out of the realm of microcontrollers (i.e. ds89c420), however all the literature is for DSP.

The Analog Devices ADSP-2181 feels very much like a micro-controller and is easy to learn.

Here are some sample links:

http://archives.e-insite.net/archives/.../16df1.htm



http://www.analog.com/support/s...ction5.pdf

http://dbserv.maxim-ic.com/quick_vie...qv_pk=1775