Software Defined Radio

aka SDR

http://en.wikipedia.org/wiki/Software-defined_radio

a radio communication system which can potentially tune to any frequency band and receive any modulation across a large frequency spectrum by means of as few as hardware possible and processing the signals through software.

Current (2007) digital electronics are too slow to receive directly typical radio signals over approx. 40MHz.

http://comsec.com/software-radio.html

GnuRadio

Jul'2012 profile of Phi from PerVices (a Y-Combinator company)