rtl-software defined radio – usb dongles
Software-defined radio (SDR) is a radio communication system where components that conventionally have been implemented in analog hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a computer or embedded system.[1] While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics render practical many processes which were once only theoretically possible.
get yerself a dongle – here’s one on amazon
software defined radio in MAX/MSP
Heres a version working in PureData, which will work on a raspberry pi.