OsmoSDR is a 100% Free Software based small form-factor inexpensive SDR (Software Defined Radio) project. If you are familiar with existing SDR receivers, then OsmoSDR can be thought of something in between a FunCube Dongle (only 96kHz bandwidth) and a USRP (much more expensive). For a very cheap SDR (with limited dynamic range), you can use the DVB-T USB stick using the RTL2832U chip, as documented in rtl-sdr. It consists of a USB-attached Hardware, associated Firmware as well as GrOsmoSDR gnuradio integration on the PC.