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.