SDR

A number of definitions can be found to describe Software Defined Radio, also known as Software Radio or SDR. The SDR Forum, working in collaboration with the Institute of Electrical
and Electronic Engineers (IEEE) P1900.1 group, has worked to establish a definition of SDR that provides consistency and a clear overview of the technology and its associated benefits.
Simply put Software Defined Radio is defined as1:
"Radio in which some or all of the physical layer functions are software defined"
A radio is any kind of device that wirelessly transmits or receives signals in the radio frequency (RF) part of the electromagnetic spectrum to facilitate the transfer of information. In today's
world, radios exist in a multitude of items such as cell phones, computers, car door openers, vehicles, and televisions.