Open-source Software-defined Radio
GNU Radio (GNU Radio) or open-source Software-Defined Radio (SDR) is a free software toolkit for learning, building, and deploying software-defined radio systems.

Origin
Launched in 2001, GNU Radio became an official project of the GNU operating system. Philanthropist John Gilmore initiated and donated $320,000 (US) to Eric Blossom to develop the code and maintain the project.

GNU Radio is a radio signal processing framework distributed under the terms of the GNU General Public License (GPL). Its goal is to provide software developers with the opportunity to explore electromagnetic waves and inspire creative uses of radio frequency (RF) waves.

As with all software-defined radio systems, reconfigurability is its most important feature. Instead of purchasing a wide array of transmitters and receivers, users only need a general-purpose device capable of running signal processing software - in this case, GNU Radio. Although it defines only a limited set of radio functions, understanding the mechanisms (algorithms) of wireless transmission systems allows users to freely configure the software to receive signals as desired.

GNU Radio originated from a branch of the Pspectra code developed by the SpectrumWare project group at the Massachusetts Institute of Technology (MIT). By 2004, the code had been completely rewritten, so the current version of GNU Radio no longer contains any original Pspectra code. It is worth noting that Pspectra was later used to create the commercial Vanu Software Radio.

Supported Hardware
GNU Radio supports various general-purpose SDR peripheral devices - such as HackRF, BladeRF, USRP, and rtl-sdr - enabling the connection between computer-generated baseband data signals and real-world physical RF signals through these hardware platforms.

Impact and Applications
Since its introduction, the concept of Software-Defined Radio has garnered widespread attention in the global radio community. Thanks to its flexibility and openness, SDR has found applications not only in military and civilian wireless communications but also in other fields such as electronic warfare, radar, and smart appliances. This is expected to significantly accelerate the development of SDR technology and related industries, including integrated circuits.