SDR technology uses software to perform radio-signal processing functions instead of using resistors, capacitors, feedback loops, or application-specific integrated circuits. In an SDR, mixers, filters, amplifiers, synchronizers, modulators/demodulators and frequency tuners can all be written in software.
SDR is a technology capable of configuring a wireless device to work with multiple communication systems: cellular phone, pager, WI-FI transceiver, FM or AM radio, satellite communications terminal, etc. SDR is also a technology that facilitates interoperability among the communications systems used by military, police and rescue-relief teams.
SDRs work much like desktop computing where a single hardware platform can carry out many functions based on the software applications loaded. SDRs use high-speed reprogrammable devices such as digital signal processors (DSP), field programmable field array (FPGA), or general purpose processors (GPP).