Smart Radio describes two related developments in radio technology: software-defined radio (SDR) and cognitive radio (CR). Because of their digital parts, these radios are much less expensive and more versatile than analog radios. SDR enables the user to send and receive analog voice, digital voice, data or all three. CR is a software-defined radio with complex software called a "cognitive engine," which enables dynamic frequency sharing, improved interoperability, and automatic adjustment of radio performance for police and other public safety officials.