Software-defined radio

Software-defined radio (SDR) is a radio communication system where components that have been traditionally implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system. While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics render practical many processes which were once only theoretically possible.ELF 3 Hz/100 Mm 30 Hz/10 MmSLF 30 Hz/10 Mm 300 Hz/1 MmULF 300 Hz/1 Mm 3 kHz/100 kmVLF 3 kHz/100 km 30 kHz/10 kmLF 30 kHz/10 km 300 kHz/1 kmMF 300 kHz/1 km 3 MHz/100 mHF 3 MHz/100 m 30 MHz/10 mVHF 30 MHz/10 m 300 MHz/1 mUHF 300 MHz/1 m 3 GHz/100 mmSHF 3 GHz/100 mm 30 GHz/10 mmEHF 30 GHz/10 mm 300 GHz/1 mmTHF 300 GHz/1 mm 3 THz/0.1 mm Software-defined radio (SDR) is a radio communication system where components that have been traditionally implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system. While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics render practical many processes which were once only theoretically possible. A basic SDR system may consist of a personal computer equipped with a sound card, or other analog-to-digital converter, preceded by some form of RF front end. Significant amounts of signal processing are handed over to the general-purpose processor, rather than being done in special-purpose hardware (electronic circuits). Such a design produces a radio which can receive and transmit widely different radio protocols (sometimes referred to as waveforms) based solely on the software used. Software radios have significant utility for the military and cell phone services, both of which must serve a wide variety of changing radio protocols in real time. In the long term, software-defined radios are expected by proponents like the SDRForum (now The Wireless Innovation Forum) to become the dominant technology in radio communications. SDRs, along with software defined antennas are the enablers of the cognitive radio. A software-defined radio can be flexible enough to avoid the 'limited spectrum' assumptions of designers of previous kinds of radios, in one or more ways including: The ideal receiver scheme would be to attach an analog-to-digital converter to an antenna. A digital signal processor would read the converter, and then its software would transform the stream of data from the converter to any other form the application requires. An ideal transmitter would be similar. A digital signal processor would generate a stream of numbers. These would be sent to a digital-to-analog converter connected to a radio antenna.