SDR is widely used in amateur radio services that uses receivers. With technology using sampling receivers and detectors, the SDR is related to the ADC (analog to digital converters) of a dynamic range, where the signals of radio frequency get converted into audio frequencies.
The first ever systems used a soundcard to enable ADC functionality, but present SDRs come with embedded ADCs, which apart from having noise-resistance efficiency can give a higher dynamic range of transmission. SDR software is designed to perform various activities like processing of digital signals, making use of specific software for hardware designed for radio; demodulating process, filtering both audio and radio frequencies, enhancing quality of signals through equalization.
With these benefits SDR uses include in transmission of morse codes, modulating single sideband, amplitude and frequency modulations, apart from a number of digital modes like packet radio, slow-scan TV, teletype radio, etc.. SDR is used experimentally by amateurs for Digital Radio Mondiale, which is a DREAM Open Source Project, cable of decoding of COFDM. SDR systems are also used for many other purposes such as amateur, GNU radio et al.
In the military, SDRs are widely used for interoperable and flexible transmission of data. Apart from maritime and fixed radios, hand-held, airborne, vehicular dismounted radios are all examples of SDR systems. Using the internationally approved Software Communication Architecture (SCA), which in turn uses POSIX and CORBA systems for coordinating different modules, SDR is widely used for military applications.
Though SCA is a military approved architecture, many vendors of radio systems have evaluated it for commercial purposes although there hasn't been much progress. This is because civilian radios use a fixed architecture and are optimized to do a particular type of function, which making it more viable for mass production.