TABLE OF CONTENTS A software defined radio (SDR) is a form of transceiver in which ideally all aspects of its operation are determined using versatile, general-purpose hardware whose configuration is under software control. This is often thought of in terms of baseband DSPs, hence the term software radio, which is often used to describe this type of system; however, FPGAs, ASICs (containing a re-programmable element, e.g., an embedded processor), massively parallel processor arrays, and other techniques are also applicable. The more general terms flexible architecture radio (FAR) and software defined radio (SDR) are therefore becoming increasingly adopted. Although not strictly necessary, in order to be termed software defined, this type of radio is also commonly assumed to be broadband (multi-band or multi-frequency in operation). This assumption is made, as one of the principal applications of this type of transceiver is perceived to that of replacing the numerous handsets currently required to guarantee cellular (and in the future, satellite) operation worldwide. Even with the GSM system having achieved a certain degree of ubiquity worldwide, it is still not possible to utilise a single handset in all countries (with cellular coverage) worldwide. Furthermore, the many competing standards (GSM, CDMA, WCDMA, AMPS, D-AMPS, PDC) all have differing characteristics, tariffs, and so forth, and hence a multi-mode, multi-band transceiver, covering all of these systems, would certainly be a useful device.
The concept of a multi-band or general coverage terminal is, strictly speaking, an extension of the basic software defined radio...
