SDR

Software-defined radio (SDR) is a radio communication system in which most signal processing is performed in software rather than fixed hardware. The RF front end provides reception and transmission and converts signals to digital form, while the software stack implements modulation, demodulation, filtering, and protocol handling. This makes a single hardware platform capable of supporting multiple bands and standards by changing software rather than swapping hardware.

An SDR system typically comprises an RF front end (antenna, filters, mixers), analog-to-digital and digital-to-analog converters, and a processing engine (general-purpose CPU, DSP, or FPGA) running a software framework. Popular toolkits include GNU Radio, and hardware platforms such as USRP, HackRF, and RTL-SDR. Speech and data signals are processed digitally, enabling flexible experimentation and rapid reconfiguration.

Applications span amateur radio, academic research, wireless communications development, and defense or public-safety testbeds. SDR enables multi-mode, multi-band operation with lower incremental cost and faster prototyping compared with traditional hardware-defined radios. It is foundational for software-based cellular stacks, cognitive radio, and radio astronomy research.

Challenges include demand for substantial processing power and memory, real-time constraints, power consumption, RF front-end linearity and calibration, and regulatory compliance. Ecosystems rely on open-source frameworks and collaboration between hardware and software developers.

Note: SDR in other domains may refer to Special Drawing Rights, an IMF reserve asset; in context, SDR typically denotes software-defined radio in technical discussions.