What is a Software Defined Radio?

2 Answers
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Editorial Team - everything RF

Jan 3, 2019

A Software Defined Radio (SDR) is a radio that can be programmed to operate a particular frequency. The frequency of the radio can be tuned via software (or firmware). Traditional radios that are hardware based are usually designed to operate at specific frequency ranges or for specific applications. The frequency of hardware based radios can not be changed easily as the radio transceiver and components in the Front End are optimized to operate at a particular frequency. This is not the case in Software Defined Radios, these radios can be programmed to operate at a specific frequency. 

Traditional radios are implemented using hardware like mixers, filters, amplifiers, modulators, demodulators etc. SDR's use an ADC and DAC to convert a signal from Analog to Digital and then from Digital to Analog without the need for the various hardware components.

So an SDR that has a frequency range from DC to 6 GHz can be used for Wi-Fi (2.4 GHz and 5 GHz), ISM Band Applications (400 MHz, 900 MHz, 2.5 GHz) and various other applications within the DC to 6 GHz frequency range.

The concept of software-defined radios has been around for some time, however, their application has been limited. With higher frequency and higher resolution ADCs and DACs available, these radios are starting to become more popular and we are seeing them being used more and more.

jacob - Technion

Mar 4, 2019

SDRs usually have a broad frequency range by default and can be programmed to operate at a specific frequency within that range.