What are software defined radios

What are Software Defined Radios (SDRs)

In this post we’ll explore SDR radios or software defined radios. There’s been a common theme in most things technology related lately and that is a move to Software Defined Everything, or SDx as it is often shortened. Radios and RF communications equipment in general have been moving toward a software-defined existence just the same.

A radio is any kind of electronic device that transmits and receives signals in the radio frequency (RF) portion of the electromagnetic spectrum. These signals (often called waveforms) are used to transfer information between radios. Radios are ubiquitous today and found in almost every electronic device you own thanks to the proliferation of “smart” and “connected” devices.


Beginner's Guide to Software Defined Radios

Looking to get started with SDR radios and not sure where to begin? Check out our definitive guide to getting started with software defined radios.


The trend of radios moving to a software-defined paradigm is not too surprising, considering how just how pervasive software has become in every part of our lives. Even our phones have been software-defined multi-function devices since the advent of the app store.

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So what are software defined radios (SDRs) anyways?  Very simply, IEEE defines SDRs as a “radio in which some or all of the physical layer functions are defined by software.”  Makes perfect sense, but what it really means is that some functionality of the radio can be modified with no changes to the physical hardware.  A prime example of this could the frequency ranges and bands that a radio operates. 

The functionality of traditional hardware-defined radios can only be changed by physically changing the device. This “hard-wired” approach minimizes flexibility of operating frequencies and ability to support multiple waveforms. In contrast, software-defined radios enable multi-mode, multi-band and/or multi-functional radios capable of operating across wide-bands and able to support multiple waveforms by changing software and/or firmware loads on the device.

Several technologies have been required to move this functionality from hardware-defined to software-defined. We’ll cover the anatomy of software defined radios in a future post. One of the primary advancements includes wide-band analog-to-digital converters (ADCs), digital to analog converters (DACs) as well as advancements in baseband processors. Moving the processing elements closer to the antenna and digitizing the RF signal as soon as possible have been key to realizing useful software defined architectures.

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