Software-Defined Radios
July 25th, 2025
When talking about radios, it is important to define what a 'radio' is? A radio is any kind of device that can wirelessly transmit and receive signals in , with this in mind, everyday items are also radios; cellphones, vehicles, computers, and televisions.
Differences
Hardware vs Software
traditional radio devices had limited cross-functionality, this meant that in order to change something, it would require physical intervention, increasing costs and limiting support for other . By contrast, Software Defined Radios do are designed with efficiency and inexpensively in mind, allowing support for multiple bands, modes, and multi-function wireless devices that can be updated and managed through software.
Looking at the diagram above we can see the input and output of how a SDR functions. It inputs multiple software and hardware support which then gets converted to its respected channel and sample rate, it then runs to the Digital-ToAnalog converter which converts analog signals, a volatile way of representing, sending and receiving information to digital, a set, usually binary based way of presenting and transmitting information. Finally it is then sent to the RF hardware and onto the smart antenna, the process then goes in the opposite direction, reverting the process for the output function.
Above represents the difference between an analog and digital signal, analogs (which usually use the Fourier Transform) have swaying movements when it comes to amplitude, compared to digital (which is usually set in binary) has uniform-like data representation, when representing SDR data, most RF frequencies are represented in analog data, which is then converted back to binary once the operation is complete.
Data Processing
Hardware radios rely on multiple components such as modulators, demodulators, mixers, filters, amplifiers, etc. Operating in these fixed parameters limit flexibility of the system, in contrast to SDRs, which use software algorithms allowing for greater flexibility for communication protocols, algorithms, adaptability and reconfiguration without the need for hardware intervention.
Hardware Based-Systems
Data processing is performed using dedicated hardware circuits, this consists of the RF front end (RFFE), data converters and processors. The RFFE is designed to handle the transmission and reception of RF signals from an antenna, it also includes built in DAC and ADC converters for seamless communication. Such as everything hardware, they have limited capabilities and depending on the available resources, can allow for greater or weaker RFEE processing.
Software Based-Systems
Data processing is performed on software applications using programmable platforms, such as general-purpose processors (GPPs), digital signal processors (DSP), or field-programmable gate arrays (FPGAs). Due to the use of specific, programmable hardware, flexibility is a strong suit, hardware can easily be updated and/or changed to fit the needs of the user while applying maximum efficiency.
Duplexity
Duplexity refers to the ability to both transmit and receive information simultaneously, for instance when talking to someone on the phone, your phone is able to receive their message as well as allow you to respond to it at the same time. SDRs have this ability, but to a limit, a singular SDR most of the time will only be limited to half-duplex, which, depending on the user's preference, can only transmit or receive data. To support a full-duplex, 2 individual SDRs are required to simultaneously transmit and receive data.
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