Design and implementation of a software defined radio for real time applications

Abstract

One of the most important fields in electronic engineering is that of communications. A very important milestone in the field of communications was without a doubt that of over-the-air communication, known as wireless communication. Communication without the need of a wired connection opened the door to a new world for engineers, enabling systems to share data without the need for them to be close to each other. As time went by technological advancement brought with it the need for these wireless communication systems to provide more range and higher data rates of successful transmission. The concept of software defined radio enabled the fast development of new communication protocols, with fixed hardware and open to software manipulations, new radio protocols could make it to market at a very rapid rate. The physical implementation of Software Defined Radio (SDR) consists of some digital signal processing controller for baseband processing and an analogue front-end chip which handles the analogue signals for wireless transmission. The constant need for faster and more efficient wireless communication gave way to more robust SDR hardware platforms varying from very high-speed Digital Signal Processors (DSPs) with an analogue front end, to, Field Programmable Gate Arrays (FPGAs) with an analogue front end for wireless transmission. The most modern implemented SDRs consist of a System on Chip (SoC) with fully integrated analogue front ends, and fully integrated Application Specific Chips (ASICs) which handle both the digital baseband processing and the analogue manipulation of the signal for transmission. With varying implementations of SDR hardware the concept always remains, fixed hardware, and development in software to remove the time required to develop high frequency radio hardware and speed up the development to market time. The objective of this work was to design an electronic RF front end circuit board with communication capability to a SoC. In other words, a software defined radio hardware platform was to be designed. The designed board had to enable over the air transmission capable of enough data rate and bandwidth for real time applications such as audio and video transmission. Transmission range was also a parameter for this work and thus, power amplification had to be included in the designed circuit board. The designed SDR platform had to be used for baseband processing capable of processing high-data rate communication techniques. The designed and manufactured circuit board was based around the AD9361 RF front end chip, which was designed as a daughter board for the Eclypse Z7 board from Digilent Inc., which incorporates the ZYNQ-7000 SoC. The board was tested by the implementation of uncompressed, real time, stereo, studio quality wireless audio transmission. This implementation resulted in a wireless communication scheme capable of 3.84 Mb/s over-the-air data rate. This is a higher data rate than that achievable using other commonly used protocols and schemes such as Bluetooth®.