Developing a generic software-defined radar transmitter using GNU Radio.

Abstract

Research into the development of software defined radars (SDRs) often combines the GNU Radio software toolkit, with the Universal Software Radio Peripheral (USRP) hardware platform. Studies have already demonstrated that these tools can be combined to develop and implement versatile, low-cost, SDR systems. These studies focus on the question as to whether or not a GNU Radio and USRP based SDR can address a specific set of requirements for a particular radar application; but do not explore the characteristic behaviour of the technology. Understanding the characteristic behaviour of this technology, more specifically its limitations and accuracy, is critical to radar designers considering using these tools to achieve SDR design requirements. This thesis examines how effectively GNU Radio and the USRP can be combined to create a software-defined radar transmitter. A SDR transmitter has been developed using these tools as a subject for experimentation and implemented to produce a set of generic radar waveforms at a frequency of 5.8GHz. This set consists of continuous wave, 1 μs pulsed waveforms and frequency modulated continuous waveforms with sweep ranges from 0.5 to 25MHz. Characterisation tests thoroughly investigated and verified limitations of the USRP performance, and identified many others that were unknown at the time or did not match expected values. Waveform verification tests demonstrated that these tools can be used to accurately transmit CW, pulsed and frequency modulated waveforms with characteristics similar to those in this study. GNU Radio and the USRP can be combined to effectively produce a generic radar transmitter, however some imperfections such as intermodulation products and poor local oscillator suppression may be unacceptable for some radar transmission applications.