ANALYSIS OF INTERFERENCE IN LFM RADAR DETECTION AND IMAGING IN A MULTI-RADAR ENVIRONMENT

Abstract

Because of the growing use of radio detection and ranging (radar) systems in multiple application sectors, the radars have to be operated on the same or adjacent frequency resources. This frequency overlap can cause interference and impacts the performance of the victim radar. Besides unintended interferences, there could also be intentional interferences. The interference can cause a reduction in the signal-to-noise ratio, introduce ghost targets, and lead to poor detection capabilities of the radar as well as false detections. Thus, interference effects should be compensated to operate the radar in a safe and secure environment. In this thesis, different types of interference and their impact on traditional linear frequency modulation (LFM) based radio detection and ranging (radar) are investigated through numerical simulation and electronic radar-based experiments. The work has been extended to investigate the imaging of radar-detected objects with the help of the back-projection technique. In the simulation environment, a multi-radar environment has been created to investigate the effect of external interference radar on the victim radar. Different types of interference waveforms such as LFM, triangular and pulsed waveforms are being considered. It is found that the LFM-based waveform suffers from coherent LFM interference, which can result in the appearance of ghost targets on the range profile. Whereas, non-coherent types of interference increase the noise level, reducing the signal-to-noise ratio, thus adversely impacting the detection accuracy. Thus, a random hopping LFM-based waveform as an alternative to the LFM-based waveform has been proposed as a robust waveform to mitigate interference in a multi-radar environment. Experimental work with an mm-wave (77GHz-81GHz) radar sensor for detecting targets has been performed, and radar performance metrics such as range and range resolution have been evaluated with the theoretical values. Through the back-projection algorithm, the imaging of the detected objects has been obtained. Through extensive iteration, it is found that the back-projection with weighting function provides enhanced resolution.