Waveform Diversity and Design for Interoperating Radar Systems

Abstract

Abstract : For many years, conventional radars transmitted, received, and processed the same waveform on every pulse or burst within a coherent processing interval (CPI), independently of the environment. Now, modern radar systems have considerable flexibility in their modes of operation, both on receive and transmit. In particular, it is possible to modify the waveform on a pulse to pulse basis, and electronically steered phased arrays can quickly point the radar beam in any feasible direction. In the course of this research project, we introduced the Ambiguity Function, an analytical tool for waveform design and analysis that is useful for examining resolution, sidelobe behavior, and ambiguity in range and Doppler of a given signal waveform. Some techniques to design multiple access frequency hop codes with good auto and cross-ambiguity functions are characterized, focusing on the frequency hop patterns. We have shown that the performance of each channel of the multistatic system heavily depends on the transmitted waveform and on the geometry of the scenario, that is, the position of receivers and transmitters with respect to the position of the target. In particular, both geometry factors and transmitted waveforms play an important role in the shape of the Ambiguity Function and hence in the value of the Cramer-Rao Lower Bound (CRLB). We have calculated the bistatic CRLBs of target range and velocity of each transmit-receive pair as a function of the target kinematic parameters and to provide a local measure of the estimation accuracy of these parameters. Finally, in this work we have analyzed the problem of the optimum sensor selection along the trajectory of a tracked target in a multistatic radar systems. To this end we have evaluated the Posterior Cramer-Rao Lower Bound (PCRLB) of the sequential target state estimation and we will define an algorithm that exploits this mathematical tool to select the best channels for the tracking of the target.