Adaptive Radar with Application to Joint Communication and Synthetic Aperture Radar (CoSAR)

Until recently, the functionality of radar systems has been built into the radar's analog hardware, resulting in radars which are inflexible and that can only be used for a specific application. Modern systems, however, driven by the ever increasing speed of processors and data converters - analog-to-digital (ADC) and digital-to-analog (DAC) - are transitioning toward software defined radar (SDR) systems. The advent of SDRs inevitably leads to the question of how their added flexibilities can best be leveraged. The work within this dissertation is motivated by joint radar and communication functionality. The main objective is to study and demonstrate the ability of radar systems to employ non-traditional, specifically, communication waveforms for remote sensing.;A software defined radar (SDR) is developed. The SDR features a "closed loop" testbed interface accessible via Matlab m-code. Here, "closed-loop" means that data can be pulled from the SDR, processed, then used to select/adapt the waveform and settings of the SDR without human intervention, i.e. on the fly. The testbed interface is used to implement a joint radar and communication system which is capable of collecting and processing radar data, e.g. range-Doppler maps, while simultaneously communicating previously collected radar data. Simultaneous functionality is accomplished by interrogating with a wide band digital communication waveform which is modulated with the previously collected radar data. The joint system is used to empirically demonstrate the theoretical work on detection and change detection within this dissertation.;Optimal detectors are developed for interrogation with communication waveforms. The optimal detector for a single target with known impulse response in white noise is known to be a thresholding of the output of a matched filter. Radar systems, however, often operate in multi-target environments; notably air-to-ground synthetic aperture radars. For such applications, the hypothesis test which shows matched-filter/thresholding to be optimal does not well represent the conditions under which the radar is operating. The matched filter is, therefore, suboptimal due to substantial modeling error. The optimal detector is related to classical radar detectors. The expression for the performance of the optimal detector is given. Its performance is shown to be greater than or equal to that of the matched filter detector.;Optimal coherent change detectors are developed for diverse waveform interrogation: i.e. when the reference and mission images are the result of interrogation with different waveforms. With waveform diversity, the problem of change detection becomes more challenging. The optimal coherent change detection (CCD) does not take the form of the classical CCD and is not prone to high false alarm rates in areas of low pixel intensity. Special cases of the optimal coherent change detector are given under which the change detector reduces to intuitively satisfying forms.