Radar imaging using ultra-wideband stochastic waveforms

The University of Nebraska-Lincoln has developed an ultra-wideband random noise radar operating over the 1-2 GHz frequency range. The system uses the technique of heterodyne correlation, and is thus phase-coherent. It has therefore been used in applications such as interferometry, polarimetry, and Doppler estimation. Recently, the system has been used for SAR and ISAR imaging of targets and terrain. This work has brought to the forefront various issues, such as the type of images obtained when utilizing a truly stochastic signal as a transmit waveform, and the techniques employed to realize this image. The natural answer to the first question is that the image obtained is based upon the expected value of the return signals, in the probabilistic sense of the word. This leads to answering the second question by determining what sort of estimators one would use to estimate this expected value. In this work, we will discuss the expected value of the image and its properties. We will then examine single look ISAR images collected in anechoic chamber experiments performed at the University of Nebraska-Lincoln.