Impact of Knowledge-based Techniques on Emerging Technologies

This tutorial provides a discussion of the application of knowledge-based processing techniques to emerging technologies. Following the third of the tutorials in this series we interpret knowledge-based processing as the use of adaptivity and the exploitation of prior knowledge in such a way as to choose the optimum processing method in each case. We interpret ‘emerging technologies’ as novel applications, such as multifunction phased array radars, waveform diversity, bistatic and multistatic radars, and synthetic aperture radars. Firstly, we consider the potential of electronically-steered phased array antennas and the associated signal processing techniques. This is followed by a description of knowledge-based processing in the task scheduling in a multifunction phased array radar. It is shown that prior information on targets can be used to control parameters such as update rate and dwell time. Next, we consider waveform diversity, which may be considered to be a development of multifunction phased array radar, in which a radar may simultaneously radiate and receive different signals in different directions for different purposes. Such a scheme may entail adaptivity in the angular domain, in the time domain and in the coding domain (and conceivably in other domains as well), and the use of knowledge-based techniques in this processing has obvious attractions. Two examples are discussed: the first is target-matched illumination, which shows that there is an optimum waveform for the detection of a given target in a given environment, and the second is interpolation between two (or more) spectral bands to give the effect of a signal of very high bandwidth, and hence very high range resolution. Next there follows a discussion of the application of knowledge-based techniques to bistatic and multistatic radar, including the use of information on waveform properties in passive coherent location (PCL), tracking in multistatic radar, and ‘spatial denial’ as a waveform diversity technique to prevent the exploitation by an enemy of a radar as a bistatic illuminator. Finally, an example is given of the use of ‘context’ in target detection in synthetic aperture radar imagery, exploiting the fact that targets of interest will tend to be parked in groups close to hedges and the edges of woods rather than individually in the middle of open ground. Useful improvements in detection performance are obtained.