As radar users see ever increasing complexity in signal and data processing, it is tempting to believe that quantum increases in detection performance will become available. However, the laws of physics have not changed. and fundamental detection performance will only improve slightly as small improvements are squeezed out of one or other section of a radar. What is changing is the ability to analyze the radar signal in progressively more detail. High speed processing is allowing the use of principles which have long been understood, but which have not previously been incorporated owing to technology limitations. An airborne radar receives signals which contain not only target echoes, but additional inputs from a variety of sources. These Include; clutter from the main radar beam and sidelobes; selfgenerated thermal noise: nondeliberate electronic interference; and perhaps jamming. The first objective of signal processing is to reject the clutter, which may include not only ground returns, but rain and ground moving targets as well. Jamming requires a book in its own right and will not be covered here. but suitable processing techniques can be used to weaken its effects.

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