9.4 Target recognition

Recognition of targets is a very important task in radar science and practice. By recognition we mean the procedure of attributing the object being viewed to a certain class in a prescribed alphabet of target classes, using the radar data obtained. According to the general theory of pattern recognition, radar target recognition should include the following stages:

• compiling a classified alphabet of radar targets to be recognised;

• viewing of targets;

• determination (measurement) of some target responses from the recorded echo signal parameters to compile target descriptions, or patterns;

• identification and selection of informative signs (features) from the compiled lists;

• target classification or attribution of a particular target to one of the classes on the basis of discriminating signs.

The problem of making up an alphabet of target classes and selecting informative signs to describe each class reliably is quite complicated and is to be solved by qualified and experienced specialists. Of course, classification may be based on various principles. One of them is to group targets in terms of their function and application. For example, a successful management of air traffic needs a classification of aircraft: heavy and light passenger planes, military planes, helicopters, etc.

Each class of radar targets can be described by a definite set of discriminating characteristics to be used for classification: configuration, the presence of well-defined and readily observable parts, dynamic parameters (e.g. altitude, flight velocity), etc. A specific feature of all radar targets is that the radar input senses a target pattern...