The classification and even, if possible, identification of any object or target under observation unambiguously at a distance and in such short times that a decision and an `adapted' reaction are possible was, is and will be a most important task in the military and also security domains. There is an ongoing effort in many countries all over the world, and of course also in NATO, to improve the existing solutions. One approach, the obvious one, is the idea to allow any object entering observed areas to identify itself actively on request. Such systems have been installed for many years in the military domain and are called `Q&A' systems or `identification friend or foe' (IFF) systems. For air targets, and if radar is used as the sensor system, aircraft have been equipped for many years with systems like Mark X or Mark XII in different modes which were able to answer an interrogating pulse from the observer with a predefined code revealing, in addition to other information, its identity. Systems like that are also used in the civilian air traffic control (ATC) and because they support the interrogator they are called `cooperative identification systems'. However, they show some important drawbacks.

Chapter Contents:

• 6.1 Introduction
• 6.2 NCTI studies
• 6.3 Measurements
• 6.3.1 TIRA system
• 6.3.2 Targets
• 6.4 Idea of classification
• 6.4.1 Appropriate features
• 6.4.2 HRR and 2D ISAR
• 6.4.3 2D ISAR template correlation classifier
• 6.4.4 Selection of radar parameters
• 6.5 Classification scheme
• 6.5.1 Pre-processing unit
• 6.5.2 Feature extraction/reduction
• 6.5.3 Choosing a classifier
• 6.5.4 Test of classifiers
• 6.6 Feature extraction
• 6.6.1 Classification results using different feature sets
• 6.7 Conclusion
• References

Inspec keywords: military aircraft; target tracking; radar imaging; radar detection; object detection; military radar

Other keywords: NATO; air targets; Mark XII; interrogator; interrogating pulse; IFF systems; military domain; target identification; ATC; identification friend or foe systems; object identification; radar; Q&A systems; security domains; cooperative identification systems; classifier effectiveness; civilian air traffic control

Subjects: Optical, image and video signal processing; Radar equipment, systems and applications; Signal detection; Transportation (military and defence); Radar and radiowave systems (military and defence)