RDI is an aircraft target recognition technique, which has not been widely explored, but has potential for contributing to automatic air target recognition. The use of simultaneous range and frequency data has benefits in being able to localise aircraft propulsion systems along the range profile, which is not generally possible with other NCTR techniques. For jet aircraft it can theoretically acquire HRRP and JEM data in a single dwell with the appropriate waveform, but in practice it is not normally achievable due to difficulties in designing a radar with the appropriate characteristics. RDI can measure the signatures of jet and propeller aircraft and helicopters.

Chapter Contents:

• 3.1 Introduction
• 3.2 Fundamentals of the target recognition process
• 3.2.1 Introduction
• 3.2.2 Target features
• 3.2.3 Aircraft recognition techniques and waveform design
• 3.2.4 Target signature measurement
• 3.2.5 Radar range equation for radar target recognition
• 3.2.6 Main classification functions
• 3.2.7 Database
• 3.2.8 Classifier
• 3.2.9 Assembly of database
• 3.2.10 Classifier performance
• 3.2.11 Conclusions
• 3.3 Jet engine recognition
• 3.3.1 Introduction
• 3.3.2 Jet engine mechanics
• 3.3.3 Interaction of radar signal with engine blades
• 3.3.4 Jet engine modulation spectrum: engine rotational rate
• 3.3.5 Jet engine modulation spectrum: rotor stage spectrum
• 3.3.6 Jet engine modulation spectrum: mixing products from rotor stages
• 3.3.7 Determination of blade count
• 3.3.8 JEM waveform
• 3.3.9 System requirements
• 3.3.10 Conclusions
• 3.4 Helicopter recognition
• 3.4.1 Introduction
• 3.4.2 Main rotor blade flash
• 3.4.3 Detection of blade flash
• 3.4.4 Waveform and system requirements for blade flash detection
• 3.4.5 Blade flash detection
• 3.4.6 Helicopter classification using blade flash
• 3.4.7 Main rotor hub spectrum
• 3.4.8 Rear rotor blades
• 3.4.9 Radar range equation for helicopter recognition
• 3.4.10 Helicopter recognition summary
• 3.5 Range-Doppler imaging
• 3.5.1 Introduction
• 3.5.2 Helicopter signature
• 3.5.3 Jet airliner signature
• 3.5.4 Business jet signature
• 3.5.5 Propeller aircraft signature
• 3.5.6 Waveforms and system requirements for supporting RDI
• 3.5.7 Conclusions
• 3.6 Aircraft target recognition conclusions
• Acknowledgements
• References

Inspec keywords: military radar; radar target recognition; jet engines; military aircraft

Other keywords: automatic air target recognition; JEM; air targets automatic recognition; aircraft target recognition technique; propeller aircraft; high resolution range profiling; aircraft propulsion systems; range Doppler imaging; HRRP; RDI; jet engine modulation; helicopters

Subjects: Radar and radiowave systems (military and defence); Radar equipment, systems and applications