Measurements and signal processing of helicopter micro-Doppler signatures

Bistatic measurements of helicopter micro-Doppler signatures, made with the DiMuRa radar system, are presented. The system transmits a continuously repeated signal. Hence the received signal contains a large contribution from direct signal and static clutter interference. The signal processing ensures that the micro-Doppler signatures are unaffected by these interferences, and explicit cancellation techniques are not needed. Both main and tail rotors can easily be identified as sharp “flashes” in the cross correlation function, and information such as rotor speeds and the number of blades of the rotors may be extracted and used in target classification.