PCL-Signal-Processing for Sidelobe Reduction in Case of Periodical Illuminator Signals

Passive coherent location (PCL-) systems deal with illuminators of opportunity, whose signals are usually not adapted to radar applications. Especially in the case of signal inherent periodicities the target echoes are often covered by sidelobes of clutter. In order to reduce high correlation sidelobes and enable highly accurate range measurements, a signal adaptive filter processing is introduced. Its mathematical description explains that aiming at low sidelobes and highly accurate range estimation for arbitrary signals results in a filter method providing a phase correlation. The SNR obtained by this filter method turns out to be dependent on the amplitude variation of the signal frequency spectrum. The effectiveness of the side lobe reduction is demonstrated on experimental data of analogue TV-signals to verify that accurate unambiguous range estimation is possible, even for strongly periodical signals.