Robust DOA estimation of SSR signals for aircraft positioning

Methods to estimate Directions of Arrival (DOA) on radio signals are susceptible to hardware and signal deficiencies. In the following, the robustness of four algorithms is evaluated by numerical and experimental tests. The focus lies thereby on Secondary Surveillance Radar (SSR) signals, but the algorithms can generally be used on any kind of radio signal. It will be shown that variants of the ESPRIT algorithm provide highly accurate DOA estimates on SSR signals even without calibration.