Currently, situational awareness capabilities in civil aviation are exclusively cooperative. To address this issue, in this work we propose a new non-cooperative situational awareness concept based on leveraging airborne air-to-air communication for passive radar sensing. In particular for this study we employ the LDACS A2A signals. We introduce the system advantages and limitations and perform an initial feasibility assessment of the concept. For this purpose, we evaluate the link budget and perform a detailed analysis of the ambiguity function (AF). The latter involves the characterization of the signal ambiguities that could impact the passive radar performance. Due to the presence of these ambiguities, we evaluate the effectiveness of employing a reciprocal filter for reducing said artifacts. Finally, the performance of the reciprocal filter is evaluated in simulation.
Ragel et al. (Thu,) studied this question.