Space-based passive radar enabled by the new generation of geostationary broadcast satellites

In this paper we investigate the possibility to develop a passive radar system for mid-range air target surveillance using, as illuminator of opportunity, a high EIRP level geostationary broadcast transmitter. These satellites are being introduced recently for Satellite Mobile Digital TV broadcast purpose. Since they are designed to allow mobile users to receive satellite TV without large antennas, a sufficiently high signal power is being transmitted, making them suitable as illuminators of opportunity in a passive radar system. The possibility to resort to a quasi-stationary transmitter is shown to highly simplify the signal processing required by the passive radar system. A preliminary evaluation of the achievable SNR is conducted, showing that mid-range target detection can be achieved with reliable performance. In addition, a detailed analysis of the Doppler frequency contributions is conducted. Specifically, the Doppler frequency contribution due to the motion between target and transmitter is shown to be locally independent over the target position. The overall bistatic Doppler frequency behavior is evaluated for several possible target trajectories and some critical trajectories are identified. Finally, some remarks referred to the 2D Cross Correlation Function (2D-CCF) evaluation are reported.