In Air Traffic Control, ADS-B (Automatic Dependent Surveillance - Broadcast) systems provide surveillance information as obtained by the cooperating airplanes. This usage of air-derived data and of a common link opens various issues: performance in dense traffic area, signals validation and security. A Software Defined Radio (SDR) permits the needed flexibility and modularity in order to easily develop prototypal devices for evaluation and test of novel enhancements of ADS-B receivers. In this frame, a multi-channel receiver for 1090 MHz ADS-B signals was implemented, using an array antenna, a specific designed analog front-end and a software defined receiver. The device is useful to test signal processing algorithms...