This key R&D activity aims at enabling an improved performance monitoring of surveillance systems e.g. ¿quasi real-time¿ functionality and ensuring the correct functioning of the ATM surveillance function. This applies both at the individual sensor level and at ATC end-to-end level (input to the controller working position) e.g. spotting degradation trends early in the process. This shall consider both current and emergent surveillance techniques: WAM, ground-based and space-based ADS-B, independent non-cooperative surveillance sensors (INCS, including MSPSR), MLAT, SMR, etc.