High speed link radiated emission

In the frame of an ESA contract 22990/09/NL/GLC, Astrium performs EMC study on High-speed links. The Last generation of digital units and high-speed links, generate wide band interference from a few MHz to the S band because of fast transition times (below one nanosecond) of the new digital components. On-board satellites, these high speed links and digital units shall be compatible with the sensitive receivers (UHF, GPS, TMTC and launcher receivers). The high sensitivity of these receivers (about -140 dBm) result in very stringent radiated emission requirements in their most sensitive bands when we consider the main coupling via the side lobe of the RX antennas (including satellite and launcher antennas). The main risk of interference emission occurs at the harmonics of the digital clocks. When the RX bandwidth is limited to a few hundred of kHz, the management of the system frequency plan can solve the interference problem by a simple shift of the clock frequency that interferes in a sensitive RX band. Unfortunately, this approach is no more valid when the RX bandwidth covers several MHz.