The developments defined within this project aim at enhancing the overall competitiveness and performance of E3000 satellites in order to fully answer operators’ needs and requirements. The development concerns the TM/TC architecture. A CAN bus will replace the currently used Low Speed Serial Bus (LSSB) to connect payload units and in particular the Channels Amplifiers (CAMP) to the platform.
The benefits of such evolution are:
– Less non quality issues due to CAN bus standard.
Integrated transceiver DLA are now qualified, that guarantee the electrical compatibility between nodes, with straight forward implementation needing small PC surface.
The protocol defined by Tesat, Thalès Alenia Space and Airbus DS, part of Neosat applicable documentation and also ECSS, is another key feature of CAN bus that guarantee interoperability.
– High Data rate improves payload observability allowing reducing RF performance test duration while improving the test coverage.
– CAN bus management through shared memory allow simplified operations thanks to direct access of on board software to nodes telemetries that are cyclically refreshed.
– Less harness: the physical layer is based on standard DC cable without shielding consequently without specific harness manufacturing constraints. As CAN bus use single pair per redundancy number of connection points is limited at the minimum.
Architecture of the CAN Bus is based on a Master/Slave approach. All CAN exchanges are initiated by the CAN Bus Gateway. This approach simplifies the whole bus management and particularly time stamping aspects. As each node exchange are controlled by the CAN Bus Gateway, there is no possibility to overload the bus. The data produced by the nodes are acquired cyclically by the CAN bus Gateway and transferred on the system bus (Mil-STD 1553B). On the other way, commands received from system bus are transferred on the CAN buses by the CAN Bus gateway.