Concept and design of a fiber-optic and an I²C hybrid sensor bus system for telecommunication satellites

Abstract

In this paper the concept and design of the Hybrid Sensor Bus (HSB) system for telecommunication satellites is presented. The HSB development in the frame of an ESA-ARTES project has been started in 2011 and the system will be tested as flight demonstrator onboard the German Heinrich Hertz communication satellite (H2Sat) in 2016.In state-of-the-art telecommunication platforms hundreds of sensors are necessary for satellite control and monitoring. The sensors are wired point-to-point (p2p) to the satellite management unit (SMU) which results in a high mass impact but preliminary increases AIT effort and thereby the overall satellite costs. Sensor bus architectures reduce AIT cost by reduction of wiring effort, reduction in required test time and by providing a flexible sensor network topology.The HSB system is based on a modular concept including a controller module, a fiber-optic interrogator module and an I²C electric interrogator module The HSB system provides advanced performance which includes programmable and sensor specific alarm functions, averaging of dedicated sensor values and thereby a reduction of SMU processor load. The combination of electrical I²C sensors for punctual resolved measurements and fiber-optic sensors for e.g. thermal mapping of panels by embedding sensor fibers in the satellite structures results in a versatile system.In this paper we present the design of the HSB system taking into account the requirements from European platform manufacturers. The HSB design yields a product which can be implemented as replacement of standard p2p systems to build up a more cost efficient sensor system for geostationary satellites. MOTIVATION OF HSB DEVELOPEMENTState-of-the-art telecommunication satellite platforms have to process a tremendous amount of monitoring data to fulfill tasks, as e.g. attitude and orbit control. Especially for temperature monitoring hundreds of sensors are required. They are currently point-to-point wired in a star configuration covering the whole satellite. This results in a complex sensor harness which increases mass, AIT effort and therefore the overall satellite costs. An additional problem arises because of the inflexibility of the state-of-the-art wiring. In the integration phase of the satellite the harness and the panels are the first subsystems to be integrated. All other subsystems are integrated afterwards. If any problem arises during tests concerning the sensor harness (e.g. more sensors required or sensors on wrong position) the harness must be partly extracted from the satellite. This has the consequence, that some of the subunits also have to be extracted. The full procedure, caused by the inflexibility of the wiring, has a high effort and increases the costs dramatically.In Figure 1, part of the GALILEO harness is illustrated. The wires in brown and white color are used for temperature monitoring and control. All p2p-wired temperature sensors are fed to a multiplexing unit, to be queried by the SMU. This results in a high SMU processor load only for monitorin...

Fiber optical sensing on-board communication satellites

“…System Description The Hybrid Sensor Bus (HSB) is a modular sensor system [1,4] which is able to read out electrical sensors over the I²C bus and fiber-optical sensors based on FBG sensing technology. The system itself consists out of four different modules as can be seen in the block diagram Fig.…”