A fully integrated multi-frequency modulator assembly for Ka-band multi media missions

This paper describes the design and development of a Ka-band Modulator Assembly which is currently in EM[sol ]EQM production phase at Bosch SatCom. The assembly is part of a complete transmit section for the European multimedia satellite system EuroSkyWay (ESW) planned by Alenia Spazio and developed in the frame of the ARTES 3 line, which is a co-funded programme between ESA and the industry.The modulator assembly receives the digital data streams, performs the appropriate formatting and baseband processing according to the DVB-S standard and directly modulates the Ka-band carriers.The modulator assembly incorporates all functions to be autonomously operated on a spacecraft platform. Each function has been realized fully redundant and consists of DC supply, carrier frequency generation, carrier distribution and switching, direct modulation, a static baseband switching, the TM[sol ]TC interface and the signal distribution. Up to 10 active Ka-band channels operating with three different carriers can be supported.To deal with the complex signal distribution the assembly is constructed using a common baseplate containing the central infrastructure as well as all external DC, TM[sol ]TC and Data interfaces. With this approach signal integrity as well as spurious emission[sol ]susceptibility are tightly controlled. The RF functions and the DC[sol ]DC converters are realized as plug-in modules which gives flexibility w.r.t. the number of communication channels and carriers. Furthermore testability and integration procedures are improved by this plug-in module concept. Mechanical stiffness and the heat transfer has been optimized to comply with the S[sol ]C thermal and mechanical interfaces.The assembly is capable to cover typical multi-media applications and the results prove that highly integrated multi-functional assemblies are ready to use.