Efficient Baseband Processing System for DVB-RCS to DVB-S2 Onboard Processing Satellite

An open standard compatible onboard processing system is under development, which provides mesh connectivity between different user terminals. The system is designed to be compatible to Digital Video Broadcasting - Return Channel via Satellite (DVB-RCS) protocol in uplink and Digital Video Broadcasting - Satellite - Second Generation (DVB-S2) in downlink channels. Due to widespread use of this protocol in DTH, low cost compatible terminals are widely available in market. The main elements of this system are DVB-RCS burst demodulator and decoder, protocol convertor, baseband processor with channel estimator and DVB-S2 modulator. This work presents the architecture of baseband processing and channel estimation module. So this requires advanced micro-controller and fast digital signal processor. Also this processor can be time shared for timing recovery module of burst demodulator. Since the system is designed to be implemented as an onboard processor (OBP) for communication satellite, therefore LEON-3 processor and Digital Signal Processor (DSP) SMJ320C6701 are chosen due to availability of their radiation tolerant versions. This paper presents an interface between LEON-3 and DSP for faster execution of both base band processing and floating point operations. Simulation of interface is done on ModelSim (R) and performance evaluation and comparison has been done on simulators. TSIM2 simulator is used to simulate LEON-3 where as to simulate DSP SMJ320C6701, Code Composer Studio v5 is used.