Research And Design Of Key Modules In Synchronization System For DVB-T Demodulator

Synchronization is a core technology in the OFDM based terrestrial digital broadcasting demodulator. It determines the output data from the demodulator are correct or not. Considering to the project requirement of our Lab, this paper put research interest on the synchronization system in digital terrestrial broadcasting demodulator based on DVB-T standard.The objective of this paper is to design key modules in synchronization system after intensive research and investigation and to build a firm foundation for the complete synchronization system. In this paper, we firstly presented effective baseband synchronization algorithms based on existing algorithms and analysis of DVB-T OFDM frame structure.Main achievement was as follows:1) Improved symbol timing synchronization, carrier frequency synchronization and improved sampling frequency synchronization algorithms were proposed. Float point models were set up to verify the functionality of key modules. RTL coding description and logic and timing verification of the three key modules were performed to complete the design of the key modules. A patent had been applied for improved symbol timing synchronization.2) Optimized moving sum structure was proposed to minimize the hardware complexity. Comparing with normal moving sum structure, up to 80% of the hardware consumption can be saved. A patent had been applied for optimized moving sum structure.3) Using only the sign part of input data to achieve accurate timing offset estimation and integral CFO estimation. By applying this method we can save considerable memories.4) Optimization has been made to improve the performance of SFO sync process, by applying all digital method and using piecewise-parabolic interpolation as compensation method. By avoiding using analog part, the design complexity can be significantly decreased. PI loop filtering was introduced to make output of the SFO estimator stable.5) Ping-pong structure was introduced to implement the SFO estimation module, to make full use of ALUs. CORDIC algorithm was introduced to implement the getangle module, avoiding large memory use by Look Up Table algorithm. Complex piecewise-parabolic interpolator was implemented using Farrow structure interpolator which has both good performance and simple structure.Implement and verify of the individual sync module were preformed. Simulation results show that every key module can work normally.