Research Of OFDM Modulation And Demodulation System Based DAB

With developing of technology and standard of living improvement, digital audio broad-castting (DAB) technology is more and more important for scientific research and economic meaning. As one of the key technologies in DAB applications-the hardware application of OFDM modulation and demodulation, it is key task of countries DAB research teams.First, the principle of OFDM technology is presented. Working parameters of OFDM , its form of symbol generation in china standard '30MHz～3000MHz technical terrestrial digital audio broadcasting system 'and the importance of inserting cyclic prefix are analyzed. Then, designed the block partition module, QPSK modulation module and inserting(deleting) cyclic prefix, etc.Secondly,with the first design principle different from the less source and higher accuracy or the higher speed, designed two kinds of FFT processor,the main unit of OFDM modulation and demodulation system and researched the ASIC design based on finishing the FPGA design.Adopting modified radix-2 butterfly architecture to reduce multipliers, using float-point format to increase precision,designed a single butterfly FFT processor.It is completed design with EP2C35F672C8 FPGA of CycloneII series, result is right.And the paper analyzed currently structure about FFT processor,aiming at the DAB designed a kind of radix 2/4/8 structure FFT processor,it has high speed,the less memory and been designed easy. Adopted cordic to finish the multiplication of plural.Used the variable point unit to design 512,1024,2048 points.After it has been tested with FPGA,the design was synthesised with Synopsys Design Compiler on SUN work station under Chartered 0.35um CMOS technology.Apollo was used to place and route about the design, and had layout.With 50MHz working frequency, this design needed 40.94,20.46 and 10.22 μs to complete 2048points,1024 points,512 points FFT. ,attained design purpose about high speed.