| Orthogonal frequency division multiplexing (OFDM) has advantage of high spectrum efficiency, strong ability of anti-interference, and low cost of implementation. So it becomes more and more widely used in the field of wireless communications. DVB-T which takes OFDM as core technology, can diminish the Doppler Effect, and has a excellent transmission performance.Baseband coding system is one of the most important part in the whole DVB-T transmitting system. Our main work is as follows:(1) We design baseband coding system with compatibility with multiple processing rates, and implement it on hardware processing platform, Xilinx Spartan3A DSPs XC3SD3400A FPGA. We also design D/A circuit and digital upconverting circuit.(2) Synthetically considering time and space, some modules have been optimized in the algorithm. First, we change the finite field multiplier calculation into XOR circuit in RS coding module by using the method of constant bitwise expanding coefficient multiplication. Second, we have implemented data interleaver within one piece of RAM by controlling R/W address, and that has good property in both circuit speed and FPGA resource consumption.As show as experimental results, every sub-module of the baseband coding system realizes the expected function, and the overall debugging also has good performance. |
