Research And Implement On OFDM Modulation And Channel Estimation Algorithm In DRM

At present, digital technology has improved Broadcast TV greatly, which is widely applied in collecting, tailoring and broadcasting TV programs. Along with digital technology development, DRM organization makes digital AM modulation protocol, which is fit for LF,MF and HF wave band under 30MHz. it is as good as FM, which solves signal multipath fading effect and supplies various good digital programs in the range under LF. The whole world will focus on DRM.DRM adopts OFDM system, which improves the frequency band utility, decreases the frequency selective fading caused by multi-path effect, and wakens the Doppler shift. It can obtain reliable data transmission in the high speed. OFDM system in DRM has been carefully designed and implemented in the computer, finally transplanted into TMS320C6416 Chip evaluation board successfully.Due to the time and frequency selective variant of the channel encountered on DRM transmissions, the channel has to be estimated continuously and its influence on the data transmission could be eliminated.this is done by using the known scattered pilots transmitted in the OFDM signal. Our DRM system adopts linear Interpolation, windowed FFT Interpolation and Wiener Interpolation, In which Wiener Interpolation is the best but requires a fairly high processing power[29]. the paper analyzes those algorithms and implements them in the computer.At last, the paper designs the module structure and the feedback method between modules, implements the DRM receiver in the computer. At the same time, some performance evaluation results of the implemented DRM receiving system are presented to estimate the time of each part of the system and find out that the synchronization, channel estimation, channel decoder and AAC decoder occupy 90% of the whole time with the synchronization and channel estimation occupying 60% which is the bottleneck of the DRM receiver system. From the result, we can see that. if the DRM system uses special chips for those modulations, it will reduce the load and improve the efficiency of the system greatly. it helps the next development of the receiving system on chip.