Research And Design Of Channel Modulator Based On DVB-T Standard

The thesis is according to the project of DVB-T digital television channel code modulator, concentrates on the channel modulator research and design. Channel modulator uses OFDM modulating, it is implemented by IFFT on FPGA platform.The thesis mainly surrounds the realization of orthogonal frequency division multiplexing (OFDM) which is the key technology of DVB-T channel modulator. First, this thesis provides an overview of the digital modulating, focuses on the OFDM principle and its advantage on digital television modulating. Second, the whole DVB-T tramsmission system architecture is discussed, the OFDM module is analysed in detail and its technological parameters is confirmed, how to implement OFDM by inverse fast fourier transform(IFFT)is also deduced. Then IFFT algorithm is deeply researched, frequen-cy sample radix-2 IFFT algorithm is applied . Two IFFT calculating architecture is proposed and compared, double passages pipeline method is choosed to implement IFFT. Followed, on FPGA platform, an integrated 2k mode OFDM modulator is implemented by VHDL, that is 2048 point IFFT calculating module. Finally, simulation is performed by EDA development tool Quartus II to ensure that the functions meet the demands. In addition, some improving con-ceives with the project is presented.OFDM modulating applying in digital television transmission sytem with high request of real-time and bandwidth, for example, in 2k mode it needs to complete 2048 points IFFT transform in 224μs.The difficuty lies in how to design a quickly and efficiently mass data IFFT calculating module. In respect that neither the general CPU even DSP can satisfies the request, nor existing IC can be used, implementing OFDM mudule with FPGA is a special method. The double passages pipeline IFFT arithmetic architecture has characteristics of easily implementing on FPGA,hight processing speed and satisfying the system real-time request.