Research And Design Of Digital Audio Broadcasting System

Compared with the analog broadcasting technique,the digital audio broadcasting has the advantages of better sound quality,higher utilization of frequency band,stronger anti-interference ability,smaller transmission power and wider effective coverage.In recent years,the usage and coverage of digital audio broadcasting in Europe,America and other countries are getting wider and wider,and the traditional analog broadcasting is being phased out.In order to meet the new demand for broadcasting in the era of mobile Internet and catch up with the pace of developed countries,the State Administration of Press,Publication,Radio,Film and Television published the industry standards related to digital audio broadcasting in FM band,which opened a new chapter of digital audio broadcasting.However,at present,the number of digital audio broadcasting stations in our country is not enough,the coverage is not wide enough,the radio with few models is expensive,and the ratio of listeners is not high,so the digital audio broadcasting has not been popularized in the whole country.Therefore,it is necessary to research and study the standards of digital audio broadcasting for further promotion.According to the structure of digital audio broadcasting system in FM band,simulation and design of its main modules are completed in this thesis,focusing on its main channel coding and modulation part.The main work of this thesis are as follows:(1)Design of the main modules of the systemReferring to the relevant standards of digital audio broadcasting,the structure of digital audio broadcasting system and the function and principle of each module are deeply studied by using the theory of communication principle and information coding,the design scheme of main modules such as scrambling code module,LDPC coding module,convolution coding module,interleaving module,constellation mapping module and OFDM modulation module is determined.In the process of design,the history of research and development and mathematical principles of each module are introduced,which paves the way for next design and functional simulation.(2)Simulation and analysis of the main modules of the system using MATLABAccording to the previous design,the functional simulation of the main modules of the system is completed by using MATLAB.In scrambling part,the pseudo-random sequence required by digital audio broadcasting standards is generated by using MATLAB,and then performs XOR operation with the input data to achieve the purpose of scrambling;The function of 16 QAM is to map symbols and complete digital modulation of the input sequence.16 QAM is implemented by writing simulating files,and its constellation diagram is drawn;In the convolution coding part,the conclusion of designing(4,1,6)convolution code is obtained by referring to the introduction of channel coding and modulation standards.Then the simulation of convolution coding is completed by writing simulation files using MATLAB.In order to verify the design results,the decoding is also completed,and the final result is verified to be correct;The bit error characteristics under different conditions are obtained by simulating LDPC coding module using MATLAB;The rearrangement of information sequence is realized according to the given algorithm in the interleaving part;In the simulation of OFDM modulation,the correctness of the idea of using IFFT to implement OFDM is verified firstly,and then the simulation results such as signal spectrum are obtained.All the simulation results show that the design schemes of the main modules are correct.(3)Design of the main modules of the system using FPGABy using MATLAB to simulate the design scheme,the feasibility and correctness of the design scheme are determined.Then the main modules are designed by using Altera Cyclone IV E series of FPGA,Quartus II platform and Verilog HDL.Finally,the simulation of the function of each module is completed by using ModelSim.According to the simulation results,we can see that the design of the main module using FPGA is reasonable.The innovation of this thesis is that in addition to using MATLAB for system modeling and simulation,FPGA is also used for design,which has hardware changeability and strong flexibility.In conclusion,by researching the structure of digital audio broadcasting system in FM band in this thesis,the functional simulation of the main modules of the system is realized by using MATLAB,on this basis,the design of the main modules is completed by using FPGA,the correctness of the design is verified by the results of simulation and design,and a technical basis is provided for the whole construction of the broadcasting system in the future.The design methods of this thesis can be used as a reference for the simulation and implementation of signal coding and modulation techniques.