Research On Key Technologies Of China Digital Radio

With the gradual advancement of China digitalization in broadcasting,terrestrial TV,cable TV and satellite TV has completed digitalization.Research on the key technologies of digital audio broadcasting becomes important and urgent.In recent years,a series of standards for China Digital Radio(CDR)transmission were issued.Comparing to digital TV,the research and practice on digital audio broadcasting in China is still insufficient,which mainly in the followings:the requirement of performance enhancement on digital audio exciter and transmitter;the lack of experience on digital audio network coverage optimization;and implementation of the Low Density Parity Check(LDPC)decoder at the receiver.Based on this,the main contributions and innovations of this dissertation are as follows:First,according to improve the poor adaptability of traditional transmitter pre-correction algorithm to power amplifier in digital audio broadcasting transmission system,a set of adaptive pre-correction algorithm based on neural network is proposed.The algorithm consists of a forward network with a limited number of layers,a feedback collection based on residual neural network structure and a training network based on the LM(Levenberg Marquardt)optimization algorithm.The algorithm can adaptively carry out data learning iterations in order to adapt to the amplifier’s output in various situations,and the experimental results show that the algorithm can simultaneously improve the transmitter precorrection efficiency and performance.Second,according to improve the problem of high complexity and excessive consumption of decoding resources in LDPC decoder at the receiver of digital audio broadcasting system,a Fast Polyline Minimum Sum(FPMS)algorithm adapted to CDR system is proposed.In accordance with the characteristics of LDPC code of CDR standards,the algorithm optimizes the split point of the absolute value of Log Likehood Ratio(LLR),and reduces the correction factor by half with a certain acceptable performance loss.And the simulation results show that this algorithm not only performs better than other algorithms base of Minimum Statistics(MS),but also reduces the complexity of them by half.Third,different from the traditional coverage prediction method,a coverage prediction scheme of digital audio broadcasting is proposed.In the proposed scheme,the coverage prediction of digital audio broadcasting is based on the Signal to Interferene and Noise Ratio(SINR)at the coverage point.The revision of the SINR-based system simulation coverage model for CDR broadcasting is also proposed in this scheme.The proposed scheme improves the shortcomings of the original CDR broadcasting coverage planning based on the reception field strength.This dissertation further optimized and predicted the coverage effect map according to the actual coverage parameters of Wuhan Turtle Hill transmitter and Huangshi Moon Hill transmitter in Hubei Province.The author led the construction of the coverage planning and comprehensive testing of China’s first CDR test area,and verified that the accuracy between the optimized coverage prediction map and the actual reception effect is more than 90%.