Design And Implementtation Of Digital Am Broadcasting System

There are so many defects in the process of practical application of Am broadcasting system, especially the effect of the limits of spectrum of time-variant multipath channel. After the researching of the DRM, we adopted the synchronization algorithm of the OFDM. Make the best use of the resourses of spectrum. At the same time, try to overcome interference and weakness of signal which is caused by the time-variant multipath channel. In order to achieve the synchronized of the signal, we must ensure that the receiving end of the signal is in the situation of synchronous. This thesis which combined with the actual had analyzed the DRM. It also explored and researched the error of synchronous and the calculation rules of the system of OFDM. Combined with the characteristics of the signal propagation and structure of the DRM, we have developed a detailed plan.This whole thesis is divided into three parts. The first part is mainly introduced the characteristics of digital AM broadcasting. In this part, we proposed the directions of the core core technology and established the model of the channel. The second part is maily expounded the propagation characteristics and the information of the OFDM. Also, it introduced the synchronization algorithm of the OFDM system and cntrasted the diffrences of the variety of the synchronization algorithms. This thesis also introduced the influence of the synchronization error of the symbol frequency in the system of the digital AM Broadcasting. It proposed that in order to choose the appropriate synchronization algorithm, the characteristics and the form of the signal must be considered. A new calculation of DRM time-frequency synchronization is proposed in the third section by the DRM signal enunciated correlation characteristics of part I and II. And the Monte Carlo simulation method is taken to simulate the use of DRM joint time-frequency synchronization method of calculating comparative BER performance and capture the performance of the three channel conditions of operation state, by the use of wireless broadcast channel correlation characteristics and DRM standard channel models; Through comparative analysis of these results, it can be drawn that: In the robustness mode B, when the channel is the channel two and channel three, the correct synchronization BER performance can be obtained by the calculation methods elaborated in the paper; When the channel is the channel 4, in order to listen to more good results and should be taken in addition to the transmitted signal robustness mode C or D, because the robustness mode B is no longer suitable.This study is very practical significance for the development and upgrading DRM receiver synchronization module and provides extremely relevant basic theory and basic data of far-reaching significance.