Design And Research Of The Equalizer In Digital Television Terrestrial Broadcasting

Technology of Digital Television (DTV) broadcasting is the third revolution in the technical history of TV broadcasting. Integrating with the modern communication technology, it is an important flag of unifying all kinds of communication technologies. Many countries have studied on it for a long time, and they had developed corresponding transmission systems respectively. Among these developed systems, terrestrial broadcasting is the most classic representation for its complexity. Presently, three terrestrial broadcasting standards have been set, e.g. DVB-T (Europe) and ISDB-T (Japan) based on OFDM tech, ATSC (U.S.A) based on VSB tech.In OFDM tech, multicarrier transmission with FFT is used to combat with channel fading. In VSB tech, an adaptive equalizer is used to combat with channel fading. In this paper, the author studies the OFDM tech and VSB tech, and analyzes their characteristics. A new kind of adaptive equalizer used in VSB tech is brought out. New algorithm and new structure have been developed to make the equalizer to get better performance on combating with seriously distorted channel fading: strong echo fading, large delay spread static and dynamic echo fading.Main contents of this paper are as follow:In the first chapter, the history > present situation of the DTV system is presented. Five DTV terrestrial broadcasting systems are introduced and two of them are compared, e.g. DVB-T COFDM and ATSC 8VSB.In the second chapter, the capability of combating with the channel fading of OFDM tech is studied and analyzed. Combining with the characteristics of OFDM tech, possible improvements to equalizer in VSB tech are proposed. A new channel estimating algorithm is proposed and discussed in the application of OFDM tech and VSB tech.In the third chapter, based on the study and research of the equalizer in VSB tech, many improvements and their simulations are presented.In the forth chapter, combining with the thoughts and the algorithm in chapter IK improvements in chapter III, a new adaptive indirect equalizer is presented. The simulations proved that it has lower SNR threshold and faster convergence of coefficients. All of them enable it to combating with the seriously distorted channel.