Based On Dtmb Echo Cancellation Algorithm And Simulation To Achieve

With Digital terrestrial multimedia/television broadcasting (DTMB) introduced, China speeds up the analog TV to digital TV conversion. In order to eliminate the weak signal areas in communication and achieve the popularity of digital television across the country, people pay more and more attention to the development of digital repeaters with Echo Cancellation System for the DTMB.The main function of Echo Cancellation System's digital repeater is to estimate the external coupling channel's transmission characteristics and coupling echo, and then subtract the estimated echo signal from the received signal. Thus Echo Cancellation System's digital repeater can cancel interference of the coupling echo. The advantage of this digital repeater can reduce the isolation requirements, reduce installation complexity and avoid repeater's self-excitation effectively.In the design of this digital repeater, the echo canceller is the sticking point, and it also the main content of the study in this dissertation. The key technologies of the echo canceller are channel estimation algorithm and echo cancellation proposal. In this dissertation, the main work is as follows.First, DTMB and radio channel transmission characteristics are studied. Digital TV signal source is generated for the simulation.Secondly, three kinds of channel estimation algorithms are studied and simulated in MATLAB 7.01. And improved cyclic correlation channel estimation algorithm based on m sequences is simulated. Simulation result shows that the improved algorithm has good MSE preference at high SNR.Thirdly, two kinds of echo cancellation proposals are studied. Echo cancellation proposal based on m sequences is simulated in MATLAB 7.01. Simulations results show that echo canceller still track the changes of the coupling channel in the work process.Finally, LMS algorithm is implemented in DSP, and a preliminary exploration is made for the echo cancellation algorithms'implementation in the DSP.In this dissertation, channel estimation algorithms and echo cancellation proposals are studied and simulated in MATLAB 7.01. Simulation results show that these algorithms can estimate external coupling channel effectively. These researches in this dissertation provide a theoretical basis for the echo canceller's implementation.