數位電視地面廣播軟體接收機

Abstract

本篇論文主要是利用從數位電視盒中頻訊號的部份所取樣出來的訊號，設計一個軟體接收機將電視訊號解調回來。討論在實際的無線廣播通道下，電視訊號遭受到的干擾和衰減並將其同步及補償回來。軟體接收機主要可以分為三大部分，數位處理前端、基頻訊號解調和通道解碼。在數位處理前端的部份是將取樣出來的訊號做I/Q訊號的解調變和取樣頻率的轉換。得到DVB-T基頻訊號後，就可以進行系統傳輸模式的偵測，進而處理時間和頻率的同步問題，通道估測和補償，本論文採用了一維和二維的通道估測。最後，將解調出來的訊號做通道解碼，就能得到原來的電視訊號MPEG-2 TS。由模擬的部份，可以看到利用電腦上的媒體播放器播放解調出來的MPEG-2 TS電視訊號，並可以將其他兩個節目頻道抽離出來並播放。

This thesis introduces the design of DVB-T software receiver. We simulate the software receiver to demodulate the video signal from the IF signal of set top box. The video signal is discussed by interference and fading from the wireless broadcast channel. The software receiver consists of digital processing front, baseband signal demodulator, and channel decoder. The digital processing front aims to demodulate I/Q signal and transform sampling frequency. After obtaining the baseband signal of DVB-T system, the transmission mode detector is performed, and then time and frequency synchronization as well as channel estimation are processed. Channel estimation is performed using one dimension and two dimension interpolation. Finally, the demodulated signal is performed channel decoding and MPEG-2 transport stream can be obtained. Simulation results show that MPEG-2 TS can be played by the media player on the PC, and other programs are separated out.