數位音響廣播接收機之同步子系統的設計與模擬

Abstract

數位音響廣播是繼AM、FM後，所產生的第三代廣播技術，其中Eureka 147 DAB系統更被廣泛採用。 本論文根據Eureka 147 DAB所規定的資料格式，設計其同步子系統架構，其中包含碼框同步、符元同步、小數載波頻率偏移之估測、整數載波頻率偏移之估測。對於碼框同步我們提出兩種方法，符元同步亦提出兩種方法，我們將考慮各種方法之效能與其硬體複雜度，最後針對四個同步步驟，各提出一種方法來做全系統的模擬，觀察其位元錯誤率。我們所設計之系統同步順序為：碼框同步、符元同步、小數載波頻率偏移之估測、整數載波頻率偏移之估測。因為DAB系統採用差分四相位移鍵的調變方式，所以通道估計可以不做。我們分別對各個同步步驟作電腦模擬，決定各個同步步驟所需要的參數後，再做全系統的模擬。此外，本論文提出了一個可以求出非碼際干擾區間的方法，並以電腦模擬觀察其效能表現。

After the inventions of AM and FM for many years, digital audio broadcasting has been chosen as the third generation broadcasting technique and Eureka-147 DAB system is adopted worldwide. In this thesis, we design the synchronization subsystem of an Eureka-147 DAB receiver according to its data format. The synchronization procedures include frame timing synchronization, symbol timing synchronization, fractional frequency offset estimation and integral frequency offset estimation. We propose two algorithms for both frame timing synchronization and symbol timing synchronization. After comparing the performance and the hardware complexity, we choose an algorithm for each synchronization procedure in order to see the BER of the whole system. The order of four synchronization procedures is frame timing synchronization, symbol timing synchronization, fractional frequency offset estimation, and integral frequency offset estimation. Since DAB system uses differential QPSK modulation, channel estimation is not needed. Each synchronization procedure is simulated in order to find the appropriate parameters before doing the whole system simulation. Finally, we proposed an algorithm to find the ISI free region and do the computer simulation to evaluate its performance