數位電視接收機時序與頻域同步之模擬與實現

Simulation and Implementation of Frequency and Timing Synchronization for DVB-T Receivers

鍾政哲(Cheng-che Chung)

指導教授 ： 陳永芳

國立中央大學/資訊電機學院/通訊工程研究所碩士在職專班/碩士(2007年)

摘要

近幾年來，數位電視地面廣播技術的發展與演進；在規格上可分為三大類。其中歐洲規格(DVB-T)所採用的調變方式正是被稱為正交分頻多工(OFDM)的調變技術。此技術在無線傳輸通道下能提供高速率傳輸、高效率頻譜使用率的多媒體服務以及對抗頻率選擇性的通道衰減的良好特性。然而美中不足的是，同步誤差對於OFDM系統效能影響甚劇。在這個部分，我們需要關注的包含了符碼時間及載波頻率。其作法主要依賴循環字首(Cyclic Prefix ; CP)重複的相關性以及使用已知的導引訊號(pilot signals)來進行。

本論文將就非同步對OFDM系統的影響進行研究分析，驗證估測方式，以建立一個適用於DVB-T接收機的同步系統。並以硬體描述語言Verilog撰寫RTL程式模組，搭配ModelSim軟體環境與先前Matlab所做估測作比較並交互驗證模組的時序及功能。

關鍵字

同步 ； 頻域 ； 時序 ； 數位電視接收機

並列摘要

Recently, there are three major different specifications developed for the terrestrial digital video broadcasting. The terrestrial digital video broadcasting (DVB-T) of European Standard has adopted the orthogonal frequency division multiplexing (OFDM) modulation technique, which offers high-rates, high bandwidth-efficient digital transmission, and various multimedia services over frequency-selective fading channels. However, OFDM technique is very sensitive to synchronization errors, and this deeply impacts system performance. What we concern for synchronization errors includes symbol timing, carrier frequency offset (CFO). The synchronization scheme is mainly based on the correlation of cyclic prefix and the known pilot signals.

This thesis has studied the effect of synchronization errors on OFDM systems, and presented synchronization schemes for DVB-T receivers. We use hardware description language - Verilog and MolelSim to implement the synchronization schemes and verify the design by using Matlab simulation results for the RTL model.

並列關鍵字

DVB-T ； Frequency and Timing Synchronization

參考文獻

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