臺灣博碩士論文加值系統

　　在數位視訊廣播的領域中，視訊節目品質的提升並不是數位廣播的唯一需求，多頻道同時收視並以子母畫面甚至多重畫面顯示之功能更是市場發展的趨勢。衛星數位視訊廣播透過衛星上的轉發器提供視訊節目，其涵蓋範圍廣，再加上直播至用戶服務之積極推動，衛星很快地將會成為最普及的視訊廣播傳輸媒介。本論文針對衛星之數位視訊廣播系統做深入的研究。傳統的衛星接收機爲因應多頻道同時接收之功能，必須增加多組射頻調諧電路，這增添了衛星接收機之電路複雜度及製造成本。為了能簡化接收機調諧器端之電路複雜度，本論文提出多頻道數位正交解調的方法。所謂的數位正交解調技術，是將信號依據特定規範的取樣頻率取樣，並透過規律性的數學運算式將取樣過後的信號樣本進行處理，得到正確的解調輸出。整體數位正交解調接收機的信號解調流程均在數位化下進行，有利於軟體方式之實現。若是取樣時採用帶通取樣法則，則能大幅度地降低取樣頻率，減輕硬體電路在設計時的困難。在本論文中，我們設計了適用於衛星數位視訊廣播系統之多頻道正交解調接收機，藉由運用多組射頻信號之數位正交解調技術，對符合解調中頻規格之衛星視訊頻帶做直接正交取樣，再配合後續的相關解調步驟，可得信號之解調輸出。我們以電腦模擬來驗證所設計之多頻道數位正交解調接收機的性能，電腦模擬結果顯示此架構有相當之可行性，期望未來能達到硬體實現的目標。

關鍵詞：正交取樣、帶通取樣、數位正交解調、數位視訊廣播

　　In the field of digital video broadcasting, it pursuing better quality video programs of the receiver is not the only goal. There is also increasing need in functions (such as PIP and POP). Satellite digital video broadcasts use transponders on a satellite to provide video programs. They can provide a wide broadcasting range. In addition, the direct to home service is currently under active development. Satellites will become the most popular video broadcasting transmission media. In this thesis, we investigate the satellite digital video broadcasting system. For the purpose of receiving multiple channel programs, traditional satellite receivers have to increase the number of tuners. This increases the complexity and the cost of the circuit. In this paper, we propose a multi-channel digital quadrature demodulation method to solve this problem. The so-called digital quadrature demodulation technique chooses the sample rate for signals via certain rules. The correctly demodulated multiple channel outputs can then be obtained from the sampled signal using simple operations. The whole digital quadrature demodulation process is done in the digital domain. This means that it can be easily realized by software. In addition, if the bandpass sampling is used, we can substantially reduce the sampling frequency. In this paper, we apply the multi-channel quadrature demodulation technique to the satellite digital video broadcasting system and perform simulation to verify the goodness of our design. The simulated result shows that the proposed structure is able to successfully demodulate multiple signals. We expect the proposed receiver structure to be implemented in the near future.

Keywords: Quadrature Sampling, Bandpass Sampling, Digital Quadrature Demodulation, Digital Video Broadcast.

第一章 緒論
1.1 數位視訊廣播概述
1.2 數位接收機簡介
1.3 研究動機與目的
1.4 各章節內容概要

第二章 衛星數位視訊廣播技術
2.1 數位視訊廣播簡介
2.1.1 數位視訊主要傳播方式
2.1.2 世界主要數位視訊標準
2.2 數位衛星廣播系統
2.3 衛星廣播使用之頻率範圍
2.4 傳統的數位衛星接收機

第三章 多組射頻信號之數位正交解調技術
3.1 數位正交解調技術原理說明
3.2 兩組射頻信號之數位正交解調技術
3.2.1 避免膺頻現象之正交取樣條件
3.2.2 適用取樣頻率之決定
3.2.3 解調流程原理說明
3.3 多組射頻信號之數位正交解調技術
3.3.1 避免膺頻現象之正交取樣條件
3.4 總整理

第四章 衛星數位視訊廣播之數位正交解調技術
4.1 適用於衛星數位視訊廣播之數位正交解調技術
4.1.1 避免膺頻現象之正交取樣條件
4.1.2 適用取樣頻率之決定
4.1.3 解調流程原理說明
4.2 JCSAT 110衛星之數位正交解調技術應用
4.2.1 避免膺頻現象之正交取樣條件
4.2.2 適用取樣頻率與適用解調中頻間的關係
4.2.3 解調流程原理說明
4.2.4 考慮具有相位誤差時之解調流程
4.3 總整理

第五章 電腦模擬結果
5.1 衛星數位視訊廣播系統之多頻道正交解調接收機蒙地卡
羅效能分析
5.2 考慮具有相位誤差時之蒙地卡羅效能分析

第六章 結論

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