這篇論文是在介紹台灣與韓國在推動數位電視廣播引用不同系統,兩種廣播系統規格同屬多載波正交分頻多工(OFDM)家族,正交分頻多工(OFDM)是將一個寬頻高速的資料串流,分成許多低速且窄頻的資料串流,形成多載波系統,他有許多優點但OFDM也有嚴重的缺點就是有很高的PAPR(Peak-to average power ratio),很高的PAPR值通過線性放大器會產生非線性失真,導致相鄰副載波產生干擾而失去正交性,造成信號雜訊比降低,為了分析廣播發射系統傳輸品質必須經由接收機來模擬與驗證,將兩種廣播系統規格與系統參數從工程技術的發展狀況做整體系統比較,並以傳輸資料容量評估影像品質、進一步以數學分析評估模擬驗證高功率峰均值比問題,最後以實驗法利用補集累計分佈函數CCDF (Complementary Cumulative Distribution Function)儀量測值估算結果比較二種系統。 關鍵詞:韓國KBS 數位電視廣播 數位多媒體廣播 行動手機電視 網路電視 寬頻無線接取網路
This article is an introduce of the different digital video broadcasting systems being promoted in Taiwan and in South Korea.The specifications of both broadcasting systems are families of the orthogonal frequency division multiplexing, which turns high-speed broadband data stream into a multi-carrier system by dividing it into several low-speed, narrowband data streams. OFDM has many advantages,but one of its biggest disadvantages is an extremely high peak-to average power ratio(PAPR).Extremely high PAPR value will produce nonlinear distortion through linear power amplifier,resulting in interference in adjacent subcarrier that causes the loss of orthogonality,and high signal noise.In order to anaiyze the quality of broadcasting transmission systems,the specifications and system parameters of both broadcasting systems were compared in terms of the development in engineering technology, while video quality was evaluated throuth transmission data capacity. Moreover,the method of discrete fourier transform(DFT) was used to simulate and analyze the issue of estimated high power PAPR.Finally,both systems were tested and conparred by measuring the results through experiments and instrument of complementary cumulative distribution function(CCDF). Key Word: KBS DVB T-DMB Mobile TV IPTV WiMAX