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研究生: 洪英釋
Hung, Ying-Shuh
論文名稱: 高屏地區數位電視電波傳播模擬與量測
Digital TV Radiowave Propagation Simulation and Measurement in Kaohsiung and Pingtong Area
指導教授: 蔡智明
Tsai, Chih-Ming
學位類別: 碩士
Master
系所名稱: 電機資訊學院 - 電機工程學系碩士在職專班
Department of Electrical Engineering (on the job class)
論文出版年: 2004
畢業學年度: 92
語文別: 中文
論文頁數: 115
中文關鍵詞: 數位電視電波傳播
外文關鍵詞: DTV, DVB-T, COFDM, Propagation
相關次數: 點閱:64下載:1
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  •   我國數位電視採用歐規DVB-T系統,使用COFDM調變技術,具有建立SFN (Single Frequency Network)單頻網路廣播及行動接收功能。數位廣播不同於類比廣播,有所謂的「懸崖效應」(Cliff Effect),也就是接收信號低於一定電場強度數值時,就完全收不到畫面,這使得電場強度的傳播預測對數位電視廣播網的設立有相當大的影響。透過載波雜訊比C/N值,本文計算出數位電視廣播在固定、行動等接收條件下所需的電場強度值。
      由於電波傳播模式是以外國的地理環境及氣候條件下所推估發展,套用於本地使用時,需靠實測來驗證其準確性,因此本文利用中視(539MHz)及華視(599MHz)在中寮的數位電視轉播站的信號,於高雄、屏東地區共做了76個點的實地量測資料。
      透過德國L&S公司的 CHIRplus-BC軟體,本文使用ITUR-370、ITUR- 1546、Okumura-Hata、L&S VHF/UHF、Epstein-Peterson等傳播模式對上述實測點作電場強度模擬預測,並依此預測值與實測值的誤差,統計分析各傳播模式在平地、山區、都市、鄉村、不同頻率及不同距離等條件下的預測準確度。

      The digital TV system in Taiwan is European DVB-T system, which is using COFDM modulate technology with the functions of building SFN (Single Frequency Network) broadcasting and mobile reception. Digital broadcasting is different from analog broadcasting. There is completely no reception when the reception signal value is lower than a critical field strength value, and this is so-called “Cliff Effect”. The result of “Cliff Effect” will extremely affect the prediction of field strength propagation in building digital TV broadcasting network. Through the carrier to noise ratio C/N value, this study calculates the field strength value needed under some considerable reception conditions , such as in fixed, mobile regions.
      Due to the model of radiowave propagation is estimated under the conditions of geographical and climatic environments abroad, the accuracy of result needs to be proved by practical measurement when this model is used in Taiwan. Therefore, the measurement information in this study is practically collected from 76 points around the regions in Kaohsiung and Pingtong by using the signals from digital TV transmissions of China Television (CTV, 539MHz) and Chinese Television (CTS, 599MHz) in Chung-Liao.
      Through the CHIRplus-BC software in Germany L&S company, this study uses the propagation models of ITUR-370、ITUR-1546、Okumura-Hata、L&S VHF/UHF and Epstein-Peterson to predict the field strength value measured from 76 points around the regions in Kaohsiung and Pingtong. Furthermore, by using the errors between the values of prediction and reality measurement, the accuracy of propagation models prediction under the different conditional regions of plain, mountain, urban, rural, different frequency and different distance will be also analyzed in this study.

    第一章 緒論......................................1 1.1 前言......................................1 1.2 研究目的..................................2 1.3 研究方法及章節介紹........................3 第二章 歐規數位電視地面廣播DVB-T傳輸系統簡介.....4 2.1 傳輸資料編碼格式..........................4 2.2 通道編碼(Channel Coding)................6 2.2.1 亂碼器(Randomizer)....................6 2.2.2 外編碼器(Outer Coder).................6 2.2.3 外交錯器(Outer Interleaver)...........7 2.2.4 內編碼器(Inner Coder).................8 2.2.5 內交錯器(Inner Interleaver)...........9 2.3 編碼正交分頻多工 ........................11 2.4 保護區間Guard Interval...................14 2.5 載波模式.................................16 2.6 傳輸容量的計算...........................18 第三章 DVB-T傳輸通道的影響及所需電場強度計算....20 3.1 傳輸通道對DVB-T接收的影響................20 3.2 都卜勒頻移(Doppler Shift)................24 3.3 DVB-T所需電場強度的計算..................25 3.4 數位電視接收端所需電場強度之計算.........27 第四章 電波傳播模式簡介.........................33 4.1 ITRU-370 Model...........................33 4.2 ITRU-1546 Model..........................42 4.3 Okumura-Hata Model.......................42 4.4 L&S VHF/UHF Model........................43 4.5 Epstein-Peterson Model...................44 第五章 電場強度實測.............................45 5.1 接收天線場型驗證測試.....................45 5.2 量測點的規劃.............................51 5.3 測試點的量測步驟:.......................54 5.4 電場強度量測值的變動量(Variation):......55 第六章 軟體模擬與量測結果分析...................56 6.1 模擬軟體簡介.............................56 6.2 模擬方法.................................56 6.3 模擬數值與比較圖示.......................60 6.4 量測點地形高度剖面與電場強度預測關係圖...71 6.5 傳播模式效能分析方法.....................76 6.6 中視及華視傳播模式效能分析方法...........76 6.7 平坦地區傳播模式效能分析.................79 6.8 山區地形傳播模式效能分析.................83 6.9 都市、郊區、鄉村地貌效能分析.............84 6.9.1 都市地貌傳播模式效能分析...............84 6.9.2 郊區地貌傳播模式效能分析...............85 6.9.3 鄉村地貌傳播模式效能分析...............86 6.10 發射傳播距離在傳播模式上的效能分析.......87 6.10.1 傳播距離15km~21km傳播模式效能分析......87 6.10.2 傳播距離22km~27km傳播模式效能分析......88 6.10.3 傳播距離28km~33km傳播模式效能分析......89 6.10.4 傳播距離34km~39km傳播模式效能分析......90 6.10.5 傳播距離40km~55km傳播模式效能分析......91 6.10.6 傳播距離大於56km傳播模式效能分析.......92 6.11 電波涵蓋範圍圖(Contour)..................93 6.12 傳播距離曲線修正量.......................93 第七章 結論與討論...............................96 參考文獻.........................................99 附錄............................................101 附錄A. 量測地點及地理描述......................101 附錄B. 華視599MHz實測紀錄......................105 附錄C. 中視539MHz實測紀錄......................109 附錄D. UHA-9105 Dipole Antenna Specification....113 附錄E. 華視數位電視高雄中寮發射站發射天線增益及輻射場圖............114 附錄F. 中視數位電視高雄中寮發射站發射天線增益及輻射場圖............115

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