臺灣博碩士論文加值系統

近來無人飛行載具(Unmanned Aerial Vehicle, UAV)的發展日漸成熟，並應用於許多不同的領域，無人飛行載具在進行任務時，常透過空中攝影來記錄、監控地區當下的情況變化，因此搭配一套可適用於高速移動與遠距離的影像傳輸系統是不可避免的。
本論文提出以軟體無線電(Software Defined Radio, SDR)平台搭配樹莓派（Raspberry Pi）來建立一套未來可適用於無人飛機或中小型火箭等遠距離與高速情境下的發射接收機系統。利用樹莓派錄製高清影像，以數位視訊廣播（Digital Video Broadcasting-Terrestrial, DVB）為基礎，使用GNU Radio軟體開發平台和通用軟體無線電周邊設施(Universal Software Radio Peripheral, USRP)，設計與實現DVB-T收發機。透過USRP實際發送接受訊號，量測BER及RSSI等數值，評估整體系統效能，並搭配高頻功率放大器(RF power amplifier)來延伸與最大化傳輸距離。最後實際測試，在2.4GHz的頻段下，可以順利達到公里等級與時速約50 ~ 90公里的高速遠距之穩定影像傳輸。
利用軟體定義無線電平台開發不僅能實現收發影像訊號的功能並大幅降低成本，未來亦可利用此平台搭配多輸入多輸出(Multiple Input Multiple Output, MIMO)技術，得到更高的傳輸效能。

Recently the applications of Unmanned Aerial Vehicle (UAV) enter a prosperity phase, especially for image recording and surveillance, and therefore it is highly needed for developing a UAV-dedicated image transmission system that supports high-speed mobility and Long distances.
In this thesis, we develop the image transceiving system with Software Defined Radio (SDR) as well as Raspberry Pi, which can support both high-speed and Long image transmission demands for UAVs and small rockets. The high definition image recorded with Raspberry Pi is transceived by our Digital Video Broadcasting-Terrestrial (DVB-T) transmitter and receiver developed with Universal Software Radio Peripheral (USRP) and GNU Radio. The USRP transmitter equipped with RF power amplifier extends the transmission range, and then the USRP receiver evaluates the signal quality in terms of the Received Signal Strength Indication (RSSI) and Bit Error Rate (BER). We prove that the proposed system provides stable image transmission under the field trial scenarios of moving speed about 50~90 km/h and transmission range about thousands of meters.
The use of SDRs for image transmission not only reduces the cost but also has the potential of Multiple Input Multiple Output (MIMO) function supports for better performance in the future.

摘　要 i
ABSTRACT iii
表目錄 vii
圖目錄 viii
第一章 序論 1
1.1 研究背景與動機 1
1.2 章節介紹 2
第二章 DVB-T發射接收機介紹 3
2.1 OFDM簡介 3
2.1.1 OFDM系統架構 4
2.2 DVB-T系統架構 7
2.3 DVB-T之OFDM系統參數 18
第三章 使用USRP B200 mini實作設計發射接收機 23
3.1 軟體定義無線電 23
3.1.1 Ettus通用軟體無線電週邊設備 24
3.1.2 GNU Radio 25
3.1.3 GNU Radio Companion (GRC) 26
3.2 DVB-T SDR系統設計 26
3.2.1 接收訊號強度指標 28
3.2.2 接收訊號ML估測 29
3.2.3 接收訊號分析 30
3.3 影像傳輸系統建置架構設計 33
3.3.1 影像傳輸系統SDR系統建置 34
3.3.2 自動增益控制 35
第四章 高速遠距影像傳輸系統實作結果 37
4.1 2.4GHz功率放大器 37
4.2 靈敏度量測 38
4.3 遠距離實測結果 41
4.4 高速移動實測結果 43
第五章 結論 46
參考文獻 47

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