| 姓名 |
蔡頤(I Tsai)
查詢紙本館藏 |
畢業系所 |
通訊工程學系 |
| 論文名稱 |
數位電視廣播OFDM系統基頻接收器取樣率偏移同步之FPGA設計與實現
(Design and FPGA Implementation of Sampling Frequency Offset Synchronization for DVB-T Receiver in baseband)
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| 相關論文 | |
| 檔案 |
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| 摘要(中) |
正交分頻多工（OFDM）技術為DVB-T所採用的核心技術。雖然OFDM系統具有抵抗多重路徑干擾及頻譜使用效率高等優異特性，卻有著對系統同步相當高要求的門檻，當發射與接收端的取樣率不匹配時，會發生取樣率偏移(Sampling Frequency Offset)。
在消除取樣率偏移消除有許多相關方法，本論文研究方向為於頻域估測出取樣率偏移量，後得修正過取樣率以再取樣器(Resampler )調整時域訊號，以數位地面電視廣播系統(DVB-T)為規格於FPGA硬體實現。取樣器方面利用費洛濾波器(Farrow Interpolator)的架構來設計，估測器則利用頻域相鄰兩符元訊號之連續領航訊號(Continual Pilot)的相關性估測出SFO偏移量送回費洛濾波器對訊號做調整。系統架構在Matlab模擬分析後，選取適當之參數去設計硬體，用Verilog語言撰寫數位同步系統，再下FPGA板子做測試及驗證。
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| 摘要(英) |
Orthogonal Frequency Division Multiplexing(OFDM) technique is the core technique of DVB-T. Although the OFDM system exhibits outstanding characteristics in terms of simplicity in combating multi-path transmission and efficiency in spectral utilization, it requires highly accurate synchronization in carrier and sampling frequency. When the sample rate between the transmitter and the receiver is not matched, the performance of the system is suffered by sampling frequency offset.
There are some methods proposed for the compensation of sampling frequency offset in the OFDM systems. In this thesis we discuss the design and implement of a sampling frequency offset compensator for the DVB-T OFDM system with FPGA.The sampling frequency offset is estimated in frequency domain based on the continuous pilots and the compensated implement in time domain with a Farrow Interpolator. The performance of the sampling frequency offset compensator, which is determined by the nominal over-sampling ratio and the filter coefficients/order of the Farrow Interpolator, is studied in this thesis. Furthermore, a real-time sampling frequency offset compensator for the DVB-T OFDM system is implemented and verified with FPGA.
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| 關鍵字(中) |
★ 再取樣器
★ 內插器
★ 取樣率 |
關鍵字(英) |
★ resampler
★ sampling frequency offset
★ OFDM |
| 論文目次 |
摘 要 iv
ABSTRACT v
致謝 vi
目錄 vii
圖目錄 ix
表目錄 xii
第一章 緒論 1
1-1 研究動機與背景 1
1-2 章節提要 2
第二章 數位電視地面廣播規格 3
2-1 OFDM的調變原理與架構 3
2-2 保護區間(Guard Interval)與循環延展(Cyclic Extension) 7
2-3 參考訊號 8
2-4 DVB-T實作規格 9
第三章 取樣率偏移之同步 11
3-1 取樣率偏移對於OFDM系統之影響 11
3-2 再取樣器設計及原理介紹 19
3-2-1 再取樣器原理 20
3-2-2 再取樣器系數及設計 22
3-3 取樣率偏移估測 25
第四章 系統硬體架構 28
4-1 時序同步器(Timing Synchronizer) 28
4-1-1 再取樣器(Resampler) 28
4-1-2 延遲相關器(Delay Correlator) 33
4-1-3 峰值檢測器(Peak Detector) 35
4-1-4 符碼同步器(Symbol Synchronizer) 37
4-2 快速傅立葉轉換處理器(FFT Processor) 38
4-2-1 座標軸數位旋轉計算器 42
4-2-2 旋轉因子產生單元 44
4-2-3 FFT時序控制 45
4-2-4 位元反轉排序 46
4-3 取樣率偏移估測器(SFO Estimator) 48
4-3-1 導航訊號處理器 49
4-3-2 相位計算器 51
4-3-3 再取樣率處理器 54
4-4 電路合成報告及效能 58
第五章 結論 61
參考文獻 62
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| 參考文獻 |
[1] P.Y. Tsai and T.D.Chiueh,“Frequency-Domain Interpolation-Based Channel Estimation in Pilot-Aided OFDM Systems” Proc. of 2004 IEEE 59th VTC, Milan, Italy, vol.1 ,May 2004, pp. 420-424.
[2] Yih-Min Chen ‘‘On the Design of Farrow Interpolator for OFDM Receivers with Asynchronous IF Sampling’’ November 2009
[3] Muh-Tian Shiue and Chin-Long Wey “Efficient Implementation of Interpolation Technique for Symbol Timing Recovery in DVB-T Transceiver Design”
[4] J. J. van de Beek, M. Sandell, and P. 0. Borjesson, “ML Estimation of Time and Frequency Offset in OFDM Systems,”IEEE ’Itans. Signal Processing, Vol. 43, pp. 761-766, Aug.1997.
[5] G. Watkins. “Optimal Farrow Coefficients for Symbol Timing Recovery”, IEEE Communications Letters, vol. 5, no. 9, pp. 381-383, September 2001.
[6] 林韋丞 ‘‘Synchronization for DVB-T in High-mobility Environment’’ July 200
[7] 張瑞彥 ‘‘Design and Implementation of Digital Down Converter and Resampling for DVB-T System’’ July 2006
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| 指導教授 |
陳逸民(Yih-Min Chen)
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審核日期 |
2012-2-1 |
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