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。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.
