數位廣播之取樣頻率偵測與補償

Sampling Frequency Detection and Compensation for DAB receiver

周加慶(Jia-Cing Jhou)

指導教授 ： 尤信程

國立臺北科技大學/電資學院/資訊工程系研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00111

摘要

近年來，正交分頻多工系統(OFDM)在通訊應用上越來越普及。跟單頻載波系統相較之下，OFDM系統對於同步的問題相當敏感。然而，由於傳送端和接收端振盪器的不完全一致，因此會產生取樣偏移的現象，進而導致其他同步問題。本論文中，我們主要探討DAB接受端因A/D取樣頻率偏移所產生的問題，並以DAB receiver當做實驗平台。
取樣頻率偏移的偵測方法，在許多的文獻中有提過，當中最常見的是利用正交分頻多工系統(OFDM)中含有引示符號這個特性所延生出來的方法，在本論文中，我們針對DAB的OFDM提出一個方法，並以統計建表的方式呈現，也可以有效達到偵測取樣頻率偏移的效果。此外，在偵測之後進而以複雜度較低的方法進行補償，讓訊號持續正常解調，並以實驗探討其有效性，也是本論文之討論重點。

關鍵字

DAB ； 正交分頻多工 ； 腓特比 ； 取樣頻率偵測 ； 取樣頻率補償

並列摘要

Recently, OFDM has become a popular technique for broadband communications. Compared to single carrier system, OFDM-based receiver is more sensitive to sampling rate offset. However, the mismatch of oscillators between the transmitter and the receiver causes the sampling frequency offset, among other synchronous problems. This thesis studies the sampling frequency offset problems for a DAB receiver.
Many sampling frequency detection algorithms have been proposed previously. A widely used detection method is based on the pilots in the OFDM symbols. Since the DAB signal doesn’t transmit pilots, this approach can not be used in a DAB receiver. In this thesis, we propose a detection method to effectively detect the sampling frequency offset. After sampling frequency detection, compensating for the offset with lower complexity in order to demodulate signal correctly is also proposed. Finally, we show its validity with experiments.

並列關鍵字

DAB ； OFDM ； Viterbi ； Sampling frequency offset detection ； Sampling frequency offset compensation

參考文獻

[5] 劉大興, “數位廣播接收機之實作,” 國立臺北科技大學碩士論文, 2004.

[6] 李卓澔, “數位電視通道解碼及解調變之實作,” 國立臺北科技大學碩士論文, 2006.

[1] ETSI EN 300 401, Radio broadcast systems: Digital audio broadcasting to mobile portable and fixed receivers,v1.3.3,2001.

[4] Shu Lin, Costello J. Daniel, Error Control Coding, Prentice Hall Inc. 1983

[8] Louis Litwin, and Michael Pugel, “ The Principle of OFDM ,” www.RFdesign.com, pp.30-48, Jan. 2001