正交分頻多工系統之軟體無線電設計與實現：使用個人電腦音效卡及TI C6x數位訊號處理器

Design and Software Defined Radio Implementation of Orthogonal Frequency Division Multiplexing System using PC soundcard and TI C6x DSP

林韋志(Wei Chih, Lin)

指導教授 ： 黃正光

元智大學/工程學院/電機工程學系/碩士(2003年)

摘要

在本論文中，吾人欲將正交分頻多工系統，利用個人電腦音效卡及TI C6x數位訊號處理器實現。正交分頻多工系統的參數規格，仿造IEEE 802.11a規格，但將取樣速率由20MHz降至2000Hz，再經插補濾波器(interpolation filter)將原本的過渡取樣率(oversampling rate)由1.33再提升4倍，如此一來，取樣速率便達到8000Hz，符合個人電腦音效卡使用。
所謂正交分頻多工系統使用個人電腦音效卡實現，是在電腦上開啟兩個MATLAB視窗，一個執行發射機的程式，另一個則執行接收機的程式，發射機產生正交分頻多工訊號，利用音效卡的SPK OUT送出，經由線路傳送至音效卡的LINE IN接收，接收機針對LINE IN所接收到的訊號進行解調，在這樣的裝置下，吾人又設計了兩個應用，傳送文字及傳送單一正弦波形。
上述實驗，從系統參數設定到軟硬體的實現，吾人所依循的設計流程為Top-Down設計流程，推展此流程，可以藉由改變系統參數，進而改變系統的規格，符合近代軟體無線電的設計準則，而吾人的實驗，一方面推崇Top-Down設計流程，另一方面可以利用最少的成本，設計高階系統的模組。對於教學而言，吾人的論文提供了一個很好的範例。
完成了正交分頻多工系統使用個人電腦音效卡實現後，吾人進一步，將整個系統移植到TI C6x數位訊號處理器上實現，發展即時資料交換(Real Time Data eXchange, RTDX)的即時系統。

關鍵字

正交分頻多工系統 ； 封包偵測 ； 頻率估測及補償 ； 通道估測及等化器 ； 相位追蹤及補償 ； 即時資料交換

並列摘要

In this thesis, we aim at designing the software defined radio implementation of Orthogonal Frequency Division Multiplexing (OFDM) system by use of PC sound card and TI C6x DSP. The parameter setting of OFDM system is according to the IEEE 802.11a specification, but we reduce the sampling rate from 20MHz to 2000Hz. Then we exploit the interpolation filter to increase the oversampling rate 4 times from 1.33, therefore obtaining the sampling rate of 8000Hz, which conform to PC sound card used.
In the implementation of OFDM system through PC sound card, is we open two MATLAB windows on the computer, one is to run a transmitter program, and the other run a receiver program. The transmitter program generates the OFDM signal, and use SPK OUT of sound card to transmit the signal. Then at the receiver end, the LINE IN of sound card received the signal form SPK OUT, and begin to demodulate the received OFDM signal. Based on this transceiver, we apply it to two transmission modes, letter transmission and single-tone sine waveform transmission.
After finishing the implementation of OFDM system using PC sound card, more over, we extend this system to execute on TI C6x DSP to fulfill the Real Time Data eXchange(RTDX) real time system.

並列關鍵字

OFDM System ； Packet Detection ； Frequency Estimation ； Channel Estimation ； Phase Tracking ； TI C6711 DSK ； RTDX

參考文獻

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