數位多載波傳輸系統之模擬與實現

The Simulation and Implementation of the Single-DSP DMT Transceiver

陳蒔鋒(Shih-Feng Chen)

指導教授 ： 馬杰

元智大學/工程學院/電機工程學系/碩士(2003年)

摘要

數位訊號處理器(digital signal processor, DSP)具有可程式化的優點。因此以DSP為核心所設計的產品可以經由重覆修改程式來縮短產品研發至上市時間，也可以利用更新韌體(Firmware)程式來擴充功能而無須更改其硬體設計。例如:DSP語音數據機只要更新韌體程式後便可以由V.34升級為V.90的新功能。基於這個想法，本論文以TI TMS6701 DSP與TI 6x EVM模擬板為平台來實現目前ADSL數據機廣泛使用的調變技術 --- 數位多載波(DMT)傳輸。
利用實作完成DMT傳收器(Transceiver)在雙絞線通道上進行即時的資料傳輸。藉此可以估測通道的脈衝響應(Impulse response)。程式中加入了頻域等化器(FEQ)與位元分配(Bit-Loading)的方法來克服脈衝響應造成的影響。本論文還對系統中DSP所耗費的運算量做統計，根據統計的結果來評估在DMT系統上DSP的運算瓶頸為何。並提出可行的增進傳輸速度的方法，以增進傳收器的效能。

關鍵字

數位訊號處理器 ； 數位多載波

並列摘要

The most significant benefit of the programmable general-purpose DSP (Digital Signal Processor) is its flexibility. The products using DSP design can easily upgrade the firmware to expand their functions without modifying any hardware. For example, the DSP-based voice modems were software-upgradeable to the V.90 standard from V.34 as soon as the V.90 recommendation was approved. Due to this conception, we try to implement a DSP-based DMT(Digital Multi-Tone) transceiver. DMT is one of the multi-carrier modulation popularly used at today’s ADSL modem.
In this thesis, we design a DMT transceiver based on the TI’s TMS320C6701 DSP EVM (Evaluation Module) platform. The copper twisted-pair line is used to test the real-time data transmission performance of the DMT. The test results demonstrate the implemented DMT transceiver is the capable of estimating the channel response and mitigating the influences of channel response by using the FEQ (Frequency domain Equalizer) and bit-loading algorithm. We also analyze the computation loads of the DMT on DSP board and find its computation bottleneck. Finally, the practical method to speed-up the transmission rate are proposed in order to promote the DMT transceiver performance.

並列關鍵字

DSP ； DMT ； ADSL

參考文獻

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