音訊在藍芽傳輸中的延遲與失真研究探討;Study of Audio Signals Latency and Distortions in Bluetooth Transmission

NCUIR > College of Electrical Engineering & Computer Science > Executive Master of Communication Engineering > Electronic Thesis & Dissertation > Item 987654321/88541

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/88541

Title:	音訊在藍芽傳輸中的延遲與失真研究探討;Study of Audio Signals Latency and Distortions in Bluetooth Transmission
Authors:	賴隆彬;Lai, Long-Ping
Contributors:	通訊工程學系在職專班
Keywords:	藍芽音訊;低延遲;失真;重傳;Bluetooth Audio;Low Latency;Distortion;Retransmission
Date:	2022-01-26
Issue Date:	2022-07-14 13:53:16 (UTC+8)
Publisher:	國立中央大學
Abstract:	本文研究首要目的為降低音訊延遲，藉由同一藍芽晶片商之耳機開發板與藍芽接收器(Dongle)開發板實作一縮短傳輸時間之通路，將音訊資料以最短的路徑依照特定ACL(Asynchronous Connectionless Link)格式傳輸至藍芽底層送出，但在干擾環境下，傳輸越快，會產生越多的掉包失真，因此透過一重傳機制在此傳輸通路下處理與實驗分析因訊號干擾造成的失真與重傳造成的延遲之間的關係。實驗將在干擾環境下透過調整此通路之重傳次數來研究延遲與失真的相關性並分客觀實驗與主觀評估實驗，客觀實驗首先以APx525b聲學量測儀器測得THD+N(Total Harmonic Distortion + Noise)，SNR(Signal-to-noise ratio)等用於定量表示訊號性能的量測指標以評估訊號干擾造成的失真與延遲的線性關係，接著第二部分再透過錄音軟體CoolEdit觀察輸出音訊波形並擷取其失真占比當作失真與延遲的客觀參考依據。主觀評估實驗則請受測人員幫忙在干擾環境下觀看與收聽影音平台的MV搭配字幕評估其延遲與失真的程度後評分，其結果輔以客觀實驗數據找出在此干擾環境下較佳的抗干擾與低延遲重傳數值設定。 ;The primary purpose of this research is to reduce the audio Latency. The headset development board and the Bluetooth receiver (dongle) development board of the same Bluetooth chip manufacturer are used to implement a path that shortens the transmission time, the audio data is sent in the shortest path according to a specific ACL (Asynchronous Connectionless Link) format is transmitted to the Bluetooth low layer and sent out. In the interference environment, the faster the transmission, the more packet loss distortion will be generated. Therefore, a retransmission mechanism is used to process and experimentally analyze the relationship between the distortion caused by signal interference and the latency caused by retransmission in this transmission path. The experiment will be divided into two parts: objective assessment and subjective evaluation under interference environment. The objective assessment experiment uses APx525b acoustic measuring instrument to measure THD+N (Total Harmonic Distortion + Noise), SNR (Signal-to-noise ratio), which are used to quantify signal performance. Measure indicators to evaluate the linear relationship between distortion and delay caused by signal interference. And then observe the output audio waveform through the recording tool “CoolEdit” and capture its distortion ratio as a reference basis for distortion and latency. In the subjective assessment experiment, the subject is asked the testers watching and listening to the MV of the audio-visual platform in an interference environment with subtitles/captions to evaluate the feeling of latency and distortion. The result is supplemented by objective experimental data to find out the best retransmission value setting in this interference environment. This value is the best choice for the anti-interference and low latency under this method.
Appears in Collections:	[Executive Master of Communication Engineering] Electronic Thesis & Dissertation

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