基于51單片機(jī)的多功能門鈴的設(shè)計(jì)外文資料翻譯-展示頁
2024-12-06 03:43本頁面
【正文】 模塊由語音編解碼芯片 MC145481 完成，語音信號(hào)處理模塊由 CPLD 對數(shù)字語音信號(hào)進(jìn)行打包和解包以及同步處理，從而提高抗干擾能力 。 三、語音傳輸處理 語音傳輸處理雖然數(shù)字信號(hào)比模擬信號(hào)有很大的優(yōu)點(diǎn) ，但是數(shù)字信號(hào)比模擬信號(hào)難于接收，處理的要求比模擬信號(hào)更為嚴(yán)格 。無線通信中必須按數(shù)據(jù)幀分組傳輸數(shù)據(jù)，并且必須采可靠的幀同步方式來保證從混亂的數(shù)據(jù)中將合法的數(shù)據(jù)幀識(shí)別出來。位同步對硬件設(shè)備要求比較高，實(shí)現(xiàn)比較困難，一般很少使用而多采用碼同步 。 如果幀之間設(shè)置有超時(shí)定時(shí)器并且傳輸協(xié)議規(guī)定了幀數(shù)據(jù)長度，那么幀同步碼則可以任意選擇，一般選擇 0xAA， 0x55之類 0 1均勻分布的數(shù)據(jù)，并且為了提 高可靠性，往往選擇多字節(jié)的幀同步碼，比如 0xAA， 0xBB (兩字節(jié)幀同步碼 )。 (2) 冗余碼 ： 根據(jù)經(jīng)驗(yàn)，通常采用 0xff 或者 0xff， 0x66的效果比較好，用來糾正通信建立階段位錯(cuò)誤引起的串口接收失步，在低速時(shí) ( 19 200bps)，往往使用兩個(gè)冗余碼 L本設(shè)計(jì)中不采用。無線可視對講門鈴系統(tǒng)中采用的是 0xCCCCCC。在采用曼徹斯特編碼或 DPCM 方式傳輸中，數(shù)據(jù)長度一般不要超過 256字節(jié) ； 反之 ， 不要超過 64 字節(jié)。 其中 0x99為前導(dǎo)碼，用于初始位同步和接收狀態(tài)機(jī)復(fù)位， 0xCCCCCC為數(shù)據(jù)幀同步碼，幀同步碼后面八位用來傳控制碼。 室外到室內(nèi)的控制信號(hào)只有一個(gè)呼叫按鍵，所以我們設(shè)計(jì)時(shí) ， 將幀同步碼后的一個(gè)字節(jié)留給傳輸控制信號(hào)，在控制信號(hào)后面再緊跟以字節(jié)為單位的語音數(shù)據(jù)。頂層文件的系統(tǒng)時(shí)鐘為 2048 kHz。 如果第 3個(gè)字節(jié)還是 0xCC，由 狀態(tài) 2 進(jìn)入狀態(tài) 3，進(jìn)入同步態(tài)，否則返回狀態(tài) 0L其中數(shù)字鎖相環(huán)是進(jìn)行位同步。由于一個(gè)采樣點(diǎn)的量化數(shù)據(jù)最后一位權(quán)值最小，所以這樣處理不會(huì)帶來什么影響 。 測試結(jié)果表明本設(shè)計(jì)方案具有性能穩(wěn)定可靠、語音清晰、設(shè)計(jì)簡單等特點(diǎn)，具有實(shí)用價(jià)值 L當(dāng)然本文提出的方案在性能上還有待改進(jìn)，接下來我們要做的工作是進(jìn)行圖像信息的數(shù)字化實(shí)時(shí)傳輸，從而實(shí)現(xiàn)全數(shù)字無線可視對講門鈴系統(tǒng) 。s overall structure and working principle and the key technology fullduplex digital voice munications for the design and realization of， Analysis of the digital transmission of voice processing, a frame structure on the design and realization of the CPLD in a wireless doorbell system visualization Roundframe synchronization . Finally, the prototype system by the field test, stable performance, reliable, clear voice, has good practical value. The development of electronic, wireless and work technology provides the strong technical support for security and convenience of modern residential quarters. In this paper, we introduce a new style wireless visual interconversation doorbell system, which is used in the intelligent residential quarters. Then explains the structure of this system, and it’s fullduplex digital voice munication is designed and implemented. We emphasize the digital voice process in transmission, and discuss the design of the structure of frame, and the frame synchronization realized in CPLD. Finally, the test result shows a stable and reliable quality, clear voice and fairly practical value. Second: Features At present domestic doorbell has been a lot of visualization products, mainstream product is wired, oneway voice and Simulation. Visual Round wireless doorbell system bines puter technology, wireless munications and digital signal processing technology used in highfrequency wireless transmitter receiver, installation without cabling, would not undermine the effectiveness decoration. Visual Round wireless doorbell system is the next generation of electronic security systems, modern gardens, Villa, Villa ideal security device. Family in the living room, through the screen to see images, voice speaking
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