adpcm的matlab仿真精講-資料下載頁(yè)
2024-11-17 22:30本頁(yè)面
【正文】 , 1878, 2066, 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767]。prevsample = 0。previndex = 1。Ns = length(adpcm_y)。n = 1。while (n = Ns)predsample = prevsample。index = previndex。step = StepSizeTable(index)。code = adpcm_y(n)。diffq = bitshift(step, 3)。if (bitand(code, 4))diffq = diffq + step。endif (bitand(code, 2))diffq = diffq + bitshift(step, 1)。endif (bitand(code, 1))diffq = diffq + bitshift(step, 2)。endif (bitand(code, 8))predsample = predsample diffq。elsepredsample = predsample + diffq。endif (predsample 32767)predsample = 32767。elseif (predsample 32768)predsample = 32768。endindex = index + IndexTable(code+1)。if (index 1)index = 1。endif (index 89)index = 89。endprevsample = predsample。previndex = index。raw_y(n) = predsample / 32767。n = n + 1。end輸入一個(gè)模擬信號(hào)的編碼解碼過(guò)程：t=0:pi/50:2*pi。y=cos(t)。adpcm_y=adpcm_encoder(y)。Y=adpcm_decoder(adpcm_y)。Z=Yy。subplot(2,2,1)plot(t,y)title(39。輸入模擬信號(hào)y39。)。subplot(2,2,2)stem(adpcm_y)title(39。ADPCM編碼39。)。subplot(2,2,3)plot(t,Y)title(39。ADPCM解碼39。)。subplot(2,2,4)plot(Z)title(39。誤差39。)。該程序運(yùn)行后得到結(jié)果入下圖：四、 結(jié)果分析從上面的運(yùn)行結(jié)果來(lái)看，ADPCM編碼的效率較高，解碼后誤差小。而且編碼位數(shù)都為4位二進(jìn)制，提供跟高的壓縮比，減小了帶寬利用，提高了頻率利用率，因此在頻帶緊缺的現(xiàn)代通信中具有廣泛的應(yīng)用前景.內(nèi)容總結(jié)
（1）ADPCM編碼與解碼
實(shí)驗(yàn)原理與目的
目前，脈沖編碼調(diào)制（PCM）的數(shù)字通信系統(tǒng)已經(jīng)在大容量數(shù)字微波、光纖通信系統(tǒng)，以及市話網(wǎng)局間中繼傳輸系統(tǒng)中獲得廣泛的應(yīng)用
（2）這種噪聲稱為顆粒噪聲
（3）while (n = Ns)
predsample = prevsample
（4）Z=Yy
化學(xué)相關(guān)推薦
鄂ICP備17016276號(hào)-1