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feat(matlab): comm lab 5

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iridiumR 2022-11-26 17:24:08 +08:00
parent 19d2491d51
commit 05c2027520
1 changed files with 22 additions and 38 deletions
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60
Matlab/comm/lab5_0.m
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@ -1,23 +1,23 @@
clc clc
clear
%================================================ %================================================
%已知抽样值以△为单位 %已知抽样值以△为单位
%================================================ %================================================
x = 2047 %抽样值/量化单位△ x = 500
pcmcode = pcmEnCode(x) %调用pcmCode()函数实现PCM编码 pcmcode = pcmEnCode(x)
amp = pcmDeCode(pcmcode) %调用pcmDecode()函数实现PCM译码 amp = pcmDeCode(pcmcode)
amp = pcmDecode(pcmcode) qerror = x-amp
%qerror = x-amp %求量化误差
%================================================ %================================================
%已知抽样值为实际电压值，则需先转换为以△为单位 %已知抽样值为实际电压值，则需先转换为以△为单位
%================================================ %================================================
% M = 5; %设置量化范围 -5~+5 M = 5
% delta = M/2^11; %求量化单位△ d = M/2^11;
% y = +2.5 %设置抽样值/V x = 2.5
% y0 = round(y/delta) %将抽样值转换为以△为单位 x0 = round(x/d)
% pcmcode = pcmCode(y0) %PCM编码 pcmcode = pcmEnCode(x0);
% amp=pcmDecode(pcmcode); %PCM译码 amp0=pcmDeCode(pcmcode);
% amp = amp*delta %转换为实际电压值 amp0 = amp0*d
% qerror=y-amp %求量化误差 qerror=x-amp0
function pcmcode = pcmEnCode(s) function pcmcode = pcmEnCode(s)
@ -27,7 +27,7 @@ function pcmcode = pcmEnCode(s)
if s>0 if s>0
pcm=pcm+bitshift(1,7); pcm=pcm+bitshift(1,7);
else else
s=abs(s) s=abs(s);
end end
for i = 0:7 for i = 0:7
if s < start_t(i+2) if s < start_t(i+2)
@ -43,30 +43,14 @@ function amp = pcmDeCode(pcmcode)
start_t=[0,2.^(4:11)]; start_t=[0,2.^(4:11)];
width_t=[1,1,2,4,8,16,32,64]; width_t=[1,1,2,4,8,16,32,64];
code=bin2dec(pcmcode); code=bin2dec(pcmcode);
isNeg=0; ucode=bitand(code,0b01111111);
if code < 128 k=bitshift(ucode,-4);
isNeg=1; m=bitand(ucode,0b00001111);
k=bitshift(bitand(code,0b01111111),-4); amp=start_t(k+1)+double(m)*width_t(k+1)+width_t(k+1)/2;
amp=start_t(k+1) ... if code<=128
+ double(mod(bitand(code,0b01111111),16)) ... amp=-amp;
* width_t(k+1);
if isNeg=1 amp=-amp;end
end
%PCM译码函数
function amp = pcmDecode(pcmcode)
code_table=[0,2.^(4:11)]; %段落起始电平表
delta=[1,1,2,4,8,16,32,64]; %段内量化间隔表
codeDec=bin2dec(pcmcode); %二进制编码字符串转换为十进制数值
ucode=bitand(codeDec,0b01111111); %屏蔽极性位
k=bitshift(ucode,-4); %右移4位，提取段落码
x0=code_table(k+1); %查表求段落起始电平
m=bitand(ucode,0b00001111); %提取段内码
x1=double(m)*delta(k+1); %求段内量化电平
dV=x0+x1+delta(k+1)/2; %译码输出电平
if codeDec<=128 %处理极性
amp=-dV;
else else
amp=dV; amp=amp;
end end
end end