ir
/
justhomework
Archived
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

feat(matlab): comm lab 5

This commit is contained in:
iridiumR 2022-11-26 17:24:08 +08:00
parent 19d2491d51
commit 05c2027520
1 changed files with 22 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
Matlab/comm/lab5_0.m
View File

@ -1,23 +1,23 @@
clc
clear
%================================================
%已知抽样值以△为单位
%================================================
x = 2047 %抽样值/量化单位△
pcmcode = pcmEnCode(x) %调用pcmCode()函数实现PCM编码
amp = pcmDeCode(pcmcode) %调用pcmDecode()函数实现PCM译码
amp = pcmDecode(pcmcode)
%qerror = x-amp %求量化误差
x = 500
pcmcode = pcmEnCode(x)
amp = pcmDeCode(pcmcode)
qerror = x-amp
%================================================
%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
% delta = M/2^11; %求量化单位△
% y = +2.5 %设置抽样值/V
% y0 = round(y/delta) %将抽样值转换为以△为单位
% pcmcode = pcmCode(y0) %PCM编码
% amp=pcmDecode(pcmcode); %PCM译码
% amp = amp*delta %转换为实际电压值
% qerror=y-amp %求量化误差
M = 5
d = M/2^11;
x = 2.5
x0 = round(x/d)
pcmcode = pcmEnCode(x0);
amp0=pcmDeCode(pcmcode);
amp0 = amp0*d
qerror=x-amp0
function pcmcode = pcmEnCode(s)
@ -27,7 +27,7 @@ function pcmcode = pcmEnCode(s)
if s>0
pcm=pcm+bitshift(1,7);
else
s=abs(s)
s=abs(s);
end
for i = 0:7
if s < start_t(i+2)
@ -43,30 +43,14 @@ function amp = pcmDeCode(pcmcode)
start_t=[0,2.^(4:11)];
width_t=[1,1,2,4,8,16,32,64];
code=bin2dec(pcmcode);
isNeg=0;
if code < 128
isNeg=1;
k=bitshift(bitand(code,0b01111111),-4);
amp=start_t(k+1) ...
+ double(mod(bitand(code,0b01111111),16)) ...
* 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;
ucode=bitand(code,0b01111111);
k=bitshift(ucode,-4);
m=bitand(ucode,0b00001111);
amp=start_t(k+1)+double(m)*width_t(k+1)+width_t(k+1)/2;
if code<=128
amp=-amp;
else
amp=dV;
amp=amp;
end
end