feat(matlab): comm lab 5 half
This commit is contained in:
iridiumR
parent
ca2410d4ec
commit
5fd8752550
|
|
@ -0,0 +1,72 @@
|
|||
clc
|
||||
%================================================
|
||||
%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
|
||||
%================================================
|
||||
%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
|
||||
|
||||
|
||||
function pcmcode = pcmEnCode(s)
|
||||
start_t=[0,2.^(4:11)];
|
||||
width_t=[1,1,2,4,8,16,32,64];
|
||||
pcm=0;
|
||||
if s>0
|
||||
pcm=pcm+bitshift(1,7);
|
||||
else
|
||||
s=abs(s)
|
||||
end
|
||||
for i = 0:7
|
||||
if s < start_t(i+2)
|
||||
pcm=pcm+bitshift(i,4);
|
||||
pcm=pcm+floor((s-start_t(i+1))/width_t(i+1));
|
||||
break
|
||||
end
|
||||
end
|
||||
pcmcode=dec2bin(pcm,8);
|
||||
end
|
||||
|
||||
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;
|
||||
else
|
||||
amp=dV;
|
||||
end
|
||||
end
|
||||
Reference in New Issue