www.pudn.com > pcm_chianelxie.rar > pcm_a.m

echo off 
clear,clc 
 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
% SNR_Max = 12; 
Fc = 10000;  
Fs1 = 15000; 
Fs = Fs1; 
t = (0:1/Fs:5/Fc-1/Fs);   % column vector with all the time samples 
y = cos(2*pi*Fc*t)+rand(1,length(t)); 
Y=abs(fftshift(fft(y))); 
N=length(t); 
f=(0:N-1)/N*Fs-Fs/2; 
subplot(212);plot(f,Y/N) 
title('原始信号频谱') 
subplot(211);plot(t,y) 
title('原始信号(采样率Fs<2Fm)') 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
% SNR_Max = 12; 
clear,clc 
Fc = 10000;  
Fs2 = 100000; 
Fs = Fs2; 
t = (0:1/Fs:5/Fc-1/Fs);   % column vector with all the time samples 
y = cos(2*pi*Fc*t)+rand(1,length(t)); 
Y=abs(fftshift(fft(y))); 
N=length(t); 
f=(0:N-1)/N*Fs-Fs/2; 
figure 
subplot(212);plot(f,Y/N) 
title('原始信号频谱') 
subplot(211);plot(t,y) 
title('原始信号(采样率Fs>2Fm)') 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
in = y; 
Note=[32 64 128]; 
for i1=1:length(Note) 
%     %%%%%%%%%%%%%%%%%%%%分析信噪比对量化误差的影响%%%%% 
%     if i1==3 
%         snr_dB=0:2:12; 
%         for i2=1:length(snr_dB); 
%             snr = 10^(snr_dB(i1)/10);   %SNR 
%             in=in+sqrt(1/snr)*rand(1,N); 
%             out1=compand(in, 87.6, 1, 'A/compressor'); %A律压缩 
%             [out_,code]=u_pcm(out1, Note(i1));  %线性编码 
%             out21=compand(out_, 87.6, 1, 'A/expander'); %A律解压 
%             err(i2)=sum(abs(in-out21)); 
%         end 
%         clear snr in out1 out_ code out21; 
%         in=y; 
%         figure 
%         plot(snr_dB,err); 
%         xlabel('信噪比（dB）') 
%         ylabel('量化误差和') 
%         title('分析信噪比对量化误差的影响') 
%     end 
%     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
    out1=compand(in, 87.6, 1, 'A/compressor'); %A律压缩 
    [out_,code]=u_pcm(out1, Note(i1));  %线性编码 
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
    %u_pcm 一个序列的均匀PCM编码 
    %[a_quan,code]=u_pcm(a,n) 
    %a=输入序列 
    %n=量化级数的数目（偶数） 
    %a_quan=编码前的量化输出 
    %code=编码后的输出 
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
    out2(i1,:)=compand(out_, 87.6, 1, 'A/expander'); %A律解压 
end 
figure 
plot(t,out2(1,:),'-o',t,out2(2,:),'-d',t,out2(3,:),'-*',t,in,'r') 
legend('量化级数32','量化级数64','量化级数128','原始信号') 
xlabel('时间') 
ylabel('幅度') 
title('量化级数对信号恢复的影响分析'); 
figure 
plot([1:N], in-out2(3,:),'-r+');  %量化误差,out_为编码前的量化输出 
title('量化误差');xlabel('n');ylabel('dV'); 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
h0 = figure('Units','points', ... 
	'Color',[0.8 0.8 0.8], ... 
	'Colormap','default', ... 
	'FileName','start.m', ... 
	'MenuBar','none', ... 
	'Name','量化输出码组 ', ... 
	'NumberTitle','off', ... 
	'PaperPosition',[18 180 476 432], ... 
	'PaperUnits','points', ... 
	'Position',[230 150 275.25 250.5], ... 
	'Resize','on', ... 
	'Tag','UIFigure', ... 
	'ToolBar','none'); 
h1 = uicontrol('Parent',h0, ... 
	'Units','points', ... 
	'BackgroundColor',[1 1 1], ... 
	'HorizontalAlignment','left', ... 
	'ListboxTop',1.0, ... 
	'Position',[10.75 17.5 193.75 223.75], ... 
	'String','', ... 
	'Style','listbox', ... 
	'Tag','NumofSim'); 
h1 = uicontrol('Parent',h0, ... 
	'Units','points', ... 
	'BackgroundColor',[1 1 1], ... 
	'HorizontalAlignment','left', ... 
	'ListboxTop',1.0, ... 
	'Position',[210.75 17.5 93.75 23.75], ... 
	'String','', ... 
	'Style','Text', ... 
	'Tag','Rank'); 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
set(findobj('Tag','NumofSim'),'string',num2str(code)) 
set(findobj('Tag','Rank'),'string','量化级数为128') 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%