記錄一個完整ASK調(diào)制過程的matlab代碼。

%E5_1_AskMod.m

function [ASK2,ASK2_filter,ASK4,ASK4_filter]=E5_1_AskMod(Len,IsPlot,IsOutput)

%產(chǎn)生2ASK、4ASK調(diào)制信號

%Len：碼元長度，默認(rèn)值為1000

%IsPlot：是否繪圖，'1’表示繪圖，否則不繪圖

%IsOutput：是否將ASK調(diào)制數(shù)據(jù)輸出到文本文件中，'1’表示輸出，否則不輸出

%設(shè)置函數(shù)的默認(rèn)參數(shù)值

if nargin < 1

Len=1000; %數(shù)據(jù)長度為1000

IsPlot=0; %不繪圖

IsOutput=0; %不將數(shù)據(jù)寫入文本文件中

end;

Rb=110^6; %碼元速率

Fs=8Rb; %采樣頻率

LenData=LenFs/Rb; %數(shù)據(jù)長度

Fc=7010^6; %載波頻率

Qn=8; %量化位數(shù)

a=0.8; %成形濾波器滾降因子

%產(chǎn)生載波信號

t=0:1/Fs:Len/Rb;

carrier=cos(2piFc*t);

carrier=carrier(1:LenData);

%產(chǎn)生隨機分布的二進制數(shù)據(jù)

%code_2ask=randint(1,Len,2);

code_2ask=(randi(2,Len,1)-1)’;

%對基帶數(shù)據(jù)以Fs速率采樣

code_2ask_upsamp=rectpulse(code_2ask,Fs/Rb);

%對基帶數(shù)據(jù)進行成形濾波,同時進行Fs/Rb倍采樣

code_2ask_filter=rcosflt(code_2ask,1,Fs/Rb);

%產(chǎn)生未進行成形濾波的2ASK信號

ASK2=carrier.*code_2ask_upsamp;

%產(chǎn)生成形濾波后的2ASK信號

ASK2_filter=carrier.*code_2ask_filter(1:LenData)’;

%獲取2ASK信號的頻譜

ASK2_Spec=20log10(abs(fft(ASK2,1024)));

ASK2_Spec=ASK2_Spec-max(ASK2_Spec);

ASK2_filter_Spec=20log10(abs(fft(ASK2_filter,1024)));

ASK2_filter_Spec=ASK2_filter_Spec-max(ASK2_filter_Spec);

%產(chǎn)生隨機分布的四進制數(shù)據(jù)

%code_4ask=randint(1,Len,4);

code_4ask=(randi(4,Len,1)-1)’;

%對基帶數(shù)據(jù)以Fs速率采樣

code_4ask_upsamp=rectpulse(code_4ask,Fs/Rb);

%對基帶數(shù)據(jù)進行成形濾波,同時進行Fs/Rb倍采樣

code_4ask_filter=rcosflt(code_4ask,1,Fs/Rb);

%產(chǎn)生未進行成形濾波的4ASK信號

ASK4=carrier.*code_4ask_upsamp;

%產(chǎn)生成形濾波后的4ASK信號

ASK4_filter=carrier.*code_4ask_filter(1:LenData)’;

%獲取4ASK信號的頻譜

ASK4_Spec=20log10(abs(fft(ASK4,1024)));

ASK4_Spec=ASK4_Spec-max(ASK4_Spec);

ASK4_filter_Spec=20log10(abs(fft(ASK4_filter,1024)));

ASK4_filter_Spec=ASK4_filter_Spec-max(ASK4_filter_Spec);

%繪圖

if IsPlot==1

figure(1);x=0:200;x=x/Fs*(10^6);

subplot(221);plot(x,ASK2(100:300));xlabel(‘時間(us)’);ylabel(‘幅度(v)’);

title(‘未經(jīng)成形濾波的2ASK時域波形’);grid on;

subplot(222);plot((0:200),ASK2_filter(100:300));;xlabel(‘時間(us)’);ylabel(‘幅度(v)’);

title(‘成形濾波后的2ASK時域波形’);grid on;

subplot(223);plot((0:200),ASK4(100:300));;xlabel(‘時間(us)’);ylabel(‘幅度(v)’);

title(‘未經(jīng)成形濾波的4ASK時域波形’);grid on;

subplot(224);plot((0:200),ASK4_filter(100:300));;xlabel(‘時間(us)’);ylabel(‘幅度(v)’);

title(‘成形濾波后的4ASK時域波形’);grid on;

figure(2);x=0:length(ASK2_Spec)-1;x=x/length(x)*Fs/10^6;

subplot(221);plot(x,ASK2_Spec);xlabel('頻率(MHz)');ylabel('幅度(dB)');

title('未經(jīng)成形濾波的2ASK頻譜');grid on;

subplot(222);plot(x,ASK2_filter_Spec);xlabel('頻率(MHz)');ylabel('幅度(dB)');

title('成形濾波后的2ASK頻譜');grid on;

subplot(223);plot(x,ASK4_Spec);xlabel('頻率(MHz)');ylabel('幅度(dB)');

title('未經(jīng)成形濾波的4ASK頻譜');grid on;

subplot(224);plot(x,ASK4_filter_Spec);xlabel('頻率(MHz)');ylabel('幅度(dB)');

title('成形濾波后的4ASK頻譜');grid on;

end;

%量化數(shù)據(jù)并寫入文本文件中

if IsOutput1

norm_Data=ASK2/max(abs(ASK2));%歸一化處理

Q_s=round(norm_Data*(2^(Qn-1)-1));

fid=fopen(‘D:\ModemPrograms\Chapter_5\E5_1_ASKMod\ASK2.txt’,‘w’);

for i=1:length(Q_s)

B_s=dec2bin(Q_s(i)+(Q_s(i)<0)*2^Qn,Qn);

for j=1:Qn

if B_s(j)‘1’

tb=1;

else

tb=0;

end

fprintf(fid,’%d’,tb);

end

fprintf(fid,’\r\n’);

end

fprintf(fid,’;’);

fclose(fid);

norm_Data=ASK2_filter/max(abs(ASK2_filter));%歸一化處理

Q_s=round(norm_Data*(2^(Qn-1)-1));

fid=fopen('D:\ModemPrograms\Chapter_5\E5_1_ASKMod\ASK2_filter.txt','w');

for i=1:length(Q_s)

B_s=dec2bin(Q_s(i)+(Q_s(i)<0)*2^Qn,Qn);

for j=1:Qn

if B_s(j)=='1'

tb=1;

else

tb=0;

end

fprintf(fid,'%d',tb);

end

fprintf(fid,'\r\n');

end

fprintf(fid,';');

fclose(fid);

norm_Data=ASK4/max(abs(ASK4));%歸一化處理

Q_s=round(norm_Data*(2^(Qn-1)-1));

fid=fopen('D:\ModemPrograms\Chapter_5\E5_1_ASKMod\ASK4.txt','w');

for i=1:length(Q_s)

B_s=dec2bin(Q_s(i)+(Q_s(i)<0)*2^Qn,Qn);

for j=1:Qn

if B_s(j)=='1'

tb=1;

else

tb=0;

end

fprintf(fid,'%d',tb);

end

fprintf(fid,'\r\n');

end

fprintf(fid,';');

fclose(fid);

norm_Data=ASK4_filter/max(abs(ASK4_filter));%歸一化處理

Q_s=round(norm_Data*(2^(Qn-1)-1));

fid=fopen('D:\ModemPrograms\Chapter_5\E5_1_ASKMod\ASK4_filter.txt','w');

for i=1:length(Q_s)

B_s=dec2bin(Q_s(i)+(Q_s(i)<0)*2^Qn,Qn);

for j=1:Qn

if B_s(j)=='1'

tb=1;

else

tb=0;

end

fprintf(fid,'%d',tb);

end

fprintf(fid,'\r\n');

end

fprintf(fid,';');

fclose(fid);

end;

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