ASK调制与解调

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1.二进制ASK调制信号产生

2.二进制ASK信号解调

2.1相干解调

2.2非相干解调

2.ASK调制信号的matlab仿真

Len=1000; %数据长度为1000 Rb=1*10^6; %码元速率 Fs=8*Rb; %采样频率 LenData=Len*Fs/Rb; %数据长度 Fc=70*10^6; %载波频率 Qn=8; %量化位数 a=0.8; %成形滤波器滚降因子 %产生载波信号 t=0:1/Fs:Len/Rb; carrier=cos(2*pi*Fc*t); carrier=carrier(1:LenData); %产生随机分布的二进制数据 code_2ask=randint(1,Len,2); %对基带数据以Fs速率采样 code_2ask_upsamp=rectpulse(code_2ask,Fs/Rb); %对基带数据进行成形滤波,同时进行Fs/Rb倍采样 code_2ask_filter=rcosflt(code_2ask,1,Fs/Rb); %产生未进行成形滤波的2ASK信号 ASK2=carrier.*code_2ask_upsamp; %产生成形滤波后的2ASK信号 ASK2_filter=carrier.*code_2ask_filter(1:LenData)'; %获取2ASK信号的频谱 ASK2_Spec=20*log10(abs(fft(ASK2,1024))); ASK2_Spec=ASK2_Spec-max(ASK2_Spec); ASK2_filter_Spec=20*log10(abs(fft(ASK2_filter,1024))); ASK2_filter_Spec=ASK2_filter_Spec-max(ASK2_filter_Spec); %产生随机分布的四进制数据 code_4ask=randint(1,Len,4); %对基带数据以Fs速率采样 code_4ask_upsamp=rectpulse(code_4ask,Fs/Rb); %对基带数据进行成形滤波,同时进行Fs/Rb倍采样 code_4ask_filter=rcosflt(code_4ask,1,Fs/Rb); %产生未进行成形滤波的4ASK信号 ASK4=carrier.*code_4ask_upsamp; %产生成形滤波后的4ASK信号 ASK4_filter=carrier.*code_4ask_filter(1:LenData)'; %获取4ASK信号的频谱 ASK4_Spec=20*log10(abs(fft(ASK4,1024))); ASK4_Spec=ASK4_Spec-max(ASK4_Spec); ASK4_filter_Spec=20*log10(abs(fft(ASK4_filter,1024))); ASK4_filter_Spec=ASK4_filter_Spec-max(ASK4_filter_Spec); %绘图 figure(1);x=0:200;x=x/Fs*(10^6); subplot(221);plot(x,ASK2(100:300));xlabel('时间(us)');ylabel('幅度(v)'); title('未经成形滤波的2ASK时域波形');grid on; subplot(222);plot((0:200),ASK2_filter(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('成形滤波后的2ASK时域波形');grid on; subplot(223);plot((0:200),ASK4(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('未经成形滤波的4ASK时域波形');grid on; subplot(224);plot((0:200),ASK4_filter(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('成形滤波后的4ASK时域波形');grid on; figure(2);x=0:length(ASK2_Spec)-1;x=x/length(x)*Fs/10^6; subplot(221);plot(x,ASK2_Spec);xlabel('频率(MHz)');ylabel('幅度(dB)'); title('未经成形滤波的2ASK频谱');grid on; subplot(222);plot(x,ASK2_filter_Spec);xlabel('频率(MHz)');ylabel('幅度(dB)'); title('成形滤波后的2ASK频谱');grid on; subplot(223);plot(x,ASK4_Spec);xlabel('频率(MHz)');ylabel('幅度(dB)'); title('未经成形滤波的4ASK频谱');grid on; subplot(224);plot(x,ASK4_filter_Spec);xlabel('频率(MHz)');ylabel('幅度(dB)'); title('成形滤波后的4ASK频谱');grid on; 

3.ASK信号解调的MATLAB仿真

Rb=1*10^6; %码元速率 Fs=8*Rb; %采样频率 a=0.8; %成形滤波器滚降因子 [ASK2,ASK2_filter,ASK4,ASK4_filter]=AskMod(); figure(4); subplot(211);plot(20*log10(abs(fft(ASK2)))); subplot(212);plot(20*log10(abs(fft(ASK2_filter)))); %整流 ASK2=abs(ASK2); ASK2_filter=abs(ASK2_filter); ASK4=abs(ASK4); ASK4_filter=abs(ASK4_filter); figure(5); subplot(211);plot(20*log10(abs(fft(ASK2)))); subplot(212);plot(20*log10(abs(fft(ASK2_filter)))); %低通滤波 b=fir1(32,Rb*2/Fs); d_ASK2=filter(b,1,ASK2); d_ASK2_filter=filter(b,1,ASK2_filter); d_ASK4=filter(b,1,ASK4); d_ASK4_filter=filter(b,1,ASK4_filter); %绘图 figure(1);x=0:200;x=x/Fs*(10^6); subplot(221);plot(x,ASK2(100:300));xlabel('时间(us)');ylabel('幅度(v)'); title('整流后的2ASK时域波形');grid on; subplot(222);plot((0:200),ASK2_filter(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('整流后的2ASK(成形滤波)时域波形');grid on; subplot(223);plot((0:200),ASK4(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('整流后的4ASK时域波形');grid on; subplot(224);plot((0:200),ASK4_filter(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('整流后的4ASK(成形滤波)时域波形');grid on; figure(2);x=0:200;x=x/Fs*(10^6); subplot(221);plot(x,d_ASK2(100:300));xlabel('时间(us)');ylabel('幅度(v)'); title('解调2ASK的基带时域波形');grid on; subplot(222);plot((0:200),d_ASK2_filter(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('解调2ASK(成形滤波)的基带时域波形');grid on; subplot(223);plot((0:200),d_ASK4(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('解调4ASK的基带时域波形');grid on; subplot(224);plot((0:200),d_ASK4_filter(100:300));;xlabel('时间(us)');ylabel('幅度(v)'); title('解调4ASK(成形滤波)的基带时域波形');grid on; figure(3); freqz(b);