多进制调制解调（2fsk,2psk,4ask,4fsk）

%4fsk调制解调 clc clear n=100; f1=500;f2=1000; f3=2000;f4=3000; t0=1; fm=n; band1=ones(1,200); band2=ones(1,length(band1)*2); band1_num=length(band1); t=linspace(0,t0,n*band1_num); a=round(rand(1,n)); b=two_to_four(a); aa=draw(a,band1);%二进制信号画图 bb=draw(b,band2);%四进制信号画图 %*************画图************* figure(1); subplot(211); plot(t,aa,'g'); axis([0,t0,-1,2]); title('原始二进制信号'); subplot(212); plot(t,bb,'r'); axis([0,t0,-1,4]); title('2/4电平变换后的信号'); %*************调制/画图************* e_4fsk=modulate_4fsk(b,f1,f2,f3,f4,t0,fm,band2); figure(2); subplot(221); plot(t,e_4fsk); title('4fsk时域波形') N=length(t); w=(0:N/2-1)/t0; e_4fsk_fft=fft(e_4fsk); subplot(212); plot(w,(2/N)*abs(e_4fsk_fft(1:N/2))); title('频域波形'); %*************带通滤波************* %4路带通滤波器，中心频率分别为f1,f2,f3,f4 %************中心频率f1的滤波器参数******* fs=n*band1_num; fpass1=f1-fm; fpass2=f1+fm; fs1=fpass1-2*fm; fs2=fpass2+2*fm; bandpass1=bandpass_1(fs,fs1,fpass1,fpass2,fs2); e_4fsk_f1_bpf=filtfilt(bandpass1,1,e_4fsk); %************中心频率f2的滤波器参数******* fs=n*band1_num; fpass1=f2-fm; fpass2=f2+fm; fs1=fpass1-2*fm; fs2=fpass2+2*fm; bandpass2=bandpass_1(fs,fs1,fpass1,fpass2,fs2); e_4fsk_f2_bpf=filtfilt(bandpass2,1,e_4fsk); %************中心频率f3的滤波器参数******* %fs=n*band1_num; fpass1=f3-fm; fpass2=f3+fm; fs1=fpass1-2*fm; fs2=fpass2+2*fm; bandpass3=bandpass_1(fs,fs1,fpass1,fpass2,fs2); e_4fsk_f3_bpf=filtfilt(bandpass3,1,e_4fsk); %************中心频率f4的滤波器参数******* %fs=n*band1_num; fpass1=f4-fm; fpass2=f4+fm; fs1=fpass1-2*fm; fs2=fpass2+2*fm; bandpass4=bandpass_1(fs,fs1,fpass1,fpass2,fs2); e_4fsk_f4_bpf=filtfilt(bandpass4,1,e_4fsk); %*************时域和频域画图************* figure(3); subplot(421); plot(t,e_4fsk_f1_bpf); title('中心频率f1的时域图'); subplot(422); e_4fsk_f1_filt_fft=fft(e_4fsk_f1_bpf); plot(w,(2/N)*abs(e_4fsk_f1_filt_fft(1:N/2))); title('左图频谱'); subplot(423); plot(t,e_4fsk_f2_bpf); title('中心频率f2的时域图'); subplot(424); e_4fsk_f2_filt_fft=fft(e_4fsk_f2_bpf); plot(w,(2/N)*abs(e_4fsk_f2_filt_fft(1:N/2))); title('左图频谱'); subplot(425); plot(t,e_4fsk_f3_bpf); title('中心频率f3的时域图'); subplot(426); e_4fsk_f3_filt_fft=fft(e_4fsk_f3_bpf); plot(w,(2/N)*abs(e_4fsk_f3_filt_fft(1:N/2))); title('左图频谱'); subplot(427); plot(t,e_4fsk_f4_bpf); title('中心频率f4的时域图'); subplot(428); e_4fsk_f4_filt_fft=fft(e_4fsk_f4_bpf); plot(w,(2/N)*abs(e_4fsk_f4_filt_fft(1:N/2))); title('左图频谱'); %*****************相干解调****************** e_4fsk_f1_bpf_demo=e_4fsk_f1_bpf.*cos(2*pi*f1*t); e_4fsk_f2_bpf_demo=e_4fsk_f2_bpf.*cos(2*pi*f2*t); e_4fsk_f3_bpf_demo=e_4fsk_f3_bpf.*cos(2*pi*f3*t); e_4fsk_f4_bpf_demo=e_4fsk_f4_bpf.*cos(2*pi*f4*t); lpf=LBF1(fs,fm,5*fm); e_4fsk_f1_bpf_demo_lpf=filtfilt(lpf,1,e_4fsk_f1_bpf_demo); e_4fsk_f2_bpf_demo_lpf=filtfilt(lpf,1,e_4fsk_f2_bpf_demo); e_4fsk_f3_bpf_demo_lpf=filtfilt(lpf,1,e_4fsk_f3_bpf_demo); e_4fsk_f4_bpf_demo_lpf=filtfilt(lpf,1,e_4fsk_f4_bpf_demo); %***********低通滤波后的时域图************* figure(4) subplot(411); plot(t,e_4fsk_f1_bpf_demo_lpf); title('中心频率f1的低通时域波形'); subplot(412); plot(t,e_4fsk_f2_bpf_demo_lpf); title('中心频率f2的低通时域波形'); subplot(413); plot(t,e_4fsk_f3_bpf_demo_lpf); title('中心频率f3的低通时域波形'); subplot(414); plot(t,e_4fsk_f4_bpf_demo_lpf); title('中心频率f4的低通时域波形'); %%***************判决**************** d=zeros(1,length(b));%存储解调信号 N=length(b); e_4fsk_f1_bpf_demo_lpf=reshape(e_4fsk_f1_bpf_demo_lpf,length(band2),length(b)); e_4fsk_f2_bpf_demo_lpf=reshape(e_4fsk_f2_bpf_demo_lpf,length(band2),length(b)); e_4fsk_f3_bpf_demo_lpf=reshape(e_4fsk_f3_bpf_demo_lpf,length(band2),length(b)); e_4fsk_f4_bpf_demo_lpf=reshape(e_4fsk_f4_bpf_demo_lpf,length(band2),length(b)); for i=1:N if (e_4fsk_f1_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f2_bpf_demo_lpf(length(band2)/2,i))&&... (e_4fsk_f1_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f3_bpf_demo_lpf(length(band2)/2,i))&&... (e_4fsk_f1_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f4_bpf_demo_lpf(length(band2)/2,i)) d(i)=0; elseif (e_4fsk_f2_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f1_bpf_demo_lpf(length(band2)/2,i))&&... (e_4fsk_f2_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f3_bpf_demo_lpf(length(band2)/2,i))&&... (e_4fsk_f2_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f4_bpf_demo_lpf(length(band2)/2,i)) d(i)=1; elseif (e_4fsk_f3_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f1_bpf_demo_lpf(length(band2)/2,i))&&... (e_4fsk_f3_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f2_bpf_demo_lpf(length(band2)/2,i))&&... (e_4fsk_f3_bpf_demo_lpf(length(band2)/2,i)>e_4fsk_f4_bpf_demo_lpf(length(band2)/2,i)) d(i)=2; else d(i)=3; end end %*******************对比******************* a_demo=fout_to_two(d); dd=draw(d,band2); aa_demo=draw(a_demo,band1); figure(5); subplot(211); plot(t,aa_demo); axis([0,t0,-1,2]); title('解调后的二进制电平'); subplot(212); plot(t,dd); title('解调后的4进制电平'); axis([0,t0,-1,4]); %}