【正文】 39。)grid onsubplot(3,2,6)plot(f(1:N/2),abs(VP(1:N/2)))。title(39。頻域調(diào)相信號(hào)39。)xlabel(39。Hz39。)grid on②方波：T=。%采樣間隔fs=1/T。%采樣頻率N=256。%采樣點(diǎn)數(shù)n=0:N1。t=n*T。vx=square(2*pi*10*t,50)。%調(diào)制信號(hào)int_vx(1)=0。for i=1:(length(t)1) int_vx(i+1)=int_vx(i)+vx(i)*T。endvc=cos(2*pi*100*t)。%載波信號(hào)kf=2000。%調(diào)頻比例常數(shù)vf=cos(2*pi*100*t+kf*int_vx)。%調(diào)頻信號(hào)VX=fft(vx,N)。VC=fft(vc,N)。VF=fft(vf,N)。f=n*fs/N。figure(1)subplot(3,2,1)plot(vx)。title(39。時(shí)域調(diào)制信號(hào)39。)axis([0,300,])grid onsubplot(3,2,2)plot(f(1:N/2),abs(VX(1:N/2)))。title(39。頻域調(diào)制信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(3,2,3)plot(vc)。title(39。時(shí)域載波信號(hào)39。)grid onsubplot(3,2,4)plot(f(1:N/2),abs(VC(1:N/2)))。title(39。頻域載波信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(3,2,5)plot(vf)。title(39。時(shí)域調(diào)頻信號(hào)39。)grid onsubplot(3,2,6)plot(f(1:N/2),abs(VF(1:N/2)))。title(39。頻域調(diào)頻信號(hào)39。)xlabel(39。Hz39。)grid onkp=100。%調(diào)相比例常數(shù)vp=cos(2*pi*100*t+kp*vx)。%調(diào)相信號(hào)VP=fft(vp,N)。figure(2)subplot(3,2,1)plot(vx)。title(39。時(shí)域調(diào)制信號(hào)39。)axis([0,300,])grid onsubplot(3,2,2)plot(f(1:N/2),abs(VX(1:N/2)))。title(39。頻域調(diào)制信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(3,2,3)plot(vc)。title(39。時(shí)域載波信號(hào)39。)grid onsubplot(3,2,4)plot(f(1:N/2),abs(VC(1:N/2)))。title(39。頻域載波信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(3,2,5)plot(vp)。title(39。時(shí)域調(diào)相信號(hào)39。)grid onsubplot(3,2,6)plot(f(1:N/2),abs(VP(1:N/2)))。title(39。頻域調(diào)相信號(hào)39。)xlabel(39。Hz39。)grid on⑶運(yùn)行結(jié)果：①正弦波:②方波：⒉FM和PM的解調(diào)⑴程序流程圖：確定系統(tǒng)參數(shù)構(gòu)建調(diào)制信號(hào)、載波信號(hào)和調(diào)角信號(hào)鑒頻OR鑒相將調(diào)頻信號(hào)延時(shí)，得調(diào)頻調(diào)相信號(hào)鑒頻鑒相給調(diào)角信號(hào)加上固定相移載波信號(hào)通過(guò)相乘器得到解調(diào)信號(hào)⑵編程仿真程序代碼參數(shù)設(shè)置如下：調(diào)制信號(hào)頻率：10Hz；調(diào)制信號(hào)幅度：1V；載波信號(hào)頻率：100Hz；載波信號(hào)幅度：1V；調(diào)頻比例常數(shù)kf：pi/2；調(diào)相比例常數(shù)kp：pi/20；采樣頻率fs：500Hz；低通濾波器參數(shù)：正弦波：fir1(80,)，方波：fir1(80,)。①正弦波：T=。%采樣間隔fs=1/T。%采樣頻率N=256。%采樣點(diǎn)數(shù)n=0:N1。t=n*T。kf=pi/2。%調(diào)頻比例常數(shù)kp=pi/20。%調(diào)相比例常數(shù)vx=cos(2*pi*10*t)。%調(diào)制信號(hào)int_vx =sin(20*pi*t)/(20*pi)。%對(duì)調(diào)制信號(hào)積分vc=cos(2*pi*100*t)。%載波信號(hào)vf=cos(2*pi*100*()+2*pi*kf*(sin(20*pi*())/(20*pi)))。%對(duì)調(diào)頻FM信號(hào)延時(shí),*pi的恒定相移vf1=cos(2*pi*100*()+2*pi*kf*(sin(20*pi*())/(20*pi))pi/10)。%對(duì)調(diào)頻FM信號(hào)延時(shí)后，再加上pi/10的固定相移vp1=cos(2*pi*100*t+kp*vxpi/2)。%給調(diào)相信號(hào)加上pi/2的固定相移vip=vc.*vp1。%通過(guò)相乘器vif=vc.*vf1。%通過(guò)相乘器b=fir1(80,)。vof=filter(b,1,vif)。vop=filter(b,1,vip)。VOF=fft(vof,N)。VOP=fft(vop,N)。f=n*fs/N。figure(1)subplot(2,2,1)plot(vx)。title(39。時(shí)域調(diào)制信號(hào)39。)grid onVX=fft(vx,N)。subplot(2,2,2)plot(f(1:N/2),abs(VX(1:N/2)))。title(39。頻域調(diào)制信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(2,2,3)plot(vof)。title(39。時(shí)域解調(diào)FM信號(hào)39。)grid onsubplot(2,2,4)plot(f(1:N/2),abs(VOF(1:N/2)))。title(39。頻域調(diào)制FM信號(hào)39。)xlabel(39。Hz39。)grid onfigure(2)subplot(2,2,1)plot(vx)。title(39。時(shí)域調(diào)制信號(hào)39。)grid onVX=fft(vx,N)。subplot(2,2,2)plot(f(1:N/2),abs(VX(1:N/2)))。title(39。頻域調(diào)制信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(2,2,3)plot(vop)。title(39。時(shí)域解調(diào)PM信號(hào)39。)grid onsubplot(2,2,4)plot(f(1:N/2),abs(VOP(1:N/2)))。title(39。頻域調(diào)制PM信號(hào)39。)xlabel(39。Hz39。)grid on②方波：T=。%采樣間隔fs=1/T。%采樣頻率N=256。%采樣點(diǎn)數(shù)n=0:N1。t=n*T。kf=pi/2。%調(diào)頻比例常數(shù)kp=pi/20。%調(diào)相比例常數(shù)vx=square(2*pi*10*t,50)。%調(diào)制信號(hào)int_vx=25*sawtooth(2*pi*t*10,)。%調(diào)制信號(hào)vc=cos(2*pi*100*t)。%載波信號(hào)vf=cos(2*pi*100*()+2*pi*kf*25*sawtooth(2*pi*()*10,))。%對(duì)調(diào)頻FM信號(hào)延時(shí),*pi的恒定相移vf1=cos(2*pi*100*()+2*pi*kf*25*sawtooth(2*pi*()*10,)pi/10)。%對(duì)調(diào)頻FM信號(hào)延時(shí)后，再加上pi/10的固定相移vp1=cos(2*pi*100*t+kp*vxpi/2)。%給調(diào)相信號(hào)加上pi/2的固定相移vip=vc.*vp1。%通過(guò)相乘器vif=vc.*vf1。%通過(guò)相乘器b=fir1(80,)。b1=fir1(80,)。vof=filter(b1,1,vip)。vop=filter(b,1,vip)。VOF=fft(vof,N)。VOP=fft(vop,N)。f=n*fs/N。figure(1)subplot(2,2,1)plot(vx)。title(39。時(shí)域調(diào)制信號(hào)39。)axis([0,300,])grid onVX=fft(vx,N)。subplot(2,2,2)plot(f(1:N/2),abs(VX(1:N/2)))。title(39。頻域調(diào)制信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(2,2,3)plot(vof)。title(39。時(shí)域解調(diào)FM信號(hào)39。)grid onsubplot(2,2,4)plot(f(1:N/2),abs(VOF(1:N/2)))。title(39。頻域調(diào)制FM信號(hào)39。)grid onfigure(2)subplot(2,2,1)plot(vx)。title(39。時(shí)域調(diào)制信號(hào)39。)axis([0,300,])grid onVX=fft(vx,N)。subplot(2,2,2)plot(f(1:N/2),abs(VX(1:N/2)))。title(39。頻域調(diào)制信號(hào)39。)xlabel(39。Hz39。)grid onsubplot(2,2,3)plot(vop)。title(39。時(shí)域解調(diào)PM信號(hào)39。)axis([0,300,])grid onsubplot(2,2,4)plot(f(1:N/2),abs(VOP(1:N/2)))。title(39。頻域調(diào)制PM信號(hào)39。)grid on⑶運(yùn)行結(jié)果：①正弦波：②方波：⒊結(jié)果分析：