sincy5.asv

个人硕士论文的关于数字接收机调制解调方面的matlab程序

%对sin信号进行抽样得到的结论5

clc
clear
fc=1;%sin信号的基准频率
a=-4;%信号的起始时间
b=4;%信号的终止时间
ts=1/(32*fc);%为使信号能较平滑的画出，设置的采样时间间隔
fs=1/ts;%由上面的采样时间间隔得到的采样频率
t=a:ts:b;
f=-fs/2+fs/length(t):fs/length(t):fs/2;
%----
f_s=fc*8;%采样频率是sin,即每个sin周期取样8个点
t_s=1/f_s;%由上面的采样频率得到的采样时间间隔
z=sin(2*pi*fc*t);
z_spect=fftshift(abs(fft(z)));

t_c1=a:t_s:b;%采样时刻，其长度是
x1=sin(2*pi*fc*t_c1);%得到的采样值
y1=0;
for i=1:length(x1)
    y1=y1+x1(i)*sinc((t1-t_c1(i))/t_s1);
end
y1_spect=fftshift(abs(fft(y1)));
%----
t_c2=a:t_s:b-4*t_s;
x2=sin(2*pi*fc*t_c2);
y2=0;
for i=1:length(x2)
    y2=y2+x2(i)*sinc((t-t_c2(i))/t_s);
end
y2_spect=fftshift(abs(fft(y2)));

figure(1)
subplot(2,2,1)
plot(t,z,t_c1,x1,'*black');title('(a)原始信号,黑点为抽样点');grid
subplot(2,2,2)
plot(f1,z1_spect);title('(b)原始信号的频谱');grid
subplot(2,2,3)
plot(t1,y1);title('(c)用抽样点重建的信号');grid
subplot(2,2,4)
plot(f1,y1_spect);title('(d)重建信号的频谱');grid

figure(2)
subplot(2,2,1)
plot(t,z,t_c2,x2,'*black');title('(a)原始信号,黑点为抽样点');grid
subplot(2,2,2)
plot(f2,z2_spect);title('(b)原始信号的频谱');grid
subplot(2,2,3)
plot(t2,y2);title('(c)用抽样点重建的信号');grid
subplot(2,2,4)
plot(f2,y2_spect);title('(d)重建信号的频谱');grid