第1页 / 共76页
第2页 / 共76页
第3页 / 共76页
第4页 / 共76页
第5页 / 共76页
第6页 / 共76页
第7页 / 共76页
第8页 / 共76页
通信系统仿真课后答案.pdf
第3章 采样和量化
3-1
答：
输入：syms t w
Xf=fourier(5*cos(6*pi*t)+3*sin(8*pi*t))
输出：Xf=pi*(5*dirac(w+6*pi)+3*i*dirac(w+8*pi)-3*i*dirac(w-8*pi)+5*dirac(w-6*pi))
matlab 程序： t=0:0.02:8;
L=length(t);
xt=5*cos(6*pi*t)+3*sin(8*pi*t);
f1=fft(xt);
fs=10;Ts=1/fs;
t1=8:-0.02:0;
f=1./t1;
Pt=zeros(1,L);
for i=1:8:L
Pt(i)=1;
end
Xst=xt.*Pt;
f2=fft(Xst);
f3=fs*f1;
f4=ifft(f3);
subplot(2,2,1)
plot(f,f1)
axis([0 10 -1000 3000])
xlabel('f');ylabel('x(f)');
subplot(2,2,2)
plot(f,f2)
axis([0 10 -200 400])
xlabel('f');ylabel('Xs(f)');
subplot(2,2,3)
plot(f,f3)
axis([0 10 -2000 4000])
xlabel('f');ylabel('Xr(f)');
subplot(2,2,4)
plot(t,f4)
xlabel('t');ylabel('Xr(t)');
axis([0 6 -50 50])
3-2
答：matlab 程序： t=0:0.02:8;
L=length(t);
xt=5*cos(6*pi*t)+3*sin(8*pi*t);
f1=fft(xt);
fs=7;Ts=1/fs;
t1=8:-0.02:0;
f=1./t1;
Pt=zeros(1,L);
for i=1:8:L
Pt(i)=1;
end
Xst=xt.*Pt;
f2=fft(Xst);
f3=fs*f1;
f4=ifft(f3);
subplot(2,2,1)
plot(f,f1)
axis([0 10 -1000 3000])
xlabel('f');ylabel('x(f)');
subplot(2,2,2)
plot(f,f2)
axis([0 10 -200 400])
xlabel('f');ylabel('Xs(f)');
subplot(2,2,3)
plot(f,f3)
axis([0 10 -2000 4000])
xlabel('f');ylabel('Xr(f)');
subplot(2,2,4)
plot(t,f4)
xlabel('t');ylabel('Xr(t)');
axis([0 6 -50 50])
0510-10000100020003000fx(f)0510-2000200400fXs(f)0510-2000020004000fXr(f)0246-50050tXr(t)
3.5
信号
，
（a）信号的动态范围为
。
（b）信号的波峰因素为
。其中，S 为信号的功率
，所以
。
（c）信噪比
，以 dB 为单位，
比特时，计算得
当
3.11
k = 50;
% samples per lobe
nsamp = 50000;
% total frequency samples
snrdb = zeros(1,17);
% initialize memory
x = 4:20;
% vector for plotting
for m = 4:20
signal = 0; noise = 0; % initialize sum values
f_fold = k*m/2;
% folding frequency
for j = 1:f_fold
term = (sin(pi*j/k/2)/(pi*j/k/2))^4;
signal = signal+term;
end
for j = (f_fold+1):nsamp
0510-10000100020003000fx(f)0510-2000200400fXs(f)0510-2000020004000fXr(f)0246-50050tXr(t)()5sin(10)xtt25.84,49.93,98.09,194.42 dBSNR2cSFD22512.522mAS2*12.50.707110cF22()32bqcSNRF10lg()10lg(3)20lg()20lg2qcSNRFb4,8,16,32b25.84,49.93,98.09,194.42 dBSNR
term = (sin(pi*j/k/2)/(pi*j/k/2))^4;
noise = noise+term;
end
snrdb(m-3) = 10*log10(signal/noise);
end
plot(x,snrdb)
% plot results
xlabel('Samples per symbol')
ylabel('Signal-to-aliasing noise ratio')
三角脉冲波形的信号混叠信噪比
矩形脉冲波形的信号混叠信噪比
3-11
答：matlab程序： k=50;
nsamp=50000;
snrdb=zeros(1,17);
snrdb_triangle=zeros(1,17);
x=4:20;
for m=4:20
signal=0;noise=0;signal_triangle=0;noise_triangle=0;
f_fold=k*m/2;
for j=1:f_fold
term=(sin(pi*j/k)/(pi*j/k))^2;
term_triangle=(sin(pi*j/(2*k))/(pi*j/(2*k)))^4;
signal=signal+term;
signal_triangle=signal_triangle+term_triangle;
end
for j=(f_fold+1):nsamp
term=(sin(pi*j/k)/(pi*j/k))^2;
term_triangle=(sin(pi*j/(2*k))/(pi*j/(2*k)))^4;
noise=noise+term;
noise_triangle= noise_triangle+term_triangle;
end
snrdb(m-3)=10*log10(signal/noise);
snrdb_triangle(m-3)=10*log10(signal_triangle/noise_triangle);
end
plot(x,snrdb,x,snrdb_triangle,'r:');
xlabel('Samples per symbol');
ylabel('signal-to-aliasing noise ratio');
可见成形脉冲为三角脉冲时，效果更好一些。
3.12
k = 50;
% samples per lobe
nsamp = 50000;
% total frequency samples
snrdb = zeros(1,17);
% initialize memory
x = 4:20;
% vector for plotting
for m = 4:20
signal = 0; noise = 0; % initialize sum values
f_fold = k*m/2;
% folding frequency
for j = 1:f_fold
term = (cos(2*pi*j/k))^2/(pi^2)/((1-(4*j/k)^2))^2;
signal = signal+term;
end
for j = (f_fold+1):nsamp
term = (cos(2*pi*j/k))^2/(pi^2)/((1-(4*j/k)^2))^2;
noise = noise+term;
end
snrdb(m-3) = 10*log10(signal/noise);
end
plot(x,snrdb)
% plot results
xlabel('Samples per symbol')
ylabel('Signal-to-aliasing noise ratio')
% End of script file.
4681012141618201020304050Samples per symbolsignal-to-aliasing noise ratio
MSK 混叠信噪比
3-12
答：matlab程序： k=50;
矩形脉冲波形的信号混叠信噪比
nsamp=50000;
snrdb=zeros(1,17);
snrdb_triangle=zeros(1,17);
x=4:20;
for m=4:20
signal=0;noise=0;signal_triangle=0;noise_triangle=0;
f_fold=k*m/2;
for j=1:f_fold
term=(sin(pi*j/k)/(pi*j/k))^2;
term_triangle=(cos(2*pi*j/k))^2/(pi^2*(1-(4*j/k)^2)^2);;
signal=signal+term;
signal_triangle=signal_triangle+term_triangle;
end
for j=(f_fold+1):nsamp
term=(sin(pi*j/k)/(pi*j/k))^2;
term_triangle=(cos(2*pi*j/k))^2/(pi^2*(1-(4*j/k)^2)^2);;
noise=noise+term;
noise_triangle= noise_triangle+term_triangle;
end
snrdb(m-3)=10*log10(signal/noise);
snrdb_triangle(m-3)=10*log10(signal_triangle/noise_triangle);
end
plot(x,snrdb,x,snrdb_triangle,'r:');
xlabel('Samples per symbol');
ylabel('signal-to-aliasing noise ratio');
3.13
k = 50;
% samples per lobe
nsamp = 50000;
% total frequency samples
snrdb = zeros(1,17);
% initialize memory
x = 4:20;
% vector for plotting
for m = 4:20
signal = 0; noise = 0; % initialize sum values
468101214161820102030405060Samples per symbolsignal-to-aliasing noise ratio
相关推荐
2023年江西萍乡中考道德与法治真题及答案.doc
2012年重庆南川中考生物真题及答案.doc
2013年江西师范大学地理学综合及文艺理论基础考研真题.doc
2020年四川甘孜小升初语文真题及答案I卷.doc
2020年注册岩土工程师专业基础考试真题及答案.doc
2023-2024学年福建省厦门市九年级上学期数学月考试题及答案.doc
2021-2022学年辽宁省沈阳市大东区九年级上学期语文期末试题及答案.doc
2022-2023学年北京东城区初三第一学期物理期末试卷及答案.doc
2018上半年江西教师资格初中地理学科知识与教学能力真题及答案.doc
2012年河北国家公务员申论考试真题及答案-省级.doc
2020-2021学年江苏省扬州市江都区邵樊片九年级上学期数学第一次质量检测试题及答案.doc
2022下半年黑龙江教师资格证中学综合素质真题及答案.doc
