第六章实验2

实验名称例题6-3
实验目的学会求解微分方程实验设备MATLAB7.0
实验代码及结果w2b=0; w2c=0; % initialize integrators
yd=0; y=0; % initialize differential equation
tfinal = 50; % simulation time
fs = 100; % sampling frequency
delt = 1/fs; % sampling period
npts = 1+fs*tfinal; % number of samples simulated
ydv = zeros(1,npts); % vector of dy/dt samples
yv = zeros(1,npts); % vector of y(t) samples
%
% beginning of simulation loop
%
for i=1:npts
t = (i-1)*delt; % time
if t<20
ydd = 4*exp(-t/2)-3*yd*abs(y)-9*y; % de for t<20 else
ydd = 4*exp(-t/2)-3*yd-9*y; % de for t>=20 end
w1b=ydd+w2b; % first integrator - step 1 w2b=ydd+w1b; % first integrator - step 2 yd=w1b/(2*fs); % first integrator output
w1c=yd+w2c; % second integrator - step 1 w2c=yd+w1c; % second integrator - step 2 y=w1c/(2*fs); % second integrator output ydv(1,i) = yd; % build dy/dt vector
yv(1,i) = y; % build y(t) vector
end
%
% end of simulation loop
%
plot(yv,ydv) % plot phase plane xlabel('y(t)') % label x axis ylabel('dy/dt') % label y zxis
% End of script file.
仿真结果
-0.2
-0.1
0.1
0.20.3
0.4
0.5
0.6
-0.8-0.6-0.4-0.200.20.4
0.60.811.2y(t)
d y /d t
实验名称 例题7-1
实验目的 了解随机过程样本函数的参数
实验设备
MATLAB7.0
实验代码及结果f = 1; % frequency of sinusoid fs = 100; % sampling frequency t = (0:200)/fs; % time vector
for i=1:20
x(:,i) = cos(2*pi*f*t+rand(1)*2*pi)';
y(:,i) = cos(2*pi*f*t+rand(1)*pi/2)';
z(:,i) = (1+rand(1))*cos(2*pi*f*t)';
end
subplot(3,1,1); plot(t,x,'b'); ylabel('x(t)')
subplot(3,1,2); plot(t,y,'b'); ylabel('y(t)')
subplot(3,1,3); plot(t,z,'b'); ylabel('z(t)')
实验结果
00.20.40.60.81 1.2 1.4 1.6 1.82
-1
1
x
(
t
)
00.20.40.60.81 1.2 1.4 1.6 1.82
-1
1
y
(
t
)
00.20.40.60.81 1.2 1.4 1.6 1.82
-2
2
z
(
t
)
实验名称例题7-2
实验目的了解随机过程样本函数的参数实验设备MATLAB7.0
实验代码及结果function [x, bits] = random_binary(nbits,nsamples)
% This function genrates a random binary waveform of length nbits
% sampled at a rate of nsamples/bit.
x = zeros(1,nbits*nsamples);
bits = round(rand(1,nbits));
for m=1:nbits
for n=1:nsamples
index = (m-1)*nsamples + n;
x(1,index) = (-1)^bits(m);
end
end
nbits = 10; nsamples = 8;
x = random_binary(nbits,nsamples)+i*random_binary(nbits,nsamples); xd = real(x); xq = imag(x);
subplot(2,1,1)
stem(xd,'.'); grid; axis([0 80 -1.5 1.5]);
xlabel('Sample Index'); ylabel('xd')
subplot(2,1,2)
stem(xq,'.'); grid; axis([0 80 -1.5 1.5]);
xlabel('Sample Index'); ylabel('xq')
实验结果
01020304050607080
-1
1
Sample Index
x
d
01020304050607080 -1.5
-1
-0.5
0.5
1
1.5
Sample Index
x
q
作业：习题7-1。