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EX:1
High pass filter
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الكود البرمجي :
% Highpass FIR Filters
%
% *Equiripple Design*
Fstop = 350;
Fpass = 400;
Astop = 65;
Apass = 0.5;
Fs = 1e3;
d = designfilt('highpassfir','StopbandFrequency',Fstop, ...
'PassbandFrequency',Fpass,'StopbandAttenuation',Astop, ...
'PassbandRipple',Apass,'SampleRate',Fs,'DesignMethod','equiripple');
fvtool(d)
EX:2
low pass filter
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الكود البرمجي :
%% Lowpass FIR Filters
%
% *Equiripple Design*
Fpass = 100;
Fstop = 150;
Apass = 1;
Astop = 65;
Fs = 1e3;
d = designfilt('lowpassfir', ...
'PassbandFrequency',Fpass,'StopbandFrequency',Fstop, ...
'PassbandRipple',Apass,'StopbandAttenuation',Astop, ...
'DesignMethod','equiripple','SampleRate',Fs);
fvtool(d)
EX:3
simulate Pulse Position Modulation (PPM) as per message signal amplitude
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الكود البرمجي:
% This file simulate Pulse Position Modulation (PPM) as per message signal amplitude
%
% Created By: JCBRO Labs
% Date: 03/06/2017
% website: www.jcbrolabs.org
% mail: jcbrolabs@gmail.com
clc; clear all; close all;
fc = 20; %carrier frequency
fm = 2; % message frequency
fs = 1000; % sampling frequency
t = 1;
n = [0:1/fs:t];
n = n(1:end - 1);
duty = 10;
% no. of samples in one square wave period
per = fs/fc;
% no. of samples in on time
on_t = per/duty;
s = square(2*pi*fc*n,duty);
s(find(s<0)) = 0;
% message signal
m = sin(2*pi*fm*n);
% Triangular wave
A=1.25;
c=A.*sawtooth(2*pi*fc*n);%Carrier sawtooth
%
ppm = zeros(1,length(s));
% find ids where carrier is greater than message
id = find(c > m);
idd = diff(id);
iddd = find(idd ~= 1);
temp(1) = id(1);
temp(2:length(iddd)+1) = id(iddd + 1);
% ppm signal
for i = 1:length(temp)
ppm(temp(i) : temp(i) + on_t - 1) = 1;
end
% Plot
subplot(3,1,1);plot(n,m,'LineWidth',2);title('Message Signal');hold on; plot(n,c,'r','LineWidth',2);grid on;
subplot(3,1,2);plot(n,s,'LineWidth',2);title('Pulse Train');grid on; ylim([-0.2 1.2]);
subplot(3,1,3);plot(n,ppm,'LineWidth',2);title('PPM Signal'); grid on; ylim([-0.2 1.2])
EX:4
Demonstrate Amplitude Modulation.m
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الكود البرمجي:
%% Disceret Time Modulation
clc
close all
clear all
%%X[2n]
n1=-5:1:4;
Y1=[0 -1 -0.5 0.5 1 1 1 1 0.5 0];
subplot (211)
stem (n1,Y1);
grid on
xlabel ('Time')
ylabel('Amplitude')
title('Disceret Time Signal Xn')
clc
n1=-5:1:4;
Y1=[0 -1 -0.5 0.5 1 1 1 1 0.5 0];
subplot (212)
stem ((n1+2),Y1);
grid on
xlabel ('Time')
ylabel('Amplitude')
title('Disceret Time Signal X2n')
clc
close all
clear al
%%X[n-2]
n1=-5:1:4;
Y1=[0 -1 -0.5 0.5 1 1 1 1 0.5 0];
subplot (211)
stem (n1,Y1);
grid on
xlabel ('Time')
ylabel('Amplitude')
title('Disceret Time Signal')
n1=-5:1:4;
Y1=[0 -1 -0.5 0.5 1 1 1 1 0.5 0];
subplot (212)
stem (n1+2,Y1);
grid on
xlabel ('Time')
ylabel('Amplitude')
title('Disceret Time Signal')
EX:5
Demonstration of amplitude modulation.m
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الكود البرمجي:
% Demonstrate Amplitude Modulation
n= (1:1000);
fc=1/10;
ac=2;
y=ac*cos(2*pi*fc*n);
subplot(311)
plot(y);
title('signal')
n=(1:1000);
ac=2;
fc=1/10;
y=ac*cos(2*pi*fc*n);
bm= 1;
fm=1/100;
x= bm * sin(2*pi*fm*n);
am=(ac+x).*y/ac;
subplot(312)
plot(am);
title ('under modulation')
bm=2.5;
x= bm*sin(2*pi*fm*n);
am=(ac+x).*y/ac;
subplot(313)
plot (am);
title('Modulated wave')
EX:6
Disceret Time Modulation1.m
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الكود البرمجي:
% Demonstration of amplitude modulation
clc
close all;
clear all;
m = 1;
Am=5;
fa =2000 % frequency of modulating signal
Ta=1/fa;
t=0:Ta/999:6*Ta;
ym=Am*sin(2*pi*fa*t);
figure(1)
subplot(3,1,1);
plot(t,ym)
title('modulating signal')
Ac=Am/m;
fc=fa*10;
Tc=1/fc;
Yc=Ac*sin(2*pi*fc*t);
subplot(3,1,2)
plot(t,Yc)
grid on;
title ('carrier signal');
% AM modulation
Y=Ac+(1+m*sin(2*pi*fa*t)).*sin(2*pi*fc*t);
subplot(313)
plot(t,Y)
title ('Amplitude Modulated Signal')
grid on; 
7:EX
Discrete Time Modulation2.m
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الكود البرمجي:
%% Disceret Time Modulation
% EX 1 X[n]
clc
close all
clear all
n1=-5:1:4;
Y1=[0 -1 -0.5 0.5 1 1 1 1 0.5 0];
subplot (211)
stem (n1,Y1);
grid on
xlabel ('Time')
ylabel('Amplitude')
title('Disceret Time Signal')
clc
n1=-5:1:4;
Y1=[0 -1 -0.5 0.5 1 1 1 1 0.5 0];
subplot (212)
stem (-n1,Y1);
grid on
xlabel ('Time')
EX:8
Disceret Time Modulation3.m
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الكود البرمجي:
% Discrete -Time modulation % EX-1 plot a discrete time signal with a step function from -5 to 5 n = [-5 -4 -3 -2 -1 0 1 2 3 4 5]; f_one = 2*0.5.^n.* heaviside(n+2) subplot(211) stem(n,f_one)
EX:9
removes noise from the signal using filter.m
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الكود البرمجي:
% This file removes noise from the signal using filter
%
% Created By: JCBRO Labs
% Date: 28/02/2018
% website: www.jcbrolabs.org
% mail: jcbrolabs@gmail.com
close all; clear all;
%
%% simulate noisy signal
Fs = 500;
f = 20;
n = [1/Fs:1/Fs:1];
x = sin(2*pi*f*n) + sin(2*pi*f*n/5);
% add noise to the signal
y = x + rand(1,length(x));
% plot the noisy signal
subplot(2,2,1); plot(n,y);
title('Noisy Signal');
xlabel('Time (s)');
ylabel('Amplitude');
%% Spectral analysis of the signal
L = length(y);
NFFT = 2^nextpow2(L);
y_fft = abs(fft(y,NFFT));
% creating frequency axis
freq = Fs/2*linspace(0,1,NFFT/2+1);
% Plot single-sided amplitude spectrum.
subplot(2,2,2);
plot(freq,y_fft(1:NFFT/2+1));
title('Single-Sided Amplitude Spectrum of y(t)');
xlabel('Frequency (Hz)');
ylabel('|Y(f)|');
%% Design Filter and apply on the sequence
o = 5;
wn = [3 7]*2/Fs;
[b,a] = butter(o,wn,'bandpass');
% see frequency response of the filter
[h,w] = freqz(b,a,1024,Fs);
subplot(2,2,3);
plot(w,20*log10(abs(h)));
title('Magnitude Response of the Filter');
xlabel('Frequency (Hz)');
ylabel('Magnitude');grid on;
% Filter the signal
y_filt = filter(b,a,y);
subplot(2,2,4);
plot(n,y_filt);
title('Filtered Signal');
xlabel('Time (s)');
ylabel('Amplitude');
EX:10
Bandpass FIR Filters.m
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الكود البرمجي:
%% Bandpass FIR Filters
%
% *Equiripple Design*
Fstop1 = 150;
Fpass1 = 200;
Fpass2 = 300;
Fstop2 = 350;
Astop1 = 65;
Apass = 0.5;
Astop2 = 65;
Fs = 1e3;
d = designfilt('bandpassfir', ...
'StopbandFrequency1',Fstop1,'PassbandFrequency1', Fpass1, ...
'PassbandFrequency2',Fpass2,'StopbandFrequency2', Fstop2, ...
'StopbandAttenuation1',Astop1,'PassbandRipple', Apass, ...
'StopbandAttenuation2',Astop2, ...
'DesignMethod','equiripple','SampleRate',Fs);
fvtool(d)
