Plot the magnitude and phase by using Matlab

Answer 1

[Yazan]

Here is one way to get the spectrum.

clc, clear

% fundamental frequencies
f1 = 1/3;
f2 = 5/6;

% sampling frequency
fs = 50*max([f1, f2]);
% sampling period
Ts = 1/fs;
% Time span (5 periods)
T = 5*max([1/f1, 1/f2]);
% time axis
t = 0:Ts:T-Ts;
% frequency axis
f = -fs/2:fs/length(t):fs/2-fs/length(t);

% signal
x = 2 + cos(2*pi*f1*t) + 4*sin(2*pi*f2*t);
% fft
X = fftshift(fft(x));

% figure
fig = figure('Units', 'normalized', 'Position', [0.15 0.35 0.75 0.55]);

% plot signal in time
subplot(1, 3, 1), plot(t, x),
xlabel('Time (sec)'); ylabel('Amplitude');
title('Signal'); grid 'minor';

% plot fft magnitude
subplot(1, 3, 2), plot(f, abs(X)),
xlabel('Frequency (Hz)'), ylabel('Magnitude'),
title('Spectrum, magnitude'); grid 'minor';

% plot fft phase
subplot(1, 3, 3), plot(f, unwrap(angle(X))),
xlabel('Frequency (Hz)'); ylabel('Phase');
grid 'minor';
title('Spectrum, unwrapped phase');

[Muhammad Rifqi Jafri Zain]

i want magnitude and phase only can?

[Yazan]

The code is commented almost completely so that you can modify it easily. Just remove the first subplot! Any basic user should be able to do so.

Answer 2

[Madhu Sri Harsha]

Z1 = -1

Z2 = -2

Z3 = 0.6 + j1.05

Z4 = 0.6 - j1.05

P1 = -0.2

P2 = 0.3

P3 = 0.25 + j0.6

P4 = 0.25 - j0.6

1 Write an expression for H(z) and plot the poles and zeros.

2 Plot the magnitude and phase of H(z).