how to generate square wave in matlab

Hi,

I intend to generate a square wave with respect to time by following characteristic:

I want to generate square-wave force demand of 1 KN at 10 Hz. That means amplitude will be between 0 to 1000 and time will be between 0 to 1 (sec) with .1 interval.

Please someone help me.

Answer 1

[Image Analyst]

Make one period, then use repmat() to replicate as many times as you want.

% Now make one cycle with amplitude 1000 and 200 elements.
onePeriod = 1000 * [ones(1, 100), zeros(1, 100)];
% 200 elements is supposed to be 0.1 seconds so find out delta t.
dt = 0.1 / numel(onePeriod);
% Define number of cycles.
numCycles = 10;
% Copy this period that many times.
fullWaveForm = repmat(onePeriod, [1, numCycles]);
% Make time axis from 0 to 1 second.
t = dt * (0 : (numel(fullWaveForm) - 1));
% Now plot it.
plot(t, fullWaveForm, 'b-', 'LineWidth', 2);
FontSize = 20;
xlabel('Time (seconds)', 'FontSize', FontSize);
ylabel('Amplitude', 'FontSize', FontSize);
title('Square Wave With 10 Cycles', 'FontSize', FontSize);
grid on;

[TANMAYA KAANR]

Just Put a saturation block with lower limit zero. It will give only Positive value.

[Image Analyst]

I don't know what that means. What is a "saturation block"? Is that Simulink? The poster said "in matlab" but if your function is for Simulink, then perhaps your post will help Simulink users.

Answer 2

[Rashmil Dahanayake]

t=0:.001:1;
f=10;
sq=1000*0.5*(square(2*pi*f*t)+1);
plot(t,sq)

Answer 3

[Bill Tubbs]

Based on Rashmil Dahanayake's idea I made a simple function to generate regular square waves for discrete time.

function sq = square_dt(n,period)
    % Square wave in discrete time
    repeats = n/period;
    sq = square(2*pi*linspace(0,repeats-1/n,n));
end

(Works best when period is an even number)

Example

>> square_dt(10,4)

ans =

     1     1    -1    -1     1     1    -1    -1     1     1

If you want only the positive cycles, modify the code like Rashmil's:

function sq = square_dtp(n,period)
    % Square wave in discrete time
    repeats = n/period;
    sq = (square(2*pi*linspace(0,repeats-1/n,n))+1)/2;
end

Example

>> square_dtp(10,4)

ans =

     1     1     0     0     1     1     0     0     1     1

Answer 4

[udhaya ram mohan]

i need to generate the square wave with positive cycle only please send me a code for it

[Walter Roberson]

Rashmil Dahanayake's Answer already only generates positive values.

Answer 5

[pisini padmaja]

%square function%
clc;
clear all;
close all;
t=0:0.01:2;
x=sin(2*pi*t);
subplot(2,1,1);
plot(t,x,'g');
xlabel('time');
ylabel('amplitude');
title('square signal 318126512095');
subplot(2,1,2);
stem(t,x,'r');
xlabel('time');
ylabel('amplitude');
title('square sequence 318126512095');

[Image Analyst]

This does not look like an Answer for how to create a square wave. Here is what your code produces:

%square function%
clc;
clear all;
close all;
t=0:0.01:2;
x=sin(2*pi*t);
subplot(2,1,1);
plot(t,x,'g');
xlabel('time');
ylabel('amplitude');
title('square signal 318126512095');
subplot(2,1,2);
stem(t,x,'r');
xlabel('time');
ylabel('amplitude');
title('square sequence 318126512095');

[Vedanta Mohapatra]

You have to use signum to generate some sort of square wave