x = square(t)
x = square(t,duty)
x = square(t) generates
a square wave with period 2π for the elements
of time vector
but creates a square wave with peaks of ±1 instead of a sine
x = square(t,duty) generates
a square wave with specified duty cycle,
which is a number between 0 and 100. The duty cycle is
the percent of the period in which the signal is positive.
Create a vector of 100 equally spaced numbers from to . Generate a square wave with a period of .
t = linspace(0,3*pi)'; x = square(t);
Plot the square wave and overlay a sine. Normalize the x-axis by . The generated square wave has a value of at even multiples of and a value of at odd multiples of . It is never .
plot(t/pi,x,'.-',t/pi,sin(t)) xlabel('t / \pi') grid on
Repeat the calculation, but now evaluate
square(2*t) at 121 equally spaced numbers between
. Change the amplitude to
. Plot the wave and overlay a sine with the same parameters. This new wave is negative at
and positive at the endpoints.
t = linspace(-pi,2*pi,121); x = 1.15*square(2*t); plot(t/pi,x,'.-',t/pi,1.15*sin(2*t)) xlabel('t / \pi') grid on
Generate a 30 Hz square wave sampled at 1 kHz for 70 ms. Specify a duty cycle of 37%. Add white Gaussian noise with a variance of 1/100.
t = 0:1/1e3:0.07; y = square(2*pi*30*t,37)+randn(size(t))/10;
Compute the duty cycle of the wave. Plot the waveform and annotate the duty cycle.
ans = 0.3639