PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

52 Practical MATLAB® Applications for Engineers

wtri = triang(31);

wrect = boxcar(31);

wbart = bartlett(31);

plot (n,wtri,’*’,n,wrect,’d’,n,wbart,’o’);

hold

plot (n,wtri,n,wrect,n,wbart);

title (‘TRIANGULAR,RECTANGULAR and BARTLETT windows ‘);

xlabel (‘points n’);

ylabel (‘Amplitude’)

legend (‘TRIAN’,’RECT’,’BART’);

axis([-18 18 0 1.3]);

R.1.160 For completeness, a random or noise-like signal is presented below.
The MATLAB statement sqrt(P)*randn(1, n) returns a white Gaussian noise
sequence with power P.

R.1.161 For example, create the script fi le signal_noise that returns the plots of the follow-
ing signals:
a. Gaussian white noise
b. The signal—signal = cos(2πn/64)
c. The contaminated signal plus noise using n = 128 elements. Let the white
Gaussian signal power be P = 2.7 watts

TRIANGULAR, RECTANGULAR, and BARTLETT windows

1.2

1

0.8

0.6

0.4

0.2

0

− 15 − 10 − 5 0 5 10 15

Amplitude

TRIAN

RECT

BART

(31-point approximations)

points n

FIGURE 1.42
Plots of the triangular, rectangular, and Bartlett window of R.1.159.