PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

606 Practical MATLAB® Applications for Engineers

subplot(2,1,1);

semilogx(w/(2*pi),db);

ylabel(‘magnitude in dbs’);

title(‘magnitude vs. freqs.’);

axis([1.9e2 1.4e4 -50 2]);

grid on;

subplot(2,1,2);

semilogx(w/(2*pi),angle(Hhp)*180/pi);

title(‘phase ang. vs. freqs.’);

ylabel(‘phase in degrees’);

xlabel(‘frequency in Hrz’);

axis([1.9e3 1.4e4 0 90]);

grid on;

figure(3);

bode(num,den,w)

title(‘Bode plots with argument w’);

axis([5e3 2e5 0 100])

figure(4);

bode(num,den)

title(‘Bode plots with no w’);

figure(5)

% using standard circuit approach (complex algebra)

XC=1./(w.*C);

Z=sqrt(R^2+XC.^2);

magHele=(R./Z);

phaseHele=(atan(XC./R)).*180./pi;

subplot(2,2,1)

plot(w./(2*pi),magHele);

title(‘magnitude vs. freq.’);

ylabel(‘magnitude’)

grid on;

subplot(2,2,2)

plot(w./(2*pi),phaseHele);

title(‘phase vs. freq.’);

ylabel(‘phase in degrees’);

grid on;

subplot(2,2,3);

dbele=20.*log10(magHele);

semilogx(w./(2*pi),dbele);title(‘ magnitude vs. freq.’)

ylabel(‘magnitude(db)’);

xlabel(‘frequency in Hrz’);

grid on;

subplot(2,2,4);

semilogx(w./(2*pi),phaseHele);title(‘ phase vs. freq.’)

xlabel(‘frequency in Hrz’);

ylabel(‘phase(degrees)’);

grid on;

Back in the command window, the script fi le HP_fi lter_analysis is executed and the

results are shown as follows (Figures 6.32 through 6.36):

>> HP _ filter _ analysis