How to plot the magnitude and phase of this Fourier Transform frequency response that contains jw?

7 次查看（过去 30 天）
Harrison Ahn
Harrison Ahn 2018-4-2
回答： Star Strider 2018-4-2
I have a frequency response X1 = ((j.*w+100).*(j.*w+200))./((j.*w+10).*(j.*w+1000).*(j.*w+10000)); and would like to plot its magnitude in dB and phase versus the log of frequency with frequency from 0.5Hz to 3000Hz in steps of 5Hz but it doesn't seem to work because of the 'j' in my function.
This is my code:
clf % Clear any existing figure
w = log(0.5):log(5):log(3000); % Frequency from 0.5Hz to 3000Hz with increment of 5Hz
X1 = ((j.*w+100).*(j.*w+200))./((j.*w+10).*(j.*w+1000).*(j.*w+10000)); % Blue
subplot(2,1,1)
plot(w,abs(X1));
title('Magnitude')
ylabel('Magnitude (db)')
xlabel('Log of Frequency')
ylim([-1 10]);
grid on
subplot(2,1,2)
plot(w,angle(X1));
title('Phase')
ylabel('Phase (°)')
xlabel('Log of Frequency')
grid on

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2018-4-2
If you define ‘w’ differently, and change (or delete) the ‘ylim’ assignment, you can see it.
I defer to you to determine if it does what you want.
w = logspace(-3,4);
X1 = ((j.*w+100).*(j.*w+200))./((j.*w+10).*(j.*w+1000).*(j.*w+10000)); % Blue
subplot(2,1,1)
semilogx(w,20*log10(abs(X1)));
title('Magnitude')
ylabel('Magnitude (dB)')
xlabel('Log of Frequency')
set(gca, 'XLim',[0.5 3000])
% ylim([-1 10]);
grid on
subplot(2,1,2)
semilogx(w,angle(X1)*180/pi);
title('Phase')
ylabel('Phase (°)')
xlabel('Log of Frequency')
set(gca, 'XLim',[0.5 3000])
grid on
I added the conversion to dB in the magnitude plot, and the conversion from radians to degrees in the phase plot, since you apparently want those.

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Digital Filter Analysis 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by