What is Band Pass Filter (BPF)?

　・In Japanese
Premise knowledge
　・Scilab
　・Transfer function
　・How to draw a Bode diagram

■What is a bandpass filter?

A bandpass filter is a filter that allows only specific frequencies to pass, and is expressed by the transfer function below.

■Bode plot of bandpass filter

The parameters are as follows.


The results drawn with Scilab are as follows. (Reference: How to use Scilab)
==============================
s=poly(0,'s');
p=syslin('c',0.628*s/(s^2+0.628*s+6.28^2);
bode(p);
==============================

■Simulating the operation of a bandpass filter with Scilab

Create it in Scilab as follows.



＜When f=1Hz (6.28rad/s)＞
The black line is the input, and the green line is the output. Frequencies in this band pass through, so the input and filtered values are equal.



＜When f=10Hz (62.8rad/s)＞
You can see that frequencies in this band are not passed.

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