FIR Filter's Response : This Java applet analyzes FIR filter's frequency and In/Out characteristics. Make some modification in the text box, then click "Read Coeffs" to draw frequency response. You can also get filtered output by "Read InWave" button. The number of coeffs/data is up to 100. If this applet looks something weird, please reload it. If you want to analyze for the tap count exceeding 100, please go to this page. Note that it's a very heavy one. Here is a mathematical model of n th order FIR filter. "D" is a unit delay element. "n" is called "tap count".