FFT Analyzer Basic FAQ

AC coupling is a first-order high-pass filter consisting of a capacitor (C) and a resistor (R), whose primary purpose is to cut out low-frequency components, including the DC component, of the input signal. Its gain characteristics are:

 

（1）

 

This is the result. Here, f₀ This is the cutoff frequency of the high-pass filter, which is typically 0.5 Hz in Ono Sokki 's FFT analyzer. f is 0.5 Hz (= f₀ When this occurs, the value of equation (1) is approximately 0.707 (-3 dB), and at 1 Hz it is approximately 0.89 (-0.97 dB).