Filtering: Wave filtering is the operation of filtering out specific band frequencies in the signal. It is an important measure to suppress and prevent interference. Filtering is divided into classic filtering and modern filtering. Baidu Encyclopedia
Filter: A circuit that only allows signal components within a certain frequency range to pass normally while preventing another part of the frequency components from passing is called a classic filter or filter circuit. In fact, any electronic system has its own bandwidth (restriction on the highest frequency of the signal), and the frequency characteristics reflect this basic characteristic of the electronic system. The filter is an engineering application circuit designed according to the influence of circuit parameters on the circuit bandwidth. Baidu Encyclopedia
Low-pass filter image source :
High-pass filter image source :
Image source of band-pass filter image :
Band-rejection filter image source :
All-pass filter image (can be used to change the phase of the input signal (after the signal is FFT, the result is a complex number, with imaginary and real parts. For real) The square root of the sum of the square and the imaginary part is the amplitude; the inverse tangent of the ratio of the real part and the imaginary part is the phase) ):
