1. Basic knowledge
A sinusoidal signal with a frequency of 50Hz, which means that the analog frequency of the signal is f = 50 (Hz). Note that its unit is Hz. The expression of the signal is:
Note
The frequency used in analog filter design refers to the analog angular frequency Ω
Digital filtering The frequency used in device design refers to the normalized digital angular frequency w
2. Introduction to digital filters
Digital filter characteristics: The useful frequency components in the input signal and the frequency components that you want to filter out occupy different frequency bands. We need to filter out the interference through a suitable frequency selective filter to obtain a pure signal.
3. Two methods
1. Impulse response invariant method
Apply Laplace transform to equation (1):
The Z transformation of h[n] is:
2. Bilinear transformation method
3. Summary
