General description
The main objective of this block is to provide digital filtering functions to the system. FIR (Finite Impulse Response) is one of the main types of digital filters.
The filters can be designed using the tool provided in the user interface. After the filter coefficients have been designed, the new coefficient values can be taken in use with the ‘Apply’ button. A filter can be designed also with some other tool (for example with Matlab), and the coefficients can be loaded from a file using the ‘File’ button.
The frequency response of a designed filter is shown in the upper window. The scale is from zero to the Nyqvist frequency (half of the current sample rate). In the lower window the impulse response of the filter is shown. You can change your filter’s frequency response properties by window type. You can just select different window functions and see how it effects on the frequency response. You can save the filter coefficients to a file by clicking the right mouse button and then select ‘Save’.
Filter types
Taps
This is the length of FIR filter.
Lowpass
Design a lowpass filter. Parameter Fp tells the cutoff frequency.
Highpass
Design a highpass filter. Parameter Fp tells the cutoff frequency.
Bandpass
Design a bandpass filter. Parameter Fs tells the start of bandpass area and Fp tells the end of bandpass area.
Bandstop
Design a bandstop filter. Parameter Fp tells the start of bandpass area and Fs tells the end of bandpass area.
Window types
Rectangle
Filter is designed using rectangle window.
Hamming
Filter is designed using Hamming window.
Rectangle
Filter is designed using rectangle window.
Hanning
Filter is designed using Hanning window.
Bartlet
Filter is designed using Bartlet window.
Blackman
Filter is designed using Blackman window.
