Component: Filter (DSP Operators)

Author	Matrix Ltd
Version	1.3
Category	DSP Operators

Filter component

Filter component to allow basic filtering to be performed Filters include: LowPass, HighPass, BandPass, BandStop, FIR, IIR

Detailed description

Using the data recorder you can see the analogue wave and the filter response changing as the frequency changes.

Basically allows you to play with the filter coefficients and modify the frequency to see how the filter performs.

The PWM is just providing an analogue output but would need a R/C filter to make it truly analogue.

Examples

Low Pass Filter

Example of the filter component set up to create a low pass filter with the input frequency controlled using the potentiometer on the panel. LowPassFilter Low pass filter running at a low frequency - note that the amplitude of the filtered data closely matches that of the original waveform data.

Low pass filter running at a high frequency - note that the amplitude of the filtered waveform is now greatly attenuated.

High Pass Filter

Example of the filter component set up to create a high pass filter with the input frequency controlled using the potentiometer on the panel. HighPassFilter High pass filter running at a low frequency - note that the amplitude of the filtered waveform is greatly attenuated.

High pass filter running at a high frequency - note that the amplitude of the filtered data closely matches that of the original waveform data.

Band Pass Filter

Example of the filter component set up to create a band pass filter with the input frequency controlled using the potentiometer on the panel. BandPassFilter Band pass filter running at a low frequency - note that the amplitude of the filtered waveform is greatly attenuated.

Band pass filter running at a mid frequency - note that the amplitude of the filtered data closely matches that of the original waveform data.

Band pass filter running at a high frequency - note that the amplitude of the filtered waveform is greatly attenuated.

Macro reference

Filter

	Filter
Performs the filter operation to the current value in the buffer.
- VOID	Return

FilterArray

	FilterArray
Performs the filter operation to the contents of the entire buffer in one go.
- VOID	Return

SetFilterCoefficient

	SetFilterCoefficient
Allows the coefficients of low pass, High pass, band pass and band stop filters to be edited. Must be enabled using the Variable Coefficients property.
- BYTE	Index
Range: 0-1
- UINT	Value

- VOID	Return

Property reference

	Properties
	Connect To
DSP component with output buffer to collect our data from.
	Buffer Size
Number of individual elements the buffer can store, default 1.
	Buffer Type
Sets the buffer data type.
	Direction
Sets the data direction flow of the component
	Filter Properties
	Type
Specifies the filter type created by the component: Low Pass - Filters out frequencies above the cutoff frequency High Pass - Filters out frequencies below the cutoff frequency Band Pass - Combination of High Pass and Low Pass Filters Band Stop - Inverse of Band Pass FIR - Finite impulse response using standard filter coefficients IIR - Infinite impulse response using standard filter coefficients
	Variable Coefficients
Decides if the coefficient values can be altered during runtime using the SetCoefficient component macro. Only available for the simple filter types, low pass, high pass, band pass and band stop.
	Coefficient 0
Cutoff frequency = Nyquist frequency / Coefficient Cutoff frequency is described as when the unwanted frequencies in the signal have been attenuated by at least 50%
	Calculations
	Sample Rate
Sample frequency used to work out some basic useful calculations
	Nyquist Frequency
Maximum theoretical frequency that can be obtained by the sample frequency
	Cutt Off Frequency 0
First cutoff frequency