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Owning Palette: FPGA Math & Analysis VIs and Functions
Requires: FPGA Module
Attenuates a specific frequency band in one or more input signals using a second order IIR notch filter.
You can use the Notch Coefficients Express VI to generate the set of filter coefficients during run time.
|Dialog Box Options|
|Block Diagram Inputs|
|Block Diagram Outputs|
|Filter Specifications||Contains the following options:|
|Output Data Type||Contains the following options:|
|Implementation||Contains the following options:|
|Filter Response||Displays the actual magnitude response of the filter.|
|reset||Resets the filter state of the input data channel to zero if TRUE. Resetting the filter state does not reset the filter coefficients. This Express VI resets automatically the first time you call it.|
|input data||Specifies the input signal to filter. input data is a fixed-point number or integer with a maximum word length of 32 bits.|
|scaled coefficients||Specifies single-channel filter coefficients to load at run time. Scaled coefficients is a fixed-size array of three 32-bit signed integers.
This parameter is available only when you configure the VI for single-channel input in the configuration dialog box.
|configuration||Specifies the scaled coefficients to load at run time for the channel index you specify using the channel index element of this cluster. This Express VI continues to use either the default coefficients or the last coefficients you specified for the channel until you specify new coefficients. This parameter is available only when you configure the VI for multi-channel input in the configuration dialog box.|
|output data||Returns the filtered signal corresponding to the input data channel.|
You can configure the sharpness of the notch by specifying either the Notch width or the Q factor of the filter. To use Notch width, select Specify bandwidth in the Filter Specifications section of the configuration dialog box. To use Q factor, select Specify quality in the Filter Specifications section of the configuration dialog box.
Q factor and Notch width are related by the following equation:
Q factor = Notch frequency/Notch width.
Notch frequency and Notch width or Q factor are constrained such that the upper end of the attenuated frequency band is less than half of the Expected sample rate (S/s) (Nyquist frequency) and the lower end of the attenuated frequency range is greater than zero (DC).
Refer to the support document at ni.com for more information about the accuracy of the FPGA Math and Analysis VIs.
Refer to the following VIs for examples of using the Notch Filter Express VI: