This version (21 Dec 2016 09:57) was approved by Ashwin Radhakrishnan.

General FIR Filter

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The General FIR filter block lets you design LowPass, HighPass, BandPass or BandStop FIR filters using windowing technique. Following windows are supported in filter design:

  1. Hanning
  2. Rectangular
  3. Hamming
  4. Blackman

Input Pins

NameFormat [int/dec] - [control/audio]Function Description
Pin 0: Inputdecimal - audioInput signal to the FIR filter

Output Pins

NameFormat [int/dec] - [control/audio]Function Description
Pin 0: Outputdecimal - audioFIR filtered output

GUI Controls

GUI Control NameDefault ValueRangeFunction Description
Enable/BypassEnabledTrue/FalseEnables or disables the filter. On bypass, the input signal is passed through without any processing.
Frequency1000Hz0-96KhzCutoff frequency of the filter

Click on the image to configure the filter parameters.

GUI Control NameDefault ValueRangeFunction Description
Frequency1000Hz0-96KhzCutoff frequency of the filter. (Lower cutoff frequency in the case of Bandpass/Bandstop filters
Select Type00-3Selects filter type(LowPass/HighPass/BandPass/BandStop)
Window Type00-3Selects the Window(Hanning/Rectangular/Hamming/Blackman)
Gain0db-15-15dbSets the gain of the filter
BW1.410-11BW in octaves(only for BandPass and Bandstop filters)
Filter Order102-10000Sets the order of the filter. Filter length = Order + 1

Grow Algorithm

When the General FIR filter algorithm is grown, an extra pair of input/output pins is added to the control. The filtering on each of the grown Input pins is affected by the parameters chosen in the GUI in the same manner.



General FIR filter block designs a LowPass , HighPass, BandPass or BandStop filter using Windowing technique. Order, Cutoff frequency , Window Type and Gain are configured in the GUI for LowPass and HighPass filter design. Bandwidth has to be additionally configured for BandPass and BandStop filter design.

The coefficients of the filter are calculated and downloaded to the DSP based on the design chosen by the user in the GUI. FIR coefficient calculation steps are shown below.

Ideal filter response h(n) is calculated based on the filter configuration as per the table below

Note: N -Filter Order , wc - Cutoff frequency, wl - Lower cutoff frequency, wh - Higher cutoff frequency, wh=wl * 2BW

Coefficients of the window, w(n) are chosen based on the type of the window selected in the GUI.

Filter coefficients are calculated as h(n) = h(n) * w(n) over the filter length (Order + 1).

In the case of HighPass and BandStop filter, filter order is increased by 1 when odd filter Order is entered in the GUI. Filter order must be even because odd-order symmetric FIR filters has zero gain at the Nyquist frequency.

DSP Parameter Information

GUI Control NameCompiler NameFunction Description
NA (Filter coefficients are calculated based on the filter configuration set in GUI) FIRAlgSigma3001fircoeffCalculated Filter coefficients based on the designed filter

Supported ICs

  1. ADAU145x
resources/tools-software/sigmastudio/toolbox/filters/generalfirfilter.txt · Last modified: 21 Dec 2016 09:56 by Ashwin Radhakrishnan