Digital filter design and analysis

In digital signal processing, a digital filter is a system that performs mathematical operations on a discrete-time signal to either reduce or enhance certain aspects of that specific signal. For example, a digital filter can be used to attenuate noise, DC bias etc. Furthermore, a digital filter can be used to extract the signal within a certain frequency range, which is one of the most important role frequency selective digital filters. There are three main categories of digital filters: the recursive filters otherwise known as infinite impulse response (IIR) filters, and the nonrecursive filter otherwise known as finite impulse response (FIR) filters.

Digital filter

The MatDeck software contains a variety of different functions for both IIR and FIR filter design and analysis. The overview of these functions is given in a sequel.

Digital filter design

IIR filters

Filter typeLowpass/HighpassBandpass/Bandstop
Butterworthbuttlohi()buttband()
Chebyshev type Icheby1lohi()cheby1band()
Chebyshev type IIcheby2lohi()cheby2band()
Elliptic filterelliplohi()elipband()

FIR filters

  • windowing design: firbandpass(), firbandstop(), firhighpass(), firlowpass()
  • frequency sampling: firfreqsampl()
  • optimal design: firopt(), firoptord ()

Digital filter analysis and implementation

  • IIR filters: iirfilter(), initiirfilter(), iirfreqresp(), iirgrpdelay(), iirphasedelay()
  • FIR filters: firfilter(), initfirfilter(),firfreqresp()

Digital filter

MatDeck provides several toolkits which enable digital filter designing in a graphical environment, which is very convenient for many users. The list of digital filtering toolkits is given below.

  • Filtering Toolkit – IIR Filtering Form
  • Filtering Toolkit for FIR design by windowing and frequency sampling – FIR Filtering Form
  • Filtering Toolkit for FIR optimal design – FIR Optimal Form

Digital filter

Examples