digitalFilter

Digital filter

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Description

Usedesignfiltto design and editdigitalFilterobjects.

Usedesignfiltin the formd = designfilt(resp,Name,Value)to design a digital filter,d, with response typeresp. Customize the filter further usingName,Valuepairs.
Usedesignfiltin the formdesignfilt(d)to edit an existing filter,d.

Note

This is the only way to edit an existingdigitalFilterobject. Its properties are otherwise read-only.
Usefilterin the formdataOut = filter(d,dataIn)过滤的一个信号digitalFilterd. The input can be a double- or single-precision vector. It can also be a matrix with as many columns as there are input channels.
UseFVToolto visualize adigitalFilter.
These functions takedigitalFilterobjects as input.

Object Functions

Filtering

Function	Description
`fftfilt`	Filters a signal with a`digitalFilter`using an FFT-based overlap-add method
`filter`	Filters a signal using a`digitalFilter`
`filtfilt`	Performs zero-phase filtering of a signal with a`digitalFilter`

Filter Analysis

Function	Description
`double`	Casts the coefficients of a`digitalFilter`to double precision
`filt2block`	Generates a Simulink^®filter block corresponding to a`digitalFilter`
`filtord`	Returns the filter order of a`digitalFilter`
`firtype`	Returns the type (1, 2, 3, or 4) of an FIR`digitalFilter`
`freqz`	Returns or plots the frequency response of a`digitalFilter`
FVTool	Opens the Filter Visualization Tool and displays the magnitude response of a`digitalFilter`
`grpdelay`	Returns or plots the group delay response of a`digitalFilter`
`impz`	Returns or plots the impulse response of a`digitalFilter`
`impzlength`	Returns the length of the impulse response of a`digitalFilter`, whether actual (for FIR filters) or effective (for IIR filters)
`info`	Returns a character array with information about a`digitalFilter`
`isallpass`	Returns`true`if a`digitalFilter`is allpass
`isdouble`	Returns`true`if the coefficients of a`digitalFilter`are double precision
`isfir`	Returns`true`if a`digitalFilter`has a finite impulse response
`islinphase`	Returns`true`if a`digitalFilter`has linear phase
`ismaxphase`	Returns`true`if a`digitalFilter`is maximum phase
`isminphase`	Returns`true`if a`digitalFilter`is minimum phase
`issingle`	Returns`true`if the coefficients of a`digitalFilter`are single precision
`isstable`	Returns`true`if a`digitalFilter`is stable
`phasedelay`	回报或情节相位延迟response of a`digitalFilter`
`phasez`	Returns or plots the (unwrapped) phase response of a`digitalFilter`
`single`	Casts the coefficients of a`digitalFilter`to single precision
`ss`	Returns the state-space representation of a`digitalFilter`
`stepz`	Returns or plots the step response of a`digitalFilter`
`tf`	Returns the transfer function representation of a`digitalFilter`
`zerophase`	Returns or plots the zero-phase response of a`digitalFilter`
`zpk`	Returns the zero-pole-gain representation of a`digitalFilter`
`zplane`	Displays the poles and zeros of the transfer function represented by a`digitalFilter`

Examples

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Lowpass IIR Filter

Open Live Script

Design a lowpass IIR filter with order 8, passband frequency 35 kHz, and passband ripple 0.2 dB. Specify a sample rate of 200 kHz. Visualize the magnitude response of the filter.

lpFilt = designfilt('lowpassiir','FilterOrder',8,...'PassbandFrequency',35e3,'PassbandRipple',0.2,...'SampleRate',200e3); fvtool(lpFilt)

Figure Filter Visualization Tool - Magnitude Response (dB) contains an axes object and other objects of type uitoolbar, uimenu. The axes object with title Magnitude Response (dB) contains 2 objects of type line.

Use the filter you designed to filter a 1000-sample random signal.

dataIn = randn(1000,1); dataOut = filter(lpFilt,dataIn);

Output the filter coefficients, expressed as second-order sections.

sos = lpFilt.Coefficients

sos =4×60.2666 0.5333 0.2666 1.0000 -0.8346 0.9073 0.1943 0.3886 0.1943 1.0000 -0.9586 0.7403 0.1012 0.2023 0.1012 1.0000 -1.1912 0.5983 0.0318 0.0636 0.0318 1.0000 -1.3810 0.5090

Introduced in R2014a

Signal Processing Toolbox Documentation

金宝app

Deep Learning for Signal Processing with MATLAB

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