2.11.9 dfilter(Pro)

Analysis : Signal Processing : IIR Filter

Brief Information

Create and apply an IIR filter

Minimum Origin Version Required: Origin 9.0 SR0

This feature is for OriginPro only.


Command Line Usage

 dfilter method:=cheby1 order:=5 sample:=1000 wn:=50 filtfilt:=1 coef:=[<input>]<new>; 

Variables

Display
Name
Variable
Name
I/O
and
Type
Default
Value
Description
Input Signal iy

Input

XYRange

<active>
Specify the input signal.
Response Type type

Input

int

0
Specify the response type of filter.

Option list:

• low:Low Pass
Allow low frequency components to pass.
• high:High Pass
Allow high frequency components to pass.
• bandpass:Band Pass
Allow frequency components within a specified range to pass.
• bandstop:Band Stop
Allow frequency components outside a specified range to pass.
Method method

Input

int

0
Specify the filter design method.

Option list:

• butter:Butterworth
Butterworth filter design.
• cheby1:Chebyshev Type I
Chebyshev Type I filter design.
• cheby2:Chebyshev Type II
Chebyshev Type II filter design.
• elliptic:Elliptic
Elliptic filter design.
Filter Order order

Input

double

10
Specify the filter order.
Unit unit

Input

int

0
Specify the unit for the frequency settings.

Option list:

• hz:Hz
Use Hz as the unit when specifying the frequency specification.
• normalize:Normalize to (0,1)
The specified frequency is normalized to the region from 0 to 1. It is calculated by Frequency(Hz)/(SampleFrequency(Hz)/2), where SampleFrequency(Hz)/2 is the Nyquist frequency.
Sample Frequency (Fs) sample

Input

double

<auto>
Specify the sampling frequency, available when the Unit is Hz.
Cutoff Frequency (Fc) wn

Input

double

<auto>
When Filter Order is specified (not minimum), this variable is used to specify the cutoff frequency for the low pass and high pass.
Cutoff Frequency 1 (Fc1) wn1

Input

double

<auto>
When Filter Order is specified (not minimum), this variable is used to specify the first cutoff frequency for the band pass and band stop.
Cutoff Frequency 2 (Fc2) wn2

Input

double

<auto>
When Filter Order is specified (not minimum), this variable is used to specify the second cutoff frequency for the band pass and band stop.
Pass Frequency wp

Input

double

<auto>
When Filter Order is minimum, this variable is used to specify the pass frequency for the low pass and high pass.
Stop Frequency ws

Input

double

<auto>
When Filter Order is minimum, this variable is used to specify the stop frequency for the low pass and high pass.
Pass Frequency 1 wp1

Input

double

<auto>
When Filter Order is minimum, this variable is used to specify the first pass frequency for the band pass and band stop.
Stop Frequency 1 ws1

Input

double

<auto>
When Filter Order is minimum, this variable is used to specify the first stop frequency for the band pass and band stop.
Pass Frequency 2 wp2

Input

double

<auto>
When Filter Order is minimum, this variable is used to specify the second pass frequency for the band pass and band stop.
Stop Frequency 2 ws2

Input

double

<auto>
When Filter Order is minimum, this variable is used to specify the second stop frequency for the band pass and band stop.
Passband Ripple rp

Input

double

1
Specify the pass band ripples in dB.
Stopband Attenuation rs

Input

double

80
Specify the stop band attenuation in dB.
Forward-Backward Filtering filtfilt

Input

int

0
Specify whether to perform both forward and backward filtering on the input signal.
SOS Matrix sos

Output

ReportData

[<input>]<new>
Output the designed IIR filter as the second order section (SOS) parameters form.
Zeros Poles and Gain zpk

Output

ReportData

[<input>]<new>
Output the designed IIR filter as the zero-pole-gain form.
State-Space Form abcd

Output

ReportData

[<input>]<new>
Output the designed IIR filter as the state-space form.
Coefficients coef

Output

ReportData

[<input>]<new>
Output the designed IIR filter as the numerator coefficients and the denominator coefficients.
Output Signal oy

Output

XYRange

(<input>,<new>)
The output signal after filtering by the designed IIR filter.

Examples

This example will show how to perform high pass with Butterworth method.

1. Create a new project and import the data file <Origin Installation Directory>\Samples\Signal Processing\EMG Recording.dat.
2. Highlight column B, and make a line plot by menu Plot: Line: Line.
3. Activate the graph, select menu Analysis: Signal Processing: IIR Filter to open the dialog, and then set the parameters as the following image shows.
Response Type: High Pass
Filter Order: 6
Cutoff Frequency (Fc): 20