# Questions tagged [infinite-impulse-response]

Infinite impulse response (IIR) is a property of signal processing systems.

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### Cascading IIR filter with All pass filter (APF) for constant group delay and linear phase over the passband using MATLAB not working?

I've designed an IIR Low pass filter in MATLAB with the following parameters. ...
1 vote
65 views

### How to implement an easy to use IIR-Filter in C/C++

Edited: I know there are some IIR filter implementation guides on the World Wide Web, however I can't find a simple guide on how to link simple PCM values to a digital filter. Most approaches are over-...
235 views

### Filter type selection for signal envelope detection

Working on a signal envelope detection code in Matlab in which an RF signal envelope is to be created. The flow is such that filtering is performed according to the detected presence of a signal in a ...
1 vote
30 views

### How to create a frequency weighted measurement? / How to design a Pinking FIR Filter?

Disclaimer: I have read a lot about signal processing, but I taught everything myself and therefore have some gaps in theory and practice. I am currently working on a measurement software that is ...
1 vote
39 views

### Calculating and controlling the location and bandwidth of individual notches in an allpass phaser

I'm currently working on a phaser implementation with the intention of adding some parameters that generate unique effects, namely effects that involve the precise placement of the phaser notches (e.g....
1 vote
176 views

### Can sampling rate impact filter output?

I am noticing that the behavior of equalizers in music softwares varies depending on the sampling rate. If we apply a filter (IIR or FIR) to a digital signal, in what situations does the sampling rate ...
26 views

### Implementation of Deriche filter

The Canny edge detector is expressed by the derivative of the Gaussian. Its practical implementation involves the Gaussian filter, then the Sobel filter to calculate the gradient in both directions. ...
1 vote
95 views

### Finite/Infinite Impulse Response filters

Most image filters are of finite extension (which correspond to Finite Impulse Response in 1 dimension), like Laplacian, Canny, Gaussian... Instead of being of infinite extension (IIR in 1D). Why is ...
1k views

### FFT-based fast convolution vs IIR filtering

I'm doing an multichannel audio equalizer system on a chip, which is parametric EQ, usually implemented in cascaded biquad IIR filters. My problem is that I use a lot of IIR filters due to multiple ...
55 views

### IIR Filter 3dB Frequency and Amplitude and Phase of output for given input signal

Hi I have some troubles in calculating the 3dB-Frequency and the output signal of an IIR Filter with a given transfer function $H_Z = \frac{1-Z^{-1}}{1+\frac{1}{2}Z^{-1}}$ Second question is to ...
40 views

### Designing of passband and stopband frequencies

good evening guys, let us consider following image we can see from the picture designing of lowpass filter with given passband region and stopband region, only one thing what i am interesting is ...
43 views

### What formulas do I need to add poles to these two filter designs

I am coding a music composition application and it uses a couple of different types of filter effects. I have implemented single pole, two pole and sinc filters to it successfully. I would now like to ...
1 vote
41 views

### How to determined the cutoff frequency of a IIR or FIR

I am trying to design a IIR to remove the noise from my input signal. Here is my the my input signal in the frequency domain And here is the noise in the frequency domain that, So I may choose ...
19 views

### Does flat group delay bandwidth of a Thiran filter increase with increase in filter order?

Experimentally, it does seem that for a Thiran allpass delay filter of desired low-frequency group delay $D$ with filter order $N$, increase in filter order $N$ increases bandwidth of the frequency ...
82 views

### Stability of N-order Thiran delay filter when required passband delay is N+1

In this lecture note, on page 7 (or page 111, the same page), it is said that the Thiran allpass delay filter of order N with passsband delay N+1 reproduces samples with zero error. I find it hard to ...
14 views

### How should I pass a sequence of signal through a finished IIR filter in MATLAB

I am new to IIR filter. Lets say if my input signal is [1 -10 3 6 9], and the sampling frequnecy is $f_{s}=360Hz$, the cutoff frequency is $f_{d}=60Hz$, so the calculated $W_{n}$ is $0.4$. I just use ...
1 vote
28 views

### what space of functions can be represented by the impulse response of an IIR?

I'm trying to understand the expressiveness of the impulse response of an IIR. For example, I know that second order causal IIRs are capable of having impulse responses that are growing or decaying ...
91 views

### Fixed-Point Filter Design: Where comes the DC-Gain difference between the bode plot and the step response from?

Introduction: What I wanted to achieve I am currently trying to implement a digital fixed-point filter on a STM32-Microcontroller by using the ARM CMSIS-DSP Library Link to reference manual. The ...
61 views

### Formula to compute FIR and IIR Filter coefficients

I am trying to understand filter design. I am trying to implement butterworth filter which would have high,low and bandpass using the difference equation representation for FIR and IIR. Given the low ...
72 views

### How to compute the inverse Z-transform

How to compute the inverse Z-transform of the form $$G(z)=\frac{z^{2n}}{a(z^{2n})+b(z^n)+c}$$ I started by taking $$F(z^n)=G(z)$$ so $$\frac{F(z)}{z}=\frac{z}{az^2+bz+c}$$ This can be solved ...
26 views

### Question in DSP signal flow graph

How to convert signal flow in Fig3 to Fig4? Is these two equivalent? ZHANG Xiuli, ZHANG Ruihua, CHEN Weidong. Design of digital parametric equalizer based on second-order function[C]// IEEE ...
119 views

### Does FIR filter remove DC offset properly?

I was checking FIR and IIR filter for offset removal. But I found that FIR can not remove DC offset properly. I think there's something more to do with the filter coefficients of FIR to remove DC ...
60 views

### What could cause ripples in the output of an IIR filter fed with a pure sine wave?

I am using an IIR bandpass filter designed using the elliptic filter in matlab to filter out unwanted frequencies. The filter is fed with a test input that has a dc offset and sine wave of frequency ...
840 views

### What is the maximum output of an IIR filter?

I am implementing an IIR filter in an embedded device based on ARM. It is implemented as a cascaded biquad structure (series of second order filters put back to back). The filter can be considered ...
40 views

### IIR Filters H(z)=Y(z)/X(z) Why do we insert the coefficents of the input for Y(z)?

The System Function of IIR Filters is defined as $$H(z)=\frac{Y(z)}{X(z)}$$ The Output Signal as $$y(n)=\frac{1}{a_0}\left(\sum^{P}_{i=0}b_ix[n-i]-\sum^{Q}_{j=1}a_jy[n-j]\right)$$ I do not understand ...
1 vote