Questions tagged [infinite-impulse-response]

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

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Why can adaptive IIR filters result in unstable solutions?

For adaptive filtering, both finite and infinite impulse response (FIR/IIR) filters can be utilized. As an advantage of FIR filters in this context, guaranteed stability is often mentioned, while IIR ...
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Factoring digital IIR filter as a causal and anticausal pass?

Background: I'm new to signal processing and I'm reading some papers on B-spline interpolation of digital signals and trying to understand how a computation is derived. If I'm given samples from some ...
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FIR or IIR filter from poles and zeros

Is it possible to differentiate between FIR and IIR Filter just by knowing the poles and zeros of the system? If yes, how? If not, why? Thank you.
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55 views

Understanding a lowpass - comb filter implementation

I try to understand the implementation of the low-pass comb filter of the Freeverb reverberation algorithm: https://ccrma.stanford.edu/~jos/pasp/Lowpass_Feedback_Comb_Filter.html The original ...
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37 views

Lattice structure realization of an all-pole system

Given an IIR system with the system function, $$ H(z) = \frac{1}{2 + 1.4z^{-1} + 1.8z^{-2}} $$ I need to draw the lattice structure realization. I have drawn the lattice structure for $\frac{1}{1 + ...
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38 views

High order IIR Comb Notch Filter with small Bandwidth - Low atenuation of harmonics

Im filtering an EMG signal, more precisely the 50 Hz frequency and its harmonics. For that, I've constructed a comb notch filter (on filterdesigner in Matlab), with its fundamental frequency being 50 ...
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57 views

How to filter data with given numerator and denominator coefficients of an IIR Filter, in MATLAB Implementation

Coefficients are: b = [9.02201251375918 0.485095309463300 -0.571759308660462 3.63774928924158 4.42592447788520 1.30093840271037 -0.898592924453941 -9.08965268561448 -12.4939309921467 ...
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48 views

How would one design a (quasi) linear phase adaptive notch filter for a single complex tone?

While IIR notch filters are attractive, I need to retain phase linearity at the filter output. I imagine that it's possible to use a standard IIR notch filter: https://www.researchgate.net/...
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Vary poles/zeros of digital IIR filter

Many applications that produce sound, such as software synthesizers, are able to apply a filter that varies with time, such as applying a low pass filter that varies with an LFO. I currently have a ...
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60 views

IIR Direct FormII Filter second order in VHDL, false output

I am trying to implement an IIR second order in Direct FormII in VHDL. To make it easier to understand for me and to avoid former timing issues, I implemented the operations sequentially. In my ...
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Matlab IIR cheby2 bandpass, problems with Magnitude

I am trying to implement an IIR bandpass in Matlab. There are two things I don't understand. But first of all, let me post the code. ...
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1answer
40 views

Methods to evaluate the quality of an IIR Filter fixed-point implementation

I'm implementing a scattered look-ahead IIR filter in Matlab/VHDL, basically I convert an order-2 IIR filter into an order-4 IIR in order to take advantage of the pipelining of an FPGA. (reference ...
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1answer
44 views

Automotive Audio Question: IIR Filters and minimum phase

In a car, does matching the EQ of both the left and right side using IIRfilters mean that I'm matching the phase of each side? I have someone telling me that the car's environment is mostly minimum ...
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33 views

MATLAB Convolution

I am designing an IIR notch filter using pole-zero placement method. I am trying to convolve the two zero locations using ...
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184 views

Numerically Stable IIR filter

I am making an IIR Filter and I am running into problems with stability with higher orders. The values go off to infinity as soon as it starts. So far, I've been using MATLAB to generate my filters ...
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Jacobian Computation in Least Squares IIR Filter Design

Long time lurker and first time poster - but unfortunately I haven't had any joy untangling this on my own. I've been studying Mathias Lang's thesis, Algorithms for the Constrained Design of Digital ...
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113 views

Why Wiener filter not IIR

I would like to limit discussion to discrete time causal Wiener filter. By definition it is an FIR filter, and it also has optimality under Mean Square Error criterion within the class of linear ...
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1answer
44 views

Criterion to choose length of an accumulator and product

I am designing an IIR filter with fixed-point arithmetic and I have to select the proper length for the accumulator and product. I would like to know a standard to follow in order to choose its length....
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1answer
49 views

bibliography about implementation of IIR filters

I need to implement a 6th order IIR filter. The filter I need to implement is the A-weighting. I've simply used the bilinear function of Matlab with an fs of 20Khz. I need to implement this over the ...
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128 views

How to determine if an IIR filter is causal or non-causal?

It may sound impractical, as only causal system are passively realizable, but what I am facing is a general statement made regarding recursive digital filters: for them to be stable, the poles should ...
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27 views

Filter design for decimation of 1.1 kHz sensor sample rate to 100 Hz processing rate

Suppose, you have a signal source which is sampled by 1100 Hz and is "somehow" band limited to either 235 or 440 Hz. In my application, that's the ST IIS3DHHC accelerometer. There is an appnote for ...
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Calculating pre-history of recursive filter from state space representation when optimising for initial z

For a recursive filter, suppose a set of $b$ and $a$ coefficients have been calculated. Assume a state-space representation for which an initial set of $z$-values have also been calculated as in ...
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94 views

IIR filter with circular buffer - Arduino [closed]

I am trying to implement a butterworth lowpass filter with a circular buffer. The code below does not filter as intended and I am not really able to understand what is wrong. Any suggestion? ...
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142 views

Floating point to fixed point in C

I've been trying to make a digital filter. I've used the following transfer function to get my digital coefficients https://gyazo.com/00195ef119f0b2ff93fa5855715abdc9 Which i've then transfered to ...
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1answer
93 views

Using Matlab's filter() function for solving difference equation with initial conditions

I am trying to solve a difference equation with initial conditions using Matlab's filter function: $$y[n]=\frac12y[n-1]+x[n],\qquad y[-1]=1\tag{1}$$ For $x[n]=6u[...
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Presenting an all-pass filter of a high order as a cascade of all-pass filters of the 1-st order

Are all-pass filter of the n-th order just a cascade of N all-pass filters of the 1-st order? There are some nice statements regarding zeros, poles, and gain for the 1-st order. Can those statements ...
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Impulse response of discrete time system

I am learning about discrete systems and in this derivation something struck me as quite odd. Solving for $A_0$ in this equation seems dubious as it ignored all other values of $n$. For example, at $n=...
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333 views

Protect an IIR filter from being reverse-engineered

I created a somewhat unique IIR filter and I want to protect the filter from being reverse-engineered I think you all know it is quite easy to get all the different weights of an IIR by using impulse ...
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95 views

Fast Recursive 1D Signal Smoothing - IIR / Auto Regressive Implementation of Gaussian Smoothing

I have just begun to dive into the field of signal processing, but there is the need to program a digital filter, that has to smooth a realtime signal from a sensor device. As far as I know, in my ...
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1answer
149 views

Digital filter design of time series for specified frequency response function

I am currently working with vibration measurements in structures. In the netherlands there is a guideline for verifying vibration measurements for damage to machinery. This is the so-called "SBR ...
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1answer
297 views

Explanation of FIR and IIR Filters with Simple Words

It seems I am unable to understand how these filters work and what is the point of using them, no matter how many tutorials I watched. Could someone please explain, in simple words, what FIR and IIR ...
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91 views

What version of sinc function to use ? (With additional factor of $\pi$ or not.)

I have an exam tomorrow on Signal Processing and one of the questions can go two ways: Use a Hamming window to design an Nth th order (N+1 tap) band pass FIR filter with a pass-band between $f_0$-$...
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Practical implementation of IIR/biquad filters following non-textbook transfer function of real-wold analog filter

I am trying to program a DSP filter to study prototypes of loudspeaker filters, which will be implemented as passive analog circuits in the final speaker system. This process involves simulation of ...
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483 views

Why is it easier to design an IIR filter in the continuous time domain than in the discrete time domain?

Given that the goal is to approximate the ideal filter with an IIR filter, why would it be easier to design it in the continuous time domain than the discrete? This paper says: Discrete time ...
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Constructing a lowpass digital differentiator such that maximum error is $n$ dB for passband

I want to construct a lowpass digital differentiator with uniform-interval samples such that error from ideal differentiator is $n$ dB in magnitude at maximum for the passband up to frequency $\...
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1answer
99 views

How to use the iircomb filter in matlab

I have a sound file that needs filtering which looks like this: Hence I think that I have noise spaced equally at 832Hz. i tried to use the iircomb filter taken from mathworks website and i managed ...
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1answer
100 views

Determine poles and zeros of a specific filter design

I have a design question and need to determine poles-zeros of a IIR bandpass filter. Requirements are: 1-order should be 3 2-causal 3-real valued impulse response 4-stable 5-cutoff freq: pi/3-pi/...
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134 views

Relation between order and stability in IIR filter

What is the effect of increasing order of IIR filter? does it also effects stability? If we have an IIR filter of order 6, now we change its order to 7, will there be any change in its stability?
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FIR butterworth also possible or just IIR?

can we use butterworth and other such filters like chebyshev,elliptic etc with FIR or they can be only used with IIR?
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How to apply two notch filters simultaneously

I have a sound file that I need to apply a notch filter to in Matlab. comparing to original file I have two frequencies which are the noise. Applying a notch filter like this one: ...
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Phase noise modeling using gnuradio IIR filter

I need some advice regarding phase noise modeling using gnuradio IIR filter. I'm trying to synthesize phase noise (multiplicative) with a given noise mask. In one paper, the authors were able to ...
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1answer
72 views

difference between conventional analog butterworth filter and that implemented through IIR

I am confused what is difference between conventional analog butterworth filter and that implemented through digital technique using IIR
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139 views

Design of FIR and IIR filters in Matlab

I need to create 4 different pass-band filters. What remains the same throughout is the following: Sampling Frequency = $3000Hz$ Pass-band Frequency = $900Hz-1200Hz$ Now, these are the filters I ...
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Single-pole IIR low-pass filter - which is the correct formula for the decay coefficient?

A single-pole IIR low-pass filter can be defined in discrete time as y += a * (x - y), where y is the output sample, ...
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What is zero-phase filtering and forward-backward filtering?

I am pretty familiar with IIR and FIR filtering and I have implemented them in my several projects. However, recently i found something called zero phase filtering. I have tried to understand it but ...
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1answer
91 views

Orders of complimentary butterworth filters for IMU

I'm currently trying to design a complimentary filter for deployment on a drone, as part of an assessed semester project. Even though processing power is not an issue (we have GHz, lots of pipelining ...
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86 views

Why using the impulse respond of an LTI to characterize its output?

We all know that every LTI, is defined by its transfer function, so we can determine the output of any system, (using common transforms). It is also known that we can determine the output of any LTI ...
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37 views

How do I add more resolution / taps to an analog -> digital filter?

(I am trying to create an IIR audio filter that adds reverb to an initial sample) Say I designed an analog filter to model acoustic attenuation based on the following mathematical model: $$ I = I_0 ...
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1answer
106 views

Using MATLAB Function `mpiir_l2()`: Results Are Not IIR but FIR Filters - Why and How to Avoid This?

I'm using mpiir_l2() from user Matt L's PhD thesis to design IIR filters. I set the number of numerator and denominator coefficients both to the same value (between ...
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495 views

IIR high pass filter

I'm trying implement an IIR filter. I know the IIR filter come from that equation: and i found that for high pass filter the coefficients are: where fc = cut freq. here my matlab code: ...