Questions tagged [infinite-impulse-response]

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

Filter by
Sorted by
Tagged with
1
vote
0answers
298 views

Real-time audio processing FIR vs IIR

My project consists in filtering an audio signal from the microphone, in order to remove noise, and find the time distance between two peeks with the highest precision possible. I understood that an ...
0
votes
1answer
130 views

Is there a way in MATLAB to approximate an FIR filter using an IIR Filter? [duplicate]

I am a student trying to understand how this is possible. I've done some research on the web with not many sources showing up with solutions to this problem that are usable. What techniques are used ...
0
votes
3answers
172 views

What is the need of IIR filter? When FIR have generally good/desirable characteristics?

FIR filters are generally stable and have linear phase response. These two characteristics are often desired in dsp So why do we need and use IIR filters,despite the fact that IIR filters often have ...
0
votes
0answers
26 views

I am stuck on a problem that only has a center frequency of $\pi/2$ for an IIR filter pole-zero plot of this using 2 poles and 4 zeros [duplicate]

Using a pole zero placement method, design an infinite impulse response band-pass filter with center frequency of $\pi/2$ radians per second. Hint: Use two poles and four zeros.
7
votes
6answers
3k views

Meaning of Phase response of a filter? In simple words?

What is meant by phase response of a filter? Often it is associated with restoration of signal shape,so if a filter has linear phase response, its output looks like input otherwise output is ...
0
votes
1answer
329 views

Implementation of Filters in Python

I've implemented 2 filters in Python I would like to know if they look OK or not.. I've implemented an lowpass FIR Hann Filter and an lowpass IIR Chebyshev type 1 filter. My plots look like the ...
0
votes
1answer
59 views

Can't implement correctly Python IIR and FIR Filters

I'm trying to implement 2 lowpass filters and see the difference between them from plots( one FIR filter that needs to be designed with the Hann window method and another IIR filter using Chebyshev ...
0
votes
1answer
184 views

Filter: IIR Filter

How IIR Filter coefficients formula derived? for LPF, HPF, BPF, BSF there are coefficients formula for a0, a1, a2, b0, b1. How it came? I would like to know the derivation for all those coeffs w.r.t ...
2
votes
1answer
55 views

Approximate IIR filter with FIR filter with energy restrictions

Hi I was presented with this problem I would like some guidance to solve: I am given the following DT channel model: $$C(z) = 1-0.3z^{-1}$$ I am first asked to design an IIR linear zero forcing ...
3
votes
4answers
663 views

Single pole IIR filter, fixed point design

We want to do a fixed point implementation of the single pole IIR filter: $y[n] = a\cdot x[n] + (1 - a)\cdot y[n-1] \quad ;\qquad 0<a<1$ What are the main design considerations to think about ?...
1
vote
1answer
228 views

IIR - How the gain is calculated?

I try to extend my understanding of digital filter design, so I play around with some YouTube videos and the MicroModeler DSP with the following IIR design (based on a video): I use the following ...
0
votes
1answer
42 views

Gain at critical frequency for Butterworth and Chebishev filters

In Chebyshev filter the critical freq occurs with gain Gp But in butterworth filter it is always at -3dB; why does this happen? Can anyone explain intuitively on this?
3
votes
2answers
163 views

Why does this parallel IIR filter have such a weird form?

Referring to "Parallel 1st-order IIR filters" on this wikipedia page, the structure of a 4-parallel IIR filter is discussed. However, the format in which it is implemented seems very odd. Why is it ...
0
votes
1answer
280 views

Output length of an IIR Filter

In general, the output length of an FIR filter is given by (N+M-1) samples, where N stands for signal length and M stands for the number of filter coefficients. Can the same formulae be applied for ...
0
votes
1answer
93 views

Adaptive equalization vs inverse of transfer function

I have the following equalization problem as shown in the figure below: Now I can compute the coefficients for my adaptive FIR filter c (dim(c) = N) the following: $\mathbf{c_{opt}} = (\mathbf{H}^T\...
0
votes
1answer
325 views

How do I normalize a predesigned IIR filter?

Obviously my question here is very similar to this previously asked question: How to normalize predesigned IIR filter coefficients to have unity gain? Unfortunately, in the responses available to ...
0
votes
2answers
438 views

Draw a structure for IIR Filter given H(z)

This is the transfer function for the Direct Form 1 of the IIR Filter: I'm trying to understand the rules to convert $H(z)$ into its corrispondent structure I've just understood how to draw $H_1(z)$,...
0
votes
1answer
413 views

Can I get some help plotting an IIR filter frequency response in Python?

The problem I'm trying to solve is described here. In my script, I used Euler's identity to calculate z^-n, such that z^-n = cos(omegan) - jsin(omegan). I find the magnitude of these values from a ...
0
votes
0answers
48 views

pressure decay filtering

So, I've been dealing with a series of pressure decay curves from a pressure transducer. Each one has a waterhammer effect as a consequence of shutting down pumps. Here are examples of 3 curves: I'm ...
0
votes
2answers
160 views

Preloading an IIR Filter

Is there a mathematical approach to initializing an IIR filter so that turn-on transients are minimized? Background: I have a high pass Butterworth design that overloads at the start of a sine wave ...
0
votes
1answer
41 views

To find the impulse repsonse using the difference equation

A causal linear time-invariant filter has transfer function a) Denote the input signal by x[n] and the output signal by y[n]. Find the difference equations for the filter. f) Find the impulse ...
0
votes
3answers
122 views

Impulse response of an infinite-length system

I have a system which is expressed as following: $$y[n] = x[n] - \alpha y[n-N]$$ where $y[n]$ is the output and $x[n]$ is the input. When I take the z-transform of both sides, I've found the transfer ...
7
votes
2answers
360 views

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 ...
1
vote
2answers
600 views

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.
1
vote
1answer
447 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 ...
0
votes
2answers
137 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 + ...
1
vote
1answer
121 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 ...
1
vote
2answers
863 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 ...
2
votes
2answers
106 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/...
1
vote
0answers
100 views

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 ...
1
vote
2answers
338 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 ...
2
votes
3answers
323 views

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. ...
1
vote
1answer
211 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 ...
0
votes
1answer
128 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 ...
0
votes
1answer
50 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 ...
3
votes
2answers
629 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 ...
3
votes
1answer
171 views

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 ...
1
vote
1answer
494 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 ...
1
vote
1answer
98 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....
1
vote
1answer
84 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 ...
2
votes
3answers
3k 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 ...
0
votes
0answers
97 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 ...
2
votes
0answers
63 views

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 ...
0
votes
1answer
502 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? ...
0
votes
2answers
274 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 ...
2
votes
1answer
1k 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[...
2
votes
3answers
528 views

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 ...
7
votes
3answers
460 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 ...
3
votes
1answer
259 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 ...
0
votes
1answer
339 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 ...

1 2
3
4 5
9