# Questions tagged [infinite-impulse-response]

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

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### FIR estimator for IIR system

Suppose that we have a dynamical system of which the impulse responses are infinite (IIR). Now I found methods on papers (http://dx.doi.org/10.1109/9.839942) estimating states or outputs of such a ...
7k views

### How do I find the phase response of a filter from the filter equation?

I am new to this forum. I have been teaching myself DSP for the last two years, so my experience and knowledge has a long way to go. I am trying to find the phase response of a specific filter that I ...
44 views

### Calculating the product of discrete transfer functions

I'm trying to construct a higher order IIR from a biquad cascade, I know this is generally frowned upon, but it's necessary as the coefficients will be embedded into a larger formula used in a FDTD ...
693 views

### Regarding BIQUAD IIR implementation in MATLAB

I want to implement a high pass filter (order 4) in MATLAB using cascade form. ...
482 views

### Zero-Phase Algorithm in Matlab

From this document it's says 1.Filter the Data 2.Flip that 3.Filter again 4.and Flip that again for zero-phase filter. but when i do this in matlab , i'm compare ...
5k views

### Are all IIR filters unstable in nature?

I know this question has been asked here numerous times. But I am still unclear here :( My book says, A linear time-invariant system is stable if its impulse response is absolutely summable. (G. ...
782 views

### Convolution by IIR filter, a case where circular convolution is allowed?

The question is, how to attain the frequency domain representation of any signal (which is finite, non-unit length) convolved with an IIR filter. The correct answer in my opinion is that there is in ...
39 views

### why difference between this example and matlab result

everyone fs=30 000 , fc=3000; when i code apply this in matlab result is very difference ...
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### There is a mysterious factor when compute coeffiencts

everyone i m trying write higher order butterworth algorithm in c++.I can compute nominator and denominator second order. So i tell myself , i can cascade struct for higher order. But there is between ...
121 views

### Is the below filter linear phase

$$h(t) = \frac{1}{1 + t^2}$$ and is it IIR or FIR filter. I tried finding the Laplace transform of this filter to get the data flow diagram with 5 taps and T=2s, however, I am unable to solve this. ...
372 views

### What is the correct way to apply multiple IIR filters to a signal in MATLAB

I am attempting to apply multiple IIR filters (one band-pass, one high-pass, and one low-pass;each with Fs of 44.1 kHz ) to a signal in MATLAB by using the ...
920 views

### Why lattice-structured all-pole IIR filter becomes stable, if the k-coefficients satisfies $|k_i| < 1$? [closed]

Why the lattice-structured all-pole IIR filter becomes stable, if the k-coefficients satisfies $|k_i| < 1$? Anyone who can tell me the way how to prove it, would be so thankful for me :) ps. If ...
1k views

### May a causal system depend on future values of its own output

For example, let's assume a system given as y[n]-9y[n+2]=x[n] I convert the difference equation to y[n]=(y[n-2]-x[n-2])/9 ...
3k views

### Convert a FIR to an equivalent IIR

Is there a way to convert a FIR to an IIR filter with the most similar behavior?
418 views

### Discrete-time Biquad filter: Relation between peak frequency and pole frequency

This question arose from a discussion in the comments to this question and its answer. The author of that question discussed a discrete-time second order filter described by the following difference ...
320 views

### Overlap/Chunk processing possible with Zero-phase?

I'm relatively new to DSP and I'm currently investigating FIR filter and IIR filters. From what I've found FIR filters can be implemented efficiently using the overlap-save method, but I was wondering ...
436 views

### Lynn's integer filter has a linearly increasing trend

I have a PPG signal sampled at 50Hz and I want to filter the signal using Lynn's integer filter. I.e \begin{equation} H(z)=\frac{(1-1/z^m)^2}{(1-1/z)^2} \end{equation} Cutoff frequency is 5Hz, so ...
474 views

### How to compute DFT of IIR

This question pertains to frequency domain filtering. I'd like to multiply an IIR filter's frequency response by a buffer of samples that have been FFT'd. I get how I'd evaluate an FIR, I'd FFT and ...
418 views

### How to estimate filter coefficients of an all-pole system?

Suppose we have measured the frequency response of a system that is known to be all-pole; measuring impulse response is not possible. What are the methods available, if any, to estimate the ...
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### How to shift the center frequency of an IIR filter

I have a pre-designed in-series 14th-order IIR filter in second-order sections. Problem is, when I simulate and measure the behavior in my codec, there is a frequency shift downward (as compared to ...
334 views

### equations to calculate coefficients of recursive IIR Gaussian blur filter

I am reading the implementation of IIR Gaussian blur filter from this link. In the source code, the coefficients are generated by the following code ...