Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [linear-phase]

71 questions
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could anybody explains me why IIR filters do not have linear phase?

Please tell me. Also I dont know why phase is linear with FIR filters. I would like quantitative analysis. And why linear phase is not achieved by IIR filters ?
hafsa
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Minimum Phase - All Pass Decomposition For Large Linear Phase Filters

UPDATE: I am looking for a robust approach to decompose linear phase FIR filters with 100s of coefficients into its minimum phase and all pass components. I originally thought determining all the zeros from the coefficients would be a mathematical…
Dan Boschen
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Downsampling lowpass filter for audio: FIR or IIR?

I'm working on a real-time audio processing project in which I have to downsample a 44.1 kHz to a yet-to-be-determined lower sampling rate essentially for reducing computational complexity. I'm looking for a decent downsampling filter, and I found…
Phonon
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Why do linear phase filters have symmetric impulse responses?

It was given as a fact that linear phase filters have symmetric impulse responses, but I don't see why that has to be true. Can somebody please explain or prove this?
CAJ
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Delay a signal in time vs in frequency

I have a signal h that I want to delay for a time t. I know that I could use two possible approaches: $h_{\text{delay}}[k] = \delta[k-\tau]\star h[k]$ $h_{\text{delay}}[k] = \text{IFFT}\left(\lvert H(\omega)\rvert e^{j\phi(\omega)}\cdot e^{-j\omega…
Mattia Surricchio
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Examples where non-linear phase filters are used

I stumbled apon this old question: Why is a linear phase important? There the explanation of why linear-phase processing (filtering) is important is very clear. Also the effects on waveforms due to linear and non-linear phase processing are very…
Todor Petkov
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Group delay of the FIR filter

For an FIR filter, with symmetrical tap values $h[N-1-n]=h[n]$, why is the group delay $\frac{N-1}{2} T$ (where $N$ is the number of taps of the FIR filter and $T$ is the sampling time)? Why is linear phase so important for the filter response?
Jayesh Parmar
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Why can't realisable IIR filters have linear phase?

I am studying IIR Filter Design and came across this arbitrary statement in my textbook which says that 'physically realisable and stable IIR filters can not have linear phase'. Would really appreciate if anyone can elaborate on this.
Devesh Lohumi
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Group Delay for Hilbert Transformer and Resulting Dispersion

An ideal Hilbert Transformer shifts the phase for all positive frequencies by $-\pi/2$ and all negative frequencies by $+\pi/2$ while maintaining constant magnitude everywhere. Group Delay is the negative derivative of phase with respect to…
Dan Boschen
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Filter design with a phase delay specification?

Given a desired filter magnitude response, plus acceptable linear phase and minimum phase FIR filter approximations, how can one design a filter with the given response and a delay specification of some value between minimum phase and linear phase?
hotpaw2
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Are the 4 types of linear phase FIR filters the only linear phase FIR filters one can come up with?

Basically my question is the same as the title: Are the 4 types of linear phase FIR filters the only linear phase FIR filters one can come up with? And if so, then why? I'm pretty sure that they are the only ones but I really can't explain why. Can…
zer0square
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Applications for the Maximum Phase Filter

A maximum phase digital filter has all zeros outside the unit circle, and has the maximum phase and therefore longest delay for a given magnitude response. Besides the possibility of needing a filter with the longest delay possible, are there other…
Dan Boschen
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Matlab `filtfilt` provides excessive transient

I observed that filtfilt suffers from an undesired behavior when I provide IIR bandpass filters having steep transition bands. Specifically, the output signal exhibits excessive transient response; nevertheless, this behaviour does not emerge if I…
ale83FiUni
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Why make the phase of an FIR filter linear?

I am new to DSP and filter design. It is easy to design an FIR filter with linear phase by making the coefficient sequence symmetric. However, why make the phase linear?
K.n90
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Regarding the advantages of generalized linear phase filters

I know that for a linear-phase filter with frequency response given by $$H(e^{j\omega}) = |H(e^{j\omega})|e^{j\phi(\omega)} $$ if the input of the system is $$x[n] = s[n]\cos[\omega_0 n] $$ where $s[n] $ is a narrowband signal with bandwidth…
diegobatt
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