Questions tagged [linear-phase]
The linear-phase tag has no usage guidance.
85
questions
0
votes
2
answers
61
views
FFT-Phase variation of a signal
I was studying the phase variation of a signal using sliding window FFT generated using below python code. The phase variation produced for my signal starts from somewhere in middle of the signal ...
- 101
0
votes
0
answers
93
views
Derivation of the 4 types of real-valued linear-phase FIR filters
Is there any resource or literature where I can find derivations/proofs for all four linear phase filter types starting from an arbitrary real valued impulse response? I looked at some of the ...
user64710
2
votes
5
answers
362
views
Linear phase with a non-integer delay?
Let's say you are given a frequency domain specification for a filter design.
As a simple example, let's use an ideal (brickwall) LPF. Now the impulse response of an ideal LPF is a $\operatorname{sinc}...
- 1,131
0
votes
1
answer
103
views
What is the position of all zeros of a minimum phase, Type 1 Linear Phase FIR Filter?
Let me write down all the facts that I know of.
In context of the z plane:
Minimum phase system: All zeros and poles of such a system lie inside the unit circle.
Linear phase FIR filter: For every ...
- 115
0
votes
1
answer
51
views
Linear phase impulse response causes non linear phase frequency response in GNU Octave/ Matlab
Assume linear phase FIR symteric impulse response like [1 2 3 4 5 5 4 3 2 1],shoud resault in a frequency response with linear phase negative sloped phase. but it ...
- 333
0
votes
0
answers
90
views
Parallel connected FIR filters type III
I am currently studying dsp and I have a question:
Let us assume multiple FIR filters with generalized linear phase of Type III and real IRs $h_1[n], h_2[n], ..., h_k[n],$ interconnected in parallel. ...
0
votes
2
answers
182
views
Why does an FFT-based filter change phase?
I am very new to DSP, and I'm just trying to figure stuff out here. I saw a video which stated that a filter implemented using an FFT would alter the phase of different frequencies differently. The ...
- 103
1
vote
0
answers
97
views
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.
...
0
votes
1
answer
173
views
Phase of an FFT after zeropadding
How does zero padding effect phase of an FFT?
I thought that symmetric zero padding in the center of an image or signal produces no phase change in the FFT (See Here), but I am getting different ...
- 297
1
vote
1
answer
144
views
Slope of phase function
Would appreciate some help understanding if I take the phase function of some transfer function and derivative it in the linear part of it which is around the resonant frequency what does this slope ...
- 13
0
votes
0
answers
100
views
Difference between MSK and CPSK
I'm trying to understand the differences between the MSK and CPSK transmission, but I am not understanding some things about it.
I understood that they are two signals without discontinuity, but what ...
1
vote
1
answer
396
views
Matlab: How to design digital equivalent for a lowpass Bessel filter (Thiran filter)?
In the process of applying a lowpass Bessel filter to my signal, I realized that besself function does not support the design of digital Bessel filters and the bilinear function can be used to convert ...
- 53
2
votes
1
answer
80
views
subquestion 2 : original Q "Difference between MSK and GMSK?"
if we talk about a modulation, we mention a linear and nonlinear modulation.
GMSK is nonlinear modulation, but it can be derived from a linear modulation as MSK, PAM and we talk about a linear ...
- 367
0
votes
1
answer
54
views
Why can't quantum phase noise in radio astronomy amplifiers just be filtered out after down conversion, instead of down-converting first?
In the related Astronomy SE questions below and their answers, it has become apparent that radio telescope arrays down convert their highest frequency bands before the first stage of amplification.
...
- 231
0
votes
2
answers
459
views
Issue Understanding Time Delay of a Digital Filter
I am new to the world of digital filters and am educating myself with the book Introduction to Digital Filters by J.O Smith III,. The author derives the frequency response of a very simplistic filter:
...
- 142
1
vote
2
answers
129
views
Frequency Sampling Filters (FSFs) NOT the Frequency Sampling Method
A class of digital filters called Frequency Sampling Filters (FSF) has been mentioned in a side note by Richard Lyons in another related question comparing IIR digital filter design using mapping ...
- 48.2k
13
votes
4
answers
820
views
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 ...
- 48.2k
2
votes
1
answer
126
views
Combination of type I FIR linear-phase systems
Let $h_1[n]$ and $h_2[n]$ be impulse responses of type I FIR linear-phase systems with lengths $M$ and $N$. What can be said about the phase response of the following filters?
$h_3[n] = h_1[n] + h_2[...
- 704
2
votes
0
answers
93
views
Equivalence between the linear phase of FIR filters and the (anti)symmetry of the coefficients
According to the Matt L.'s answer to this question, real-valued and causal FIR filters have a (generalized) linear phase response if and only if their coefficients satisfy (anti)symmetry condition. ...
- 704
0
votes
1
answer
90
views
Arbitrary phase FIR filter design
I would like to design an FIR filter using the frequency sampling method with nonlinear phase specifications. For example, between $0$ and $\frac{f_s}{4}$ a phase of $180^\circ$ and between $\frac{f_s}...
- 11
0
votes
1
answer
733
views
Determine group delay from the frequency response of FIR filter
I have a issue to find out, is there any way that one can determine a group delay from frequency response of the FIR filter. Let's say I have I type FIR filter with order of 51. Frequency response ...
1
vote
1
answer
372
views
What is the significance of the linear phase in the phase response of an M-point moving average filter?
I have plotted the magnitude and the phase responses of an M-point moving average filter, the following are the plots when M = 10:
We can observe that corresponding to every lobe in the magnitude ...
- 155
6
votes
3
answers
1k
views
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] = \...
2
votes
1
answer
716
views
What is the reason behind complex conjugate pairs in Linear Phase FIR filter analysis from the Pole Zero plot
When we say that a Generalized Linear Phase System must satisfy the pole zero plot with the condition that a complex zero not on the unit circle exist's in a pair of 4. Then I understand that I need ...
- 33
0
votes
3
answers
375
views
Does converting an FIR filter from causal to non-causal remove phase delay?
Let's say I have a causal 3-tap FIR filter:
$$y[n] = ax[n] + bx[n-1] + cx[n-2]$$
Assuming I have access to all the data prior to filtering and generate a similar non-causal filter:
$$y[n] = ax[n+1] + ...
- 793
0
votes
1
answer
181
views
Design FIR with linear phase response
What is the best way to design a FIR filter with a given linear phase response, such that each frequency inside the passband is phase shifted according to:
$$H(f)=e^{i2\pi f k}$$
where $k$ is factor ...
1
vote
1
answer
541
views
Resampling FIR coefficients
I have received from a client a 32-coefficient FIR filter running at 1 kHz. I would like to adapt the filter to a 24-coefficient FIR filter running at 750 Hz while preserving the 0-375 Hz frequency ...
- 3,735
1
vote
1
answer
75
views
What is the phase response of SRRC/NRZ/RZ pulse shapping filters and does it matter?
So I would like to know if filters usually used for pulse shaping (like SRRC) have a linear phase response, and if not, what this response looks like and does it matters in any circumstances?
- 57
2
votes
1
answer
607
views
How should we read FIR filter phase response graph?
What should we see from the FIR phase response graph, as an example for a linear phase? And what does this straight line at $0.5\pi$ mean?
- 161
3
votes
1
answer
367
views
Applications for the Maximum Phase Filter
A maximum phase digital filter has all zeros outside the unit circle, and has the maximum phase and therefore longest delay for a given magnitude response.
Besides the possibility of needing a ...
- 48.2k
5
votes
1
answer
1k
views
Why can't realisable IIR filters have linear phase?
I am studying IIR Filter Design and came across this arbitrary statement in my textbook which says that 'physically realisable and stable IIR filters can not have linear phase'. Would really ...
- 165
1
vote
2
answers
938
views
How to properly smooth the phase of a spectrum (or any unit-complex function)
I want to smooth the phase of a measured (transfer) spectrum without destroying unit-complexity of the phase factor. Suppose
$$f:\mathbb{R}\to \mathbb{C}\qquad , \qquad f(\omega)=r(\omega)\cdot {\rm e}...
- 256
7
votes
4
answers
2k
views
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 ...
- 71
1
vote
1
answer
567
views
FMCW radar: Linear phase change determination with sinusoidal decomposition
I am struggling to understand how linear phase shift can be determined with a transform whose main purpose is to determine frequencies rather than rate of change of a function.
In FMCW radar, ...
- 269
0
votes
2
answers
1k
views
How does one make a Zero Latency, Linear Phase, or Natural Phase filter?
Looking at FabFilter's ProQ3 plug-in, they have an option at the bottom of the window to switch between Zero Latency and Linear Phase modes (and I think a Natural Phase option too).
I'm familiar with ...
- 23
0
votes
1
answer
507
views
Is this phase response linear phase?
Would the following frequency response be considered linear phase? I know that linear phase is when the phase response is a linear function of frequency. However, the phase response is only linear ...
- 103
0
votes
1
answer
499
views
FIR Linear Phase Condition
This is the linear phase condition for FIR filters as expressed by my prof:
I don't understand why $G(f)$ can be negative. Isn't the Fourier transform expressed in polar form ? So the magnitude is ...
- 117
0
votes
1
answer
94
views
Constraints for Type 3 Linear Phase Filter
This might be a strange question - but most of the Type 3 LPF I'm seeing are having this in common for $h[n]$, assuming $h[n]$ is real:
We cannot have outermost element of h[n] lower than middle ...
5
votes
1
answer
382
views
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 ...
- 48.2k
0
votes
1
answer
883
views
How to Determine if FIR has a Linear_Phase Response w/o Matlab
Given the FIR transfer function:
h(z) = $ .36 + .384z^{-1} + .1608z^{-2} +.9712z^{-3} + .352z^{-4} + .18z^{-5} - .2z^{-6} $
How do you determine if this transfer function has a linear - phase ...
0
votes
1
answer
1k
views
Finding remaining zeros of linear phase FIR filter
Question given is: if $h(n)$ is a linear phase causal FIR of order $10$ with real coefficients, find the remaining zeros of this filter if the zeros given are
$$q_{1,2} = -2 \pm 2j$$
$$q_{3} = -\...
- 13
4
votes
2
answers
737
views
Linear phase FIR filter for impulse responses that don't appear symmetric
I would like to clarify some confusion I have about linear phase FIR filters of which do not seem to have symmetric impulse responses.
Starting with a simple case, a delay, $ h[n] =\delta(n-n_0) $ ...
- 297
0
votes
1
answer
2k
views
How to prove a filter has linear phase response?
I have designed an FIR filter to have linear phase response using odd-symmetry design. The coefficients of this filter are {2,1,3,1,0,-1,-3,-1,-2}. I am now being asked to prove it has linear phase ...
0
votes
1
answer
1k
views
Is ideal band pass filter (brick wall filter) linear phase? [duplicate]
I'm very new in digital signal processing.
I have multiple sensors and the way I filters the signals in post processing is:
take FFT of the signals.
put zero on out range of interesting frequency (...
1
vote
1
answer
162
views
Phase plot of $H(e^{j\omega})=(1-re^{-j\omega})\left(1-\dfrac{1}{r}e^{-j\omega}\right)$, $0<r<1$
I want to find the phase plot of $H(e^{j\omega})=(1-re^{-j\omega})\left(1-\dfrac{1}{r}e^{-j\omega}\right)$, $0<r<1$ for the interval $0\leq \omega \leq \pi$.
Method 1:
$H(e^{j\omega})=1-\left(...
- 151
2
votes
1
answer
1k
views
Downsampling impact on complex phase
For my application, I have to downsample a bandpass complex signal which spectrum is located on the second Nyquist zone.
Knowing that this processing will cause a spectrum inversion, what would be ...
- 98
2
votes
2
answers
574
views
Mean delay for a M tap harmonically weighted filter
I am trying to derive the mean delay for $M$ filter taps harmonically weighted:
$$y[n] = \frac{M\,x[n] + (M-1)x[n−1]... + 1 \cdot x[n−M+1]}{\tfrac12 M (M + 1)}$$.
For a uniformly weighted filter, I ...
0
votes
0
answers
236
views
Bandpass Fractional Delay Filter
I am designing a fractional delay filter, I found this code for lagrange FIR fractional delay filter, The fractional delay filter acts as a low pass filter, it passes low frequencies from 0 to 0.25*fs....
- 389
0
votes
1
answer
215
views
If group delay is a constant for all $\omega$, Does this system have a linear phase response?
I want to know if a system has a linear phase response using frequency response of this system.
So I got phase response of it and also group delay.
and after that I got to know that if group delay ...
- 43
0
votes
2
answers
274
views
How do I show an impulse response leads to a zero-phase frequency response?
I'm trying to understand how to show that with real coefficients, the phase response of a filter is 0. Here is the impulse response
$h[n] = b_1d[n+1] + b_0d[n] + b_1d[n-1]$
How should I approach ...
user34931