Questions tagged [group-delay]

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1answer
68 views

What is the relationship between group delay and propagation delay for a filter?

I was trying to design a filter for a system and I was able to obtain the group delay plot in matlab using grpdelay. The group delay output is in samples. However, I was not able to relate that data ...
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50 views

Matlab group delay not corresponding to reality

I studying effects of digital filters group delay (IIR). In Matlab there is a function grpdelay which allows for particular frequency get a value of delay in samples But after filter applying and ...
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0answers
27 views

Stability of filters with negative phase delay, group delay, and positive phase

Lets assume I have an IIR filter with : bz = [1.0195 0 0]; az = [1 0.0166 0.0020]; fvtool(bz,az) The filter is stable as i can see. If you check the phase delay ...
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1answer
44 views

Group Delay of Mulitrate system

how do I find the group delay of multirate system.(sample rate converter) , IIR non-linear phase filter Say decimation by 2 (with lpf) = tf1(num,den) then again decimation by 2 (with lpf) = tf2(num,...
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3answers
120 views

How to practically correct for group delay imposed by a digital filter (Python)

I'm using Python to filter a signal using a Butterworth filter (scipy.signal.butter) and subsequently passing this through a forward-backward filter with cascaded second order sections (scipy.signal....
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1answer
55 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 ...
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2answers
37 views

Bandpass with large group delay

I read that a simple delay filter that delays all frequencies requires at least $\frac {N-1} {2f_s}$ taps. In my case this would result in way too many taps (20000). Can I achieve this with ...
0
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1answer
91 views

Group delay plot of a Moving average filter

I am implementing the moving average filter in Matlab. Using fvtool on this filter, gave the following output curve, is this group delay curve correct? Edit: My confusion is regarding the values of ...
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1answer
74 views

Group delay of non differentiable unwrapped phase

As we know group delay as a function of frequency, computed as differentiation of unwrapped phase, but what happen at those frequencies where unwrapped phase is non differentiable?how to calculate ...
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0answers
34 views

Estimation of Group Delay from Noisy Frequency Response Measurements

Consider a linear, time-invariant system. Noisy measurements of the magnitude and phase associated with the frequency response of the system are available over some dense generally non-uniform grid ...
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2answers
165 views

How do you calculate the group delay in samples of a Biquad Filter at a given frequency from the coefficients?

If I have a BiQuad all-pass filter with a given set of coefficients such as: g: 0.903228 a1: -1.88142 a2: 0.903228 B1: -2.08299 B2: 1.10714 And my operation per ...
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2answers
345 views

Negative group delay and envelope advance

I am having a doubt reading about delays in signal processing. Let there be an input to a LTI system with frequency response $H(f)$, given signal $x(t) = a(t)\cos(2\pi f_ot)$, where $a(t)$ is a ...
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2answers
290 views

Calculate the time delay introduced by group delay for IIR-Filters

First of all, let me show what I mean by a simple example of an FIR-Filter: I designed an FIR-Filter with a constant group delay of 323 samples and my sampling rate is 500 Hz. Now I can calculate the ...
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4answers
308 views

What is meant by “Group delay”?in simple words?

Although likes of this question have been asked many times on DSP SE But i am unable to understand those and i wish to have a crystal clear explanation in simple words with example The only thing ...
5
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1answer
174 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 ...
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1answer
173 views

Compensate delay of non-symmetric (non-linear phase) filter

Lets assume I want to apply a matched filter h which is non-symmetric to my signal x and the output is ...
3
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1answer
255 views

Compensating the Group Delay of an Analog Filter using DSP

I am having a problem in my current project where I need to measure different biological signals (like ECG) simultaneously. As the instrumentation hardware is developed by different people over time, ...
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1answer
154 views

Measuring group delay through a linear phase filter

I'm having a difficult time wrapping my head around a phase/ group delay problem and it corresponding to where you start sampling so I built up a system to test some of these issues. The system passes ...
0
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1answer
111 views

Ideal Discrete Time Hilbert Transformer with constant group delay

Let's assume we have an ideal discrete time Hilbert Trasnformation system (90-degree phase shifter) with a frequency response over one period: $$H(e^{jw}) = \left\{ \begin{array}{ll} -j & \...
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1answer
75 views

average linear phase (group delay)- how can be calculated, given a signal samples at frequency F?

Average linear phase (group delay)- how can be calculated, given a signal samples at frequency F? The definition doesn't help since the frequency is constant: $-[signalPhase(n)-signalPhase(n-1)]/[...
2
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1answer
639 views

Compute group delay of an audio file from STFT

I'd like to reproduce results from this paper in which the authors used Group Delay-grams as an input to the Machine Learning model. The Machine Learning side is not the one that I have problems with. ...
2
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2answers
440 views

How to compare many bandpass filters (for their signal propogation delay)?

Let's say we have an audio signal sampled at 96 kHz, and we want to compare several bandpass filters to find the one with the lowest rectangular-envelope-propagation-delay (see graph below). The band ...
2
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2answers
436 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 ...
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0answers
64 views

The grid frequencies In the design of a digital filter

I want to find many difference 'h' with same group delay and length filter using this code : https://gist.github.com/mattdsp/17f508d2b368db61f47689e4622d8841/c1518f22a5aa451951601b56c5d9f72743868bfe ...
0
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1answer
372 views

Compensating for group delay in FIR with symmetrical coefficients

Suppose I have a sinusoidal signal of 50Hz sampled at 6.4kHz and I wished to filter it at: Band pass: 160Hz, Bands stop: 800Hz, Apass:0.1db, Astop: 106db For a FIR filter order of 40 I would get 41 ...
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0answers
999 views

All pass filter design for group delay compensation

I've designed an IIR bandpass elliptic filter in Scilab with the following parameters. Sampling Frequency = 25000 Hz Lower cutoff frequency = 100 Hz Upper cutoff frequency = 150 Hz Pass band ripple = ...
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0answers
661 views

IIR filter group delay

I've designed an IIR bandpass elliptic filter in Scilab with the following parameters. Sampling Frequency = 25000 Hz Lower cutoff frequency = 100 Hz Upper cutoff frequency = 150 Hz Pass band ...
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2answers
425 views

Interpolated FIR filter group delay

I'm trying to design a digital low pass filter with a narrow transition band. My sampling rate is 25 kHz, the cut off frequency is 60 Hz & the transition band width is 4 Hz. I'm looking for about ...
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2answers
2k views

Physical Meaning of Negative Group Delay for causal LTI systems

I have implemented in Matlab (with minor variations) the example 5.1.2 "Illustration of Effects of Group Delay and Attenuation" I found in Alan Oppenheim's Discrete-Time Signal Processing 3rd edition. ...
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0answers
79 views

Interpretation of instaneous time and instaneous frequency in time-frequency plane?

In this paper: Sparse time-frequency representations, Given signal $x(t)$, the time-frequency representation was got by Gabor transform and was denoted by $\chi(t,\omega)=|\chi(t,\omega)|\exp(\mathrm{...
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1answer
69 views

position of useful filtered data inside DFT based filtered output

I'm trying to filter a 400 samples signal with various bandstop FIR filters (constant group delay), one at a time to see which one gives me the desired result. Every filter was build using the Kaiser ...
0
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2answers
628 views

Finding phase from group delay

I know that group delay is defined as : $$\begin{align} \tau(\omega) = grd [H(e^{j\omega})] &=-\frac{d[\arg[H(e^{j\omega})]]}{d\omega}\end{align}$$ But if what is available is group delay itself,...
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0answers
58 views

How to initialize shift registers in polyphase filter based resamplers to avoid or compensate for group delay?

I have a signal a = [a(t0),a(t1),a(t2),..,a(tN-2),a(tN-1)] I'm using a polyphase filter based resampler with filter length $L$ of $8$, fixed interpolation rate $I$ of $10000$ and decimation rate of $...
5
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3answers
363 views

Group delay of $H(\omega)= 1- re^{j \theta}e^{ - j \omega} $

I'm studying chapter 5 of Discrete-Time Signal Processing 3rd edition by Alan Oppenheim and I'm having serious difficulties understanding how he obtained equation 5.57. For those who don't have this ...
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3answers
3k views

Group delay of moving average filter

I have implemented a moving average filter (in Python) where I fill a list with values and average them. When new values arrive the oldest will be deleted. Now I am wondering how much delay I get ...
2
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1answer
289 views

How to obtain a meaningful group delay graph using matlab

Problem: I'm trying to analyze the behavior of an FIR filter with the following impulse response/kernel: Using Matlab's function grpdelay(myKernel,length(myKernel)), I obtained the following figure:...
4
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1answer
706 views

How to implement a FIR filter with correction of group delay on c#?

I read respect to digital filters, and implemented both IIR and FIR filters and I found that this type of filters have a called "group delay". Now I know that the IIR have a non-linear group delay and ...
2
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0answers
169 views

How to design all-pass filter by specifying phase requirements?

I want to delay the part of signal above (or below) specified frequency, but I don't find any books or tutorials to tell how to design is. The commonly used biquad APFs (such as the one introduced in ...
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2answers
432 views

How to Add Group Delay?

I was confused about the value of group delay, I am not sure whether my opinion is correct. For example, if I want to add a group delay of $0.25$ time units to a zero-phase signal, does it mean that I ...
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2answers
264 views

Showing linear-phase frequency response when only real part is known

I'm studying for an exam, and this particular practice problem is missing the solution: Given a causal LTI system where only the real part of the frequency response is known, $$\Re\left\{H(j\...
2
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1answer
2k views

Differences between phase and group delay

Yet another group delay vs. phase delay question! Though this is a question that's been asked several times I don't feel like it's been fully discussed so I'll post an example that I can't quite seem ...
3
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1answer
515 views

Group delay of the integrator

I have a set of sensors, some velocity-meters and others accelerometers. To process the two groups together, I integrate the accelerometers signals (in time domain, using MATLAB's ...
4
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1answer
3k views

Interpolating/Decimating CIC Filter Group Delay

I have an Interpolating Cascaded Integrator Comb (CIC) filter designed as so: Rate Change = 100 Number of Stages = 4 Differential Delay = 1 I'd like to calculate ...
1
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1answer
596 views

Group delay (MATLAB $\tt grpdelay$)

I have been trying to figure out how it is I have an IIR filter with large negative group delay. It's my understanding that if a filter is causal and stable, the group delay can't be negative at all ...
1
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1answer
1k views

How to remove a costant group delay?

I have to subtract, from a signal x[n], its version filtered thorugh an LPF FIR filter, like this: xf=filter(h_lpf,1,x); y=x-xf; How can I remove the group delay introduced by the filter h_lpf into ...
2
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1answer
224 views

Lag in financial trading vs Group Delay in signal processing

I'm a newbie to Signal Processing - and so I'm providing a "background" and a "question" section separately. Background: Suppose I have a linear filter (w.r.t. given as $\theta_{t+1} = \theta_t + ...
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1answer
149 views

Sketching Phase Spectra Using Group Delay and Magnitude Spectra Informations

I have only magnitude spectra and group delay information and I need to sketch phase spectra from this information. For example, group delay is given like this: $\tau_{g}(\omega) = c$ where c is a ...
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2answers
2k views

How to design a filter with custom group delay — why is it an IIR?

Say I have an FIR filter with desired magnitude characteristics. I could imagine using an allpass IIR in series with the FIR to alter the group delay characteristic to provide both a 'magnitude ...
1
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1answer
2k views

once again,confusion between phase and group delay [duplicate]

Despite,reading up on this I'm unable to find crystal clear clarity on the differences b/w phase and grpdelay functions and interpretation of grpdelay's output. I have designed a low pass butterworth ...
3
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2answers
1k views

Allpass group delay formula and effect on Karplus-Strong

Some introductory questions: What is the unit of the group delay in a digital filter (is it samples?) What is $\Omega$ in the equations below (is it $\Omega=2 \pi\frac{f}{f_{sample}} ?) $ If I got ...