Questions tagged [delay]

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21
votes
3answers
50k views

What effect does a delay in the time domain have in the frequency domain?

If I have a signal that is time limited, say a sinusoid that only lasts for $T$ seconds, and I take the FFT of that signal, I see the frequency response. In the example this would be a spike at the ...
13
votes
5answers
4k views

Is a notch filter for 50 Hz without delay possible?

I am processing an EEG signal (2 kHz sampling frequency) from hardware and the built-in filter doesn't work as intended. FIR gives a delay, and IIR is unstable. The signal of interest is from 4&...
9
votes
1answer
6k views

Measuring time delay of audio signals

Before anyone yells at me I fully realize that this question has been asked numerous times. I assure you that I've read through the existing questions and answers but I am still confused about part of ...
6
votes
4answers
4k views

How to calculate a delay (correlation peak) between two signals with a precision smaller than the sampling period?

I would like to calculate a delay between two signals in MATLAB. Normally, I would do this with a cross-correlation (xcorr), and then calculate the position of the ...
5
votes
3answers
753 views

Digital delay effect: avoiding clicks on delay time change

I'm implementing a digital audio delay effect using a simple circular delay line. Changing the delay time by making the delay line longer or shorter introduces discontinuities in the audio signal, ...
5
votes
3answers
583 views

Continuous phase for phase delay calculus in FIR filters

I would like to estimate the phase delay accurately for any random FIR filter. The definition of the phase delay is the continuous phase divided by the angular frequency (with a sign change). That ...
4
votes
2answers
796 views

Flat fading criterion of OFDM subcarrier spacing

I have always thought that the OFDM subcarrier spacing $\Delta f$ is chosen such that not too small because Doppler spread can destroy subcarrier orthogonality not too large to avoid Cyclic Prefix (...
4
votes
1answer
225 views

Maximum cross-correlation coefficient value for time delay estimation

I am using cross-correlation for time delay estimation of two synchronized recordings ($x_1$ and $x_2$) of a fixed sound source from two different locations. I understand that the delay is associated ...
4
votes
3answers
3k views

Cross correlation with short or non periodic signals?

I am a total newbe to signal processing and i have a problem which may be quite trivial to most of you guys. I want to align two short sensor signals (speaking of max. 1000 samples recorded with ...
4
votes
1answer
463 views

What is a Phase Delay filter?

I'm looking at a job spec, detailed below. I'm perplexed as to what is being asked for. Could someone offer a basic understanding of this material? I can imagine a solution may involve performing ...
4
votes
1answer
746 views

Time delay estimation in low SNR

So I am interested in finding delay between two noisy narrowband signals,for example, two arterial pulse waveform. I can easily get a correct estimate of delay using cross-correlation method, but it ...
3
votes
3answers
2k views

Digital filters with more zeros than poles

I am having trouble wrapping my head around digital filters with different orders of numerator and denominator. Let me know if any of these points is wrong: All (digital or analog) transfer ...
3
votes
2answers
218 views

Are there equations for placing sounds in the stereo field using delays?

I'm thinking of the typical stereo widener (haas, binaural) effects here, those that extend from the typical pan knob to create "out of the headphones" -experience. These processors can be automated ...
3
votes
1answer
1k views

Emulate tape delay

I'm trying to emulate a tape delay in a VST plugin, but I'm not sure how to handle the delay changing? I want it to sound like a tape is actually fast forwarding/rewinding. Most digital delays I've ...
3
votes
1answer
72 views

Is it possible to design a band-pass filter with fewer taps than a series HPF + LPF?

I am digitally filtering a signal that is streaming live. The goal is to reduce the filter delay as much as possible while maintaining the quality of some measurements based on the filtered signal. ...
3
votes
0answers
74 views

Minimum time delay that can be estimated between two sensors

Consider a 1-dimensional toy problem. I have two sensors at different points along the $x$-axis. Somewhere away from the sensors, a disturbance is created which travels towards the sensors, first ...
2
votes
2answers
482 views

What's a “delay line”?

I know what a delay is, but what's a delay line? What's the reason for calling it a "delay line"?
2
votes
1answer
558 views

How to calculate a delay between two signals in frequency domain?

Calculation of a delay between two signals is generally done by finding the maximum in the cross-correlation of the two signals (in time domain): $$ \tau_{delay} = \arg\max_\limits{t}(f(t) \star g(t)) ...
2
votes
2answers
570 views

Confused with filtering linear chirp signal using band-pass filter

everyone. Recently, I am doing simulations about filtering a linearly chirp signal, and have been confused about the result. The signal was linearly chirped from 0 to 1000 Hz. At first, the chirping ...
2
votes
1answer
521 views

Implementation of a Variable Fractional Delay with Lagrange Interpolation using Farrow Structure

I am writing a C++ simulation software working in time domain. I generate regularly sampled data, and need them to be delayed, in "real-time", by a variable fractional delay. This is a pretty common ...
2
votes
1answer
217 views

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[...
2
votes
2answers
2k views

How to generate realistic echo to sounds?

I guess the most straightforward way of adding an artificial echo to a sound signal is to add its time-delayed version to the original signal. However, I am not sure how realistic that would sound ...
2
votes
1answer
213 views

Can a unit delay in discrete time be represented by exponential functions?

If we have a signal $y[n]$ and its unit delayed version $y[n-1]$, can we write $y[n-1]$ in terms of $y[n]$ times some exponential? The reason I want to do this is to then take $y[n]$ common and ...
2
votes
1answer
51 views

Books on delay / lag compensation

Which books do you recommend that provide comprehensive overview of delay compensation techniques in control systems?
2
votes
1answer
112 views

Processing and feature extraction from very short signals

I recently have encountered very short time signals (from three to 12 samples, typically). They appeared for instance in small time frames in engine simulation that should be extrapolated in a robust ...
2
votes
1answer
409 views

Low order sinc interpolation vs. polynomial interpolation for variable fractional delay

I'm implementing a variable fractional delay element for use in online audio processing. Applications include ie. Karplus-Strong synthesis, flanger, chorus, echo, vibrato. I'm not oversampling, so ...
2
votes
0answers
164 views

How can I oversample the received signal by double of sampling time and have two signals

I have a question, how can I make the sampling in Matlab for the received the signal by half of time duration of symbol (Ts), and have two copies of signal (that's the process of fractional sampling ...
1
vote
1answer
410 views

Designing a discrete-time inverse system

I am trying to design a discrete-time inverse system to eliminate an undesired echo in a data transmission problem. The echo caused by the transmission channel is represented as attenuation by a ...
1
vote
1answer
678 views

GCC-PHAT (Generalized cross correlation) always peak at delay=0 on real audio signal

I have studied the GCC-PHAT algorithm to estimate TDOA on audio signals at 2 mics. Here is my MATLAB implementation: ...
1
vote
1answer
213 views

FIR filter to delay signal [duplicate]

About filter design, mostly we want to control frequency amplitude response and the linearity of phase response. I wonder whether there are FIR filters specialized to delay signal? For instance, let'...
1
vote
3answers
747 views

How do delay lines create so many effects?

I was trialing this audio plug-in from SonicCharge (there's a program demo in the site). It claims to be based on a delay line and uses some logic to modify it: At its core is a 12-bit digital ...
1
vote
1answer
319 views

Fractional/Interpolating Delay Line still sounding glitchy

I'm trying to implement a simple digital delay line. I want it so that when the user changes the delay amount, it sounds smooth and not glitchy. Currently I'm implementing a fractional delay line but ...
1
vote
2answers
598 views

Distorted output of delay VST effect in C

I'm getting some odd results with some code I'm working on. Help me with the implementation of this delay effect? The code takes an input, adds delayed input to it and then passes it to the output ...
1
vote
1answer
619 views

Allpass filter feedforward/feedback design and code

I want to design/implement a simple feedforward/feedback all-pass filter, and I am having some troubles and questions with it. From Shroeder design (based on J. Smith article here): I came up ...
1
vote
1answer
706 views

Time delay estimation using ultrasound

I have a sound source that generates an ultrasonic pulse. I have two microphones seperated by a distance which are at a distance from the source. I want to find the time delay of arrival of the ...
1
vote
1answer
84 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 ...
1
vote
1answer
35 views

Plotting phase delay from first principles giving different result from phasedelay() function. Why?

I have a length 10 Finite Impulse response as shown below, and I am trying to find the phase delay of this FIR. $$h[n]=\begin{cases}0.1,& 0\le n \lt 10\\ 0,&\textrm{otherwise}\end{cases}$$ I ...
1
vote
1answer
365 views

digital IIR filter delay and oversampling

Can oversampling decrease the delay of digital IIR filter? Imagine there is some digital signal going into processor that applies low pass filter.Lets say its 1 KHz sample rate and the filter is ...
1
vote
1answer
77 views

How to quantify delay in filtered output?

I have a signal containing two sine tones 30 kHz and 60 KHz. I used a second order IIR notch filter to filter out the 60 KHz component from the signal, so now the signal has only 30 KHz component. ...
1
vote
2answers
1k views

Determine Phase Difference and Time Delay Between Two Pulsed Sinusoidal Signals

I am working on a code that generates two signals: A pulsed sinusoidal signal ($1\textrm{ MHz}$) beginning at $0$ phase, and lasts for say $5\ \mu\text{s}$, then trails zeros. The other signal has the ...
1
vote
2answers
238 views

Filters applied separately to right and left channel of stereo microphone yielding inaccurate results

I must estimate the direction of arrival of an acoustic source, and I hope to distinguish between a voice input and musical input using a frequency cutoff. In order to do this, I apply the same ...
1
vote
1answer
792 views

Causal and Non-causal filtering. Strange behavior

I'm trying to understand the behavior of a causal filtering exemplified by figure below. This behavior is making LDA (Linear Discriminant Analysis) misclassify our data, by clearly reverse the signal ...
1
vote
2answers
517 views

Farrow fractional delay filter - Range of delay?

I am implementing a fractional delay for resampling purposes, using the Farrow structure to enable continuously variable delays. For now I am simply using windowed sinc functions as my low-pass ...
1
vote
1answer
461 views

What is the difference between transport delay and dead time?

I am confused on what the difference between transport delay and dead time is. They seem to have the same function, but I'm not sure. Can someone explain the difference if there is one?
1
vote
2answers
200 views

Emulating guitar pickup position with delays

If I have a vibrating string, then there will be no motion at the endpoints. If I move away a bit from an endpoint then I'll get a signal, but particularly the fundamental will still be attenuated. ...
1
vote
1answer
198 views

Filter design with 8-tap latency on recursion

I'm curious about the feasibility of designing a noise shaping filter (but might generalise to any recursive filter) with the constraint that the most recent output samples aren't available for ...
1
vote
0answers
23 views

Quantifying the frequency shift of a delay with LP filtered feedback

I am working at a Karplus-Strong sound synthesis technique where an excitation impulse is subjected to a delay with feedback and a one pole LP filter in the feedback line. The process is simply y[0]=(...
1
vote
0answers
149 views

Implementing real-time variable fractional delay line in Matlab

I am attempting to implement a fractional delay line in Matlab which operates in real time, uses an object-oriented approach, and whose length can be modulated each time a sample is processed. I have ...
1
vote
0answers
59 views

Time delay estimation of signals increasingly decorrelated

The problem may be summarized as follows: I have a stochastic signals and I want to measure an increasing delay, as depicted in the following picture. The picture represents the signal as it is being ...
1
vote
1answer
483 views

How to calculate the delay generated by a 2nd order all-pass filter

I'm trying to simulate the dispersion effect of a stiff string in a digital waveguide system, by using second-order all-pass filters. I use a second order all-pass filter with this transfer function:...