Questions tagged [time-domain]
The time-domain tag has no usage guidance.
59
questions
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0answers
17 views
Time Frequency bin
I am doing research in audio signal processing for DOA estimation. I came across the term Time-Frequency bin. I have gone through several articles but none of them specify a TF bin rather it specifies ...
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3answers
257 views
Butterworth filter transfer function in time domain
Preliminaries
I need to know the response of Butterworth filter in time domain of the following input (at least numerically):
$$
x(t) = \theta(t)(1-\exp\{-at\})\exp\{-bt\}, \quad a,b>0,\quad a\gg ...
0
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1answer
46 views
Complex time domain signals and QAM
Is there an inherent connection between complex time domain signals and QAM?
Given a complex time-domain signal is it always implied that this is a QAM-demodulated form of a real time domain signal?
...
0
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1answer
53 views
Converting a discrete real time domain to a discrete complex time domain signal
To test my understanding of amplitude modulation in the frequency domain I'm trying to replicate the center frequency with 2 side-bands in an Octave plot with the following code
...
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2answers
53 views
Intuitive meaning of complex time domain signal representation (quadrature sampling)
I saw What is the meaning of imaginary values in the time domain?.
My question is about I Q samples as recorded from an SDR receiver (e.g. RTL-SDR).
My understanding is that we can call these I Q ...
1
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2answers
88 views
How do I find the convolution of the following signals? [closed]
$h(t)$ is the inputted to convolve the $x(t)$
The signal written in unit step are:
$x(t) = (5-t)u(t-3) - (5-t)u(t-5)$
$h(t) = 2u(t-1) - 2u(t-3)$
So to convolve I first change the function to:
$h(...
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0answers
45 views
IFFT during ISTFT - and Nyquist
Using a compilable programming language (not Librosa, Matlab, etc), I am attempting to perform ISTFT on filtered (masked) source STFT matrices obtained from NMF. During the original construction of ...
5
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4answers
801 views
Can every type of linear filter be modelled by a convolution?
I have an input time series going through a filter that creates another time series as output.
If I assume in first approximation that my filter is linear, does it necessarily mean that I can model ...
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0answers
40 views
Underwater acoustic channel is giving me a flat BER vs SNR curve
I need to do OFDM and GFDM signal transmission in underwater acoustic channel. I have my underwater acoustic channel as follow.
...
0
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1answer
34 views
Test for Equivalence of two time series
I wish to test whether two time series are equal. So I believe best way to define equivalence is that given two time series, say $\{x1_t\}$ and $\{x2_t\}$, we show that both the series come from the ...
1
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1answer
56 views
How to determine the phase of a time-sampled periodic signal?
I know this is a rather common and a rather simple problem, but somehow I can't find a solution that is equally simple to understand (and implement).
I have a signal that closely resembles a noisy ...
0
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2answers
57 views
Is it valid to calculate the magnitude, power, and phase of a real time-domain signal without converting it to the frequency-domain?
I would assume you perform the calculations the same way, but since there would be no imaginary component because the signal is not complex it would be simpler:
...
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2answers
88 views
Why the following discrete type system,variable accumulator, is time invariant?
$y[n]=T{x[n]}=\displaystyle\sum_{k=n-n_{0}}^{n+n_{0}} x[k]$
it is some sort of moving summer which computes $n^{\text{th}}$ output sample by adding all samples lying within length $n_{0}$ around some ...
1
vote
2answers
81 views
Can a 1-dimensional signal be in a domain other than the time or frequency domain?
In signal processing I have only heard of signals being in the "Time" domain or in the "Frequency" domain, but are there situations where a signal is not in either of these?
If so, what are these ...
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2answers
153 views
negative value of signals
can we say there is no sound produced when the amplitude is 0?
if yes what can we say when the amplitude is negative?
0
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1answer
68 views
Extracting audio from picture of time-domain signal
I saw this nifty art thing where they dress up the time-domain audio signal in some pretty way.
https://www.etsy.com/ArtbloxShop/listing/621561709/sound-wave-art-custom-soundwave-print
My question is ...
2
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0answers
94 views
How do audiobook players manage to quickly speedup/slowdown playback speed without using more memory?
Many audiobook player apps on Android have a reading speed slider which lets us choose the reading speed e.g. 0.5x 0.75x 1.00x 1.25x 1.50x. This is time-stretching ...
1
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1answer
212 views
What is the relationship between the discrete time and continuous time variables?
While going through Proakis's Digital Signal Processing (page 21) ,he stated that
if a continuous time signal $~x(t)~$ that has been sampled each $~T~$ seconds to produce a discrete time signal $~x(n)...
0
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1answer
34 views
Practical insightful time domain functions [closed]
This question might be a little bit different, but i am having hard time to find some sort of a list/book/website/advice, with very practical time domain functions that provides useful insgihts for a ...
2
votes
1answer
203 views
Is it right to talk about dynamic range on frequency domain?
I'm comparing three frequency response's plots from simulations and experiments and I observed that two of them look like clamped to a DC component, where the max dB value is i.e. 100 and the min is ...
3
votes
1answer
169 views
What is wrong with my residue partial expansion method? (Transfer Function into State-Space Modal/Diagonal Form)
I'm using reference from here and here.
This is Laplace transfer function of DC Control Speed System:
$$\frac{\omega(s)}{V(s)}=\frac{K}{(Js+b)(Ls+R)+K^2}$$
Where,
$\omega$ is the motor angular ...
5
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6answers
424 views
Optimal $ n $ -th Order IIR /AR Approximation of a Moving Average Filter
I would like to approximate a moving average filter with an IIR filter of much lower order than the tap-length of the moving average filter. Optimality shall refer to the $L_2$ norm of the impulse ...
1
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2answers
1k views
Finite and Infinite support in time and frequency domain
It's known that signals with a finite support in time has an infinite support in frequency (talking about Fourier Transforms).
A common example that is given for the claim is the triangle function ...
0
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1answer
62 views
Complex FFT reversing
I've succeeded to compute complex FFT of a data array of interleaved values using the arm_cfft_f32() API of the CMSIS DSP library for Cortex-M4, and got in the same array the FFT results as frequency ...
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0answers
82 views
Making longer a time domain signal by adding values on its frequency domain. What am I doing wrong?
Background
Here's the thing: using software for Finite Element Acoustic Simulation I got the dataset of frequency response from a room; software works by solving the wave equation in the interval $`[...
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0answers
71 views
Plot Background Noise
I am a total newbie in signal processing.
I have been trying to plot on simulink a time/frequency domain noise in PLC (Powerline Communication) that matches a real-world research "...
0
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2answers
80 views
Noise when dividing or multiplying signal in C
I'm trying to create a echo effect and have managed to add multiple delays but when i try to divide or multiply these numbers the signal is completely distorted and adds a lot of noise to the system.
...
2
votes
1answer
270 views
Eigenfunction property for LTI sinusoidal and the sinusoidal steady-state response
All LTI systems possess the eigenfunction property for complex exponential inputs. That is (restricting our attention to periodic complex exponentials), if $e^{j\omega_k t}$ is an input to the LTI ...
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2answers
111 views
How to estimate ALL time-delays across MULTIPLE signals?
Imagine there are 100 recordings of the same signal or pattern, but those recordings are not properly aligned with each other in time. In other words, each sample has some unknown time delay in ...
0
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1answer
318 views
characterization of DC component
Consider the following two statements:
In time axis:
A signal without a DC component is a signal which doesn't have the zero frequency (the DC frequency)
A signal without a DC component is averaged ...
2
votes
1answer
662 views
Time scaling of discrete-time sequences and the DTFT
In the second edition of Signals and Systems by Alan Oppenheim, he discusses the DTFT of a "time-expanded" sequence that is effectively a slowed down version of the original sequence and can be ...
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2answers
1k views
Extracting peak frequencies using FFT vs. time-domain peak finding
I am trying to compare two processing algorithms that I believe should be producing very similar results. I am processing acceleration signals over the course of the day and we expect to see a ...
2
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2answers
501 views
Linear Constant Coefficient Differential Equations: Zero-Input and Zero-State responses
The solution to a linear constant coefficient differential equation of the form $$\sum_{k = 0}^{N} a_k y^{(k)} (t) = \sum_{k = 0}^{M} b_k x^{(k)} (t)$$ can be written as $y(t) = y_{ZI} (t) + y_{ZS} (t)...
1
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2answers
352 views
Convolution and Modulation Theorem with Octave Example
As far as I know, convolution theorem stated that
$$
x[n] * y[n] = X(e^{j \omega}) Y(e^{j \omega})
$$
$$
X(e^{j \omega}) * Y(e^{j \omega}) = x[n] y[n]
$$
I tried a simple experiment using GNU Octave ...
2
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1answer
418 views
Confused on the difference between the frequency spectrum of an entire song, and the frequency spectrum of a point in time
I am very much a beginner in this field - but find it really interesting. However I am a little confused on a certain area of knowledge.
If I have understood correctly:
At any point in an audiosignal,...
0
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3answers
355 views
How to filter out everything but a single frequency in the time domain?
I'm new to signal processing and would like some insights about the best way to filter simple data without being too computationally intensive.
I have an audio signal and I want to extract a single ...
0
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1answer
30 views
Does waveform-based ASR with lowpass filtering preprocessing still require the assumption of FFT?
I read some recent papers about time-domain speech recognition, and wondering if it steers away from the stationary assumption of FFT. However, some preprocessing operations like pre-emphasis and low-...
2
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2answers
1k views
Is it possible to apply a frequency filter a time domain signal?
Is it possible to frequency filter a time domain signal, without converting the signal to a frequency domain..
My question comes in regards how MFCC according to wiki and other pages describe the ...
1
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1answer
48 views
Index of stationarity of a time domain signal
During my internship, I've come across a software that calculates a percentage called "Index of stationarity". This index shows how much stationary is the signal. Does anyone have any idea on how to ...
3
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3answers
1k views
Time synchronous averaging - MATLAB
I have a time domain signal that corresponds to a vibration signal of a machine. I have a second signal that corresponds to a tachometer signal (There is a pulse every one revolution of the shaft).
I'...
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0answers
36 views
Multitapering in time domain to obtain smoother filtered signals?
Suppose we want to approximate the instantaneous power $z(n) = |y(n)|^2$ of the discrete-time signal $y(n)$, where $y(n)$ is the result of filtering $x(n)$ with a given window $h(n)$, $y(n) = x(n) \...
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2answers
6k views
Difference between RMS and a moving RMS
I don't quite get the difference between RMS and a moving RMS.
When one calculates RMS, one integrates (or sums in case of a discrete signal) over a period of time(number of samples).
When it comes ...
1
vote
2answers
218 views
Is there an equivalent time-domain operation to the spectrum averaging in Welch's method?
In Welch's method a time-series is segmented and then the subsequent FFTs of the segments are averaged. Is there an equivalent time-domain operation?
I guess doing the the Welch estimate and ...
0
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1answer
103 views
Convert fixed frequency bandwidth samples to time domain
I'm trying to convert signal (bandwidth 1400 MHz, start freq 9300 MHz, stop freq 10700 MHz, step 3.5 MHz) from frequency domain to time domain. Signal data in frequency domain, as well as signal data ...
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1answer
314 views
Stationary signal: time-domain vs frequency domain
If I understand correctly, a signal is stationary if:
time domain: it's generated from the same distribution at each instant time.
frequency domain: its frequency content does not change in time.
...
1
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1answer
65 views
Frequency of Signal of a point tracked in a video?
I have used MATLAB to track a feature point (corner point) using Lucas-Kanade tracker and plotted its movement through each frame now I need to find its frequency content, how should I find it? (I ...
0
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1answer
86 views
Representing a positive 0-limiting continuous time domain function, in terms of spectral samples, outside of a window
Bit of an odd question
Assume you have a known function $x(t)$ which is continuous, but approaches but is not equal to, 0, on the interval $[-\infty,\infty]$ . You know also that it approaches 0 ...
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0answers
2k views
Operations applied to functions in time domain and frequency domain
I am trying to make a succinct summary of how algebraic operations in the time domain translate in the frequency domain (via the use of Fourrier/Laplace transforms). Here is what I have derived so far:...
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4answers
3k views
Effect of low pass filter on the time domain
Consider an ideal (rectangular profile in frequency domain) low-pass filter (LPF) which simply sets to zero all the frequencies beyond a certain cut-off frequency. Let $x$ be a discrete-time signal of ...
0
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1answer
456 views
Time-spread multiple echoing of audio signals
I have been reading papers related to adding echos into digital audio signals recently. I guess I understood the logic behind, yet I guess I am still having lack of DSP knowledge to figure out ...
