Questions tagged [time-domain]
The time-domain tag has no usage guidance.
-1
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1answer
40 views
Periodicity + Fourier Transforms [closed]
I was hoping to clarify if the following was true:
1 if a function is discrete in the time domain, it is periodic in the frequency domain
2 if a function is discrete in the frequency domain, it is ...
0
votes
1answer
52 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
71 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 ...
0
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0answers
15 views
Signals time fluctuation
I am following this paper.
I am lost in equation 3. What exactly is a signal's fluctuation? What does the $\delta$ here represents?
Also why does it's autocorrelation is represented as $\langle \...
1
vote
1answer
24 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
33 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 ...
1
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2answers
70 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 ...
2
votes
1answer
36 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 ...
0
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0answers
39 views
Time domain comparison of periodic signals of different durations and sampling rates
I am trying to "visually" compare the periods of periodic signals in the time domain which may have been sampled at different sampling rates.
See the picture below for example,
The blue one has a ...
5
votes
6answers
252 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
vote
2answers
351 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
40 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 ...
0
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0answers
68 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 $`[...
0
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0answers
58 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
votes
2answers
64 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.
...
1
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1answer
126 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 ...
0
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2answers
76 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
190 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 ...
1
vote
1answer
175 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 ...
1
vote
2answers
793 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 ...
1
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2answers
191 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
199 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 ...
3
votes
1answer
284 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
votes
2answers
119 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
votes
1answer
24 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
votes
2answers
647 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 ...
0
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0answers
259 views
Removing fundamental frequency and harmonics from time domain signal
I have a time domain acceleration signal. I would like to remove a fundamental frequency and all its harmonics from the signal without really eliminating close sidebands? Is there a way to accomplish ...
1
vote
1answer
45 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
votes
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'...
1
vote
0answers
35 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) \...
3
votes
2answers
3k 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
158 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
votes
1answer
81 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 ...
-1
votes
1answer
227 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
vote
1answer
62 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
79 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 ...
0
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0answers
1k 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:...
1
vote
4answers
2k 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
votes
1answer
351 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 ...
3
votes
2answers
264 views
Ripple in time-domain using lanczos resampling
I'm seeing ripple in the time domain when resampling a "unity signal", that is, all ones, with lanczos filters. The ripple/error exactly resembles a cosine with a period of the sampling rate - ie. the ...
-2
votes
1answer
220 views
Finding frequency of data given in time domain
Think there is an analog signal source and we are recording it with a data logger. Sampling rate isn't important in here. We know the analog signal is 0 mV when time 0 and goes to 1000mV in 1000 ...
0
votes
1answer
89 views
Pixel-wise Write into a video file in MATLAB
A video file (in .ptw format) is read in MATLAB in the form of a 3 dimensional matrix (a structured format). My aim is to process the video in time domain on each coordinate pixel individually and ...
1
vote
2answers
932 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 ...
2
votes
1answer
243 views
Time-Frequency Analysis of Big Data - Data Size Reduction: averaging the most appropriate method?
Explanation:
I would like to analyse the data from an experiment, which investigates the performance of a mechanical component using sensors, that has generated 2000 CSV files. Each file contains 513 ...
2
votes
0answers
103 views
$\tt ifft()$ function - absolute vs real form
I have multiple files from an experiment in frequency-domain that I would like to use ifft() function to convert to the time domain in R to apply signal processing ...
0
votes
1answer
221 views
Impulse response (general form for linear systems as two-variables function $h(t,\tau)$) applied to Time-invariant systems
If a system is linear, then the operator $S$ mapping input signals into output signals - i.e. $y(t)=S\{u(t)\}(t)$ - is the integral of the input weighted by the impulse response:
$$ y(t) = \int_{-\...
4
votes
3answers
268 views
Time domain maximum from frequency domain data?
Is it possible to calculate the maximum value of a time-domain signal from frequency-domain representation without performing an inverse transform?
