Questions tagged [time-domain]

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2answers
51 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
68 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?
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51 views

How to find location of impedance in electrical (transmission line) network using reflectometry?

I am trying to find the location of impedance mismatch on the transmission line network using sequence time-domain reflectometry through MATLAB Simulink. In this work, I can find the location of some ...
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1answer
56 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 ...
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0answers
76 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 ...
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17 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 \...
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1answer
31 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)...
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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 ...
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2answers
117 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 ...
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1answer
60 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 ...
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6answers
298 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 ...
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2answers
615 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 ...
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1answer
45 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
75 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
67 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 "...
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2answers
68 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. ...
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1answer
151 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
84 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 ...
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1answer
261 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 ...
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1answer
277 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
978 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 ...
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2answers
247 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)...
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2answers
240 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 ...
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1answer
303 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,...
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2answers
158 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 ...
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1answer
25 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-...
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2answers
812 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 ...
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1answer
46 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 ...
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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
4k 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 ...
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2answers
189 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 ...
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1answer
86 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
259 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. ...
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1answer
63 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 ...
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1answer
83 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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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:...
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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 ...
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1answer
388 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 ...
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2answers
310 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 ...
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1answer
236 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 ...
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1answer
94 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 ...
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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 ...
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1answer
285 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 ...
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0answers
117 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 ...
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1answer
249 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_{-\...
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3answers
349 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?