# Questions tagged [time-domain]

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### Meaning of the frequencies vector using fft

I'm so confused, and it would be nice if someone could clear my head, or at least direct me to suitable references. Assume that I have two gaussian pulses with the same bandwidth in time, but for 2 ...
20 views

### Derive Time-Domain Biquad Coefficients from Z-Domain

I'm trying to derive the time-domain coefficients of a biquad filter based on its z-domain coefficients. The purpose is to import externally-generated EQ filters (in z-domain) into Max/MSP (in time-...
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### Generating a time domain signal using the fundamental frequencies

I currently have the power spectrum (in dB) of a signal through which I obtained the fundamental frequencies and amplitudes. My question is: how to generate a time domain signal using these amplitudes ...
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### Rectangular Pulse Train and Sinc Function

I wanted to ask that in frequency domain the rectangular pulse is a sinc function, so is this sinc function periodic or aperiodic? Also if signals that are continuous in time domain then they are ...
18 views

### Third octave band zero-phase forwards-backwards Butterworth filter adds amplitude to complex signals?

Overall aim: to take a short signal (likely to be noisy with some tonal components) and filter it into third-octave bands (TOBs), apply frequency-dependent spectral adjustments, then recombine the ...
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### Determining the right order of time-domain low pass filter for desired cutoff frequency

I've been stuck on a problem regarding complex demodulation of a signal for a while and wondered if anyone could help. Suppose I have a signal $X(t)$ such that \begin{align} X(t) &= A(t)\cos(\...
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### How to calculate DTFT of cosine function divided by n

I'm having a hard time to calculate the next function, and I don't really know Matlab good enough to calculate it there. Help would be appreciated: $$h[n]=\frac{A_1 \cos⁡[\theta_1(n-N/2)]}{n-N/2}$$
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### Time domain analysis vs frequency domain analysis? Applications wise? [closed]

When do we use time domain analysis and when do we use frequency domain analysis? As far i studied i know that when we need to study individual sinusoidal components of a signal, we choose frequency ...
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### Are there any recursive online max/min filters for time-series

Are there any online recursive filters that can approximate local, time-varying minimum and maximum values of a time series?
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### A one-pole LPF (6 dB/oct) has a step response to $1/e$ amplitude of ${\tt time} = 1/(2 \pi f)$. What would the response time be of a 3 dB/oct filter?

I was instructed in another question here that if a one pole (6 dB/oct) low pass filter is fed a discontinuity (ie. going from 1 to 0) it will take ${\tt time} = \frac{1}{2\pi f}$ to reach $1/e$ ...
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### Is a LTI system with dead-time equivalent with a LTI system with no dead-time but delayed input signal?

I wonder if the system parameters would remain the same after all. According to the definitions, the gain is the change of the output induced by the change of the input if we assume that the gain is ...
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### 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? ...
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### 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 ...
207 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 ...
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### 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 ...
275 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 ...
234 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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### 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 ...
2k 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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### 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 ...
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 $`[... 0answers 74 views ### Plot Background Noise I am a total newbie in signal processing. I have been trying to plot on simulink a time/frequency domain noise in PLC (Powerline Communication) that matches a real-world research "... 2answers 94 views ### Noise when dividing or multiplying signal in C I'm trying to create a echo effect and have managed to add multiple delays but when i try to divide or multiply these numbers the signal is completely distorted and adds a lot of noise to the system. ... 1answer 380 views ### Eigenfunction property for LTI sinusoidal and the sinusoidal steady-state response All LTI systems possess the eigenfunction property for complex exponential inputs. That is (restricting our attention to periodic complex exponentials), if$e^{j\omega_k t}is an input to the LTI ... 2answers 161 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 ... 1answer 346 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 ... 1answer 951 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 ... 2answers 2k 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 ... 2answers 761 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 asy(t) = y_{ZI} (t) + y_{ZS} (t)...
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 ...