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Questions tagged [frequency-domain]

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Synchrosqueezing of frequency-wavenumber spectrum

I am bigenner to signal processing. I am working on improving frequency-wavenumber spetrum obtained from multisensors sound data. I read about Synchrosqueezing as a technique widely used to compensate ...
Engineer's user avatar
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2 answers
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Linear convolution of a 100 sample time series and a 20 tap filter in the frequency domain

I came across this question on an internship application. For context, I'm three years into my bachelor's for electrical engineering right now. I have learned continuous and discreet convolutions, so ...
Ashik Islam's user avatar
1 vote
1 answer
48 views

transform time series different length and sampling rate with frequency domain

i want to transform my time series (each same scale) to frequency domain. There are 2 things to conside: some time series are longer then the other i have different measuring intervals which means e....
user71812's user avatar
1 vote
2 answers
69 views

In the frequency domain of a phase-shift keyed signal, why there are are prominent frequency components which are multiples of sampling frequency?

In the frequency domain representation of a digital phase modulated signal, why there are prominent other frequency components which are multiples of the sampling frequency, other than the main ...
Kiran Gunathilaka's user avatar
2 votes
1 answer
48 views

Impulse response synthesis in the frequency domain

Background - Create context I am trying to synthesise some impulse responses to simulate an active noise control system. I have already formulated the problem in the frequency domain so now I want to ...
ZaellixA's user avatar
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2 answers
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How do I isolate a part of this signal in time-domain in Matlab?

I want to isolate a reflection part of a signal which I've transformed from Frequency to Time-Domain (see Picture). So far, I've tried to create a Hamming-Window with the specific window-width for the ...
Anne-Mary's user avatar
4 votes
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85 views

Recover the first half of the time-domain signal of the N-point frequency domain signal using an N/2-point FFT

Let X be an N-point sequence in the frequency domain (where N is a power of two): $$ X = (X[0], ..., X[N-1]) $$ where $X$ is the complex and conjugate symmetric forward DFT of the real sequence $x = (...
keith's user avatar
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Is a bandpass filter superfluous when the frequency band of interest after applying the FFT is below the Nyquist frequency?

I have time-series data with a sampling rate of 1 Hz, hence the Nyquist frequency is 0.5 Hz. I am interested in the frequency band 0.01-0.1 Hz and I would like to apply a Periodogram to transform the ...
Philipp's user avatar
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1 answer
127 views

Calculation of frequency correlation function based on power delay profile

We know that the frequency-domain correlation function and the power delay profile appears as a Fourier transform pair, i.e., $$A_{c}(\Delta f) = \int_{-\infty}^{\infty}PDP(\tau) \cdot e^{-j2\pi \...
Vic's user avatar
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2 answers
48 views

Estimating acoustic sound signal energy radiated

Im recording sound generated by a drilling machine against an object. I have the recording of following : Ambient noise with drilling machine switched off. Drilling machine on+ambient noise Drilling ...
V.M Sypher's user avatar
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Advice for first steps in time domain simulations

I am reaching out because I’ll soon have to tackle signal processing questions that were so far handled by colleagues of mine. I come from the macroscopic link budget computation world in a satellite ...
Sycropane's user avatar
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What does the frequency domain of bipolar Alternate Mark Inversion (AMI) look like?

Someone said to me that Bipolar AMI is not low-pass; it does not include the 0Hz in its frequency domain. I doubt that that is the case. However, at present I am unable to do Fourier transformations. ...
tryingtobeastoic's user avatar
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1 answer
113 views

Filtering in time domain vs filtering in frequency domain

The signal is an impulse repsonse. I am filtering the signal using a windowed sinc filter in both frequency and time domain. I am interested in knowing the differences between the two methods and ...
Tanmayee Pathre's user avatar
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50 views

Bode plot phase shift equation when poles and zeros are not at the origin

Let $$H(s)=\frac{s^{n}}{s^{m}}$$ For $n \ne m$ the phase shift between output and input will be $\frac{\pi}{2}(n-m)$. For situations where the poles and zeros are not at the origin, I could find the ...
Cerise's user avatar
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Sampled data plot doesnt make sense

I've measured an accoustic signal for approx. 90 seconds with a sample frequency of 192 kHz (Note: the used device can sample data with maximaly 192 kHz, therefore i am not 100% certain, what sample ...
Tom's user avatar
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1 answer
97 views

IFFT caused inverted phase

I've created ifft of signal: Wf=[0 zeros(1,19) conj(W) zeros(1,6000) flip((W)) zeros(1,19)]; w=real(ifft(Wf)); Now take a look ...
mohammadsdtmnd's user avatar
1 vote
1 answer
62 views

Mixer and control systems

A mixer in the time domain usually multiplies 2 signals of the time domain , however what does it do in the Laplace domain?Is there a equivalent block diagram of a mixer in the Laplace domain?The ...
Cerise's user avatar
  • 153
2 votes
2 answers
270 views

How can I convert a 1/3rd octave spectrum into a linear spectrum for use as a frequency response?

I have a one-third octave spectrum with 23 frequencies, and I want to use it as a frequency response to filter another spectrum, however that spectrum is specified linear with 2049 points. I know I ...
stix's user avatar
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1 answer
1k views

Why is the convolution of two sine waves a sinc function?

Problem/Question After taking the convolution of two discrete sine waves of the same frequency and length the result appears to be a sinc function but I was expecting to get a sine wave since this ...
Usman Mutawakil's user avatar
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1 answer
39 views

Freq domain filtering in a sample by sample basis

Im simulating a system in code, the real system uses a 3Mhz sample rate on PDM, trying to simulate the feedback response, in the feedback path there is a system, this system has a impulse response of ~...
user2982010's user avatar
2 votes
1 answer
205 views

Frequency domain derivation of Hilbert transform of $\cos(\omega t)$

I'm reading "Understanding Digital Signal Processing, 3rd Edition" by Richard Lyons. Chapter 9 derives Hilbert transform impulse response by defining it in frequency domain first and then ...
Aleksander Alekseev's user avatar
1 vote
3 answers
238 views

FMCW Radar - What's wrong with the transmitted signal model?

I am new to FMCW radar and trying to plot the transmit signal over time. As you know, the transmitted signal is modelled as: $$s(t) = cos(2\pi f_c t + \pi S^2),$$ where $S = BW/T_{chirp}$ is the slope,...
pej's user avatar
  • 13
2 votes
1 answer
103 views

Does subtracting a phase from the frequency components of a DFT output result in rotation?

I'm currently reading a paper (Page 23 of the PDF) about the application of the Fourier transform to standardize some climatic data to easily compare them. I have the following text : 2.3 ...
Franck Might's user avatar
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2 answers
40 views

Routh's stability condition

Assume we have a LTI system which has poles in the half left plane of the s domain. Before I learnt Routh's stability condition I had imagined that this was enough to decide whether a LTI system was ...
Volpina's user avatar
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1 answer
68 views

Can we do down sampling by taking fft, omitting samples on the ends of the spectrum, and then taking inverse fft?

Suppose that we have a signal with a length of 4096 and want to down sample it by a factor of 2 and obtain a signal with a length of 2048. Suppose that the the maximum frequency content of the signal ...
alireza's user avatar
  • 117
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1 answer
180 views

What is the symbol for angular frequency?

I am reading the book Signals and Systems Laboratory with Matlab Book by Alex Palamides and Anastasia Veloni I was going through chapter 6 (Fourier transform) and I came across a confusing thing ...
DSP_CS's user avatar
  • 1,870
1 vote
1 answer
580 views

Removing zero frequency peak in fourier spectrum

I have been looking at the FFT (in python) of various simple functions. Everything was working as expected, except when I take the Fourier transform of the function: $$ f(t) = e^{-\gamma t}\cos^2\...
Angus's user avatar
  • 13
2 votes
1 answer
121 views

How to Solve a Composition of Convolutions from Regularized Least Squares Model in Frequency Domain

Assume we need to solve the model: $$ \arg \min_{\boldsymbol{x}} \frac{1}{2} {\left\| \boldsymbol{h} \ast \boldsymbol{x} - \boldsymbol{y} \right\|}_{2}^{2} + \frac{\lambda}{2} {\left\| \boldsymbol{g} \...
Royi's user avatar
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1 vote
1 answer
124 views

What should be the size of my FFT values for speed,acceleration,..?

I am not from electrical eng. or physics background, so a layman explanation would be appreciated. I work with sensor data (accelerometer) from wearable device, collected for few hours. I take few ...
Amina Umar's user avatar
1 vote
0 answers
185 views

IFFT confusion, sampling frequency

I made a previous post about what I am trying to do Previous Post I have band-limited data in the frequency domain from a VNA and I am trying to convert it into the time domain. VNA data saved in .s2p ...
Frank's user avatar
  • 33
4 votes
1 answer
751 views

Why do we calculate the second half of frequencies in DFT?

As far as I know, for any signal the first $N/2$ frequency samples and second $N/2$ frequency samples are equal (by magnitude), so (sorry, if I made mistake in indices): $$X[k]=\sum_{n=0}^{N-1}x[n]e^{-...
Curious's user avatar
  • 355
3 votes
1 answer
882 views

Why does interpolation with zeros introduce frequency artifacts?

Consider the original signal (just a sine) and the same signal interpolated with zeros: The Fourier transform of them: In this example I inserted only one zero between the samples, as if I sampled ...
Curious's user avatar
  • 355
1 vote
1 answer
266 views

FIR filter design using DFT matrix inversion

In my previous question I use a system identification case as an example. Here I came across another question. I want to design a FIR filter of length $L$ to equalize an LTI system whose impulse ...
DSP novice's user avatar
0 votes
0 answers
82 views

How to remove PWM cycles present in a signal?

I have applied PWM across a DC motor. The voltage measured across the motor is shown above. I want to count the ripples present in the data. The ripples exist at a different frequency than the PWM ...
Nitin Singh's user avatar
0 votes
2 answers
103 views

Causality of an estimated filter

Assume $\tilde{h}(f)$ is a filter estimated by an algorithm for (room) impulse response estimation working in the frequency domain. Is there a way to assert if such filter is causal? Specifically, ...
Chutlhu's user avatar
  • 113
2 votes
2 answers
329 views

Frequency-domain deconvolution

I want to estimate the impulse response of an LTI system using frequency-domain deconvolution. Suppose that the input signal $x[n]$ of length $N$, and the unknown system impulse repsonse $h[n]$ of ...
DSP novice's user avatar
0 votes
1 answer
746 views

Constellation Mapping In OFDM

If i am not mistaken, the two following hold : a. In OFDM Conceptualization, the constellation mapping at Tx (or de-mapping at Rx) is done in Frequency domain b. However the basic theory (Including ...
Vinayak Anant Karandikar's user avatar
1 vote
1 answer
286 views

Calculating SNR of one N-point DFT over another M-point DFT in frequency domain

Consider N-point sine signal mixed with a random noise (implemented in Python below): ...
Curious's user avatar
  • 355
4 votes
1 answer
91 views

Extract the Frequency from the Index of the Bin in 2D DFT

How can I find the distance from DC term (center) to the peak point of the frequency in the image Fourier transform? In the figure below, we know that the distance of the peak point goes to the edge ...
bsg's user avatar
  • 43
0 votes
1 answer
143 views

How can you get the mean wavelength/frequency of a Discrete Fourier Transform (DFT)?

I am very new to the concept of Fourier transforms and DFTs so please explain in as simple terms as possible. I am messing around with Fourier transforms in processing. I wanted to determine the ...
Alexander's user avatar
0 votes
2 answers
47 views

frequency Domain with bandlimit

May I ask why does the frequency Domain Picture of a signal look like that? Is the signal built with many different frequencies?
kidox's user avatar
  • 3
0 votes
1 answer
42 views

Frequency domain equivalent to center oriented rotated convolution?

I have a convolution kernel which I need to apply to an image. However, at each pixel in the image, I'm convolving using a rotated kernel, with respect to the center (think hands on a clock, with the ...
Krupip's user avatar
  • 111
1 vote
1 answer
56 views

Frequency difference measurements

I am trying to find the frequency difference ($\Delta f= f_1 - f_2$) between two complex sinusoidal signals using Matlab. The two signals are: $$r_1 (t)= A~ e^{j 2 \pi f_1 t}= A \cos(2 \pi f_1 t)+j A\...
wesam amiri's user avatar
1 vote
1 answer
2k views

Detecting and Removing Noise from Signal using Python

Through this platform, I want to ask that how can I remove unwanted noise from the signal when you do not have much information regarding the frequency at which they appear? Data is collected from an ...
Aisha Nasir's user avatar
1 vote
1 answer
145 views

Need help with DTFT problem

Prepping for exam and this is one of the practice problems: I just want some clarification on some of the steps my professor took. This is the answer in the answer sheet Only thing I dont understand ...
dnimatullo's user avatar
1 vote
2 answers
4k views

S domain vs frequency domain?

Laplace domain is also known as "s domain". Is there any difference between "s domain" and "frequency domain"? Can we use both terms interchangeably? If we want to ...
DSP_CS's user avatar
  • 1,870
0 votes
1 answer
296 views

Confusions understanding frequency spectrum?

I am trying to learn about frequency domain and I am using audacity software. I selected a small YouTube video (link below): https://www.youtube.com/watch?v=rGHrKkieqCY&ab_channel=PANKAJSAO I ...
kjl's user avatar
  • 9
0 votes
0 answers
70 views

Analytical derivation of convolution and multiplication implement of time-domain signal

I have a system model as shown in figure 1. I want to change the model to a new schematic as in figure 2. How to analytically derive the filter $H_2$ if all parameters are known? I guess that we will ...
user190055's user avatar
12 votes
2 answers
8k views

What is the maximum possible frequency of human voice/speech(That can be generated through human vocal cords)?

Human hearing range is commonly known to be 20 Hz to 20 KHz But what about speaking range? We know that speech Sounds are generated through our vocal cords. So What is the maximum value of frequency ...
DSP_CS's user avatar
  • 1,870
12 votes
5 answers
1k views

What is the frequency representation of nonuniform sampling?

Uniform sampling can be thought of as multiplication of a function $x(t)$ with a Dirac comb function: $$\text{III}_T(t) = \sum_{k=-\infty}^{\infty}\delta(t-kT)$$ Multiplication of $x(t)$ with $\text{...
Gillespie's user avatar
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