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Questions tagged [frequency-domain]

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671 views

Frequency domain to time domain conversion-(varying sample count)

I need to convert 150 Frequency domain samples to the time domain. The problem is, I have been provided with 250 time domain samples for comparing my results. How am I supposed to relate the 150 ...
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1answer
61 views

Square of Frequency characteristic of the system

What does $|H(j\omega)|^2$ in $20 \log_{10}|H(j\omega)|$ mean? Is it some ratio of energy or power? And why? How to derive it? I'm sorry for curtness of my questin.
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1answer
422 views

Time -Domain to Frequency Domain

I am constructing a MFCC and come to a section which is kind of confusing me. It is: Step 4: Fast Fourier Transform and has this equation: Now I understand that FFT needs to be carried out, I ...
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0answers
40 views

Do negative frequencies count towards null-to-null bandwidth?

I am aware that negative frequencies do not normally count towards the bandwidth when transmitting in the baseband. However when specifically asked to look at the null-to-null or zero-crossing ...
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0answers
25 views

Find repeating sequences in audio file

I have a long audio file (12+ hours). I know that there are some unknown small (2 minutes each or thereabout, it varies) repeating (not bit by bit: it is recorded with a mic) chunks in it, repeating ...
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0answers
15 views

How to search for irregular signals: Fourier, DWT or k-means?

See my notebook here I want to search for irregular time signals in a data set of ~3 500 000 time signals. By eyeballing I have found hundreds of flat and oscillating signals, but just a few that are ...
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1answer
42 views
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0answers
12 views

Is the Channel Equalization corrects Carrier Frequency Offset (CFO) in signal?

As we know channel equalization is used for restoring the distortion ocured in signal. Hence, can we say the Carrier Frequency Offset (CFO) is being corrected and restored the actual signal.
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23 views

Generating a phase modulation frequency spectrum with jitter

I would like to produce a frequency spectrum plot like this: (from All About Circuits) I know that one can take the modulation frequency and multiply it by a given order and scale by the modulation ...
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0answers
24 views

How to get PSD from frequency domain representation of time-series data [duplicate]

Let's say we have a realization (time-series data) of a random process. I take fft() of that to get its frequency domain representation. Then how can I estimate the PSD of this random process by ...
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0answers
14 views

How to match resolution of two or more signals

I have received the following 4 time-series signals and wanted to do some data analytics using these. Although the sampling is the same for all of these signals, 2 samples per second, problem is that ...
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2answers
143 views

Circular Convolution Matrix of $ {H}^{H} {H} $

We all know that Discrete Fourier Transform (DFT) corresponds to circular (not linear) convolution. That is to say, if $x(n),h(n)$ and $y(n)$ is the original signal, the filter and output signal in ...
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0answers
17 views

Analysis of linear acceleration and angular velocity, how to?

Excuse me If you don't feel that this question is good enough, but at the moment this is my level of entry knowledge. Imagine that you have 200 recordings from the sensors, and information that you ...
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0answers
74 views

Encoder: Quantization in Frequency Domain

The article, "Let’s build an MP3-decoder!" describes quantization noise in the time domain: [masking] This property is very useful: not only can the nearby masked signals be removed; the audible ...
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0answers
32 views

Frequency Domain - Meaning [duplicate]

I'm new in digital signal processing and having hard time understanding this. By Fourier Transform I mean Discrete Fourier Transform as it's the only one I'm learning. As far as I know Fourier ...
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1answer
62 views

LP to BP transformation steps

Considering the following problem, What i know to convert from LP signal to BP signal is to: Draw the FD of the LP equation From it I can draw the FD for BP From this graph I can deduce the equation ...
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2answers
51 views

How to interpret correlation angle from frequency domain

Since the coefficient of one frequency could be seen the length of the signal projects on that frequency basis. And the length is $$|a|\cos\theta= \frac{a\cdot b}{|b|} $$ If I divide the ...
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0answers
15 views

Is there a criterion that says at what point you can distinguish 2 partially overlapping Lorentzian peaks?

If you have 2 Lorentzian peaks that partially overlap and you have some frequency resolution df (your points in frequency space are separated by df) and both Lorentzian peaks have FWHM $\Gamma$ is ...
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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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0answers
16 views

What is the best spline to interpolate freq analiser graph

the question is as it is in the topic: What is the best spline to interpolate freq analiser graph? I am looking something simply and fast to implement. I read about catmull-rom it looks it could be ...
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1answer
484 views

When listening in to an AM signals of various frequencies, how do we exactly tune in?

Alright, so I read on AM and Double Sideband AM, but I don't the more fundamental idea - the frequencies. Frequency is just: $ \frac{1}{T} $, where T is period So difference between 5 Hz and 30 Hz ...
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1answer
89 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
591 views

frequency domain zero padding in OFDM

I have a matlab code for OFDM system, in this code the auther added a zero padded subcarriers before the IFFT stage, in the middle of the raws, and added zero padded guard interval after IFFT, my ...
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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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1answer
28 views

Unexpected result after calculating the response of a system in frequency domain

I'm implementing a Python script that calculates the response of a system given an input. The system is $y(t) = x(t-2)$, i.e. it delays the signal by $2$, and the signal is $x(t) = \sin(3t)u(t)$. As ...
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2answers
1k views

Equalize Speaker using Frequency Response Curve

I have a speaker for which I know the frequency response curve (-5dB at 600Hz, -3dB at 700Hz, ... +5dB at 10kHz). This response curve is not as flat as I would like, and so I want to write a script ...
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1answer
59 views

How to determine the central frequency from a vectorial spectrum analyzer?

I have taken measures of an antenna with a vectorial spectrum analyzer. I need to obtain the central frequency at which the antenna works. In order to do so, I have selected S11 (reflection) and I ...
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2answers
119 views

question regarding convolution theorem

As per the convolution theorem, a convolution in time domain is equivalent to a multiplication in the frequency domain. Then say (MATLAB code), ...
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0answers
62 views

Frequency Domain Equalization [Sources request]

When I read papers, I often see the term "Frequency Domain Equalizer". I do not understand what a "frequency domain equalizer" is. Do they mean equalizers like MMSE, LMMSE? Or is there an equalizer ...
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3answers
421 views

Time period to Instantaneous frequency

I have simple smooth time signal with different time period. I would like to transfer period over the time to frequency, and to track frequency changing over the time, I would call it Instantaneous ...
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0answers
158 views

Poles and zeros from FRF

How can I determine the poles and zeros of a system given its frequency Response? I can understand how one can find the Frequency response from poles and zeros of a system. Is it possible to do it ...
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0answers
218 views

Determining Valid DTFT's

Are the following frequency domain signals valid DTFT's (Discrete Time Fourier Transforms)? Answer yes or no, and justify your answer. a) $X(\omega) = \omega + \pi$ b) $X(\omega) = i + \pi$ c) $X(\...
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0answers
372 views

FFT frequency domain averaging and zero padding

I'm trying to get the average frequency response of an entire piece of audio by splitting it into segments, doing an FFT on each one, and averaging the magnitudes together. Its working great until I ...
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1answer
95 views

Image with specific frequencies

I have created a frequency domain image filter and would like to test it against some images where it is known that the frequencies only occur within a given band. Trouble is, I don't know how to go ...
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0answers
396 views

FFT of irregular shaped data

I have an irregular shaped 3D image that I want to do frequency domain filtering on. Currently I simply zero-pad the data to make it a cube, then do an fft. I was wondering if this was a valid ...
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1answer
201 views

what I'll get if I take FFT of a frequency domain data

What I'll get if I take FFT of a frequency domain data. I have two questions related to this. For ex, x is a time domain data where X = fft(x), now fft(X)= what i'll get ? While reading SCFDMA, data ...
-1
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1answer
283 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
41 views

Sampling of frequency response

Let's consider any physical quantity depending on the frequency. For example, the impedance of a certain electrical component: $Z(f)$. Now, imagine to measure it in a continuous interval of ...
-1
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1answer
287 views

Alignment of signals for ensemble averaging? Something else?

I have been applying ensemble averaging (adding signals of different trials to obtain one signal) to improve Signal to noise ratio in my data. I have achieved good results in terms of classification ...
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1answer
370 views

fft2 of interferometric image - how to interpret the result in term of dominant frequency

I have an interferometric image which shows fringes at a certain frequency, basically a dominantly periodic signal overlaying the information that I want to extracthere are the fringes that I want to ...
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1answer
77 views

How do I decide which frequencies are signal and which are noise?

I have an arbitrary recorded digial signal, on which I have run a Fourier transform. I'm not sure what conventions are on a case like this, but I have 1024 frequency bins. Second bin is the highest ...
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1answer
466 views

WIDELY UNKNOWN?? Wireless Channel Transfer Function or freq response - frequency vs attenuation

We know that the signal attenuates out with distance and according to the channel transfer function or frequency response, the signal frequency components attenuate to different values based on ...
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1answer
1k views

Effect of frequency shift on a sound signal

I had two sound files and did the following to it: ...
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1answer
243 views

How Fourier decomposition is performed?

The Fourier decomposition explains a time series entirely as a weighted sum of sinusoidal functions and with the Fourier series,it is possible to do it. But I have some doubts Suppose ,for any ...