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35 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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0answers
5 views

Comparing the spatial frequency between groups of images

I have 2 groups of images, and I want to compare these groups based on the spatial frequencies of the images. In the end, I'd like to be able to say "group A is/is not significantly different from ...
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0answers
23 views

Normalized Cross Correlation in Frequency Domain Windowing for Object Tracking

I'm implementing a normalized cross correlation algorithm in frequency domain on a DSP for object tracking. I have a search window and a reference window. Both windows are zero padded to accommodate ...
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0answers
46 views

derivation of Transfer Function from bode plot

I have some data from a device described in frequency domain (an accelerometer (second-order oscillator) plus a low-pass filter (in cascade)). I sketched the bode plot in Matlab. I must find their ...
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1answer
57 views

How to find phase shift and process I/Q channel

I am currently working of 24GHz FMCW radar signal processing. The Module I'm using has 2 receiving antennas and each has 2 outputs (I and Q channel). So overall I've 4 channels. I'm using combination ...
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3answers
125 views

Reflecting negative frequency to positive frequency

I am trying to synthesize sinusoids by using window function in the frequency domain. It involves: In frequency domain, shift the window to center around the peak frequency To generate a DFT ...
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2answers
113 views

Comparison between 2 images in Frequency domain

As you can see there are 2 images from the Tom and Jerry cartoon program. In the 1st image both Tom and Jerry are present. But in the 2nd one,only Tom is present.Now,we can clearly see this ...
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1answer
50 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 ...
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3answers
196 views

How to effectively teach topic of frequency domain?

This is a soft question. The frequency domain has made revolution in the field of Mathematics, Digital Signal and Image Processing etc. Some of concepts which are very difficult to analyse in spatial ...
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1answer
66 views

Effect of frequency shift on a sound signal

I had two sound files and did the following to it: ...
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2answers
150 views

filtering in frequency domain

I am performing decorrelation of two channels of audio using all pass filtering. The two all pass filters for two channels are of very high order (>1000 but with not all coefficients non zero). I have ...
0
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1answer
56 views

Calculate amplitude of noise added Sine Gaussian signal from frequency domain

How to calculate the time domain amplitude of noise added Sine Gaussian signal from corresponding frequency domain. Here time domain amplitude is 2. How to get this from frequency domain. ...
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1answer
110 views

Applying Gaussian Blur in frequency domain

Please see second update I'm trying to implement gaussian blur in frequency domain using c#. Those are steps that I'm doing: Load bitmap. Split bitmap into separate color channels. Convert every ...
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1answer
75 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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3answers
162 views

What is the type of noise in this image?

what reason could make the noise/effect in this image? Below is the original Thanks!
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2answers
318 views

Perform Convolution in Frequency Domain Using FFTW?

I'm trying to convolve two signals $x(n)$ and $h(n)$ in C by using the FFTW library's functions to perform a Fourier transform on each, multiply the appropriate complex components together, and take ...
0
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1answer
140 views

Oversampling and Aliasing

I am really confused about oversampling and upsampling. I know that upsampling means stretching our signal in time domain by a factor of K, then interpolating some values or using just zeros. As I ...
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0answers
286 views

DFT and Inverse DFT in Image Processing

I have implemented DFT from this link. 1) Tried taking dft for the three Channels(R, G and B) and reconstructed the original image by taking inverse dft for all three channels and merged them ...
0
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1answer
51 views

Discrete Time Fourier Transform to Frequency Domain

I failed to do this question on the exam and finding it very difficult, I would be glad if you can help me solve it. How shall I start?
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0answers
14 views

Creating synthetic frequency domain box filter vs 4 pixels in corners

Creating two 10x10 black images. 1st image, adding a 2x2 white box in the middle (Low pass filter). 2nd image, adding 1 pixel in each of the corners. Then performing the following steps in that ...
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2answers
141 views

Using only positive frequencies in fourier domain, How will it affect the ifft?

I am going to do some kind of transformation and transform a data to another domain, and again back to the first domain. For this, I take a fourier transform of the data and separate the positive part ...
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3answers
146 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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1answer
48 views

How to convert filter into frequency domain to do filtering?

I have this filter: filter_2 = firceqrip(2,0.6,[0.05 0.03]); I want to convert it to the frequency domain to multiply it by a signal (i.e filter in the frequency ...
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0answers
37 views

Constant-Q transform - summing complex DFT coefficients vs. summing DFT magnitudes

The constant-Q transform computes a spectrum on a logarithmic frequency axis. When analyzing music signals, this can be a more meaningful representation than the Discrete Fourier Transform (DFT), as ...
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0answers
460 views

How to perform Wiener deconvolution in Matlab

I have an output signal y which is an input signal x convolved * with an impulse response ...
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2answers
241 views

How does taking the absolute value of a complex signal reflect in the frequency domain?

I have a frequency-domain representation $X(e^{i\omega})$ of the complex discrete one-dimensional signal $x[n]$: $X(e^{i\omega})=\mathcal{F}\{x[n]\}$. Is there a frequency-domain transformation of ...
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0answers
57 views

Simplest approach to classify signal based on its 'smoothness'?

First of all, I have no experience with signal processing whatsoever and I may not even use proper terms so please bare with me. I am just humble software developer trying to find the simplest and the ...
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0answers
80 views

Why does my overlap-add integrator in frequency domain result in distorted signals?

With help from the dsp guide and DSP-Related, I tried to implement a leaky integrator in octave/matlab. It seems to work in general, but there are a few problems. So that's what I do: Calculate the ...
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1answer
230 views

What is doppler tolerance

Can anybody explain the meaning of Doppler tolerance for the waveforms(Linear frequency modulated, Barker code, Polyphase codes) used for Pulse compression. The Doppler frequency shift $f_{d}$ due to ...
3
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1answer
172 views

How does the number of frequency-domain sampling points influence the outcome of an inverse FFT?

Given some frequency-domain representation of an impulse response. How does the number of frequency-domain sampling points influence the outcome of an inverse FFT, if I keep the sampling frequency ...
0
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1answer
130 views

how to get the phasor(frequency domain) representation of a digitalized signal?

I know that we can get the phasor representation(frequency domain) of a signal through Fourier transform, but the picture above gives a method that can get the phasor representation of a signal in a ...
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2answers
77 views

Convolution theorem

As stated by the convolution theorem, a convolution in spatial domain is equivalent to a multiplication in the frequency domain.Nevertheless, when should the first be preferred over the latter?
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0answers
38 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 ...
4
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1answer
1k views

Which information do we get from magnitude and phase spectrum?

I am learning image processing. I want to ask very basic question related to FFT topic Which information do we actually get from "phase spectrum" and "magnitude spectrum" about an image?
2
votes
1answer
151 views

Magnitude of gradient in frequency domain

I'm learning some basics of image processing. Recently I've read about image filtering and two-dimensional Fourier transform, because I'm preparing for exam. And I have one question I don't know ...
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1answer
24 views

2 by 2 bit orthogonal encoding mult-kronecker expansion matrices?

What is the name of the following bit encoding generator matrices?
1
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1answer
87 views

Why multiplying frequency kernel with sinusoid results shifting frequency domain

I am having great time while reading "The Scientist and Engineer's Guide to Digital Signal Processing" book. In "Chapter-14 Introduction to Filters" author indicates we can create high pass filter ...
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1answer
61 views

Similarity theorem in Fourier analysis

I have a homework problem that I'm not quite sure how to complete. The problem is as follows: PROBLEM Write the definition of the Fourier coefficients, and show that $$f(t + \frac{1}{2}T) = f(t) ...
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1answer
1k views

Convert normalized frequency to real frequency in AR model

Let us suppose that we have modeled signal using AR model, and suppose we have following model: I used spectral estimation function from MATLAB pyulear Now ...
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0answers
47 views

question about the frequency of Gabor filters

The Fourier transform of 2D Gabor filters is shown below: F is the radial frequency of the Gabor functions. Another parameter Fm is denoted as highest central frequency. Fr is the constant ...
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0answers
73 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) ...
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2answers
1k views

Convolution in the frequency domain

We often hear that "convolution in time is the same as multiplication in frequency", and vice versa, that "convolution in frequency is the same as multiplication in time". So in a typical windowing ...
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1answer
88 views

What's the frequency transform of a random matrix?

Assume the following: img = 255*rand(512); %Generating a 2D matrix with random numbers between 0 to 255. fftimg = abs(fft2(img)); %FFT of the image. The frequency transform of this image is a ...
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1answer
76 views

Standard deviation of Gaussian corresponding to perfect low pass filter [1,1]

For a time discrete signal, the rect-filter (for 1D signal [1,1]) is a perfect low pass filter. I was wondering, what is the best gaussian approximation of this filter? For a current problem, I ...
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3answers
272 views

What does the negative sign mean in the image frequency domain?

When I transform an image from the spatial domain to the frequency domain, some frequencies are negative. What is the meaning of the negative sign? For example:
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3answers
440 views

How to get Instantaneous Magnitude for a Instantaneous Frequency From FFT?

My understanding if a frequency in my signal doesn't line up exactly with a bin, it is smeared over a few bins to the right and left. How can the instantaneous magnitude be determined? (do I have to ...
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1answer
186 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 ...
0
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1answer
284 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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2answers
340 views

What is relationship between entropy and frequency in image

When I was studying spatial frequency and entropy, it occured to me that "is there a relationship between entropy and frequency?". As you can see, if we consider only horizontal line, the frequency ...
1
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0answers
250 views

Adding shot noise in frequency domain

I have a current signal represented by an array in python, which I would like to add shot noise to. Shot noise is defined as $$ σ_i = \sqrt{2qI \Delta f} $$ where $q$ is the elementary charge, $I$ ...