Questions tagged [frequency-domain]

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In audio analysis, is the first rahmonic from the cepstrum equivalent to the first partial of a pitched sound?

I was reading this text from Oppenheim and Schafer, briefly explaining the concept of the cepstrum. I'm new to this concept. He explains that the cepstrum is useful to quantize the distance between '...
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20 views

Cutoff Frequency of Low Pass Filter for Image Processing

Im working on an image processing problem where i need to implement lfilter from a paper. The filter is done in Frequency domain. In the paper stated that the filter is a low pass with following ...
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1answer
36 views

Continuously changing pitch of stable-pitch audio sample

I have an 44100-rate 4 second sample of a legato violin playing at 440 Hz. I would like to modulate this sample so that it starts at 440 Hz, then transforms its frequency continuously and ...
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3answers
119 views

If a square wave is a sum of odd harmonic impulses, why is it continuous in the frequency domain?

A square wave is a sum of sinusoids so surely it should be represented as individual discrete impulses in the frequency domain, where all other frequencies are 0. Why instead are those intermediate ...
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2answers
249 views

Showing linear-phase frequency response when only real part is known

I'm studying for an exam, and this particular practice problem is missing the solution: Given a causal LTI system where only the real part of the frequency response is known, $$\Re\left\{H(j\...
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33 views

How to downsample a fourier transformed signal?

I have a signal of length 100000 timestamps sampled at a frequency of 25kHz. First I apply a high pass filtering at (300Hz) and then do the Fast Fourier Transformation. Then the absolute values are ...
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2answers
520 views

Derivation of downsampling in the frequency domain

I'm having some trouble with this derivation $$s_d = \begin{cases}1&\text{for}\quad m\quad\text{multiples of}\quad D\\ 0 &\text{otherwise} \end{cases}$$ then $s_d$ is somehow rewritten to: $...
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1answer
34 views

phase offset extraction using matched filter

I'm looking for an application of detecting the drift of a received signal carrier frequency from ADC clock of the receiver (in case of no drift, ADC clock should be optimally an integer multiple of ...
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1answer
26 views

Names of system functions in frequency domain

I was just trying to refresh my systems theory known from long ago, and I realized that I had forgetten the name of the basic functions. Specifically, what are the names of these functions ...
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1answer
59 views

ouput of low pass filter

$$y[n]=(-1)^n w[n]+w[n]$$ $n$ ranges from $-\infty$ to $\infty$ where $w[n]$ is output of frequency response block with cutoff frequency = $\pi/2$, and input is unit impulse function. I know ...
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1answer
52 views

Is pitch detection for bass instruments a solved theme?

I would like to know if pitch detection is a solved theme for an instrument like a bass (bass tones). Is it, or there is always a percentage of error rate on the detection?
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1answer
51 views

Steady state variance of a stochastic differential equation - relation between the frequency and time domains

Consider a stochastic differential equation: $$ dx(t) = a x(t)dt + b y(t)dt \quad (1) $$ where $y(t)$ is a stochastic process satisfying $\langle y(t)y(t')\rangle = \delta(t-t')$. We will assume that ...
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1answer
56 views

Why use PSD to analyze a signal instead of its Fourier Transform?

Let's imagine I have a perfectly known signal $s(t)$ and I want to analyze its frequency components. I noticed that mostly everyone would use the PSD of $s(t)$ to do that, instead of simply use the ...
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21 views

Does it make sense to apply convolution in the frequency dimension of a fourier transformed signal?

What I have is more likely a theoretical question. Since I am not from a signal processing background it is hard for me to grasp the issue in using convolution in the frequency dimension of a Fourier ...
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1answer
23 views

Is it possible to prove that dither VS PWM can result the same output?

Assume that we have a SISO transfer function model $G(s)$ and we want to look how the output looks like when we have a input signal $u(t)$ that looks like this: $$u_1(t) = \left\{\begin{matrix} 50 + ...
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2answers
64 views

Proof of fourier transformation of multiplication of two signals

I've been trying to find a proof of the following, but still I m unable to proof it, can someone help me? $$ ℱ[x(t)g(t)] = \frac{1}{2\pi} [X(\omega)*G(\omega)] $$
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3answers
61 views

What is the Effect of Multiplying a Function by the Unit Impulse Function in the Frequency Domain?

I know about the the shifting property of the impulse function in the time domain as can be seen in equation $(1)$. $$ \int_{-\infty}^{\infty} f(x)\delta(x - a)dx = f(a)\tag{1} $$ But what is the ...
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1answer
35 views

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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1answer
98 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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1answer
38 views

GPS Receiver in Frequency Domain

I'm trying to transmit and receiver the GPS payload in both Time and Frequency Domain. For transmitting and receiving in time domain : ...
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1answer
60 views

Derivation of Circular Mean Square Error

I would like to understand how Eq. (36) in [2] was derived: The rationale behind the definition of circular sample mean in Eq. (37) is clear, but there is no motiviation for the CMSE definition in Eq....
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1answer
55 views

Why does this transfer function estimation not work? System identification

Goal: I have an unknow dynmical system $G(s)$ and I want to find it from measurement data, output $y(t)$ and input $u(t)$. The data is frequency responses. Method: I begun first with creating the ...
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2answers
34 views

Digital filtering based on frequency component amplitude… why not?

I've got a very general question. I've just implemented a filter working in frequency domain that simply cuts every frequency component whose modulus amplitude falls below a certain threshold value. ...
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1answer
456 views

Can I use frequency hopping spread spectrum technique for audio steganography?

I have been trying to use spread spectrum technique for audio steganography. I read a lot about it.But i didn't find any information about the steganography scheme using FHSS(frequency hopping spread ...
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1answer
32 views

Continuous frequency grid to discrete grid

I am designing a controller for a system using several methods, one of which is a discrete method. In the continuous time I am looking at a logarithmically spaced frequency grid in the range $$\omega \...
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1answer
53 views

Harmonic Product Spectrum from FFT output to the fundamental frequency

I'm trying to do the HPS algorithm on my FFT output, but I'm stuck here. My signal is from a bass (cable), 16bits, 48.000Hz. I split in time domain the array of the whole record into multiple arrays ...
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1answer
666 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
115 views

Break a signal into segments, add them together and then perform an FFT on the result

If you break a 4 second signal into 0.5 second segments, add them together and then perform an FFT on the resultant 0.5 second data. Will the FFT / frequency spectrum be the simlar to an FFT on the ...
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2answers
97 views

How to avoid overtones in audio signal

I'm trying to make a program that catch and audio signal of a bass and show the notes that have been played. My program: Gets the sound and put it in a double data type array. (48 000Hz, 16bits) ...
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1answer
244 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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2answers
712 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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1answer
162 views

get poles and zeros of frequency response

I am working on a python based LTSPICE project. I would like to get poles and zeros of AC simulation data. Is there a way to get them under use of the magnitude and phase out of the frequency ...
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2answers
100 views

Smoothing in frequency domain and impulse reponse of the filter in time-domain

I have a low-pass signal in frequency domain, $$\left[f_{min}=0, f_{max}=20\,\mathrm{GHz}\right]_{n=100}$$ After re-configuring the input signal as $$X=\left[-f_{max},\ \dots\ -f_{min},\ \mathrm{DC},...
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41 views

Convolution Theorem using DCT

I am trying to digest this paper. [2002] Anna Usakova. Using Of Discrete Orthogonal Transforms For Convolution So far, I've been successful with DFT and DHT. Could someone give a hand with DCT? I am ...
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1answer
45 views

Is it true that each and every signal has multiple frequency components?

Usually when we observe spectrum of a signal,we see multiple frequency components, each having different contribution to amplitude But is it true that each and every signal has multiple frequency ...
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1answer
30 views

Time and Frequency Domain Relationship

Why do we say that a good time response means a bad frequency response?
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1answer
209 views

How do I perform a time domain phase shift in the frequency domain?

I've seen some information on this topic around, but I don't quite understand it. I have a time domain signal. I understand that if I want to time shift this signal, I can do so by multiplying its ...
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1answer
259 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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46 views

Frequency and Order maps

I'm new to python and I'm using it to analyse accelerations from an accelerometer ie. vibration analysis. For that I need to plot 2 types of diagrams: 1) Frequency map; frequency and time on the axis ...
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28 views

Time Frequency bin

I am doing research in audio signal processing for DOA estimation. I came across the term Time-Frequency bin. I have gone through several articles but none of them specify a TF bin rather it specifies ...
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3k views

What's the meaning of a complex zero/pole?

I have been studying signal processing and control for a while now, and I use Laplace and Fourier transforms almost everyday. Also another tools such as Nyquist or Bode plots. However, I had never ...
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1answer
59 views

Absolute value based AM envelope detection viewed in the frequency domain

In my understanding when a passband AM signal is demodulated with an envelope detector taking the absolute value restores the original baseband version of the signal and the low-pass filter removes ...
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4answers
102 views

Remove brighter regions in an image on frequency domain

I'm newbie and maybe this is not the right place to ask this question, or this question has no sense. I'm very interested in working on filtering images on frequency domain. I have found a few ...
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3answers
4k views

Impulse Response to Frequency Response in Octave

Having an impulse response of an audio system recorded as a wav file, how to calculate the frequency response of the system with octave?
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2answers
74 views

Sampling Theorem: T-Sampled Signal

I am stuck in a small question which I am trying to solve. The signal $f$ defined by $f(t) := \text{sinc}(t)$ is to be sampled. How should I draw the illustrations of the $T$-sampled signal $f_{T} = (...
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1answer
73 views

Spectrogram of an executable binary [closed]

One of the approaches I have been searching so far is the application of utilizing Neural Network to classify Spectrogram images, which is heavily used in speech recognition. I am conducting an ...
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0answers
17 views

Where can I find more information about how to create filters on frequency domain?

I'm newbie and I'm very interested in filtering images on frequency domain. I haven't found a lot filters on frequency domain and I wondering how can I create new ones. How can I create new ones? ...
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45 views

Range Migration Algorithm in FMCW MIMO radar

I’m using a FMCW MIMO radar [77-79 GHz] with a virtual linear array made of 48 channels. I’m wondering if the adaptation of the range migration algorithm (typically used in SAR processing) is ...
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2answers
77 views

Idea for Noise Level Estimation / Automatic Thresholding in the Presence of Peaks

I have the fft of some signal, and want a rough estimate of the noise level in order to choose an appropriate threshold for our peak detection algorithm. In general, the fft contains mostly noise with ...

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