Questions tagged [frequency]
Frequency in signal processing is the number of cycles (of the signal) per second.
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How do I construct a working 4th order active low pass Butterworth filter circuit with tunable cut-off frequency? [closed]
I have found 4th order low pass Butterworth filter but i have no idea how to produce tunable cut-off frequency. it is for a college project
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How to handle cross products in feedback loop?
I'm trying to simplify the following block diagram from
to the following block diagram
However, h(t), H(s) in time domain, has a cross product in it (gyroscopic torque). How can I represent the ...
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3answers
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Discrete-time signals increase in frequency and period
I am studying Discrete-Time Signal Processing by Alan V. Oppenheim and Ronald W. Schafer. I am confused when it says
periodic discrete signal oscillates more rapidly when its frequency is increased ...
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1answer
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what does frequencies in non periodic signals mean?
What do the frequencies in the a Fourier transform of a non-periodic signal mean physically?
Are there another definition of frequency that doesn't include the FT?
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Aliasing below $f_s/2$
phi = exp(linspace(0, log(511), 1024)) - 1
x = cos(2 * pi * phi)
Above will alias, despite peak instantaneous frequency evaluating to ...
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1answer
36 views
A basic question regarding frequency analysis of an EEG signal
Assume that an EEG signal is sampled at $f_s = 300$ Hz then a 10000-point segment of it is selected, called $x[n]$. The corresponding 10000-point DFT is then computed and called $X[k]$.
Assume further ...
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1answer
39 views
SMA, SVM and PSD python
I'm looking for python functions (package) to calculate SMA (signal magnitude area), SVM (signal vector magnitude) and PSD (Power Spectral Density). The goal is to extract features from an ...
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1answer
36 views
What is the importance of signal bandwidth in radar systems for velocity and localization estimation
So I know about the basics of doppler shift which relates the velocity of a moving object with the frequency carrier shift seen at the reciever.
But, I don't understand the importance of the ...
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1answer
43 views
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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Plot frequency tiling wavelets/curvelets
Is there a convinient way to plot the frequency tiling of for wavelets/curvelets? For example the input would be the number of scales $j$ and the output would be something like this:
Preferably in ...
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1answer
103 views
Calculate the magnitude and phase of a signal at a particular frequency in python
I have a signal for which I need to calculate the magnitude and phase at 200 Hz frequency only. I would like to use Fourier transform for it. I am very new to signal processing. And this is my first ...
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Are there standards/references for determining spatial scale in photographic images?
EDIT, 12/12/20:
Images below are of the radial sinusoid pattern. Left side is the "unrotated" version. Right side is what the a photograph of the pattern would look like if the disc was ...
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Measuring the frequency of the Analog input signal of an ADC, which is operated by Raspberry PI
I'm building a monitoring package for a sensor via a raspberry PI and an ADC, which reads the analog signal (for the moment from a DC power supply instead the real sensor) and transfer it to my ...
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Frequency slows faster when it's decreasing
I'm sure there's a simple explanation but I can't discover it. Consider two frequencies, a and b. a is higher than b. I can create a wave with both frequencies. But when I create a wave with frequency ...
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Determine the change of selectivity
I've stacked on solving this problem and can't find an answer in the web, so I decided to ask a question here.
There are the problem:
Preselector of boadcast receiver contains of one oscillation ...
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1answer
30 views
How to add a frequency offset to a buffer of MPSK signal for simulation purposes?
I need to simulate some channel effect to a buffer of MPSK signal. How to add a frequency offset to a buffer of baseband MPSK signal?
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1answer
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Why is fourier analysis used in doppler effect?
I am a high school student that carried out the experiment on the Doppler effect to therefore analyze the graph but after doing some research, I saw one of the articles saying “ Fourier analysis is a ...
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1answer
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normalized frequency to frequency [closed]
as the definition of normalized frequency is the frequency divided by the sample frequency, I'm confused about my signal so as an example a signal sampled at ($f_s=500 000$) Hz when applying a FFT, an ...
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1answer
127 views
Mixing square waves
I want to mix two square waves of different frequencies together - I'm driving a speaker, and I'd like to play two frequencies at once on it (to whatever extent that is possible). I would just add the ...
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Log derivative interpretation
In the origin paper on Synchrosqueezing Wavelet Transform, the phase transform, used to extract the instantaneous frequency of a signal $f(t)$, is defined as
$$
\omega (a, b) = -j[W_\psi f(a, b)]^{-1} ...
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1answer
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Confusion regarding frequency of Discrete Time Periodic Signal
While Analyzing the DFT Plot for a signal with N samples, say we find a peak in the magnitude of the DFT plot at index $k$, this implies that our signal has a high amount of similarity with an ...
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1answer
226 views
What can be meant by “bandlimited”?
This question was a source of disagreement on whether "amplitude aliasing" can occur for a signal bandlimited to below half the sampling frequency. The question was closed before the ...
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3answers
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Suitable signal processing techniques for frequency response functions?
Good day everyone
I have recorded experimental frequency response functions (frfs) for a loose bolt monitoring project. Please see figure 1 below for an example of the frf.
Figure 1
The purpose of my ...
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2answers
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Amplitude modulation vs sampling rate? [closed]
As a sampled tone's frequency nears $f_s / 2$, amplitude modulation grows apparent:
("Actual" curve in grey; blue is what we get if taking samples (dots) "at face value"). This is ...
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Alternatives to the median filter
I have a embedded system where I get some type of sensor readings with varying frequency between 0.3 to 1 Hz. Sometimes these readings may have impulse like noise. To filter out this noise, I've ...
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1answer
129 views
Normalized Frequency to rads/sec, Hz and discrete/digital frequency [duplicate]
I have a signal sampled at 16000 Hz
I need to convert the normalized frequency of Matlab 0.325 to radians/sec Hz and Discrete frequency.
Can anyone explain this to me?
And btw Matlab plots the ...
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Goertzel filter for non-equidistant sampling
We have a sensor that reports a new value asynchronously only when the value changes. Therefore, we receive samples at arbitrary time stamps. We basically receive value + timestamp of the measurement ...
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Downsampling vs. ADC with lower Sample-Rate
I would like to know in general where the advantages and disadvantages are:
Downsampling of a high sampled continuous analog signal in FPGA or µC and
Direct use of a lower sampling rate, i.e. using ...
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2answers
119 views
OFDM sampling frequency offset
how the 4G LTE Or 5G NR OFDM measures and corrects the sampling frequency offset? if there is an algorithm using matlab please help
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Is there anyway to find the frequency of DFT eigenvectors (basis) from its eigenvalues?
I've read this document which talks about the DFT. It describes that DFT bases are the eigenvectors of a circulant matrix. I know that every basis has a frequency in it, but I don't know what is it? ...
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1answer
26 views
UWB Indoor Positioning
I am trying to understand the UWB technology and how it can be used for localization.
Are there any resources where I can study about the algorithms it uses to calculate the direction?
Also why does ...
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1answer
60 views
How harmonics happens when you mix two signals?
Doing a search in quora about Why does Amplitude Modulation have sideband frequencies? i found an answer and within it, a user answered with the following statement:
"When you try mixing two ...
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FSK technique to superpose the digital communication on top of 4–20 mA signals
I start a working with HART devices and I really try to understand how digital data is transferred trough 4-20ma current loop.
I start read this article: https://instrumentationtools.com/hart-...
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Frequency Estimation Using Multiple Signal Classification Algorithm (MUSIC)
I'm working on side research that deals with signals and data in the time domain. currently, I want to use the multiple signal classification algorithm (MUSIC) which is mainly used for frequency ...
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1answer
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How to calculate PSD if i have power vs freq spectrum?
i have a signal something like this
how to calculate PSD?
i have freq from 191000200 to 196500000
time gap or delta t = 1 or 2 sec, (what i mean is [tn] - [tn-1])
i will be computing in python any ...
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2answers
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Frequency Support of Window Functions
All window functions, which go from zero amplitude, up, then back to zero amplitude, are all base-band signals. Why is this? Are all functions that have this behavior always band-band aka low-pass?
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3answers
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Why does dot product return zero at non-harmonic frequency
If I understand correctly, dot product between two sinusoids should return zero if they are orthogonal. Since dot product is at the heart of the DFT, we can only clearly compare the frequencies that ...
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1answer
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How to do Frequency Scaling on an Audio File
Please excuse me if my terminology is wrong. I'm from a music production background and have no experience in signal processing.
I was wondering if it was possible to stretch out the overtones (...
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Fundamental frequency in DFT [duplicate]
I was looking into the fundamental frequency in DFT and I noticed many sources mention that the fundamental frequency is $1/N$, where $N$ is the number of samples. (When doing the DFT, we have $k/N$, ...
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1answer
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What's the relation between frequency band of $X(j\omega)$ and $\Phi_{xx}(j\omega)$?
in which:
$x_{c}(t)$ is a continuous-time signal
$X(j\Omega)$ is the Fourier Transform of $x_{c}(t)$
$\Phi_{xx}(j\Omega)$ is the Power Spectrum Density of $x_{c}(t)$ which defined as Fourier ...
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1answer
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Why does toning up a piano make it sound similar to that a string instrument
I have a .wav file of a piano being played at 220 hertz. When I tone this up to 880 hertz, it begins to sound "stringy". However, if I were to use the piano plugin in fl studio and play it ...
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2answers
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What is a speaker behaviour for out of range frequencies?
I was watching this video. The experiment is to create a square signal and record what is outputted by a speaker. We see two diracs signal (+ and -) that looks like the derivative of the signal. Can ...
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Which equation for analyzing mixed mode sparameters?
I am reading about converting single ended sparameters to mixed mode here.
"As shown by Equation 43, single-ended S-parameters can be converted into mixed-mode S-parameters with the [M]-matrix (...
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1answer
55 views
Frequency Domain Distribution
I have a complex signal in the time domain normally distributed. What will be its distribution in the frequency domain?
I assumed since the frequency domain is a linear transformation the distribution ...
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1answer
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Accelerometer sensor's data analysis [closed]
Here is a sample data that I got from the accelerometer sensor:
The first selected area shows the acceleration of the IMU device to right side and the second shows the movement to left side.
I am ...
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0answers
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Interpretation of Complex modes in Frequency Domain Decomposition
When I do a Frequency Domain Decomposition (FDD) I always get mode shapes with significant imaginary components.
Let's say I see a strong modal response. Still have strong complex nature.
When I do a ...
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2answers
221 views
How do I remove “jitter” when detecting frequency of Sine Wave
Input: Sine wave of any frequency centred at 1.66V
Output: Square wave with a frequency equal to input
I have been working on implementing a common DSP problem -- Detect the frequency of a Sine Wave. ...
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1answer
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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
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Match an Equalizer Curve
I’ve passed a sine sweep wave file into an equalizer plugin I have, now I want to model it in matlab so that I can ‘copy’ the equalizer setting sound. I’ve both in.wav and out.wav audio files and ...
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2answers
336 views
Continuous frequency vs discrete frequency? [closed]
I have understood idea of discrete time and continuous time but I am feeling difficult to comprehend this idea in regard to frequency.
As for example the DFT output is discrete and the DTFT output ...
