Questions tagged [frequency]
Frequency in signal processing is the number of cycles (of the signal) per second.
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questions
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Does the Nyquist frequency of the Cochlear nerve impose the fundamental limit on human hearing?
The bandwidth of human hearing by empirical data is $20 \; Hz$ to $20 \; kHz$. A cochlear implant stimulates the auditory or acoustic or Cochlear nerve directly so that the hearing can be improved in ...
2
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1answer
58 views
Scalograms in python
I am reading this paper to learning basic concepts of dsp and I want to reproduce the following scalogram of a test signal (fig 4.2 of the paper):
It has been produced from the discretization of the ...
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4answers
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Estimation of Amplitude, Frequency and Phase of Linear Combination of Harmonic Signal Beyond the Leakage Resolution of DFT
How can I find a rough ( as accurate as possible) Amplitude of each frequency when there is spectral leakage.
Currently, I am dealing with a system that contains special leakage which seems ...
2
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2answers
34 views
How to Quantify a Difference in Spectral Information of two Signals?
As the title states, I am looking for established methods to quantify the difference in two FFTs. I have come across methods such as using cross correlation in the time domain or the coherence ...
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7answers
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Where do harmonics come from?
At first, I thought harmonics come from the signal being periodic. However, we know a sine wave is also periodic but contains a single frequency and no harmonics.
A harmonic for me is a component (...
3
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1answer
372 views
Meaning of a null coefficient at 0 Hz
I am analysing a wave with a timespan $\tau$ and after applying the fft I obtain the following plot of the coefficients
I assume that the peak at $t=1$ followed by smaller coefficients means that the ...
0
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2answers
47 views
Estimating sampling frequency offset
I am searching a paper or article on this subject.
I have heard of a function that estimates the sampling frequency offset between nominal and actual (sample rate of samples) sampling frequency and ...
0
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0answers
29 views
Instantaneous amplitude of a constant frequency sine wave?
I am playing around with the Hilbert transform using Python's scipy.signal.hilbert package to better understand what the various instantaneous properties are given different input signals. One input ...
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0answers
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estimating peak frequency close to bin zero
Given a half complex spectrum (positive frequency bins from DC to Nyquist) as the result of a real FFT, to estimate the true (non integer) peak frequency I usually rely on Eric Jacobsen's estimator:
$$...
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2answers
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How to implement an RF Mixer for chirp signal in python?
According to this link, all I need to do to mix two signals is to multiply them.
I have two chirp signals with same properties, one leading the other. If I multiply them to get the IF output, I don't ...
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0answers
16 views
SPL dB to voltage conversion misunderstanding
base on these links:
https://electronics.stackexchange.com/questions/96205/how-to-convert-volts-to-db-spl
https://electronics.stackexchange.com/questions/302833/convert-digital-and-analog-values-to-...
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1answer
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how to find frequency response of microphone
hello I want to find the frequency response of a microphone. I give the input signal to my speaker and it produces a specific SPL with specific frequency. on the other side, I read the microphone ...
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1answer
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What is the effect of a larger window size on “temporal resolution”?
I guess my question boils down to what "temporal resolution" means?
I'm taking a signal processing class right now and we're learning about DFT and windowing at the moment. We've learned ...
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2answers
140 views
Most efficient way to find single dominant frequency (without amplitude) in analog signal
I want to construct a reference locked sine oscillator. The multibit sine wave is calculated using DDS. The multibit reference signal is typically not sinusoidal, can have offset and substantial noise,...
0
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1answer
64 views
What is the Uncertainty or error due to sampling frequency?
If I want to detect the distance between two peaks in a signal sampled at 100 Hz. Then is it right to say that the first and second peaks occurred within 0.01 seconds of uncertainty? Therefore, the ...
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0answers
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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 ...
6
votes
3answers
201 views
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
46 views
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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1answer
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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 ...
2
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1answer
40 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 ...
0
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1answer
65 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 ...
1
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1answer
43 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 ...
0
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1answer
48 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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0answers
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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 ...
2
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1answer
753 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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2answers
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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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0answers
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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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2answers
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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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0answers
20 views
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 ...
0
votes
1answer
31 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?
0
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1answer
75 views
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 ...
0
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1answer
49 views
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 ...
0
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1answer
173 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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0answers
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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
274 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
105 views
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
473 views
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 ...
0
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0answers
137 views
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 ...
0
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1answer
165 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 ...
0
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0answers
35 views
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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3answers
155 views
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
138 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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0answers
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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? ...
0
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1answer
28 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 ...
0
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1answer
78 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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0answers
28 views
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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0answers
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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 ...
0
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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
52 views
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?
