Questions tagged [frequency]

Frequency in signal processing is the number of cycles (of the signal) per second.

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How does one interpret an element of the “transfer matrix” used to calculate frequency domain granger causality (via VAR models)?

I am attempting to gain a better mathematical understanding for how autoregressive models can be used to infer frequency-domain granger causality. All freq. domain measures of causality that utilize ...
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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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148 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,...
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613 views

What does it mean for a function to have frequencies?

In a lecture, my professor mentioned that $\cos$ has two frequencies. I see that using the inverse Euler's formula we can express $\cos$ as a some linear combination of complex exponentials, each with ...
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What is role of BW and frequency in internet speeds?

First the bandwidth (BW): It is the amount of data that can be transferred simultaneously.just like more no. of highway lanes so that many cars can travel side by side simultaneously. Frequency It ...
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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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FFT Zero Padding - Amplitude Change

I'm just learning about Fourier Transforms and as an input I'm using a WAV file (Matlab) and taking one channel of it and performing a quick Fourier transform. I've zero padded the input, as I've been ...
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1answer
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How to change a continuous signal to form a discrete signal? [closed]

I have a continuous signal $$ x(t)= 2\cos(200\pi t)+8\cos(250\pi t)$$ and it is sampled at 400Hz. How is this changed into the discrete time domain in order to determine the two discrete frequency ...
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1answer
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Frequency of a DFT Bin

I've been wrestling with this question for way too long. I appreciate any insight you can offer. Thanks. If the $9$-point sample sequence $x(n)$ represents a time domain signal sampled at $48\...
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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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Understanding FFT of an Image

I am having trouble identifying the frequency components of an image, Here I simply generated, 256x256 binary-image. a = [zeros(256,128) ones(256,128)]; imshow(a); ...
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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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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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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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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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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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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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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
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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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674 views

Mapping the Value of a Sample in a 2D DFT to Cycles/Pixel

If I have an image and its 2-D DFT of that image, what is the mapping between the value of the DFT at (u,v), and the frequency in the spatial domain in the x and y components, in cycles/pixel? I want ...
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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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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
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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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How to Map CWT to Synchrosqueezed wavelet transform?

I don't understand the mapping time-scale plane to the time-frequency plane in synchrosqueezed wavelet transform, i.e. $(3)$. You can find the paper here. For the given signal of $x(t)$ and mother ...
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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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What Is the Bilateral Filter Category: LPF, HPF, BPF or BSF?

I`m reading about Bilateral filter with images, I knew that it uses Gaussian filter (which is a LPF) as a domain filter plus a range filter and it is used to preserve edges(high freq component). Can ...
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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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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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507 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 ...
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Sampling Frequency Math

The Nyquist formula for digitally sampling and recovering a continuous waveform is well known. Are there any mathematical formulas that show that it is computationally infeasible (or impossible) to ...
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197 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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1answer
42 views

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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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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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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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
192 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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Efficient frequency offset estimation of known signals

Let's say that my receiver will be receiving known data signals that range from the very simple (tone) to the complex (known data sequence that is modulated (PSK/QAM/OFDM/etc.)). What are the most ...
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Does negative frequency actually exist or it is just theoretical?

This below questions gives good explanation regarding negative frequency What is the physical significance of negative frequencies? But I have one query Does negative frequency only exist ...
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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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How to decipher this Microphone sensitivity Chart for Choosing a SPL meter

I have a mic having sensitivity chart as below which has relative dB on y-axis showing 1V/0.1Pa what does this convey how to read my mic's sensitivity a document on microphone sensitivity from ...
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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
29 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
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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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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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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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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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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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