Questions tagged [frequency]

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

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What is the maximum frequency that can be captured by a given sampling rate?

Let's say that we want to digitally sample an analog signal and have a sampling frequency of 8000 samples/second. Usually the maximum frequency that can be captured is the half of the sampling ...
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Frequency spectrum of signal - Matlab

Here is the code I use to plot a function in frequency domain in Matlab: ...
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279 views

FM demodulation amplifier with saturation

I'm trying to understand how FM demodulation works. I read a lot on the internet and as far as I understand, the main process is to extract the phase difference (that is also the output) between a ...
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Correlation between Sin and Square wave

I would like to know how $\frac T2$ came for time period in the image below.Because I think the frequncy is 1 so time period should be 1.Is that correct? or can anyone help me.. The article from ...
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Effect of Sampling frequency on RMS estimation

I have a simple, but interesting question for you. I have to compute the RMS (root mean square or standard deviation) value of a time signal which represents in my case a velocity mesasurement over ...
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219 views

what is the maximum instantaneous frequency of Dirac delta?

I wish to find the maximum frequency of $\sin(\varphi(t))$, where $\varphi(t)=u(t)$. We have $\omega(t)=d\varphi(t)/dt=\delta(t)$. What is the the maximum instantaneous frequency $\omega_{\max}$?
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Understanding Hertz

This question is in two parts, both related in some way or another. Suppose I have a signal where the sample rate is 44100 and compute a normal 1D DFT on this signal. The size of this signal is ...
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334 views

The impulse response, $h(t)$, of a system

I have this differential equation $$ y''(t) + y'(t) + y(t) = x(t) - 3x'(t) $$ I found the system response of the system: $$ H(f) = \frac{1 - 6\pi fj}{(2\pi fj)^2 +2\pi fj+1} $...
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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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What is difference between Signal frequency and data rate

I read somewhere the below two line and got confused what is the actual difference between the two line. These two lines are related to CAN 1.Maximum Signal frequency used is 1 Mbit/sec 2.Typical ...
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Relationship between filters, Fourier magnitude, and frequency

I'm just beginning to study Fourier transforms and I'm having trouble getting this concept down. I know what a low/high pass filter does to a signal. What is the relationship between Fourier ...
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FM synthesis fuzzy sound

I'm trying to reproduce this !!!WARNING LOUDNESS!!! sound in C. In the website, it says to use Carrier: 500 Hz, modulator frequency: 1 Hz, modulator index: 500, however I'm getting lots of clicks and ...
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How do you calculate/compute/determine the spectral coverage of a frequency spectrum?

I'm comparing frequency spectrum of FSK, ASK, QPSK, and MSK. And I'm asked which has the least and greatest spectral coverage. Could someone enlighten me on how to get it?
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How to calculate the quantum of the difference between two value of clock counter where the values are divided by 64?

I have a counter in my embedded system with f = 64 Mhz. let's say its read value is $cnt_i$ where $i$ is the index of the time I sampled it. $$\Delta = cnt_{i+1} -...
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34 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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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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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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Coding an LFO in C

I want to know how I could implement a Low Frequency Oscilator on a simple synth I've coded in C. First in order to understand how to make this happen I would like just to modulate a sine wave by a ...
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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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Perceptual Based Adversarial Audio Attacks

I am reading this paper Perceptual Based Adversarial Audio Attacks I have a doubt what is meant by weighting in the frequency domain and what does Section 3.4-equation-4 wants to convey .Please refer ...
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Frequency response Test (Bode Diagramm) on system controlled with a PLC

i have to perform frequency response test on a pump system with servo Motor controlled by a PLC von ALlen Bradley (Logix 5156). I not sur how to proceed and will like to know if someone did such work ...
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What is the Effect of Multiplying a Function by the Unit Impulse Function in the Frequency Domain? [duplicate]

I know about the the shifting property of the impulse function in the time domain as can be seen in the picture. But what is the effect of multiplication of a function by the impulse function in the ...
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modulation depth

When a value for the power dissipated by an AM signal is given, and the depth of modulation is also given. Then you are told to find the modulation depth required to increase the power to a higher ...
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1answer
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A-GPS frequency (fd) search ranges

A-GPS is able to reduce the fd search range from several kHz (GPS search range) to several hundred Hz (a-GPS search range). I know the GPS search range has a center at 0 Hz. What is the center ...
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Error in measuring wavelength/frequency using autocorrelation

I am currently using these two fonctions to compute to autocorrelation of a signal in order to measure the wavelength: ...
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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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frequencies in frequency spectrum with no correlation together

I have a lack of understanding of the following questions: If I have a signal from a motor that is recorded with an accelerometer. And the rotating speed of the motor is 150Hz(rpm 9000 ), I can see in ...
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Signal is not audible after frequency re-sampling

I'm trying to change the frequency of an audio signal from 22050hz to 500hz. I'm using librosa to read the wav audio and pass the custom sampling rate as 500. Once read, I'm saving it back to audio ...
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Possibilities to get the amplitude of a signal at specific frequency from IQ

I'm newbie to the dsp topic and my understanding of math symbols is limited. So at the moment I'm little bit lost to find the right resources. I receive an IQ stream from a SDR. Sample rate: 250k/s ...
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Carrier Frequency Offset Correction Limitations

I know that carrier frequency offset is typically detected and corrected in OFDM systems. I was wondering if there is a way to determine the theoretical limit to how much offset can be successfully "...
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55 views

Frequency Smoothing for Noise Reduction

I'm trying to understand the Noise Reduction implementation in Audacity and I was wondering how the Frequency Smoothing is implemented. Frequency Smoothing (bands): At values of 1 or higher, this ...
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frequency amplitude asymmetry

I want to calculate the frequency amplitude asymmetry between two signals, EEG signals in particular. As a result, I expect a value ranging from 0 to 1. I have some references regarding that, but it's ...
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FFT first frequency

I have some problems understanding FFT. If I know Fourier analysis frame (1024 samples) and sample rate (48 000 Hz), how can I find the first frequency of harmonic sines and cosines?
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Physical meaning of a signal with 4 IMF?

If a signal is composed of four implicit mode functions, where the last one is a constant residue, does the instantaneous frequecy of the signal have physical meaning?
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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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115 views

Difference between OFDM and FDM

In Frequency Division Multiplexing we provide one channel to one user. Example like BandWidth of user1's voice is 200Khz. I provide one channel of 200KHz in FDM for uplink as shown in the figure. ...
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73 views

DFT and integer valued basis functions'sf requencies

In Matlab the function W=dftmtx(N) gives the DFT matrix of size N. Each row is computed for an integer frequency k. $W_{k,n} = e^{-i2\pi kn/N}$, k-th frequency, ...
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histogram bin size vs. data sampling rate

I have a set of numerical signals that give me a set of zeros calculated based on some numerical procedure. I make a histogram of those zeros. Here, a following problem arises: If the histogram ...
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May I know how to find Time frequency power spectrogram of a signal?

I am analyzing EEG signal and I am unable to understand the term Time-Frequency Power Spectrogram. Please Can anyone help me? Thank you in advance.
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Temporally locating beats in an audio file

Imagine you have a long recording of a guitar player playing an arpeggio at a slow speed. To simplify, assume the tempo is 60 bpm or lower. I want to annotate this recording with the exact moments ...
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299 views

What is normalized angular frequency? [duplicate]

I am new to DSP, and I am self-studying. I came upon this question, and I am stuck at it. Could someone please help me? Here is the question: In order to digitally create a sinusoid with frequency $...
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Is there just a carrier in each frequency band in FDMA?

The figure is the FDMA,and i know that FDMA is that dividing the bandwidth into many blocks(frequency band),i want to ask Is there just a carrier in each frequency band in FDMA?i mean one carrier for ...
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The grid frequencies In the design of a digital filter

I want to find many difference 'h' with same group delay and length filter using this code : https://gist.github.com/mattdsp/17f508d2b368db61f47689e4622d8841/c1518f22a5aa451951601b56c5d9f72743868bfe ...
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Estimating frequency when there's little isolation between signal and noise frequencies

Say I have a signal which is guaranteed to have a frequency between 110-120 Hz but is corrupted by interference signals that're very close to this frequency range. For example, let the interference ...
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649 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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Matlab produces two unknown spikes in custom FFT

I'm making a relatively small Cooley–Tukey FFT in Matlab and I'm noticing unusual spikes in the result compared with Matlab's own FFT. The figure below shows the signal flow of my program. It's a ...
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498 views

Sine Wave spectrum showing multiple frequencies - Audacity

I am generating a sine wave using audacity with 2000 Hz, 30s duration, amplitude 0.5 48 kHz is the sampling rate of the recording device. I just play and record the generated sound, this is the ...
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Calculate average mean FFT Magnitude in bins [duplicate]

I am analyzing sounds of daily activities recorded by a smartphone. For example walking, getting up from bed, falling, running etc.. (one at the time). Let’s take one them. My goal is to convert from ...
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Frequency identification as a convex problem

Suppose I have two time series, $x(t)$ and $y(t)$: $x$ is the output of a sine wave generator, and $y$ is the generator's frequency setting. Given a training set of $(x, y)$ pairs, Is it possible to ...
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Reduce impact of outliners for frequency analysis by increasing signal length?

I am working on a project to detect drivers drowsiness with EEG signals. I am using the frequency values retrieved by FFT. I have some outliners (artifacts) in my signals, which I don't want to remove ...

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