Questions tagged [frequency]

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

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Why is the frequency measured in radians in filter design?

This is my first time posting a question, so sorry if my articulation is not proper. I'v just started out with FIR filter design and I see the domain being -$\pi$ to $\pi$. Now I understand that ...
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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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RF Downconversion using Heterodyne Principle

after a RF down-conversion using heterodyning principle, will there be an information loss? If we translate to a fixed IF frequency, is there is an intuitive way of explain that the information can be ...
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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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How do I find a 50Hz sin/cos signal in a measurement among other frequencies and noise?

I measure magnetic fields with high precision, in a gradiometer setup with fluxgate magnetometers, sampling at 2000Hz. I can have big data sets if I want to - one is 600000+ samples long. I need to ...
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time in Sine Wave equation

According to Wikipedia, The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. The formula for the Sine wave is, A = Amplitude of the Wave ω = the ...
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791 views

Distribution of energy in frequency bands

On my wav-file (music), I do a short-time Fourier transform (STFT). I have spectrum, which spans from $0\textrm{ Hz}$ to $f_s/2$. I took out the range between $1$ and $1000\textrm{ Hz}$, which I ...
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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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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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How to measure SNR of an image with banding noise (high and low spatial frequency noise)?

I have a thermal image of an object, for example, a lamp. Initially, the lamp is off at ambient temperature. The resulting thermal image should look highly uniform (a), but it contains expected ...
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What is the Gabor filter? And what are its main uses?

I'm doing research on the Gabor filter. When I Googled it, I found very long and complicated articles. Can anyone help me to find a simple explanation about it, or recommend a website or article to ...
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800 views

Chebyshev I or Chebyshev II?

I am new to DSP, and I am trying to recreate some analysis of a signal, They use a chebyshev I filter to go from a 100Hz signal to a 50Hz signal. Whereas I am currently using a chebyshev II filter, ...
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What does “frequency” mean for various kinds of signals?

I've been involved in Signal processing for quiet a time but I'm still so confused of what frequency could possibly is, as it has different meanings in different scenarios, for example, According to ...
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What does following statement mean: “ Simulation was done at the rate of 12 samples per cycle of 50Hz a.c.”

I am very new to the signal processing world and i am currently doing a project of studying frequency components in electrical machines. I am simulating the system in PSCAD. But i need to simulate the ...
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629 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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What is the difference between phase noise and frequency noise?

I'm reading Audoin and Guinot's The Measurement of Time: Time, Frequency and the Atomic Clock, and ran across a confusing an interesting passage (Section 5.2.5, pp 72-73): The physical origins of ...
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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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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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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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Increasing parameter $\omega$ in $x[n] = e^{j\omega n }$

Suppose $x[n] = e^{j\omega n }$. I've seen following statement many times in the different sources: For the discrete-time sinusoidal signal $x[n]$, as $\omega$ increases from $\omega = 0$ toward $\...
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How to see the amplitude of each frequency?

do you know software that exports spectrograms to images of 500x22000 pixels? all the spectrograms that I know show diffused frequencies and it does not look very good I just want to see the amplitude ...
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Is it better to use sampling rates which are a power of 2? 32-64-128-256-512Hz? instead of using for example 30- 60-100-250-500Hz?

I am recently working with a sensor that I its sampling frequency can only be configured to either 32hz- 64hz- 128hz-256hz... and I was wondering whether using such sampling frequencies have any ...
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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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Difference in frequency spectrum of continuous time signal and discrete time signal?

I am studying chapter 4 of book signal processing first There i came across a concept which says that(what i have understood)the spectrum of continuous time signal has limited number of lines while ...
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Frequency Analysis (DFT / FFT) of a Signal Without a Constant Sampling Frequency (Non Uniform Sampling in Time Domain)

I'm a stack exchange user for some time and now I'm registering to ask a simple question (I think!). I have a vibration signal with an amplitude and time (sampling frequency not constant) in a $...
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Tracking a sine wave with noise

This will probably be an extremely simple question for some one with any background in signal processing(not my background) Let say I have signal $$x(t)=A\sin(\omega t)$$ where A is known and $\omega$...
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625 views

Nyquist frequency and DC

Im studying the DSP book by Steven W. Smith. On page 41 he covers the Nyquist frequency. He makes up an example by writing the following. ... consider an analog signal composed of frequencies ...
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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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1answer
48 views

Detection Bandwidth for Noise Power Calculation

I am trying to calculate the $P_{noise}$ in an experimental setup, such as given below. The DUT is excited at a predefined frequency, $f$ , with power $P_\text{in}$. The total power is measured by the ...
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68 views

PLL for Phase Demodulation and Carrier Tracking

I've been playing around with using a PLL for phase demodulation and it's working pretty well. The PLL locks to the carrier and the error term is the demodulated message signal. However, depending on ...
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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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Angular frequency ($\omega$) vs regular frequency($f$)?

What is difference between angular frequency ($\omega$) and regular frequency($f$)? As far as i am able to understand is that electric power signal has $f=60Hz$ and many other cases where i see "$f$" ...
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165 views

How Is a Signal Changed After Sampling?

I can't understand sampling signal mathematically. for example $x(t) = 2\cos(100\pi t) + \cos(300\pi t)$ and I know I should use sampling frequency $300\textrm{Hz}$ to sample this signal. and after ...
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Representing a sinusoidal signal in terms of positive and negative frequency components?

I am reading "signal processing first " by Mcclean https://www.amazon.com/Signal-Processing-First-James-McClellan/dp/0130909998 In article 2.5.4, author discusses about representation of real ...
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What is difference between frequency and pitch?in nutshell and simple words?

Although both are some how directly related Such that when one increases,the other one also increases I have read different Google results but couldn't understand . I want to know what is exact ...
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How can I improve the resolution of a spectrogram of a low-frequency signal with high sampling frequency (Python)?

Imagine you have signals $x_1(t)$ and $x_2(t)$ that contain a limited number of periods of low frequency oscillations and are sampled at 44100Hz (coming from an external source) and you want to obtain ...
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29 views

Time and Frequency Domain Relationship

Why do we say that a good time response means a bad frequency response?
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Extracting different frequency bands (alpha, beta, gamma) from brain activity data

I am new to signal processing and despite googling about my question, I still couldn't find the solution. I have an Electrocorticography (ECoG) dataset. This consists of recording brain activity from ...
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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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Determine whether a signal is periodic or not and get fundamental period

Here is my signal Cos(n/2)*cos(pi*n/4) cos(n/2) has period 4pi and cos(pi*n/4) has period 8 Now, the question is will the signal be periodic for fundamental ...
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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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How do I find the peak frequency of a wav file in python?

I am fairly new to python and signal processing and I was given a task to record audio for 'x' seconds and then find the peak frequency in the audio file. So far I have successfully implemented the ...
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Why is the digital frequency highest at $\pi$ and what does it mean in terms of analog frequency? [duplicate]

I can't seem to comprehend why the digital frequency is highest at $\pi$. I know the relationship between the digital and analog frequency is given by: $$\omega = 2\pi\frac{F}{F_s}=2\pi f$$ Where $F$ ...
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How to extract information about each constituent 'wave' of a signal?

I have a vector containing wind speeds sampled at 1Hz over ten minutes. I have applied a lowpass filter of 0.25Hz to get only the wind speeds I am interested in. I now want to use MATLAB to ...
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Discrete-time system: getting the true frequency from normalized frequency

Lеt's say that i have a plot where i can see the spectrum of some discrete signal and let's say that it's x axis is normalized (by normalized i mean $\omega/\pi$ on the $x$ axis). Now, i know that in ...
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Time response of complex frequency response function

In the frequency domain I have the following function: $$ H(f)=A(f)\cdot e^{i\beta(f)} $$ Where both $A(f)$ and $\beta(f)$ are known functions. The thing I would like to do is to model the response ...
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A question about sampling rate of cosine signal

Given $$c(t) = \cos(2\pi\cdot 30 \cdot t) $$ If we sample this signal at the Nyquist rate 60 Hz and at a higher rate of 80 Hz, we get the following: There is no aliasing as $f$ = 30 Hz is less than ...
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No of samples 4mega samples per second,using 8 bit ADC,V p_p is6V. calculate frequency and peak power

This place has been great in helping me to understand my online image and signals class! I've moved on to another question and wanted to see if I'm correctly grasping the subject. The next question ...
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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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192 views

The selection of the amplitude of the signal, consisting of rectangular pulses, at different frequencies

I already asked a similar question, but did not receive an answer and did not find a solution, I want to make another attempt to get to the bottom of the truth. There is a signal consisting of ...

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