Questions tagged [frequency]

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

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finding frequency range and dominant frequency of a stored signal

I have sEMG signals, captured from commercially available device. the signals are stored in .tdms file format. i want to varify whether the captured signals are really sEMG (or simply EMG) signals or ...
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258 views

How does bandwidth relate to the bitrate?

This might be a really trivial question, but I can't wrap my head around it. In almost every textbook, we're told that bandwidth (among power and noise), is the factor for both range and bitrate. I'...
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Finding notes played in an audio clip

I am working on a program that will be able to tell when a musical note is played in audio and what that note is (ie. guitar or piano). You can assume can assume any audio used for the program will be ...
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Down sampling in the frequency domain

I would like to down sample a signal from it's original sampling rate of 2,000,000 samples per second to 48,000 (or 44100) starting from the output of an FFT. This FFT delivers 16384 data points (...
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Difference between Fine and Coarse Frequency Offset in OFDM

I need to explain for a project the difference between Fine and Coarse Frequency Offset in OFDM signals. I know what the frequency offset is and what it does to the carrier frequencies but I cannot ...
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604 views

Generating inaudible sound waves using MATLAB

I want to generate inaudible sound waves (above 18kHz) with 48kHz sampling rate using MATLAB. Generating a sound wave with 18kHz frequency makes it inaudible. I've inserted the data in the 18kHz ...
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74 views

Plot spectrum of $X(-k)$

Assume FFT of $x[n]$ is $X(k)$ and I would like to find $X(-k)$. I have implemented two techniques: I am calculating the X(k) = fftshift(fft(x)) and then find <...
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49 views

How to discover the caracteristic frequency of the use of an app by someone

Let's say I have an user that uses the application one time every monday exactly... That means once a week. If I do the dfft I can see a peak in this frequency How can I analyse the general case for ...
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43 views

Algorithm to identify pitch-shifted recordings?

new to this whole DSP thing. Two related questions: Does there exist an algorithm or classifier that, when given two sound files, would be able to tell me if one is a pitch-shifted version of the ...
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398 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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440 views

Regarding phase and frequency components in the signal [closed]

As I am not a signal processing student, I have limited understanding of the concepts. The general formula for sine wave is $$s(t)= A \sin(\omega t-p)$$ where $A$ is amplitude $\omega$ is ...
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771 views

How to calculate the spatial frequency of an image in cycles per image

I have been attempting to calculate the spatial frequency of a colour image. I first converted it to grayscale and used a Fast Fourier transformation (fft2) that codes the quantity of each spatial ...
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506 views

Formula of frequency modulated sine wave from data points

I'm trying to determine the formula of a variable frequency sine wave based on the values of max1, max2, min1 and min2. y(0) isn't necessarily 0 and I can assume the frequency increases or decreases ...
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1k views

What is the relationship between scales and frequency in a Morlet wavelet transform?

I'm using PyWavelets, with a complex Morlet wavelet. Its complex wavelet transform function requires scales as one of its parameters, rather than frequencies. However, I don't understand the ...
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729 views

Removing cyclic noise from signal

I'm using a sensor with output that looks like the following figure. The cyclic noise is common to ask measurements made by the sensor. Is there a way to remove the noise without negatively effecting ...
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504 views

How we do frequency shaping and amplitude shaping in hearing aid

My project name is Digital Hearing Aid with frequency shaping and amplitude shaping using adaptive noise cancellation DSKC6713 DSP kit . Almost I have done this noise cancellation using code studio ...
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130 views

Sub-band partitioning of filter-banks

In ECE-700 Filterbank Notes the partitioning is $ \Delta = \frac{2\pi}{M}$ with center-frequencies at $ \omega_k = \frac{2\pi}{M}k$ which makes me wonder, considering that frequencies in the range ...
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Periodic signal filtering: transform from frequency domain doesn't meet expectation

The signal in question is: $$x(t)= \sum_{n=-\infty}^{+\infty} \text{rect}\left(\frac{t-4nT}{2T}\right)+\text{trian}\left(\frac{t-n4T}{T}\right)\quad\text{with}\quad T=1\,\textrm{ms}$$ Passes through ...
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687 views

Generating sound of particular frequency matlab

I want to generate a high frequency (single) tone. I am using matlab (any other platform/tool for the same will also work). I am using the following snippet which I wrote by referring to various ...
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1answer
63 views

Frequency of Signal of a point tracked in a video?

I have used MATLAB to track a feature point (corner point) using Lucas-Kanade tracker and plotted its movement through each frame now I need to find its frequency content, how should I find it? (I ...
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56 views

I want to find the first period $T_0$ in a signal $x[n]$ and save it to a vector?

I want to find the first period $T_0$ in a signal $x[n]$ and save it to a vector $\hat x$? $x[n]$ is read in by the command: ...
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2k views

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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323 views

Average FFT Magnitude in bins

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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3answers
18k views

Calculating values of frequency bins in Python

I have to use FFT to determine the period of waves inside a signal. After applying FFT on a window of 10000 point from a signal, I get something like this: What I don't understand is that FFT is ...
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How to look at Rubidium frequency standard using the oscilloscope?

This question is about the checking hardware, please help if someone who has done it before. I have the Rubidium frequency standard: http://www.thinksrs.com/products/PRS10.htm and the Oscilloscope: ...
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Why doesn't a sudden loud noise sound high pitched?

The jumpiness or high change of a signal is due to the higher frequency components in the signal. So if I have a sound signal that increases suddenly in amplitude, why doesn't the signal sound very ...
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819 views

Acceptable Carrier Frequency Offset for Specific BPSK system

I've been working to build a transceiver system, with details as follow: Consists of Lime LMS6002D MyriadRF-1 board (RF front-end) and own-designed multi-proc SoC (baseband processor). SoC is running ...
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33 views

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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681 views

Impact of modulation index in FM

If I have the spectrum of a FM modulation, does the frequency of the carrier disappear when the modulation index is too big? Does the amplitude of any side band depend from the modulation index? And ...
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100 views

How to add the noise covariance matrix of my measurements to tmy 1D kalman filter?

So I am new to kalman filters. This is my first experience with it. I have some measurements but sometimes due to external factors those measurements become totally wrong (hence the peak when you run ...
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334 views

Detecting a low frequency cue in audio recording

I am hoping to find a linux program or library for a language like perl or python (open to ...
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88 views

Why the bandwidth of the system with the minimum-order observer is higher than the full-order observer?

In Ogata's Modern Control Engineering (5th Ed., page 786) it says: The bandwidth of the system with the minimum-order observer is higher than that of the system with the full-order observer, ...
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406 views

Identify the frequency spectrum of an audio file by using matlab [closed]

I need to identify the first few harmonics of a audio file by cancelling the noise of the specific signal. So I have partitioned the signal into 1024 Hz sample blocks and then took the FFT values of ...
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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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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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Signal Processing/FFT gives very high magnitudes for low frequencies

The script essentially pulls PCM data from the sound card and stores them in a buffer. Then I apply fft and graph it. I am looking through this blog post for some examples and ideas on how to ...
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380 views

Sampling and the creation of multiple images at integer multiples of the sampling frequency

From what I thought I learned about sampling is that when you draw a sampled signal in the frequency domain, you can show copies or "images" of that signal at integer multiples of the sampling ...
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461 views

Guitar String frequency

I'm making a guitar tuner for iOS.Due to the fact I'm Beginner I'm struggling a bit to gather all the resources and information about it. I know the theory like ( correct me if I'm wrong ) :- First I ...
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242 views

Finding frequency of data given in time domain

Think there is an analog signal source and we are recording it with a data logger. Sampling rate isn't important in here. We know the analog signal is 0 mV when time 0 and goes to 1000mV in 1000 ...
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Frequencies from unsorted data

I have a 2D samples f(x,y) = z in a circle (disc). Values x, y are not generaly uniform, but they can be resampled. Is there ...
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78 views

Correcting for Doppler shifts at the speed of sound for a 800 MHz signal

I'm working with a system which is planned to reach velocities of about 340m/s. It's likely that we'll be using a frequency around 800 MHz for rx and tx. At these speeds, supposing a fixed source, the ...
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232 views

Identify fundamental frequencies in short-period waveform

Maybe I'm being stupid and failing to see something here... I need to analyse a signal over a relatively short time period (~1-2 cycles for the lowest frequency, perhaps 20-30 cycles for the highest ...
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613 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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434 views

Find the dominant low frequency

I have this signal, with an arbitrary x-axis, and I want to find the (visually) dominant frequency of the signal. There may be a high frequency component, but I'm interested in the component with a ...
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Does frequency shifting double needed bandwidth? [duplicate]

Suppose we have a low pass signal and it's spectrum is like this: If we define bandwidth as the difference between signal minimum and maximum frequencies, above picture says that the signal has a ...
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487 views

why human voice is band limited while it's time limited?

According to Wikipedia, time-limited signals can not be band-limited and vice versa. Also we know that human voice is band-limited and has frequencies from $50\textrm{ Hz}$ to $4\textrm{ kHz}$. So ...
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Deciding on the FFT length for water waves in flume (wave facility)

Soon I'll be conducting experiments in a wave facility (flume) for my MSc thesis. And I would like to analyse wave spectra (amplitude and energy density). The time step (or 'accuracy') of the wave ...
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410 views

Frequency bin of the positive and negative frequency

I am using this MATLAB tutorial for Frequency-Domain Linear Regression. There is one part of code they provide, where it is necessary to determine the "frequency bin of the positive and negative ...
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285 views

A very basic question about processing high frequency signals

A standard frequency for a modern computer processor is 1-3 GHz. The frequency of a GPS signal is ~1.5 GHz. My question is how is it possible for a computer to do anything at all with a signal that it ...
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What is the bandwidth of human speech?

What is the actual frecuency bandwidth of human speech. I know there is variation for gender, age and so, but what is the general range... I seem to find different ranges. Like here http://...