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Questions tagged [frequency]

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

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251 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 ...
30 views

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 ...
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 ...
245 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 ...
642 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 ...
487 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 ...
25 views

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 ...
523 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 ...
113 views

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 ...
426 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 ...
306 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 ...
20k views

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://...
74 views

Doubling the frequency of a sound fragment in real time?

I'm given given a stream of sound, as a serie of little buffers . Is it possible to make this stream sound one octave up ? Or an arbitrary number of semitones up ? My goal is to add it to the ...
82 views

Regressing/interpolating between quasi-periodic sinusoids

This is a cross-post (on recommendation) from CV. My problem is very simple. I currently intend on using Kriging (Gaussian process regression) to perform regression between the trajectories marked ...
525 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 ...
35 views

How can I change parameters into a text string in MATLAB? [closed]

I am trying to compute the Morlet wavelet transform (cmor) of a signal, but I have to do it several times with different parameters Fb and Fc. Is there a way to automate it? For example, I have to do ...
58 views

Digital frequency for images

From this Wikipedia link, the fastest fequency for digital frequency is 0.5cycle/sample. It can be rewritten as 1cycle/2sample. What does it mean? Does it mean that at least two pixles are required ...
70 views

Is there a function in MATLAB similar to $\tt freqz$ but for $H(\omega)$?

I wanted to know if there's a MATLAB function that equates the frequency response, $H(\omega)$ of a system. Something similar to freqz like a ...
55 views

Which one of these signals will be least distorted by this communication channel

So I was solving a problem that resulted in a communication channel that heavily distorts high frequency but does not significantly affect low frequency and I got stuck at figuring which one of these ...
246 views

Why LFO should be alias-free?

I'm really tripping about this point! I try to reason with you and explain what's my trouble. Consider a scenario with Sample Rate 44100hz and a LFO square wave that will modulate some internal ...
5k views

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 ...
4k views

Calculating maximum signal frequency knowing its sampling rate?

I was curious as to how I could calculate the maximum frequency of a signal knowing only its sampling rate (for example 125 nanoseconds). Does the sampling theorem have anything to do with it (...
316 views

Understanding the $\mathcal Z$-transform

I was studying $\mathcal Z$-transforms and found pretty good material on the topic, though I feel I do not have a proper understanding of the concept. Could someone help me clarify this? I know that ...
85 views

freqency resolution of 48khz 16bit WAV?

I was doing experetiments in Audacity,creating sine waves and trying to find out what is the smallest amount of freqency change possible,how it looks like... I found out that the super small changes ...
36 views

i have an audio signal. i have to find whether my audio signal is from given avi scene

I have audio signal. I want to find whether my audio signal is from a given avi file . I tried using correlation and mfcc. But i'm not getting accurate output. So please help me in this.
2k views

Discussion - Integrating Accelerometer data to Position data from Frequency domain FFT

I came across one blog who suggested to convert from accelerometer data to position data from frequency domain. Here are the steps that the original individual suggested: Remove the mean from ...
205 views

Pilot tone frequency doubling

U.S. Broadcast FM stereo includes a $19\textrm{ kHz}$ pilot tone that needs to be frequency doubled to help demodulate the DSB stereo difference signal. How can this frequency doubling be done ...
181 views

Lock-in amplifier

From what I have studied so far I have understood that the benefit of a lock in amp is its ability to resolve the amplitude of a signal which is deep into noise. I was wondering if the same concept ...
49 views

How does SC-FDE modifies $E_b$ (in AWGN function)

In lot of matlab scripts of SC-FDE simulations I see $E_b = N$ (being $N$ the length of the block to be transmitted through the channel and Eb energy per bit) to generate the AWGN. I would like to ...
444 views

Are there any cases where the negative frequencies of an FFT are used?

In performing FFTs and looking at spectra for real signals (say, taken from a sensor) we ignore the negative frequencies. I understand that the negative frequencies often reflect the positive ...
79 views

Is there a special reason why the principal range is defined as $-0.5\le F \le 0.5$?

According to Digital Signal Processing by Ashok Ambardar, The principal range is defined as follows: Put another way, a DT sinusoid is periodic in frequency (has a periodic spectrum) with unit ...
4k views

What is the real meaning of “frequency” for a non periodic signal?

For a non periodic signal, in the first one second the frequency of a particular amplitude (value) may be of 4 Hz, and then in the next one second it may or may not be 4 Hz. Then which value of ...
1k views

614 views

How to detect decaying oscillations in a signal

I have a sampled signal which contains (among other things) some damped oscillations. From the underlying theory I have reasons to believe that it can be characterized by some specific frequencies of ...
140 views

How do I measure frequency of an audio file into an array?

So I know how to plot fft the audio file within Matlab and a window pops up. My question is, what next? I want to know how to go about measuring the frequency(s). I have two similar audio files, of ...
949 views

Compressing a time-domain signal in the frequency domain Matlab

I'm new to frequency domain analysis. Let's say I have a frequency domain representation from a time domain signal. What I want to do is taking frequencies with a low amplitude out of this frequency ...
403 views

Aliasing Square Wave

I'm having a really weird issue with generating waveforms from frequencies C1 to C8. When I generate sine waves, everything sounds good; no problems whatsoever. However, when I generate a square ...
3k views

The relationship between downsampling and frequency resolution

I am having trouble understanding a concept that I have seen in many published papers. For example, in this paper (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0082748) they wrote ...