Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [frequency]

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

The frequency of a signal is identified by calculating the number of a repeating event (a cycle in case of a signal) is accomplished by counting the number of times that event occurs within a specific time period, then dividing the count by the length of the time period.

Source: Wikipedia.

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What is the physical significance of negative frequencies?

This has been one of the holes in my cheddar cheese block of understanding DSP, so what is the physical interpretation of having a negative frequency? If you have a physical tone at some frequency and it is DFT'd, you get a result in both the…
Spacey
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What is meant by a system's "impulse response" and "frequency response?"

Can anyone state the difference between frequency response and impulse response in simple English?
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Is there an algorithm for finding a frequency without DFT or FFT?

I was looking in the Android app store for a guitar tuner. I found a tuner app that claimed it was faster than other apps. It claimed it could find the frequency without using the DFT (I wish I still had the URL to this specification). I have never…
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Which time-frequency coefficients does the Wavelet transform compute?

The Fast Fourier Transform takes $\mathcal O(N \log N)$ operations, while the Fast Wavelet Transform takes $\mathcal O(N)$. But what, specifically, does the FWT compute? Although they are often compared, it seems like the FFT and FWT are apples and…
endolith
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What mathematical model of audio can make possible pitch shifting of individual notes in (timbrally complex) polyphony?

My question is: What mathematical model of polyphonic sound can make possible the changing (i.e. pitch shifting) of individual musical notes in a multi-voice-in-single-channel audio recording of a polyphonic acoustic musical instrument? By 'changing…
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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 read? I want to understand this filter in order to…
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Image Reconstruction:Phase vs. Magnitude

Figure 1.(c) shows the Test image reconstructed from MAGNITUDE spectrum only. We can say that the intensity values of LOW frequency pixels are comparatively more than HIGH frequency pixels. Figure 1.(d) shows the Test image reconstructed from PHASE…
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How can I plot frequency vs magnitude of wavelet transform?

I am running Morlet continuous wavelet transform. I have got wscalogram of signal and now I want to plot freq-magnitude like the following picture., but I don't know how to do it: I've used scal2freq MATLAB function to convert scales to pseudo…
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Most efficient way to extract frequency components of audio signal with near-human accuracy in real time

I'm trying to work out how (if possible) to extract the frequency components of an arbitrary audio sample (typically music) in an FFT-like manner, but in my research on the FFT algorithm, I'm learning that it suffers some severe restrictions for…
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On using eigenvectors to estimate a signals' fundamental frequency, via MUSIC

Context: (Disclaimer: This is NOT a comm problem). I am trying to estimate the fundamental frequency of a real, periodic signal. This signal, was constructed by match filtering a raw signal, to that of a pulse. (the matched filter). The resultant…
Spacey
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FFT for a specific frequency range.

I would like to convert a signal to frequency domain. The desired frequency range is 0.1 Hz to 1 Hz and the frequency resolution is 0.01 Hz. With the sampling rate of 30 Hz, FFT gives the frequency components up to 15 Hz. Raising the sampling rate…
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How do I determine if a discrete signal is periodic or not?

I want to know how I can determine whether a series of data is periodic or not. I want to use Fourier transform/series. My data looks either aperiodic [111100001111000110010101010000101] or periodic [11001100110011001100] and I need to decide…
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Choices of convention and notation for the Fourier transform?

The definitions of the Fourier transform and inverse Fourier transform I learned in college were $$ F(j\omega) = \int_{-\infty}^{\infty} f(t) e^{-j\omega t}\ dt $$ $$ f(t)=\frac{1}{2\pi}\int_{-\infty}^{\infty}F(j\omega)e^{j\omega t}…
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How to make frequency axis for even and odd FFT length?

Can I get help on how to make frequency axis going from negative frequency to positive frequency, (in Hertz), that will be the x-axis in an FFT result, but given either an even length FFT, or odd length FFT. I am having some troubles making it in…
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What is the bandwidth of a (real) sinusoidal tone, and pulse?

I would like to know how to go about calculating the bandwidth of: A constant (real) sinusoidal tone A (real) sinusoidal pulse. The question is as simple as that, but I am having a hard time with the concept of what exactly the bandwidth of a…
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