Questions tagged [frequency]

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

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Audio frequency modulation algorithm

I have a digital audio signal (float samples). I need to apply the Vibrato effect to a signal. "Vibrato" is no common term, but it is the same as the frequency modulation. So, I need to modulate my ...
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940 views

VIbrato (pitch variation) function

I'm looking for an algorithm for Vibrato audio effect for a cross-platform C++ program of audio processing. Now I use the realization from Chaotic-DAW sources. The problem is that Chaotic-DAW has a ...
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What are the implications of resampling the derivative of a signal with a higher frequency than the original signal?

Suppose I have a digital signal measured with sampling time, $T_s=1$ sec. If I take it's derivative, it will, naturally have $T_s=1$ sec. But what are the implications if I re-sample this derivative ...
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152 views

What does pre-emphasis $\alpha=1$ will do to a signal?

I am trying to understand pre-emphasis equation. $$ y[n]=x[n]-\alpha x[n-1]$$ Where $\alpha = 0.95$. My question is what does it mean if $\alpha = 1$?
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Find Natural Frequency $\omega_n$

You are testing a new device to determine its characteristics. You find the magnitude of its frequency response shows a peak at 500 Hz, and the measured overshoot of the step response is 40% of the ...
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231 views

how to find breakpoints of a signal based on the frequency of the signal

There are 4 cos signals with 10,20,30 and 100 Hz each. The main signal is the sum of those 4 and I have to create a low pass filter, on the main signal for the frequency's > 50 Hz. ...
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108 views

Resonance and Pitch classes

Suppose we denote the frequency of the note $\textbf{C}_{0}$ by $f$ then we know that $f,2f,3f,...$ are all resonating frequencies. However the frequencies $2f,4f,...,2^{m}f$ belong to the same pitch ...
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Is the book wrong? — How to sketch frequency response obtained from H(z)?

This question is directly related to digital signal processing, so I am asking here. How to sketch frequency response obtained from $H(z)$? I'm adding an example and its solution below. I did not ...
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Find unknown broadcast frequency

I'm very new to this stuff, so please excuse the dumb sounding terminology. I'm trying to capture the data from my elster smart hydro meter. How can I find its frequency (I know its between 902 and ...
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533 views

Relation between bandwidth and data rate

I have trouble understanding the following from wikipedia - Bandwidth (Signal Processing) A key characteristic of bandwidth is that any band of a given width can carry the same amount of ...
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Are there libraries for extraction of sound wave features?

I am looking help for my project for which I need C++ (or any other language) libraries useful for extraction of sound wave features like frequency, loudness, pitch and orientation. Using these ...
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169 views

Find minimum sampling rate of non-ideal notch filter

Old test problem: "You have been asked to design a real-time digital filtering system that eliminates a band of frequencies between 20 and 30 MHz but preserves everything else. The system uses an ...
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sampling rate for band pass signal

The sampling frequency for band pass signal which is having frequency from 4 kHz to 6 kHz(rectangular shape from 4 to 6 kHz), can I prefer the sampling frequency of 12 kHz(2*the highest frequency ...
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342 views

Determining frequency deviation FM

I am trying to understand the concept of frequency modulation. As written in Wikipedia, if I have a signal containing information $x_m(t)$ and I want to transmit it using frequency modulation, I need ...
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102 views

Sample Frequency - Recommended Practical Nyquist, Lower Used by majorities appications

Doubt1: What is the Lowest Sampling Frequency used by majorities sound applications. Is there limited frequency sampling lower than 8KHz In C/C++? Comment In Java I haven't detected any problem, but ...
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Retrieve frequency value of an 2D frequency spectrum

How do you retrieve the values of the frequency component occurring in a 2D freq spectrum? I have this, and if I wanted to know the values of the white dots. what should i do ? I apolgize ...
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Find the frequency of a pole (Discrete Form) [closed]

I am studying a Notch filter. I found its Transfer Function (in Z) and its poles. How can I find the frequency of theses poles (which corresponds to the cut-off frequency)? Thank you very much for ...
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Obtaining power spectral density without having knowledge about frequency bandwidth or sampling frequency of the signal in Matlab?

Is there a way to plot PSD of a signal which show true frequency amounts ( not normalized one) without having knowledge about frequency bandwidth or sampling frequency of the signal in matlab ?
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Doppler shift in time domain?

I have some clarifications required in this topic So initially I know that to shift a signal $X(f)$ by $f_0$ we need to take its inverse fourier transform and multiply it with a factor of $\exp(−j2\pi ...
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What is a note?

That simple. What is a note in digital signal processing? Is it a single value of y[n] in a system with a difference equation e.g. ...
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87 views

Given a real signal, increase modulation frequency

Lets say I receive the signal $$x(t)\cos(\omega_c t)$$ and I want to change the the carrier frequency $x(t)\cos(1.001\omega_c t)$ How can this be done? If I modulated it with a complex exponential, ...
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168 views

Why is discrete cosine preferred to FFT in neuroimaging GLM

High-pass filtering is often used in neuroimaging data analysis. Commonly, whenever a general linear model is fitted to the data (as for instance in statistic parametric mapping) a number of columns ...
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phase locked loop

I have seen that to get the phase angle of a signal, we have to use PLLs. this PLL is modeling in order to get the phase angle about one frequency, which is the free running frequency of the VCO. If ...
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Calculate Min/Max value of multiple sine waves added together

So I feel like this should be possible, I'm just not sure how to do it. Let's say I'm generating a signal with a sample rate of 10K samples/second. Then let's say my signal is comprised of X number of ...
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Using K-Space Filtering to Filter by Speed

I want to read waves with an electret consender microphone that are slower than the speed of sound, and I figure it would make those waves easier to identify if I could process out all waves moving ...
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Frequency of a DFT term

I've been wrestling with this question for way too long. I appreciate any insight you can offer. Thanks. If the $9$-point sample sequence $x(n)$ represents a time domain signal sampled at $48\...
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How to Flip Spectrum Around DC?

Is it possible to flip a signal's spectrum around DC? I have a simple spectrum that I made up (MATLAB code): ...
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How to calculate the frequency of a signal without knowing the sampling frequency using Matlab

I have a signal and I am using Matlab command pwelch to calculate the frequency of the signal, but the frequency I obtained is changed as I change the sampling frequency. For example, when using ...
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Frequency Shifting in MATLAB

I am currently attempting to demodulate an audio file using MATLAB. After taking the fft of the signal, I receive this: After some more coding, I found the following values: Fs = 44100; Window ...
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Filtering with filters without even or odd symmetry in the fourier domain

I am doing a project where I have to use the fourier domain for convolution. I have been reading Digital Image processing by Rafael Gonzalez but I unsure about one thing, and I could not find anything ...
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Why is the magnitude of the second component of my FFT spectrum always the largest one?

While working with FFT, I have a strange case with a current experimental setup. I am working with beat frequencies (intermediate frequency output) and using a standard FFT algorithm (complex to ...
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Curve fit for fft dplot

I have data from accelerometer (time domain) and convert it to fft using Fourier Transform. However, I need to do the curve fit to the plot. Can somebody share with me the coding.I don't know how to ...
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406 views

Very high SNR BPSK modulation

I am using BPSK modulation to modulate a signal in continuous time (making rectangular waveform, multiplying by a carrier). The channel is band-limited and frequency-selective, and has the following ...
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Real-time frequency recognition in python

I'm a newcomer to signal processing, so forgive my ignorance. I'm working on a project in Python that will play a .wav file and pick out the dominant frequency as it plays. I've found a few examples ...
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Calculate and interpret the instantaneous frequency

I'm new to the principle of calculating the instantaneous frequency, and came up with a lot of questions on it. You find them all in a bullet-point list at the end of this text. The text might be a ...
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Cannot recreate a simple Nyquist series in Matlab

a Nyquist series should look something like {...-1, 1, -1, 1, ... }, which i think means it is a sine wave sampled at the peaks and valleys exactly. Now, given a sampling rate of 48 Hz, the Nyquist ...
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Zero-frequency response of an IIR transfer function

I have a question about the zero-frequency (DC) response of a IIR filter. The coefficients of the 3rd order IIR filter are as follows, ...
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Find Stopband Edge Frequency

I tried to find the stopband edge frequency.I know that the signal amplitude falls to -3 dB below the passband edge frequency.I examine a lot of DSP books so i don't any information about how to ...
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Getting the frequency of a 0.33Hz to 3Hz signal

I read a noisy signal from an accelerometer which is attached to the pedal of a stationary bike and need to find the frequency of the signal/ speed of the person cycling. I taught of the following ...
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Am i performing Sinesweep correctly?

I am bit unsure whether i am doing i sine sweep correctly. I am feeding my system a sine wave with f hertz within a given time interval and log its output. And then i do the same for another ...
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652 views

Parallel Goertzel filters in C# [closed]

I have 2 frequencies in my application: $12000\mathrm{Hz}$, $13000\mathrm{Hz}$. I want to set a parallel Goertzel filters and every 100ms I want to take the bigger magnitude for detecting the tone ...
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350 views

FFT peak estimation: Zero-padding vs signal repetitioon

I am working on obtaining the vortex shedding frequencies behind a 2D square using CFD. Time-varying data is being extracted from a specific cell behind the square. I've written a little python script ...
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How to show the time history of a signal down-sampled ? under the rate of 25Hz & 40Hz and find its DFT analysis?

How to show the time history of a signal down-sampled under the rates of 25Hz & 40Hz and find its DFT analysis using Matlab ? The sample signal is in a data file (sensor_data.mat) its sampling ...
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Why every musical instrument sounds different than any other while listening?

This is soft question.I am not expert in music. We know that English language has 26 letters (which are again grouped into vowels and consonants) , while language of music is same all over the world ...
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nyquist fequency

simple question, but I cant seem to understand how they got the answer. I have $x(t)$ as a signal, and I'm told that its Nyquist frequency is $\omega_0$ I'm asked - what is the Nyquist frequency of ...
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What is the difference between upsampling and up conversion (done during signal transmission)? Also is upconversion different from modulation?

Up sampling is when you increase the sample rate of a continuous signal. Modulation is when you, by multiplying with a carrier, shift the base frequency of a signal. But what is up conversion? How is ...
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input output read/write frequency

I am trying to identify a system based on input/output response and thereby estimate a transfer function. I generated a frequency sweep function in Mathematica which gives me the discrete values of a ...
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Find the Differential Equation of an Analog Band Pass Filter

I don't even know how to start. We're supposed to find the differential equations that links $V_{in}$, $V_{out}$, and $V_{io}$, as well as the values of $C_1$, $C_2$ and $R$ so the filter works in the ...
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Frequency and amplitude estimation with missing samples

My input signal is given by $$ x[n] = A\sin(2\pi f n/F_s + \varphi)$$ The signal is uniformly sampled at a sampling rate of $F_s $[Hz]. However some of the samples are missing. Assume that there are ...
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Dominating frequency in a “clear” 50 Hz signal

I am trying to find out the dominating frequency of a signal with a frequency of 50 Hz (sampled at 200 Hz - every 5 milliseconds). The python code I am using to do this is the following (based on ...