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

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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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28 views

How to normalize frequency in MATLAB

I know all about conversion of frequency from HZ to normalized frequency and from normalized frequency to angular frequency ,but I wonder how it is done in MATLAB. I have the following code: ...
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50 views

how to design a high pass filter to remove dc offset from signal

I want to design a high pass filter (f0*S/1+f0*S) in order to remove the dc offset from a signal ? (i.e. how to choose the frequency f0). Thanks, Hacene Ps : the filter is for matlab implementation, ...
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38 views

Calculating Energy Spectral Density from Magnitude and Phase data

I'm trying to do a program that can judge whether 2 audio files have the same pronunciation or not by comparing the frequency of them with each other. The first step, finding the magnitude and phase ...
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61 views

Tuning a radio to a certain frequency

I've a fundamental problem with understanding terminology used in DSP. What does it mean to tune a radio (for example, a software defined radio) to a certain carrier frequency $f$? The received signal ...
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67 views

What is the rate of change of amplitude? Frequency?

I know that frequency is not the same as the rate of change of amplitude, but why? Surely a high frequency is when your amplitude changes rapidly. Does an FFT perform something similar to ...
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41 views

Polarity inversion in frequency domain (polar coordinates)

I don't fully grasp how polarity inversion is performed in the polar coordinates of frequency domain. The frequency components of the signal do not change, so the amplitude part is going to stay ...
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1answer
64 views

what is the maximum instantaneous frequency of Dirac delta?

I wish to find the maximum frequency of $\sin(\varphi(t))$, where $\varphi(t)=u(t)$. We have $\omega(t)=d\varphi(t)/dt=\delta(t)$. What is the the maximum instantaneous frequency $\omega_{\max}$?
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36 views

Frequency-wavenumber filter

I have some data from a linear array and am trying to design a filter in frequency-wavenumber domain using 2D fourier transform. It is essentially a bandpass filter where I want to keep information in ...
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117 views

Android: fundamental frequency

I want to find the fundamental frequency for human voice in an Android Application. I want to use autocorrelation method. My code is this: ...
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61 views

Comb-like peaks in frequency spectrum

I am currently working on a project which involves measuring the sound produced by the onset of a vapour bubble in boiling water. All the experiments went perfectly well and I'm now trying to obtain a ...
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61 views

linear-phase lowpass filters: frequency responses alignment

These two filters have very similar frequency responses, but those responses are not identical except at a single frequency ωo. I want to find ωo. One way I've seen that done is like this: ...
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2answers
71 views

Finding the best principle component

The title might be unclear, but the problem is this. I have a signal sampled 1500 times with a rate of 60/s, and a sensor array 512 units large. There is a lot of noise, echo and other frequencies ...
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1answer
40 views

Time-varying waveform

My situation is as follows: i am trying to generate a waveform the hard way, by constructing the samples one by one and then saving the result to a .wav file using Python. When the frequency is ...
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1answer
136 views

If low frequency travels longer distance, why our speech is not travelling longer distance?

It is know that low frequency signals travel longer distance that of high frequency signal. If so, our speech signal is low frequency signal, why it is not travelling further?
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56 views

Cepstrum, peak picking

I try to obtain fundamental frequency from cepstrum. I decide to use peak picking algorithm, which pick maximum value of the Cepstrum (c) with sampling rate fs. ...
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1answer
57 views

Pitch Detection: HPS not working

I'm trying to code the HPS (harmonic product spectrum) algorithm and the problem I'm facing is that using my guitar, the fundemental frequency (Here it's 82Hz) just isn't there, so is the 5th Harmonic ...
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1answer
59 views

Sampling bandpass signal with spectral replications

I want to clear my thinking on how to approach problems of the type characterized below. I guess what we want to do is select a sample rate of a sufficient size such that this signal can be fully ...
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1answer
36 views

resonance demodulation for bearing faults [closed]

Can someone explain me how are the different frequency bands useful for detecting bearing faults using resonance demodulation?
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52 views

Doppler shift using PLL

I am trying to apply phase lock loop to calculate phase shift due to doppler effect and finally calculate the doppler frequency($\Delta f$). I am assuming that the received wave is of the form, $r(t) ...
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139 views

Sampling frequency of modulated signal

A very naive question... A signal with bandwidth of 20 MHz is modulated using a carrier of 1 GHz. What will be the sampling frequency? I was asked this question during an interview. I answered 2 GHz ...
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41 views

How to transmit voice signal and receive on radio?

I want to transmit data like radio stations do. Like radio stations broadcast music and etc. using frequency, so I am also curious to know about it that actually how it works. I also want to make ...
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55 views

How to use pseudo frequencies with wavelet transforms

I'm slowly getting my head around the use of wavelet transforms (CWT & DWT) with my data, but I'm interested in how the wavelet transforms correspond to certain bands of frequencies. I'm using ...
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1answer
113 views

How can I reduce noise errors when detecting DTMF with the Goertzel algorithm?

Thanks a lot to whoever downvoted my question for no good reason. I wrote an implementation of the Goertzel algorithm in JavaScript and made a demo that detects DTMF dial-tones. You can find the ...
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200 views

Algorithms for finding fundamental frequency based on ACF result

I am developing a software for fundamental frequency tracking. For this purpose, I have designed a function which calculates autocorrelation over the signal and a second function which, based on ...
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1answer
87 views

Time domain signal $y(t)=\sin(50\pi t)+3\cos(60\pi t)$ [closed]

A time domain signal $y(t)=\sin(50\pi t)+3\cos(60\pi t)$ must be sampled with no amplitude ambiguity of aliasing. What minimum sampling period should be chosen to meet this goal? What is the ...
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47 views

Lowest frequency within pitch detection in polyponic sound

I perform some tests where I run cepstrum pitch detection algorithm over polyphonic sound. Result shows that there is almost always occurrence of lowest frequency of tones played simultaneously. I ...
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350 views

Upsample data using FFTs. How is this exactly done?

I am basing my question on this post here, because I would like additional details on it, as I have not had any success in re-creating it. I would like to simply learn, in no uncertain terms, how to ...
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133 views

How to get the 10-5 most dominant frequency in an audio signal

I have this wav file that I recorded using my laptop, It contains the sound of a G chord of a guitar. Since the guitar have 6 strings the sound should contain different frequencies I want to determine ...
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4answers
173 views

given a mixture of two signals, how to separate it to its base components?

I have a signal that contains two components. How can I separate it two its two components in matlab? Please note that the location and shape of components are different in each experiment and we do a ...
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65 views

bearing frequency detection

I am working on bearing faults detection. I am doing the following steps: signal->mean zero->high pass->hilbert->y->fft->cepstrum of y. my code is: ...
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3answers
672 views

Adequate representation of frequency domain amplitude/magnitude of FFT of a signal

I'm quite new to the subject and am having fun playing around with the FFT. What I am currently doing is trying to sample an audio signal and display its frequency spectrum at the same time. This ...
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3answers
74 views

Connection between filter equation in frequency domain and difference equation in time domain?

I know that the frequency response of a filter is described by equation: H(w) = 1-1.176*e^(-jw) + e^(-j2w) , where w is the angular frequency. Then in time domain ...
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73 views

How do I find the corner (aka cutoff) frequency?

I would like an equation for finding the corner frequency in the attached periodogram. Note the periodogram is plotted in logs. As you can see there is a white noise component over the lower ...
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38 views

Frequency contour cross-correlation

I'm trying to segment (or extract) different calls from a spectrogram. My current method, calculates a threshold value (variance) and then using RMS can detect voiced/unvoiced signals: $$ Thres = (1 ...
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7 views

Encoding signals to selectively mute out when recording

Pardon my bad description but I am not from elec background. I have say 3 sources S1, S2 and S3 at positions X1, X2 and X3. I have 5 receivers R1 through R5 at positions Y1 through Y5. Can you ...
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1answer
43 views

Standard representation of FFT of an Image?

Statement 1 : When we take DFT of an image matrix, we get DFT co-efficient matrix. What does the DFT Co-efficients tells about the image? (For example, take the 1st co-eff in the DFT matrix, what ...
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2answers
144 views

Why we need Frequency and Time information at the same time

The big disadvantage of a DFT is that it has only frequency resolution and no time resolution. This means that although we might be able to determine all the frequencies present in a signal, we do not ...
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43 views

Calculating hertz / kHz

Over the past few weeks, I have been working on a problem of segmenting an audio file containing some bat samples. I have now successfully come up with a moderate algorithm to do this. I am trying ...
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1answer
37 views

Frequency filtering - Audio

Sound are digitalized in computers as an archive with its intensity amplitude at the given time. I want to ask a very simple question about frequency filtering. How it's done, if there's no frequency ...
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189 views

Why does the high frequency component of an image contain more noise?

I am working with wavelet transforms. When we apply a discrete wavelet transform to an image, it decomposes into four components named the approximation component, thevertical component, the ...
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9 views

Roots of polynomial divided by 6/6 daubeches?

My question is when the complex and real roots are divided by daubeches 6/6 factorization. How would you draw the roots. Okay so basically one of my filter has five zeros at z=-1 and the second filter ...
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37 views

make a treshold frequency based on persentage of frequencies less than that?

Using MATLAB signal processing toolbox, I have created signals like dirichlet, chirp and etc and and obtained their fourier and cosine fourier transform. Now I want to find the frequency where for ...
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83 views

Understanding Hertz

This question is in two parts, both related in some way or another. Suppose I have a signal where the sample rate is 44100 and compute a normal 1D DFT on this signal. The size of this signal is ...
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2answers
73 views

Estimating the amplitude of a particular frequency

I am relatively new to DSP and have been reading a lot on the internet. I have a couple of questions. I have a signal in the form of a function $$ f(x) = A_0 + A_1 \cos(\omega_1 x) + A_2 ...
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321 views

Understanding Spatial Frequency of Images (using matlab)

I wish to isolate a crosswalk from its surrounding, and I thought that as crosswalks have a repetitive pattern of thick white stripes, I might be able to isolate them by measuring their frequency ...
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1answer
92 views

How to derive a rate (e.g. water dripping) from an audio file

I want to learn how to go about analyzing some audio files I have acquired. Let's say the files contain some sort of repeating sound (e.g., water dripping), and I want to derive the pattern of the ...
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2answers
61 views

How to estimate the frequency at certain time of linear sine sweep?

experts. I have a question concern "linear sine sweep". Here is the equation of linear sine sweep(from Wikipedia Chirp). $$ x(t) = sin\biggl[ 2\pi( f_0 +\frac{f_1-f_0}{2T}t)t\biggr] $$ where, ...
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179 views

The impulse response, $h(t)$, of a system

I have this differential equation $$ y''(t) + y'(t) + y(t) = x(t) - 3x'(t) $$ I found the system response of the system: $$ H(f) = \frac{1 - 6\pi fj}{(2\pi fj)^2 +2\pi fj+1} ...
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Generating a sound where end frequency is 1/2 of the start frequency

I am very very new to signals, and I am trying to generate sounds based on some parameters from a database. So, the database stores the following: startFrequency endFrequency startAmplitude ...