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

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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
60 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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2answers
164 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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35 views

time domain signal y(t)=sin(50πt)+3cos(60πt) [duplicate]

A time domain signal y(t)=sin(50πt)+3cos(60πt) must be sampled with no amplitude ambiguity of aliasing. What minimum sampling period should be chosen to meet this goal? What is the minimum sampling ...
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1answer
63 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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1answer
28 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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1answer
311 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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2answers
86 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
145 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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35 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
371 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
69 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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53 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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29 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
135 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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39 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
36 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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4answers
144 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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0answers
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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19 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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82 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
59 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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1answer
189 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
89 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
52 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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167 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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2answers
76 views

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 ...
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1answer
67 views

Find “base” frequency of pulse wave

I have some samples that are read from a square pulse wave and I'm looking for a way to find the characteristics of this wave. It's a pulse wave, let $T_1$ be the non-pulse duration and $T_2$ to be ...
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3answers
85 views

How to find period/envelope that is larger than sample size?

Mercury's distance from the solar system's barycenter (in kilometers) can be approximated as: ...
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127 views

Solving linear system and find impulse response

I have this linear system that is defined by the differential equation $$ y''(t) + 4y'(t) + 5y(t) = 2x(t) + 3x'(t) $$ with x(t) the input and y(t) the output. I'm asked to find two ...
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118 views

Frequency domain confusion

I'm a bit confused with some details about frequency domain or studying systems with Laplace and Fourier analysis. Let's say we have a system with a transfer function $H(s)$ with no poles and zero's ...
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2answers
162 views

What is an octave? It is said to be eight, but I cannot see the eight anywhere

When I searched for octave, I listened to the fact that if you take an octave band the lower cutoff is double the upper cutoff. Where is this name octave coming from, that is, where does the figure ...
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1answer
60 views

How to decipher this Microphone sensitivity Chart for Choosing a SPL meter

I have a mic having sensitivity chart as below which has relative dB on y-axis showing 1V/0.1Pa what does this convey how to read my mic's sensitivity a document on microphone sensitivity from ...
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165 views

HPS Algorithm for detecting the fundamental frequency of a guitar string

When you plucked on a string, the string is vibrate and except the fundamental frequency, there are an integer multiple of the fundamental frequency, which are the harmonics. I know that the HPS ...
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1answer
60 views

magnitude of intermodulation distortion products?

Assuming I have a set of frequencies F, and I pick 2 frequencies f1 and f2 randomly from the set, generate sine waves for them, and pass the signals through a non linear distortion process while ...
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2answers
62 views

DFT detemine frequencies

I am just begining learning about DFT and I am bit unsure on what is happening mathematically during DFT. I've sampled a signal , a sine wave sin(1000*2*pi*t). And performed DFT to calculate the ...
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31 views

inquires for prony estimation method

I want to estimate the frequency components of a time series by prony method, Is there any matlab routine for this purpose? tnx
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70 views

What is difference between Signal frequency and data rate

I read somewhere the below two line and got confused what is the actual difference between the two line. These two lines are related to CAN 1.Maximum Signal frequency used is 1 Mbit/sec 2.Typical ...
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120 views

How are the time scales of an exponential decaying autocorrelation related to the duration of peaks?

I'm reading a biology article (full text here) that analyzed the variation of a cell parameter over time at different stimulus intensities (calcium concentration). The frequency of peaks increases at ...
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1answer
127 views

Time shifts and change in phase

My question here is in regards to implicit information/terminology. Basically, whenever we say that "a shift in time means a change of phase in fourier space", is it implicit that the shift is ...
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2answers
691 views

Bandpass Filter Implementation in C

I've been googling for a while and came across the audio cookbook and Bjorn's blog explaining it further Link Here. Background info: I've modified the rtl-sdr open source code to tune to a VOR ...
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319 views

Estimate frequency and peak value of a signal's fundamental

How can I find out frequency and peak value of a signal's fundamental? Please do consider the following: The peak value of some harmonics might be higher than that one of the fundamental The ...
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66 views

Reducing frequency of a signal

I have a signal that I want to make it sound like a whisper. This is probably better than using a voice conversion system, but I was just want to do some experimenting before. I was thinking maybe ...
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2answers
114 views

How does one know how many times to downsample in Harmonic Product Spectrum?

I have been working on a Harmonic Product Spectrum Algorithm. Now, all the literature I've read about the subject tells me to downsample an N amount of times. How does one determine what this N value ...
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1answer
158 views

What is the frequency of $\cos x -\sqrt 2\cos\sqrt 2 x$?

Question Considering that $1\over{2\pi}$ is the frequency of $\cos x$ and also of $\cos x - 2\cos 2x$, what is the frequency of $\cos x - \sqrt 2\cos\sqrt 2 x$? Thoughts Perhaps "frequency" isn't ...
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96 views

Using Doppler velocimetry with digital signals such as Bluetooth

I have found several sources describing how to use Doppler velocimetry/anemometry to measure the Doppler shift with analog signals, but i cannot find much about using this method for digital signals ...
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101 views

Relationship between filters, Fourier magnitude, and frequency

I'm just beginning to study Fourier transforms and I'm having trouble getting this concept down. I know what a low/high pass filter does to a signal. What is the relationship between Fourier ...
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84 views

What is the best pitch (frequency detector) for a Voice Activity Detection Algorithim?

I am programming a Voice Activity Detection algorithm. After researching several methods, I implemented a simple method that determines whether or not the person is speaking based off the RMS of the ...