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Questions tagged [frequency-analysis]

393 questions
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How to extract the peak at a specific frequency in python

I want to know how much energy is at a specific frequency in a signal. I am using FFT to get the spectrum, and the frequency step is determined by the length of my signal. My spectrum looks, for example, like this : I want to get the spectrum peak…
FunkySheep
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SQL for two-way frequency table using a string valued variable

Consider the following event data in PostgreSQL 9.4: eventTime | eventName 2015-09-25 18:00:00 | 'AAA' 2015-09-25 17:00:00 | 'BBB' 2015-09-25 16:00:00 | 'BBB' 2015-09-25 15:00:00 | 'BBB' 2015-09-25 14:00:00 | 'AAA' 2015-09-26 13:00:00 |…
JohnH
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Word Frequency in text using Python but disregard stop words

This gives me a frequency of words in a text: fullWords = re.findall(r'\w+', allText) d = defaultdict(int) for word in fullWords : d[word] += 1 finalFreq = sorted(d.iteritems(), key = operator.itemgetter(1), reverse=True) …
demos
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Python: Compute largest Fourier coefficient of a signal

I am trying to determine the most dominant frequency of a signal. However, when artificially creating a 50 Hz signal and applying sufficient zeropadding to enhance fft resolution, I get a top frequency of 49,997 Hz. For my application this is a…
Tom Baksteen
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Length of FFT and IFFT

I have some signals which I add up to a larger signal, where each signal is located in a different frequency region. Now, I perform the FFT operation on the big signal with FFTW and cut the concrete FFT bins (where the signals are located) out. For…
mbed_dev
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Is it possible to programmatically edit a sound file based on frequency?

Just wondering if it's possible to go through a flac, mp3, wav, etc file and edit portions, or the entire file by removing sections based on a specific frequency range? So for example, I have a recording of a friend reciting a poem with a few…
K-RAN
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How could I do frequency analysis on a string without using a switch

I am working a school project to implement a Huffman code on text. The first part of course requires a frequency analysis on the text. Is there a better way aside from a giant switch and an array of counters to do it? ie: int[] counters for(int i…
Maynza
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manipulate/process audio signal in android?

I'm new to android and new to anything related to audio processing. So I will need step by step guidance from where to start. I have already used android AudioRecord to input sound from the microphone and the AudioTrack class to output it through…
boyfromnorth
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Android application that extracts volume and-or frequency data from a mp3 stream

Still a novice java developer, I need to build an Android app that 1 streams a single mp3 from a supplied URL and then 2 extracts volume and-or sound frequency data from the mp3 stream 3 drives a light show from the data in #2 I have a possible…
Bachalo
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How do I interpret audio encoded binary data?

I have built a little program that encodes binary data into a sound. For example the following binary input: 00101101 will produce a 'sound' like this: ################..S.SS.S################ where each character represents a constant unit of…
Patrick Oscity
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Background noise removal from audio signals using FFT Python

I am currently doing a project at university where I am distinguishing between different instruments playing notes of the same pitch using python. I have recorded various notes on different instruments using a microphone attached to a computer. I…
Marchy
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How to use inverse FFT on amplitude-frequency response?

I am trying to create an application for calculating coefficients for a graphic equalizer FIR filter. I am doing some prototyping in Matlab but I have some problems. I have started with the following Matlab code: % binamps vector holds 2^13 =…
JustAMartin
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How to count frequency of elements from a columns of lists in pyspark dataframe?

I have a pyspark dataframe that looks like the following, data2 = [("James",["A x","B z","C q","D", "E"]), ("Michael",["A x","C","E","K", "D"]), ("Robert",["A y","R","B z","B","D"]), ("Maria",["X","A y","B z","F","B"]), …
Droid-Bird
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Frequencies from a FFT shift based on size of data set?

I am working on finding the frequencies from a given dataset and I am struggling to understand how np.fft.fft() works. I thought I had a working script but ran into a weird issue that I cannot understand. I have a dataset that is roughly sinusoidal…
pmoh
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Implementing Real Time frequency spectrum for a beginner

I want to develop an application that would take audio(.wav) as input and display its real time simultaneous frequency spectrum . From what i have looked upon the subject , this requires fourier transform of the waves . Can someone suggest where i…
woodstok
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