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Questions tagged [frequency-analysis]

393 questions
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Android app to record sound in real time and identify frequency

I need to develop an app to record frequencies in real time using the phone's mic and then display them (in text). I am posting my code here. The FFT and complex classes have been used from http://introcs.cs.princeton.edu/java/97data/FFT.java.html…
user2463212
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bode plot discrepancy

I am plotting the following Cu4 = tf([1 2], [1 2 6]); [magCu4 phaseCu4 wout] = bode(Cu4,logspace(-2,7,300)); magCu4 = squeeze(magCu4); phaseCu4 = squeeze(phaseCu4); semilogx(wout,20*log10(magCu4)),grid; hold on bode(Cu4,'r') I would expect that…
suzu
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What should I look for in the analysis of the attached signals?

I'm looking to analyze and compare the following `signals': (Edit: better renderings here: oscillations good and here: oscillations bad) What you see are plots of neuron activations from a type of artificial neural network plotted against time.…
Ben J
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how to compute frequency and detect pitch of a compressed (mp3) audio file? - Android

I'm having a problem with recording audio using Audiorecord class because the data returned is always zero (the read method does not record audio). So, I thought of playing a compressed audio and read it for processing or decompressing. How could…
netti
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Converting Real and Imaginary FFT output to Frequency and Amplitude

I'm designing a real time Audio Analyser to be embedded on a FPGA chip. The finished system will read in a live audio stream and output frequency and amplitude pairs for the X most prevalent frequencies. I've managed to implement the FFT so far,…
Dave Moore
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R Frequency table with multiple choice question that allows more than one response

I am analyzing survey data, where people could choose more than one county in a question about where their organization is located. I am trying to create a frequency table that counts every time a county is chosen, whether or not they choose one or…
KLenny
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Normalize a melspectrogram to (0, 255) with or without frequency scaling

I am converting multiple log-mel spectrograms from .wav files to images. I want to destroy as little information as possible as I plan to use the resulting images for a computer vision task. To convert the data to an image format, I currently use a…
Thomas Jalabert
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How can I transfer a discrete signal from the time domain into the frequency domain and back without losing data?

For a few weeks now, I have been trying to implement a DFT that takes an arbitrary set of bytes and treats them as a signal. It then transforms them to the frequency domain. Following that it transforms them back. It originally only attempted to use…
Matt
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How to convert x-axis from samples into time (s) and frequency (Hz) with python?

here I have plotted an ecg signal in time-domain and frequency-domain with fft(): time-domain frequency-domain but as you can see, the x-axis of both images are still in samples. I have searched some references how to convert samples into time (s)…
Ngr Wisnu
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how to calculate and plot frequency of csv time series data from FFT

Hi i have the following data set. the data is large and here i am presenting the 1st 30 data. it is a time series of water level data with 15minute interval. datetime time (min) time(Sec) WL…
Engr M Faysal
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How often observations occur together in rows R

I have a dataframe that is comparable to the one below: V1 V2 V3 V4 V5 V6 V7 A B C D NA NA NA A E F NA NA NA NA D A C B F E NA A E NA NA NA NA NA Each row is a patient and each letter in the dataframe represents a specific…
medic12345
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Normalization - Signal with different sampling rates

I am trying to solve a signal processing problem. I have a signal like this My job is to use FFT to plot the frequency vs. signal. This is what I have coded so far: def Extract_Data(filepath, pattern): data = [] with open(filepath) as…
Tan Phan
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how can the noise be removed from a recorded sound,using fft in MATLAB?

I want to remove noises from a recorded sound and make the fft of it finding fundamental frequencies of that sound, but I don't know how to remove those noises. I'm recording the sound of falling objects from different heights. I want to find the…
yuna
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Alternative methods of computing real-time event frequency

I'm working in an application where there is a lot of reporting of external events. One of the metrics that is used often is the event rate as a function of time. For example, measuring the sample-rate of some external asynchronous sensor. Currently…
Paul Belanger
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Determine fundamental frequency of speaking voice

I am trying to determine the perceived pitch of an audio sample (voice only, no background or music) to then identify the voice as bass, tenor, alto, mezzo-soprano, soprano. To do so, I use aubio which returns a list of timecodes and the respective…
Armin Hierstetter
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