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2answers
55 views

Implementing Short Time Fourier Tranform

I have a 512 sample frame, lets call it X. The frame is further divided into four sub-frames of 128 samples each. Each of these sub-frames have a different ...
0
votes
0answers
27 views

Frequency and time marginals of STFT and Wigner-Ville Distribution

I want to compare time and frequency marginals of Wigner-Ville distribution and STFT. I can calculate WVD's marginals by simple sum operation since WVD is real. But I could not figure out how to deal ...
-1
votes
1answer
58 views

how to read full input signal with STFT in matlab

Please help! I am trying to figure out why in the code i have below my input signal is being cropped but in the code I have a full signal created. The white noise created is 5000 samples for the right ...
1
vote
1answer
80 views

How to get Envelope of Audio Signal

I am having a problem understanding how the author gets the onset envelope of an audio song in this paper. The entire section in question has been quoted below: First the input sound is resampled ...
0
votes
1answer
146 views

Computing narrowband spectrograms using MATLAB [closed]

I'm having an assignment of computing narrowband spectrograms using MATLAB. And I totally have no idea about the code. Can someone help me writing the code and explaining what's going on to me. Lots ...
0
votes
2answers
88 views

Audio compression with STFT

Let STFT[frame, freqbin] be the short-time Fourier transform of some audio data. (here frame is the index in time, and ...
0
votes
1answer
29 views

Matrix form of STFT

IS there a Matrix form of the STFT that could be applied to a signal directly, as in the case of DFT? We know the matrix structure of the DFT Matrix. Can we derive that somehow for a STFT Transform? ...
0
votes
1answer
52 views

How to obtain the Spectrogram of a signal

I am trying to use Matlab to compute the spectrogram of a signal but I can't seem to figure out how Matlab computes the spectrogram.Consider the case where I have a ...
1
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0answers
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 ...
0
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0answers
37 views

Time of sound-signal

Let's say I have a sound file, I then compute the Spectrogram and segment each part of it. Assume that it is a recording of someone saying the word "Hello" and therefore, each piece is given like so: ...
0
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0answers
42 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 ...
-1
votes
1answer
46 views

Which FIR filter should I choose?

If I have the following spectrogram: And only wanted to have the signals that are in a particular frequency range (2627 - 3939htz).. Can I run a FIR filter to only allow these signals through, and ...
-1
votes
2answers
75 views

Suggested algorithms for detecting voiced / unvoiced signals [duplicate]

Right. I'm trying to understand the concepts for determining where the signal contains voiced and unvoiced parts. I have created a spectrogram (STFT) of a signal and I'm trying to separate from ...
-1
votes
1answer
81 views

STFT Time Variance - Threshold

This is a follow up question to: Segment/Idenfication of signal from a spectrogram My main goal is to identify (segment) all of the calls from a given signal. The signal looks like the following ...
2
votes
0answers
63 views

Segment/Idenfication of signal from a spectrogram

I have the following Spectrogram of a signal: Essentially, in this signal, I know there is one point of interest (between 60-80) and between the the particular frequencies. I could, potentially ...
0
votes
1answer
87 views

Normalizing a spectrogram or a pitch class profile

I am developing a chord recognition program using neural networks.I need to normalize the spectrogram or my pitch class profile to provide inputs for the neural network. The pitch class profile ...
0
votes
0answers
52 views

STFT - Stride the windows?

In matplotlib's spectrogram function, this is how they "seperate and overlap windows": result = stride_windows(x, NFFT, noverlap, axis=0) What this is doing: ...
1
vote
1answer
168 views

PSD - Is this formula correct?

Trying to understand whether or not I am calculating the PSD correctly. Below is the equation that I am using: $$ PSD_{rms}(f_{m} = m \cdot f_{res}) = \frac{PS_{rms} }{ENBW} = \frac{2 \cdot \left | ...
2
votes
1answer
69 views

PSD - Correct Formula for removing Noise

Ok, so finally some things are making sense. I'm trying to scale the results, which I have done by the following equation: $$ PS_{rms} = \frac{2 \cdot \left |y ...
1
vote
2answers
62 views

STFT - Putting it all together

I'm currently reading this paper: http://www.rssd.esa.int/SP/LISAPATHFINDER/docs/Data_Analysis/GH_FFT.pdf On page 21, it has a section called "Putting it all together", it states the following ...
0
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1answer
42 views

phenomenon when window size for STFT is too short

Hi I was researching on STFT when I encountered this slide online I don't understand the points, Can anyone explain them? Thanks in advance.
2
votes
1answer
133 views

PSD - Spectrum analysis

Could someone tell me where it is that I might be going wrong with the following problem? Ok, so I'm computing a spectrogram, and, trying to return the PDS of the signal (to show where the signal ...
0
votes
1answer
71 views

Inverse Short time fourier transform

I am I am working with 'wav' files in audio signal processing. I am able to find out STFT by using the function " spectrogram(file name, window length). Now I want to apply Inverse Short time fourier ...
0
votes
1answer
569 views

Power Spectral Density estimate (PSD)

I'm trying to understand PSD, and, it's functions. So far I have carried out the following: Segmented a signal with NFFT = 256 and ...
0
votes
1answer
51 views

filter bank of gabor filters with different frequencies and orientations

I was reading a paper which uses a filter bank of gabor filters with different frequencies and orientations. However, I often see the construction of a filter bank of gabor filters with different ...
1
vote
1answer
58 views

How to find the Freqs bins

Ok, so I'm kind of moving forward with implementing the STFT. I realise that I was taking the entire FFT and not the first half. The problem that I'm having now is, understanding how to get the Freq ...
0
votes
3answers
104 views

Relationship between windowed fourier transform and wavelet transform

I was reading on windowed fourier transform and wavelet transform, and i was thinking that the windowed fourier transform is a subset of wavelet transform. Is that true?
0
votes
2answers
89 views

STFT - DFT size of the bins

Having some trouble understanding this concept, really could do with some advice. I want my STFT to have the following parameters: NFFT = 256 ...
1
vote
2answers
101 views

STFT - Plotting is not a true representation

I might be going crazy here. Following my question: here I did some thinking and probably understood that my STFT algorithm was not performing correctly. I followed this algorithm: -> Get 256 of ...
3
votes
0answers
97 views

Why are the frequencies associated with the STFT bins not representative of the energy?

I'm experimenting with a 30 Hz sine wave and I want to extract the frequencies of this, and have implemented the algorithm to do so. This gives a correct reading, well, gives 29 Hz. I'm now wanting ...
1
vote
2answers
123 views

Analyse audio/music frequencies without STFT, at 1/f temporal resolution, using probe phasors at logarithmically-spaced frequencies, O(N log N)?

First, some background: The STFT is the best general-purpose tool I know of for analysing a (musical or other) signal into its component frequencies. For many purposes the STFT works fine, but there ...
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votes
2answers
130 views

Spectrogram - Am I missing something?

I have the following signal: I'm trying to compute a Spectrogram algorithm, but, don't think I'm doing it right.. I have computed the following: 1) STFT (size 256 with an overlap of 128) 2) ...
1
vote
3answers
83 views

Will the resulting spectrogram from this algorithm be 1D or 2D?

I'm implementing a spectrogram algorithm and I get the basic concepts, however, I'm struggling with something. Let's say I have a 1D vector: ...
2
votes
3answers
604 views

Choosing the right overlap for a window function

On Wikipedia there is quite a list of window functions. However, when you are doing a lot of STFTs, you often have to have some overlap to get better results. Generally an overlap factor of 2 (i.e., ...
1
vote
2answers
236 views

Zero-padding in STFT

I a recent topic, it has been told that zero-padding in the STFT can improve it, and avoid some circular convolution related things. Here is my Python code for STFT : ...
3
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3answers
284 views

Filtering with STFT

I have sucessfully implemented a STFT (+inverseSTFT with perfect reconstruction of original signal, with overlap add, etc.) in order to work on audio files. Using this STFT / iSTFT framework, I have ...
0
votes
3answers
159 views

importance of symmetric windows for STFT for practical applications

I am wondering why is the linear phase property of filters with symmetric coefficients important for some practical applications of short time fourier transform, such as image processing? I have read ...
1
vote
2answers
271 views

Discretized CWT vs. DWT vs. FWT vs. MRA

By reading some books about wavelets, it seems that Discretized CWT is not the same thing as DWT. Can we give a classification of Discretized CWT vs DWT vs FWT etc. ? A few remarks : All I read ...
5
votes
2answers
559 views

STFT and DWT (Wavelets)

STFT can be successfully used on sound data (with a .wav soundfile for example) in order to do some frequency-domain modifications (example : noise removal). With ...
1
vote
1answer
515 views

Comparison between Fourier transform, short time Fourier transform and wavelets

What is the difference between the Fourier transform, short time Fourier transform and wavelets?
0
votes
1answer
107 views

STFT zeropadding

I am trying to implement the STFT by MATLAB, and I read somewhere that we must do zeropadding to the subsequence of the signal before windowing it with a Gaussian window. What happens if we don't do ...
1
vote
1answer
106 views

What information is lost, if any, in normalizing Seismic/Earthquake time-frames in an STFT to equal variance?

This might be more of a statistical question, but let us assume that we take a spectrogram, or STFT, where time is on the x-axis, and frequency is on the y-axis in this matrix. What information might ...
1
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2answers
1k views

Estimate phase using STFT in Matlab?

My signal oscillates back and forth on the interval [-1, 1] at varying frequencies, with some added higher frequency noise components (example data shown below). I want to to estimate the phase of the ...
1
vote
1answer
149 views

STFT - Window Functions

I'm looking for your opinions. I have obtained a Speech Signal and computed a STFT on this signal. I have split the signal into blocks of (100 x 256) and computed the STFT based on different ...
1
vote
1answer
200 views

Confusion with regards to STFT and MFCCs

I'm wondering if someone can clear the following up for me as I'm having a difficult time understanding the concept. I'm looking to implement and learn about the processes and uses using Short Time ...
4
votes
3answers
593 views

What's the difference between the Gabor-Morlet wavelet transform and the constant-Q transform?

At a glance, the constant-Q fourier transform and the complex Gabor-Morlet wavelet transform seem the same. Both are time-frequency representations, based on constant-Q filters, windowed sinusoids, ...
5
votes
3answers
3k views

Can you increase frequency resolution of FFT without increasing window size?

I'd like to use STFT for multipitch analysis. I realise detecting the partials existing in the signal is just the beginning. Still I have problem with it. Let's say I have signal sampled with 'CD' ...
0
votes
2answers
141 views

Discarding phase

What would happen if you took the STFT of a signal, discarded the phase information, and re-synthesized it? For example, just modulate oscillators tuned to each frequency bin by the amplitudes for ...
0
votes
1answer
205 views

Spectrogram for created signal

I'm trying to test the specgram function located in the signal package in octave but I'm a little confused at the variables in specgram. What I would like to do is be able to get the specgram data ...
12
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1answer
3k views

Inverse Short Time Fourier Transform algorithm described in words

I'm trying to conceptually understand what is happening when the forward and inverse Short Time Fourier Transforms (STFT) are applied to a discrete time-domain signal. I've found the classic paper by ...