Questions tagged [spectrogram]
A spectrogram is a time-varying spectral representation (forming an image) that shows how the spectral density of a signal varies with time.
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Do not understand spectrogram of signal created from many sines with different frequencies
I get this spectrogram
From the following code:
...
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2answers
30 views
Augmentation for EEG signal classification using Deep Learning
Augmentation is a technique that we use in deep learning for expanding the training dataset. It includes different ways of modifying an image and adding it to the training dataset. My question is if ...
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26 views
Spectrogram using SciPy - bad scaling of the timeline [duplicate]
I have a real value signal which has 197 samples (every 1 second). I made its spectrogram using the SciPy library:
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4 views
Why can ARSS not recreate audio from a spectrogram without sounding muffled?
Why do ARSS and all audio to spectrogram then back to audio program's create audio files that sound muffled?
I know their is some physics and math with the short-time Fourier transform and etc. I ...
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2answers
25 views
Using different algorithms/formulas to create spectrograms
On the internet, I have seen people use Matplotlib/Python and short-time fourier transformations to create spectrograms. Are their other formula/algorithms to create spectrograms? And are they ...
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4answers
50 views
Alternatives to Spectrogram [closed]
What is a more accurate alternative to a spectrogram that can be represented in an image? Also, what is a python script/exe that can be used to convert audio into the image format then back from image ...
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1answer
28 views
Spectrogram Time Resolution with Overlap
I understand that the time resolution of a spectrogram with no overlap is the sampling frequency divided by the window length. How does this change with, say, 50% overlap? Does this double the time ...
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1answer
51 views
How to interpret these MP3 spectrums?
Recently, I found I had this song duplicated in my music library, but when listening to them I noticed one version was of noticeably higher quality than the other despite both claiming to have a ...
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0answers
26 views
When do phases not exist for spectrograms?
I have been reading a paper on the "Single pass spectrogram inversion"
and I came across this in the Introduction part.
In many applications, the analysis and modification of the Short-Time
...
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1answer
65 views
Finding where signal is showing some (unknown) periodicity
I have readings of the vertical displacement of someone over time, as in the picture below:
At some points in time, the person will be exercising or jumping up & down, creating more or less ...
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26 views
Optimizing Spectrogram Parameters
I'm looking for references that explain the trade-offs between more averages with shorter fft sizes or longer fft sizes with fewer averages when generating a spectrogram to perform energy detection of ...
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1answer
171 views
Spectrogram of a single tone complex signal has two dark lines?
I am trying to plot the spectrogram of a complex signal I generated. I have written code to generate this signal and plot the spectrogram. It works. However I see that there are two dark lines present ...
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2answers
74 views
audio spectrogram normalization
I am performing language classification from audio signals using mel-spectrograms as my inputs for a ResNet. It works well as long as all of my audio data from different languages is from the same ...
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1answer
58 views
How to convert a spectrogram back to a signal [duplicate]
I'm converting a signal to a spectrogram, manipulating that (nonlinear stuff), and then want to use the modified audio signal. I can make it so the segments are not overlapping, but am unsure how to ...
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14 views
Spectrogram of chirp sequence radar signals
I am confused as to whether SFFT makes sense to process chirp sequence signals. The radar fires up a sequence of 100 linear ramps with that are only interrupted by the very short period in which the ...
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1answer
46 views
Spectrogram power/magnitude normalization in analogy with image intensity normalization
In analogy with the 8-bit grayscale image color depth, in which the intensity of a sample pixel is normalized to a value between 0 and 255 by taking into account the minimum and maximum intensities ...
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17 views
finding harmonics from fundamental
https://s3.amazonaws.com/izotopedownloads/docs/rx700/en/interactive-tools/index.html#selection-tools
From the above link, under the "Magic Wand" tool description, how does that algorithm work?
In RX,...
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1answer
37 views
Normalizing vectors to be the same size to retain PSD data
Context:
PSD=periodogram(y) in MATLAB gives the PSD (power spectral density) estimate of a sound-source signal. I want to find the local maximum within 3 different ...
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162 views
How to Extract frequency bands from Short-time Fourier Transform?
I am reproducing the results reported by the author in a research paper. In which he takes the STFT of EEG signals. The input data has a shape of (1 X500) and I used Scipy library built-in function to ...
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1answer
56 views
Extracting audio from picture of time-domain signal
I saw this nifty art thing where they dress up the time-domain audio signal in some pretty way.
https://www.etsy.com/ArtbloxShop/listing/621561709/sound-wave-art-custom-soundwave-print
My question is ...
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1answer
44 views
How to classify the movement type of a target into two categories(direct motion or else) by using a doppler radar?
How to classify the movement type of a target just into two categories(one is direct motion which is almost straight line movement and the other is anything else) by using a doppler radar with a ...
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1answer
570 views
How to go from wav file to spectrogram back to wav file in python?
Close to this question but different : Wav To Spectrogram, Back To Wav
I already posted this on StackOverflow(https://stackoverflow.com/questions/54743968/how-to-go-from-wav-file-to-spectrogram-back-...
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214 views
Recover Audio from Spectrogram Image
I have applied transformation(Constant Q Transformation) to my audio time domain signal, this gives me Frequency vs Time representation. Now, the CQT values consists of complex values(84*260), but ...
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0answers
32 views
Scipy Welch's gives different first element
I've re-implemented Welch's method and want to compare it to scipy.signal.welch. However, the first two and last elements of the resulting array are different.
My ...
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2answers
34 views
What is Causing a Noise Signal in USB Audio Recording?
I am experiencing the following peculiar noise signal when recording from my Behringer Xenyx Control 2 over USB.
There is frequency at around 2293 hz as show:
And over time, it produces the ...
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0answers
86 views
How to use a context window to segment a whole log Mel-spectrogram (ensuring the same number of segments for all the audios)?
I have several audios with different duration. So I don't know how to ensure the same number N of segments of the audio. I'm trying to implement an existing paper, so it's said that first a Log Mel-...
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83 views
How can I calculate the Number of bins per octave?
I am trying to calculate the Constant Q Transform for Monophonic audio using Python.
The Python has the library to calculate the CQT , the default value of num_bins_per_octave is 12.
How would one ...
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2answers
274 views
How to calculate the PSD from the complex calculated STFT?
I have calculated the STFT with scipy python library:
...
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0answers
63 views
How to know the time of my window to calculate the STFT with python knowing only the length?
I am trying to implement a work presented in an IEEE paper where they have mentioned that the STFT was performed on the signal measurements to obtain a spectrogram with no overlap window of 3 min :
I ...
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1answer
58 views
Fourier like spectral analysis with uneven intervals and redesigned DFT matrix
I intended to use a discrete Fourier transform (DFT) on a time series sampled at uneven intervals. What I did was to calculate a DFT matrix where the elements are the values at the uneven locations ...
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1answer
148 views
Audacity Spectogram view: how to see exact frequency and intensity under the cursor?
In the Spectogram view, simply clicking anywhere with the selection tool gives a vertical line to the top ruler, and shows at the bottom the exact sample, H:MM:SS, or other time coordinate you'd want.
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1answer
35 views
What's the right scale to represent a frequency spectrum?
To represent a 16 bits temporal spectrum, it's "easy" : my scale is going from -32000 to +32000. But What's the scale for a frequency spectrum ?
I made that try : I calculated a pure single frequency ...
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130 views
Mirrored Spectrogram Mp3
First of all sorry if this is a stupid question, but I am an absolute beginner in this field and have been trying for days now.
I'm working on a java program that uses fft to analyze audio files.
To ...
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16 views
time-frequency masking with shared properties between vector masks
I am working on a source separation problem and I have a logical mask that when applied to the STFT matrix, gives me expected results. The problem here, is that the mask is based on a spectral feature,...
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1answer
20 views
When does a color channel such as RGB carry more info than a grayscale channel or image?
Typically a gray-scale image gives us more information about an image in terms of a signal processing problem. But when does a color channel carry more info than a gray-scale channel?
I understand ...
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1answer
92 views
Spectrogram of 493 signals at a time [closed]
I have been working with some seismic data and recently submitted a paper to a journal.
My seismic data has 493 traces: each trace are 8300 seconds long with sampling frequency of 2000 Hz.
One of ...
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1answer
151 views
Spectrogram Interpretation
I collected vibration data (amplitude and time) on a component that was attached to an engine. Using MATLAB I plotted a spectrogram to see what frequencies it vibrated at.
The code:
...
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1answer
196 views
how to create a harmonic mask from fundamental frequency?
Using an algorithm that gives the fundamental frequency across time, example https://www.mathworks.com/help/audio/ref/pitch.html (or some other one?)
how would I then use that, to create a harmonic ...
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2answers
185 views
Different ways of decomposing signals into sinusoids
For purposes of generating a spectrogram, the signal can be divided into overlapping chunks, each chunk multiplied by a window function and transformed to frequency domain using Discrete Fourier ...
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2answers
91 views
Recommended resources for noise reduction
I know the question What Resources Are Recommended for an Introduction to Signal Processing (DSP)? and I have already read some general DSP books, such as Rick Lyons's "Understanding DSP," and also ...
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1answer
361 views
Spectrogram with square or non-square magnitude of STFT: power vs. magnitude
As seen in this question and answer, to do a spectrogram, it's common to plot either:
the square magnitude $|\text{STFT}(\text{frame}, \text{bin})|^2$ ("power spectrum")
the magnitude $|\text{STFT}(\...
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1answer
372 views
Calculating SNR from Frequency-time domain
I tried to analyse the time-frequency of specific appliances. As it shows in the following frequency-time graph
I have High frequency noise from different appliances here. 4096 is the number of ...
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2answers
162 views
Window length in matplotlib's specgram
In the paper about speaker verification I can read that
Two quantities have
to be set: the length of the window and the shift between two
consecutive windows. For the length of the window, two ...
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1answer
47 views
Phase of a signal with multi delayed windowed (rectangular window) signal with different amplitudes
I have a signal $x(t)$ which is composed of multi delayed linear chirps with different amplitudes and phases but they share the same $w$ and $\alpha$, the signal can be expressed as follows:
$$\...
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2answers
2k views
Spectrogram from scipy.signal with Python
To test the python spectrogram (from scipy.signal) , I've created a signal with 2 harmonics: 2 Hz and 8 Hz. Then I've added 50Hz noise and a trend (https://i.imgur.com/t1SnQck.png). I wanted to ...
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1answer
483 views
How do I apply a binary mask and STFT to produce an audio file?
So here's the idea: you can generate a spectrogram from an audio file using shorttime Fourier transform (stft). Then some people have generated something called a "binary mask" to generate different ...
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111 views
Spectrum of received signal from radar fm-cw
I obtained actual data from a researcher, consisting of a matrix composed of several received signals from an up-ramp fm-cw radar.
Wouldn't be reasonable to plot the spectrogram of a ramp up and ...
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1answer
144 views
What unit is the z axis of a power spectrogram of audio?
the question might seem dumb but since I tried it out and got values well above 2000 (watts?) it got me thinking... Check this out:
...
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1answer
174 views
1D signal to 2D spectrogram
I struggling at transforming a 1D breathing signal into 2D spectrograms,
power spectral density as a function of time and frequency.
Does anyone have an idea about that?
0
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1answer
74 views
nearest neighbor implementation matlab
I am trying to implement this research paper:
I understand everything in the paper except the part about the nearest neighbors calculation (section 3).
The only MATLAB function I can think of that ...
