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The processing of signals for the purpose of extracting a parameter or property embedded in a signal. Signal goes in and far fewer numbers come out.
6
votes
Feature extraction from spectrum to aid categorisation
First thing to mention is that you must have some kind of Machine Learning algorithm to perform your recognition. You might want to use the following - what's yours?
Neural Networks (easy to impleme …
2
votes
Open debate: Protocol for signal analysis
Personally, when working with audio signals I use:
File metadata and parameters (if there's a calibration associated with it, bit-depth, sampling frequency, etc.)
Metrics, such as RMS/peak dBFS level …
1
vote
Playing sound in left and right speaker alternatively and storing output in array in matlab
If you want to play only one channel then you must set zeros at one of your matrix columns, i.e.:
sound_L = sound_array;
sound_L(:,2) = 0;
sound_R = sound_array;
sound_R(:,1) = 0;
So your code bec …
52
votes
Accepted
Meaning of Hilbert Transform
One application of the Hilbert Transform is to obtain a so-called Analytic Signal. For signal $s(t)$, its Hilbert Transform $\hat{s}(t)$ is defined as a composition:
$$s_A(t)=s(t)+j\hat{s}(t) $$
The …
1
vote
Accepted
How to add repeated beeps to sound created with a pause in between each beep in MATLAB
Any pause can be done by using vector/matrix concatenation. Let's say you want to make a signal with pause of length P after it, then do the following:
P = 400;
beep = [sound_array; zeros(P, 2)];
N …
1
vote
Accepted
How to store the signal in a variable and plot the signal in MATLAB
I suggest you to do something like (one plot with two curves):
figure
plot(sound_L(:,1), 'b'); % blue
hold on; grid on; % prevent from redrawing and add grid\
plot(sound_R(:,2), 'r'); % red
legend({' …
2
votes
How convert scal to frequency when use cwt in matlab
I think you should try MATLAB's scal2frq. You provide the vector of scales, wavelet name and optionally sampling period. This will return vector of pseudo frequencies.
In your case that should be som …
6
votes
Time-frequency representation of sound signal using Matlab
I believe that this "color graph" you are looking for is a spectrogram (although it looks to me more like a scalogram, but you did not mentioned wavelets). Let me give you an example in MATLAB of obta …
5
votes
Accepted
How do I generate sound using MATLAB?
Something like that should do. Please keep in mind that this code can be further improved by windowing your signal, using decibel scale for spectrum, taking only first half of a spectrum, etc. This is …
3
votes
Accepted
Pre-emphasis filter design
I don't really understand what are you trying to achieve with vector B that has 6 elements. Pre-emphasis filter is defined as:
$$y[n]=x[n]-\alpha x[n-1]$$
Where $\alpha$ is $0.97$ in your case.
Yo …
1
vote
Accepted
Order analysis or order tracking
Well my friend, if you read the following B&K tutorial about the Order Tracking, then you should encounter so called Vold-Kalman Order Filtering. Personally I don't like it (rather prefer Chirp-Fourie …
6
votes
Accepted
Negative values of the FFT
The rfft function returns complex values ordered in specific way. In order to retrieve the amplitude of your DFT you must take the absolute value of it. Easiest way to do that is to call y_a = np.abs( …
2
votes
Baby Cry recognition robust against the distance
This question is very broad and it is not possible to give a very good answer without even knowing the internals of your system (the type of the network and features make a big difference). However, I …
5
votes
Processing Accelerometer Vibration Data With FFT
After taking a closer look at your results, here is what I think.
Because you are playing back sinusoid through your speaker you are also observing it's properties. It has some significant harmoni …
1
vote
Accepted
Create a third octave spectrum from a time signal
Hate to answer this question, but it is a plotting issue, not the actual design problem. Basically, you don't have enough points at low frequencies cause they are spaced linearly and you are plotting …