analyzing biosignals in Matlab
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Hi, I am having a project where I have to open a signal from muscles in matlab and use to it find a few parameters. I'm a beginner in matlab so I apologize if my questions might sound too simple. first, the file for my signal is a .mat file. I know how to load it in matlab but how can I open it as a figure? (a plot of my signal) I mean I wanna see my signal in matlab. second, I need to find the median frequency for this signal which is in the time domain itself so it has to turn into freq domain first. I need the median frequecy for 2 parts of signal, from the beginning to near the middle, and then middle to end. How do I do that? I know about the functions in matlab that take median freq etc but I need the exact code as an example. any help would be really appreciated.
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Accepted Answer
Rick Rosson
on 2 Jul 2011
Hi Mary,
The functions that you need in MATLAB include:
plot
median
fft
fftshift
To use these function, you will need a time-domain representation of your signal, which according to your question you can load from a MAT file.
If you need information about how to call these functions, please type
doc functionName
at the MATLAB command line, where functionName is the name of one of these function. For example, type
doc fft
to open the function reference page for the fft function.
You will also need to know the sampling rate (call it Fs) in samples per second of the signal. Once you have Fs, you can compute the time domain t and the frequency domain f.
HTH.
Rick
More Answers (4)
Rick Rosson
on 2 Jul 2011
Hi Mary,
When you load the file into MATLAB, what are the names and sizes of the variables that appear in the MATLAB Workspace? To find out, please try the following:
filename = 'myfile.mat'; % or whatever the file is called
load(filename);
whos
Then please copy and paste the table from the Command Window to this forum.
Thanks.
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Rick Rosson
on 3 Jul 2011
Hi Mary,
The easiest way to visualize a signal in MATLAB is to simply plot it. Please try:
plot(x);
where x is the name of the variable containing the samples of the signal.
HTH.
Rick
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Mary G
on 16 Jul 2011
2 Comments
Walter Roberson
on 16 Jul 2011
Is there a name for the data file format you are using? If not, then what kind of device produced it?
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