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generating random noise in MATLAB

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mro83

mro83

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white noise matlab

Hi to all
I have an acoustic project an I shoud generate a noise-like signal in MTLAB based on ASTM E1050 standard.
the noise specification is :"It is recommended that the test signal
consist of broadband random noise; however, other test
signals such as pseudo random noise or sine-sweep excitation
could also be used."

please introduce me an efficient way to produce either of signals above.

cheers to all
 

matlab white noise

Here's pseudo-random broadband white noise played to the speakers:
wavplay(rand(10000,1) - 0.5)

I don't know "sine-sweep excitation". Can you find more info?
I don't know ASTM E1050.
 

matlab random noise

Here is a question: What will be used to have a white noise: rand(uniform distribution) or randn(normal distribution) functions of matlab. And here is a comment on the subject: a stream of uncorrelated random numbers constitutes white noise. Then what is your comment?
 

random noise matlab

thanx
rand is good for my job. but here is another question: when i plot frequency spectrum of this noise, the plotted spectrum is not flat anough and I think that broadband random noise should have flat spectrum ( i don't if this is true?).

what is your opinion for its spectrum.
I think that using an equalizer would solve my problem. if yes help me to design it.

cheers
 

white noise in matlab

Gaussian (aka white) noise gives you flat spectrum, not random noise.
 

generate white noise matlab

Dear mro83,
I think u better try this m file
 
generate white noise in matlab

Uniform white noise and gaussian white noise both give you flat spectrum. They have different point distributions.

s = rand(10000,1) - 0.5;
plot(abs(fft(s)))

s = wgn(10000,1,1); % maybe requires communication toolbox
plot(abs(fft(s)))

mro83, do you see something non-flat there? Maybe you simply need to increase the number of data points to see the flatness. The spectrum is noisy of course, but it's flat.
 

random noise in matlab

Hi
you are right echo
the spectrum is inposed by noise and is somewhat flat.
 

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