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I am trying to generate a band limited noise signal on a Raspberry Pi. I calculate samples at every 1/48000 sec on the Pi. If I generate normally distributed random numbers as data points at every sample would it be gaussian noise signal. Here is what i am having a hard time to understand, how to interpret the frequency of the noise signal. And also how to limit the frequency values to be between a band?

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  • $\begingroup$ I couldn't understand you. Are you trying to generate Gaussian Noise at sampling rate of 48000 Hz? $\endgroup$ – Royi Jun 20 '14 at 8:40
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    $\begingroup$ Note that "white" and "gaussian" are two different things (it is not clear from your question if you want to generate white noise or noise with a gaussian distribution, or white gaussian noise). "White" means that each sample is correlated only with itself (autocorrelation function is 1 at 0, 0 everywhere else), and this depends on the quality of your random number source. "Gaussian" refers to the distribution of samples values. $\endgroup$ – pichenettes Jun 20 '14 at 10:40
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If you are generating sample of white noise (Normal distribution value) with frequency of 48 kHz, then you already have this in frequency range of 0 - 24 kHz (at least you should if generator is truly random). If you use same samples with different sampling frequency, then they will also be a white noise.

Now if you want to make it a band-limited white noise, then you must use a digital filter. Choice is up to you, but for sake of simplicity I would recommend FIR filter. You must use it to filter in real time your incoming samples. How to do it? Well, that's totally up to you, you can even use short buffer to perform filtering by linear convolution for each generated sample but it won't be very efficient.

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