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Re: Random numbers with predefined spectral density [message #4945 is a reply to message #4853]

Tue, 22 August 1995 00:00

steinhh
Messages: 260
Registered: June 1994

Senior Member

In article <41ab22$jp5@rs18.hrz.th-darmstadt.de>, hahn@hrz.th-darmstadt.de (Norbert Hahn) writes:
|>
|> I want to calculate random numbers with other than white noise
|> spectrum. The noise spectrum (amplitude vs. frequency) is
|> given and I need random numbers that adhere to this spectrum.
|>
|> Actually, the spectrum is given by a FIR filter of order 12:
|> coeff = [ 1.48, 1.64, 0.927, ..., 3.1e-3]
|>
|> How to proceed from here ?
|>
|> Norbert Hahn

Simply produce white noise, and filter it with your desired noise
spectrum (beware of the difference between *amplitude* and the
*power* spectrum).

Given N = Noise amplitude vs. frequency, an array with NN elements,
you simply use:

NOISE = fft( fft(randomn(seed,NN),-1)*N , 1)

You should also include some renormalization of the total power
in your noise, of course.

Stein Vidar

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[Message index]

		Random numbers with predefined spectral density By: hahn on Mon, 21 August 1995 00:00
		Re: Random numbers with predefined spectral density By: David Ritscher on Thu, 24 August 1995 00:00
		Re: Random numbers with predefined spectral density By: steinhh on Tue, 22 August 1995 00:00

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