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annotate m-toolbox/classes/@specwin/kaiser_alpha.m @ 0:f0afece42f48

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Import.
author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
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Daniele Nicolodi <nicolodi@science.unitn.it>
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1 function alpha = kaiser_alpha(req_psll)
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Daniele Nicolodi <nicolodi@science.unitn.it>
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2
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Daniele Nicolodi <nicolodi@science.unitn.it>
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3 % KAISER_ALPHA returns the alpha parameter that gives the required input
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Daniele Nicolodi <nicolodi@science.unitn.it>
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4 % PSLL.
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Daniele Nicolodi <nicolodi@science.unitn.it>
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5 %
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Daniele Nicolodi <nicolodi@science.unitn.it>
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6 % Taken from C code of Gerhard Heinzel:
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Daniele Nicolodi <nicolodi@science.unitn.it>
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7 %
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Daniele Nicolodi <nicolodi@science.unitn.it>
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8 % Compute the parameter alpha of Kaiser windows
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Daniele Nicolodi <nicolodi@science.unitn.it>
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9 % from the required PSLL [dB]. Best-fit polynomial
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Daniele Nicolodi <nicolodi@science.unitn.it>
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10 % was obtained from 180 data points between alpha=1
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Daniele Nicolodi <nicolodi@science.unitn.it>
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11 % and alpha=9.95. Maximum error is 0.05
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Daniele Nicolodi <nicolodi@science.unitn.it>
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12 % Maximum error for PSLL > 30 dB is 0.02
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Daniele Nicolodi <nicolodi@science.unitn.it>
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13 %
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Daniele Nicolodi <nicolodi@science.unitn.it>
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14 % M Hewitson 19-05-07
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Daniele Nicolodi <nicolodi@science.unitn.it>
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15 %
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Daniele Nicolodi <nicolodi@science.unitn.it>
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16 % $Id: kaiser_alpha.m,v 1.2 2011/04/08 08:56:36 hewitson Exp $
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Daniele Nicolodi <nicolodi@science.unitn.it>
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17 %
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Daniele Nicolodi <nicolodi@science.unitn.it>
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18
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19
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Daniele Nicolodi <nicolodi@science.unitn.it>
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20 a0 = -0.0821377;
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Daniele Nicolodi <nicolodi@science.unitn.it>
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21 a1 = 4.71469;
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Daniele Nicolodi <nicolodi@science.unitn.it>
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22 a2 = -0.493285;
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Daniele Nicolodi <nicolodi@science.unitn.it>
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23 a3 = 0.0889732;
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Daniele Nicolodi <nicolodi@science.unitn.it>
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24
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Daniele Nicolodi <nicolodi@science.unitn.it>
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25 x = req_psll / 100;
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Daniele Nicolodi <nicolodi@science.unitn.it>
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26 alpha = (((((a3 * x) + a2) * x) + a1) * x + a0);
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Daniele Nicolodi <nicolodi@science.unitn.it>
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27
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Daniele Nicolodi <nicolodi@science.unitn.it>
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28
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Daniele Nicolodi <nicolodi@science.unitn.it>
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29 % END