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[project @ 1998-10-23 05:43:59 by jwe]
author jwe
date Fri, 23 Oct 1998 05:44:01 +0000
parents
children f8dde1807dee
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3191
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1 ## Copyright (C) 1995, 1996, 1997 Andreas Weingessel
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2 ##
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3 ## This program is free software; you can redistribute it and/or modify
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4 ## it under the terms of the GNU General Public License as published by
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5 ## the Free Software Foundation; either version 2, or (at your option)
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6 ## any later version.
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7 ##
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8 ## This program is distributed in the hope that it will be useful, but
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9 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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11 ## General Public License for more details.
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12 ##
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13 ## You should have received a copy of the GNU General Public License
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14 ## along with this file. If not, write to the Free Software Foundation,
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15 ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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16
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17 ## usage: blackman (m)
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18 ##
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19 ## Returns the filter coefficients of a Blackman window of length m.
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20 ##
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21 ## For a definition of the Blackman window, see e.g. A. V. Oppenheim &
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22 ## R. W. Schafer, "Discrete-Time Signal Processing".
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23
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24 ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at>
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25 ## Description: Coefficients of the Blackman window
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26
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27 function c = blackman (m)
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28
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29 if (nargin != 1)
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30 usage ("blackman (m)");
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31 endif
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32
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33 if !(is_scalar (m) && (m == round (m)) && (m > 0))
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34 error ("blackman: m has to be an integer > 0");
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35 endif
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36
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37 if (m == 1)
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38 c = 1;
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39 else
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40 m = m - 1;
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41 k = (0 : m)' / m;
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42 c = 0.42 - 0.5 * cos (2 * pi * k) + 0.08 * cos (4 * pi * k);
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43 endif
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44
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45 endfunction