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53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
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/*****************************************************************************/
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/*
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* rrcfreq.c -- Square Root Raised Cosine Function (Frequency Domain).
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*
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* Copyright (C) 2001, 2002
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* Thomas Sailer (t.sailer@alumni.ethz.ch)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*
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*/
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/*****************************************************************************/
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#define _GNU_SOURCE
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <math.h>
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#include <float.h>
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#include "raisedcosine.h"
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/* --------------------------------------------------------------------- */
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double root_raised_cosine_freq(double freq, double alpha)
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{
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freq = fabs(freq);
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freq -= 0.5 * (1 - alpha);
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if (freq <= 0)
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return 1;
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if (freq >= alpha)
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return 0;
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freq /= alpha;
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freq *= M_PI;
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return sqrt(0.5 * (1 + cos(freq)));
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}
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