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/* -*- c++ -*- */
/*
* Copyright 2002 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include <atsc_consts.h>
#include <atsci_exp2_lp.h>
#include <stdexcept>
#include <cmath>
#include <iostream>
using std::vector;
using std::cerr;
using std::endl;
/*
* FILTER SPECIFICATION FILE
* FILTER TYPE:LOW PASS 1H
* PASSBAND RIPPLE IN -dB -.0100
* STOPBAND RIPPLE IN -dB -66.0000
* PASSBAND CUTOFF FREQUENCY 5.69000 HERTZ
* STOPBAND CUTOFF FREQUENCY 6.12000 HERTZ
* SAMPLING FREQUENCY 21.5200 HERTZ
*/
static const float atsci_exp2_lp2x[] = {
#include "atsci_exp2_lp2x.dat"
};
/*
* FILTER SPECIFICATION FILE
* FILTER TYPE:LOW PASS 1H
* PASSBAND RIPPLE IN -dB -.0100
* STOPBAND RIPPLE IN -dB -66.0000
* PASSBAND CUTOFF FREQUENCY 5.69000 HERTZ
* STOPBAND CUTOFF FREQUENCY 6.12000 HERTZ
* SAMPLING FREQUENCY 20.0000 HERTZ
*/
static const float atsci_exp2_lp20[] = {
#include "atsci_exp2_lp20.dat"
};
#define NELEM(x) (sizeof (x) / sizeof ((x)[0]))
// is A within 5% of TARGET?
static bool
close_enough_p (double a, double target)
{
double delta = fabs (target * 0.05); // 5 percent
return fabs (target - a) <= delta;
}
vector<float>
atsci_exp2_lp::taps (double sampling_freq)
{
if (close_enough_p (sampling_freq, 20e6)){
return vector<float>(&atsci_exp2_lp20[0], &atsci_exp2_lp20[NELEM(atsci_exp2_lp20)]);
}
if (close_enough_p (sampling_freq, 2 * ATSC_SYMBOL_RATE)){
return vector<float>(&atsci_exp2_lp2x[0], &atsci_exp2_lp2x[NELEM(atsci_exp2_lp2x)]);
}
else
throw std::out_of_range (
"atsci_exp2_lp: no pre-designed filter close enough");
}
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