3 * Copyright 2002 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2, or (at your option)
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
23 #include <atsc_consts.h>
24 #include <atsci_exp2_lp.h>
34 * FILTER SPECIFICATION FILE
35 * FILTER TYPE:LOW PASS 1H
36 * PASSBAND RIPPLE IN -dB -.0100
37 * STOPBAND RIPPLE IN -dB -66.0000
38 * PASSBAND CUTOFF FREQUENCY 5.69000 HERTZ
39 * STOPBAND CUTOFF FREQUENCY 6.12000 HERTZ
40 * SAMPLING FREQUENCY 21.5200 HERTZ
42 static const float atsci_exp2_lp2x[] = {
43 #include "atsci_exp2_lp2x.dat"
47 * FILTER SPECIFICATION FILE
48 * FILTER TYPE:LOW PASS 1H
49 * PASSBAND RIPPLE IN -dB -.0100
50 * STOPBAND RIPPLE IN -dB -66.0000
51 * PASSBAND CUTOFF FREQUENCY 5.69000 HERTZ
52 * STOPBAND CUTOFF FREQUENCY 6.12000 HERTZ
53 * SAMPLING FREQUENCY 20.0000 HERTZ
55 static const float atsci_exp2_lp20[] = {
56 #include "atsci_exp2_lp20.dat"
60 #define NELEM(x) (sizeof (x) / sizeof ((x)[0]))
62 // is A within 5% of TARGET?
65 close_enough_p (double a, double target)
67 double delta = fabs (target * 0.05); // 5 percent
69 return fabs (target - a) <= delta;
73 atsci_exp2_lp::taps (double sampling_freq)
75 if (close_enough_p (sampling_freq, 20e6)){
76 return vector<float>(&atsci_exp2_lp20[0], &atsci_exp2_lp20[NELEM(atsci_exp2_lp20)]);
78 if (close_enough_p (sampling_freq, 2 * ATSC_SYMBOL_RATE)){
79 return vector<float>(&atsci_exp2_lp2x[0], &atsci_exp2_lp2x[NELEM(atsci_exp2_lp2x)]);
82 throw std::out_of_range (
83 "atsci_exp2_lp: no pre-designed filter close enough");