1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
|
/* -*- c++ -*- */
/*
* Copyright 2011 Alexandru Csete OZ9AEC.
*
* Gqrx 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.
*
* Gqrx 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 Gqrx; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include <cmath>
#include <gr_io_signature.h>
#include <gr_firdes.h>
#include <dsp/resampler_ff.h>
#include <iostream>
/*
* Create a new instance of resampler_ff and return
* a boost shared_ptr. This is effectively the public constructor.
*/
resampler_ffo_sptr make_resampler_ffo(unsigned int input_rate, unsigned int output_rate)
{
return gnuradio::get_initial_sptr(new resampler_ffo(input_rate, output_rate));
}
static const int MIN_IN = 1; /* Mininum number of input streams. */
static const int MAX_IN = 1; /* Maximum number of input streams. */
static const int MIN_OUT = 1; /* Minimum number of output streams. */
static const int MAX_OUT = 1; /* Maximum number of output streams. */
resampler_ffo::resampler_ffo(unsigned int input_rate, unsigned int output_rate)
: gr_hier_block2 ("resampler_ffo",
gr_make_io_signature (MIN_IN, MAX_IN, sizeof (float)),
gr_make_io_signature (MIN_OUT, MAX_OUT, sizeof (float)))
{
/* calculate interpolation and decimation */
d_interp = lcm(input_rate, output_rate) / input_rate;
d_decim = lcm(input_rate, output_rate) / output_rate;
std::cout << "resampler_ff:" << std::endl;
std::cout << " inter: " << d_interp << std::endl;
std::cout << " decim: " << d_decim << std::endl;
/* generate taps */
float fract_bw = 0.4;
float trans_width = 0.5 - fract_bw;
float mid_trans_band = 0.5 - trans_width/2.0;
d_taps = gr_firdes::low_pass(d_interp, // gain
1.0, // sampling freq
mid_trans_band/d_interp,
trans_width/d_interp,
gr_firdes::WIN_KAISER,
5.0 // beta
);
/* create band pass filter */
d_rrb = gr_make_rational_resampler_base_fff(d_interp, d_decim, d_taps);
/* connect filter */
connect(self(), 0, d_rrb, 0);
connect(d_rrb, 0, self(), 0);
}
resampler_ffo::~resampler_ffo ()
{
}
/*! \brief Greatest common divisor. */
unsigned long long resampler_ffo::gcd(unsigned long long a, unsigned long long b)
{
unsigned long long c = a % b;
while (c!= 0)
{
a = b;
b = c;
c = a % b;
}
return b;
}
/*! \brief Least common multiple. */
unsigned long long resampler_ffo::lcm(unsigned long long a, unsigned long long b)
{
return ((a*b) / gcd(a,b));
}
|
