GNU Radio Manual and C++ API Reference 3.7.14.0
The Free & Open Software Radio Ecosystem
dc_blocker_cc.h
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1/* -*- c++ -*- */
2/*
3 * Copyright 2011,2012 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
6 *
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 3, or (at your option)
10 * any later version.
11 *
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.
16 *
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., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
21 */
22
23#ifndef INCLUDED_FILTER_DC_BLOCKER_CC_H
24#define INCLUDED_FILTER_DC_BLOCKER_CC_H
25
26#include <gnuradio/filter/api.h>
27#include <gnuradio/sync_block.h>
28
29namespace gr {
30namespace filter {
31
32/*!
33 * \brief a computationally efficient controllable DC blocker
34 * \ingroup filter_blk
35 *
36 * \details
37 * This block implements a computationally efficient DC blocker that produces
38 * a tighter notch filter around DC for a smaller group delay than an
39 * equivalent FIR filter or using a single pole IIR filter (though the IIR
40 * filter is computationally cheaper).
41 *
42 * The block defaults to using a delay line of length 32 and the long form
43 * of the filter. Optionally, the delay line length can be changed to alter
44 * the width of the DC notch (longer lines will decrease the width).
45 *
46 * The long form of the filter produces a nearly flat response outside of
47 * the notch but at the cost of a group delay of 2D-2.
48 *
49 * The short form of the filter does not have as flat a response in the
50 * passband but has a group delay of only D-1 and is cheaper to compute.
51 *
52 * The theory behind this block can be found in the paper:
53 *
54 * <B><EM>R. Yates, "DC Blocker Algorithms," IEEE Signal Processing Magazine,
55 * Mar. 2008, pp 132-134.</EM></B>
56 */
57class FILTER_API dc_blocker_cc : virtual public sync_block
58{
59public:
60 // gr::filter::dc_blocker_cc::sptr
61 typedef boost::shared_ptr<dc_blocker_cc> sptr;
62
63 /*!
64 * Make a DC blocker block.
65 *
66 * \param D (int) the length of the delay line
67 * \param long_form (bool) whether to use long (true, default) or short form
68 */
69 static sptr make(int D, bool long_form);
70
71 virtual int group_delay() = 0;
72};
73
74} /* namespace filter */
75} /* namespace gr */
76
77#endif /* INCLUDED_FILTER_DC_BLOCKER_CC_H */
a computationally efficient controllable DC blocker
Definition: dc_blocker_cc.h:58
virtual int group_delay()=0
static sptr make(int D, bool long_form)
boost::shared_ptr< dc_blocker_cc > sptr
Definition: dc_blocker_cc.h:61
synchronous 1:1 input to output with history
Definition: sync_block.h:38
#define FILTER_API
Definition: gr-filter/include/gnuradio/filter/api.h:30
Include this header to use the message passing features.
Definition: basic_block.h:45