GNU Radio Manual and C++ API Reference 3.8.5.0
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costas_loop_cc.h
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1/* -*- c++ -*- */
2/*
3 * Copyright 2006,2011,2012,2014 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_DIGITAL_COSTAS_LOOP_CC_H
24#define INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
25
28#include <gnuradio/sync_block.h>
29
30namespace gr {
31namespace digital {
32
33/*!
34 * \brief A Costas loop carrier recovery module.
35 * \ingroup synchronizers_blk
36 *
37 * \details
38 * The Costas loop locks to the center frequency of a signal and
39 * downconverts it to baseband.
40 *
41 * \li When order=2: used for BPSK where the real part of the
42 * output signal is the baseband BPSK signal and the imaginary
43 * part is the error signal.
44 *
45 * \li When order=4: can be used for QPSK where both I and Q (real
46 * and imaginary) are outputted.
47 *
48 * \li When order=8: used for 8PSK.
49 *
50 * More details can be found online:
51 *
52 * J. Feigin, "Practical Costas loop design: Designing a simple
53 * and inexpensive BPSK Costas loop carrier recovery circuit," RF
54 * signal processing, pp. 20-36, 2002.
55 *
56 * http://rfdesign.com/images/archive/0102Feigin20.pdf
57 *
58 * The Costas loop can have two output streams:
59 * \li stream 1 (required) is the baseband I and Q;
60 * \li stream 2 (optional) is the normalized frequency of the loop
61 *
62 * There is a single optional message input:
63 * \li noise: A noise floor estimate used to calculate the SNR of a sample.
64 */
65class DIGITAL_API costas_loop_cc : virtual public sync_block,
66 virtual public blocks::control_loop
67{
68public:
69 // gr::digital::costas_loop_cc::sptr
70 typedef boost::shared_ptr<costas_loop_cc> sptr;
71
72 /*!
73 * Make a Costas loop carrier recovery block.
74 *
75 * \param loop_bw internal 2nd order loop bandwidth (~ 2pi/100)
76 * \param order the loop order, either 2, 4, or 8
77 * \param use_snr Use or ignore SNR estimates (from noise message port)
78 * in measurements; also uses tanh instead of slicing.
79 */
80 static sptr make(float loop_bw, int order, bool use_snr = false);
81
82 /*!
83 * Returns the current value of the loop error.
84 */
85 virtual float error() const = 0;
86};
87
88} /* namespace digital */
89} /* namespace gr */
90
91#endif /* INCLUDED_DIGITAL_COSTAS_LOOP_CC_H */
A second-order control loop implementation class.
Definition control_loop.h:62
A Costas loop carrier recovery module.
Definition costas_loop_cc.h:67
boost::shared_ptr< costas_loop_cc > sptr
Definition costas_loop_cc.h:70
static sptr make(float loop_bw, int order, bool use_snr=false)
virtual float error() const =0
synchronous 1:1 input to output with history
Definition sync_block.h:38
#define DIGITAL_API
Definition gr-digital/include/gnuradio/digital/api.h:30
GNU Radio logging wrapper for log4cpp library (C++ port of log4j)
Definition basic_block.h:46