GNU Radio C++ API Reference: costas_loop_cc.h Source File

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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 * SPDX-License-Identifier: GPL-3.0-or-later
8 *
9 */
10
11#ifndef INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
12#define INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
13
14#include <gnuradio/blocks/control_loop.h>
15#include <gnuradio/digital/api.h>
16#include <gnuradio/sync_block.h>
17
18namespace gr {
19namespace digital {
20
21/*!
22 * \brief A Costas loop carrier recovery module.
23 * \ingroup synchronizers_blk
24 *
25 * \details
26 * The Costas loop locks to the center frequency of a signal and
27 * downconverts it to baseband.
28 *
29 * \li When order=2: used for BPSK where the real part of the
30 * output signal is the baseband BPSK signal and the imaginary
31 * part is the error signal.
32 *
33 * \li When order=4: can be used for QPSK where both I and Q (real
34 * and imaginary) are outputted.
35 *
36 * \li When order=8: used for 8PSK.
37 *
38 * More details can be found online:
39 *
40 * J. Feigin, "Practical Costas loop design: Designing a simple
41 * and inexpensive BPSK Costas loop carrier recovery circuit," RF
42 * signal processing, pp. 20-36, 2002.
43 *
44 * http://rfdesign.com/images/archive/0102Feigin20.pdf
45 *
46 * The Costas loop can have two output streams:
47 * \li stream 1 (required) is the baseband I and Q;
48 * \li stream 2 (optional) is the normalized frequency of the loop
49 *
50 * There is a single optional message input:
51 * \li noise: A noise floor estimate used to calculate the SNR of a sample.
52 */
53 class DIGITAL_API costas_loop_cc : virtual public sync_block,
54 virtual public blocks::control_loop
55{
56public:
57 // gr::digital::costas_loop_cc::sptr
58 typedef std::shared_ptr<costas_loop_cc> sptr;
59
60 /*!
61 * Make a Costas loop carrier recovery block.
62 *
63 * \param loop_bw internal 2nd order loop bandwidth (~ 2pi/100)
64 * \param order the loop order, either 2, 4, or 8
65 * \param use_snr Use or ignore SNR estimates (from noise message port)
66 * in measurements; also uses tanh instead of slicing.
67 */
68 static sptr make(float loop_bw, unsigned int order, bool use_snr = false);
69
70 /*!
71 * Returns the current value of the loop error.
72 */
73 virtual float error() const = 0;
74};
75
76} /* namespace digital */
77} /* namespace gr */
78
79#endif /* INCLUDED_DIGITAL_COSTAS_LOOP_CC_H */
gr::blocks::control_loop
A second-order control loop implementation class.
Definition control_loop.h:51
gr::digital::costas_loop_cc
A Costas loop carrier recovery module.
Definition costas_loop_cc.h:55
gr::digital::costas_loop_cc::error
virtual float error() const =0
gr::digital::costas_loop_cc::make
static sptr make(float loop_bw, unsigned int order, bool use_snr=false)
gr::digital::costas_loop_cc::sptr
std::shared_ptr< costas_loop_cc > sptr
Definition costas_loop_cc.h:58
gr::sync_block::sync_block
sync_block(void)
Definition sync_block.h:28
control_loop.h
api.h
DIGITAL_API
#define DIGITAL_API
Definition gr-digital/include/gnuradio/digital/api.h:18
gr::digital
Definition adaptive_algorithm.h:22
gr
GNU Radio logging wrapper.
Definition basic_block.h:29
sync_block.h