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/* -*- c++ -*- */
/*
* Copyright 2006,2011,2012 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio 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.
*
* GNU Radio 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 GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
#define INCLUDED_DIGITAL_COSTAS_LOOP_CC_H
#include <digital/api.h>
#include <gr_sync_block.h>
namespace gr {
namespace digital {
/*!
* \brief A Costas loop carrier recovery module.
* \ingroup sync_blk
* \ingroup digital
*
* The Costas loop locks to the center frequency of a signal and
* downconverts it to baseband. The second (order=2) order loop
* is used for BPSK where the real part of the output signal is
* the baseband BPSK signal and the imaginary part is the error
* signal. When order=4, it can be used for quadrature
* modulations where both I and Q (real and imaginary) are
* outputted.
*
* More details can be found online:
*
* J. Feigin, "Practical Costas loop design: Designing a simple
* and inexpensive BPSK Costas loop carrier recovery circuit," RF
* signal processing, pp. 20-36, 2002.
*
* http://rfdesign.com/images/archive/0102Feigin20.pdf
*
* The Costas loop can have two output streams:
* stream 1 is the baseband I and Q;
* stream 2 is the normalized frequency of the loop
*/
class DIGITAL_API costas_loop_cc : virtual public gr_sync_block
{
public:
// gr::digital::costas_loop_cc::sptr
typedef boost::shared_ptr<costas_loop_cc> sptr;
/*!
* Make a Costas loop carrier recovery block.
*
* \param loop_bw internal 2nd order loop bandwidth (~ 2pi/100)
* \param order the loop order, either 2, 4, or 8
*/
static sptr make(float loop_bw, int order);
};
} /* namespace digital */
} /* namespace gr */
#endif /* INCLUDED_DIGITAL_COSTAS_LOOP_CC_H */
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