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/* -*- c++ -*- */
/*
* Copyright 2011 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_CMA_EQUALIZER_CC_H
#define INCLUDED_DIGITAL_CMA_EQUALIZER_CC_H
#include <gr_adaptive_fir_ccc.h>
#include <gr_math.h>
#include <iostream>
class digital_cma_equalizer_cc;
typedef boost::shared_ptr<digital_cma_equalizer_cc> digital_cma_equalizer_cc_sptr;
digital_cma_equalizer_cc_sptr
digital_make_cma_equalizer_cc(int num_taps, float modulus, float mu);
/*!
* \brief Implements constant modulus adaptive filter on complex stream
* \ingroup eq_blk
*
* The error value and tap update equations (for p=2) can be found in:
*
* D. Godard, "Self-Recovering Equalization and Carrier Tracking in
* Two-Dimensional Data Communication Systems," IEEE Transactions on
* Communications, Vol. 28, No. 11, pp. 1867 - 1875, 1980,
*/
class digital_cma_equalizer_cc : public gr_adaptive_fir_ccc
{
private:
float d_modulus;
float d_mu;
friend digital_cma_equalizer_cc_sptr digital_make_cma_equalizer_cc(int num_taps,
float modulus,
float mu);
digital_cma_equalizer_cc(int num_taps, float modulus, float mu);
protected:
virtual gr_complex error(const gr_complex &out)
{
gr_complex error = out*(norm(out) - d_modulus);
float re = gr_clip(error.real(), 1.0);
float im = gr_clip(error.imag(), 1.0);
return gr_complex(re, im);
}
virtual void update_tap(gr_complex &tap, const gr_complex &in)
{
// Hn+1 = Hn - mu*conj(Xn)*zn*(|zn|^2 - 1)
tap -= d_mu*conj(in)*d_error;
}
public:
void set_gain(float mu)
{
if(mu < 0)
throw std::out_of_range("digital_cma_equalizer::set_gain: Gain value must be >= 0");
d_mu = mu;
}
void set_modulus(float mod)
{
if(mod < 0)
throw std::out_of_range("digital_cma_equalizer::set_modulus: Modulus value must be >= 0");
d_modulus = mod;
}
};
#endif
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