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/* -*- c++ -*- */
/*
* Copyright 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_KURTOTIC_EQUALIZER_CC_IMPL_H
#define INCLUDED_DIGITAL_KURTOTIC_EQUALIZER_CC_IMPL_H
#include <gnuradio/digital/kurtotic_equalizer_cc.h>
#include <gnuradio/filter/fir_filter.h>
#include <gnuradio/math.h>
#include <stdexcept>
namespace gr {
namespace digital {
class kurtotic_equalizer_cc_impl
: public kurtotic_equalizer_cc, filter::kernel::fir_filter_ccc
{
private:
std::vector<gr_complex> d_new_taps;
bool d_updated;
gr_complex d_error;
float d_mu;
float d_p, d_m;
gr_complex d_q, d_u;
float d_alpha_p, d_alpha_q, d_alpha_m;
gr_complex sign(gr_complex x)
{
float re = (float)(x.real() >= 0.0f);
float im = (float)(x.imag() >= 0.0f);
return gr_complex(re, im);
}
protected:
virtual gr_complex error(const gr_complex &out)
{
// p = E[|z|^2]
// q = E[z^2]
// m = E[|z|^4]
// u = E[kurtosis(z)]
float nrm = norm(out);
gr_complex cnj = conj(out);
float epsilon_f = 1e-12;
gr_complex epsilon_c = gr_complex(1e-12, 1e-12);
d_p = (1-d_alpha_p)*d_p + (d_alpha_p)*nrm + epsilon_f;
d_q = (1-d_alpha_q)*d_q + (d_alpha_q)*out*out + epsilon_c;
d_m = (1-d_alpha_m)*d_m + (d_alpha_m)*nrm*nrm + epsilon_f;
d_u = d_m - 2.0f*(d_p*d_p) - d_q*d_q;
gr_complex F = (1.0f / (d_p*d_p*d_p)) *
(sign(d_u) * (nrm*cnj - 2.0f*d_p*cnj - conj(d_q)*out) -
abs(d_u)*cnj);
float re = gr::clip(F.real(), 1.0);
float im = gr::clip(F.imag(), 1.0);
return gr_complex(re, im);
}
virtual void update_tap(gr_complex &tap, const gr_complex &in)
{
tap += d_mu*in*d_error;
}
public:
kurtotic_equalizer_cc_impl(int num_taps, float mu);
~kurtotic_equalizer_cc_impl();
float gain() const { return d_mu; }
void set_gain(float mu)
{
if(mu < 0)
throw std::out_of_range("kurtotic_equalizer_cc_impl::set_gain: Gain value must be >= 0");
d_mu = mu;
}
int work(int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
};
} /* namespace digital */
} /* namespace gr */
#endif /* INCLUDED_DIGITAL_KURTOTIC_EQUALIZER_CC_IMPL_H */
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