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/* -*- c++ -*- */
/*
* Copyright 2006,2010,2012 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "feedforward_agc_cc_impl.h"
#include <gr_io_signature.h>
#include <stdexcept>
namespace gr {
namespace analog {
feedforward_agc_cc::sptr
feedforward_agc_cc::make(int nsamples, float reference)
{
return gnuradio::get_initial_sptr
(new feedforward_agc_cc_impl(nsamples, reference));
}
feedforward_agc_cc_impl::feedforward_agc_cc_impl(int nsamples, float reference)
: gr_sync_block("feedforward_agc_cc",
gr_make_io_signature(1, 1, sizeof(gr_complex)),
gr_make_io_signature(1, 1, sizeof(gr_complex))),
d_nsamples(nsamples), d_reference(reference)
{
if(nsamples < 1)
throw std::invalid_argument("feedforward_agc_cc_impl: nsamples must be >= 1");
set_history(nsamples);
}
feedforward_agc_cc_impl::~feedforward_agc_cc_impl()
{
}
inline static float
mag_squared(gr_complex x)
{
return x.real() * x.real() + x.imag() * x.imag();
}
// approximate sqrt(x^2 + y^2)
inline static float
envelope(gr_complex x)
{
float r_abs = std::fabs(x.real());
float i_abs = std::fabs(x.imag());
if(r_abs > i_abs)
return r_abs + 0.4 * i_abs;
else
return i_abs + 0.4 * r_abs;
}
int
feedforward_agc_cc_impl::work(int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const gr_complex *in = (const gr_complex*)input_items[0];
gr_complex *out = (gr_complex*)output_items[0];
int nsamples = d_nsamples;
float gain;
for(int i = 0; i < noutput_items; i++) {
//float max_env = 1e-12; // avoid divide by zero
float max_env = 1e-4; // avoid divide by zero, indirectly set max gain
for(int j = 0; j < nsamples; j++) {
max_env = std::max(max_env, envelope(in[i+j]));
}
gain = d_reference / max_env;
out[i] = gain * in[i];
}
return noutput_items;
}
} /* namespace analog */
} /* namespace gr */
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