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/* -*- c++ -*- */
/*
* Copyright 2016 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.
*/
#include <flat_fader_impl.h>
namespace gr {
namespace channels {
flat_fader_impl::flat_fader_impl(unsigned int N, float fDTs, bool LOS, float K, int seed ) :
seed_1((int)seed),
dist_1(-M_PI, M_PI),
rv_1( seed_1, dist_1 ), // U(-pi,pi)
seed_2((int)seed+1),
dist_2(0, 1),
rv_2( seed_2, dist_2 ), // U(0,1)
d_N(N),
d_fDTs(fDTs),
d_theta(rv_1()),
d_theta_los(rv_1()),
d_step( powf(0.00125*fDTs, 1.1) ), // max step size approximated from Table 2
d_m(0),
d_K(K),
d_LOS(LOS),
d_psi(d_N+1, 0),
d_phi(d_N+1, 0),
d_table(8*1024),
scale_sin(sqrtf(1.0/d_N)),
scale_los(sqrtf(d_K)/sqrtf(d_K+1)),
scale_nlos(1/sqrtf(d_K+1))
{
// generate initial phase values
for(int i=0; i<d_N+1; i++){
d_psi[i] = rv_1();
d_phi[i] = rv_1();
}
}
#if FASTSINCOS == 1
#define _GRFASTSIN(x) gr::fxpt::sin(gr::fxpt::float_to_fixed(x))
#define _GRFASTCOS(x) gr::fxpt::cos(gr::fxpt::float_to_fixed(x))
#elif FASTSINCOS == 2
#define _GRFASTSIN(x) d_table.sin(x)
#define _GRFASTCOS(x) d_table.cos(x)
#else
#define _GRFASTSIN(x) sin(x)
#define _GRFASTCOS(x) cos(x)
#endif
void flat_fader_impl::next_samples(std::vector<gr_complex> &Hvec, int n_samples){
Hvec.resize(n_samples);
for(int i = 0; i < n_samples; i++){
gr_complex H(0,0);
for(int n=1; n<d_N+1; n++){
float alpha_n = (2*M_PI*n - M_PI + d_theta)/(4*d_N);
d_psi[n] = fmod(d_psi[n] + 2*M_PI*d_fDTs*_GRFASTCOS(alpha_n), 2*M_PI);
d_phi[n] = fmod(d_phi[n] + 2*M_PI*d_fDTs*_GRFASTCOS(alpha_n), 2*M_PI);
float s_i = scale_sin*_GRFASTCOS(d_psi[n]);
float s_q = scale_sin*_GRFASTSIN(d_phi[n]);
H += gr_complex(s_i, s_q);
}
if(d_LOS){
d_psi[0] = fmod(d_psi[0] + 2*M_PI*d_fDTs*_GRFASTCOS(d_theta_los), 2*M_PI);
float los_i = scale_los*_GRFASTCOS(d_psi[0]);
float los_q = scale_los*_GRFASTSIN(d_psi[0]);
H = H*scale_nlos + gr_complex(los_i,los_q);
}
update_theta();
Hvec[i] = H;
}
}
gr_complex flat_fader_impl::next_sample(){
std::vector<gr_complex> v(1);
next_samples(v,1);
return v[0];
}
void flat_fader_impl::update_theta()
{
d_theta += (d_step*rv_2());
if(d_theta > M_PI){
d_theta = M_PI; d_step = -d_step;
} else if(d_theta < -M_PI){
d_theta = -M_PI; d_step = -d_step;
}
}
} /* namespace channels */
} /* namespace gr */
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