1 files changed, 117 insertions, 0 deletions
diff --git a/gr-channels/lib/flat_fader_impl.cc b/gr-channels/lib/flat_fader_impl.cc
new file mode 100644
index 0000000000..af35e29ef4
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+++ b/gr-channels/lib/flat_fader_impl.cc
@@ -0,0 +1,117 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2013 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(2.0/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();
+        }
+    }
+    
+    
+    gr_complex flat_fader_impl::next_sample(){
+        gr_complex H(0,0);
+
+        for(int n=1; n<d_N; n++){
+            float alpha_n = (2*M_PI*n - M_PI + d_theta)/4*d_N;
+#if FASTSINCOS == 1
+            float s_i = scale_sin*gr::fxpt::cos(gr::fxpt::float_to_fixed(2*M_PI*d_fDTs*d_m*gr::fxpt::cos(gr::fxpt::float_to_fixed(alpha_n))+d_psi[n+1]));
+            float s_q = scale_sin*gr::fxpt::cos(gr::fxpt::float_to_fixed(2*M_PI*d_fDTs*d_m*gr::fxpt::sin(gr::fxpt::float_to_fixed(alpha_n))+d_phi[n+1]));
+#elif FASTSINCOS == 2
+            float s_i = scale_sin*d_table.cos(2*M_PI*d_fDTs*d_m*d_table.cos(alpha_n)+d_psi[n+1]);
+            float s_q = scale_sin*d_table.cos(2*M_PI*d_fDTs*d_m*d_table.sin(alpha_n)+d_phi[n+1]);
+
+#else
+            float s_i = scale_sin*cos(2*M_PI*d_fDTs*d_m*cos(alpha_n)+d_psi[n+1]);
+            float s_q = scale_sin*cos(2*M_PI*d_fDTs*d_m*sin(alpha_n)+d_phi[n+1]);
+#endif
+
+            H += gr_complex(s_i, s_q);
+        }
+
+        if(d_LOS){
+#if FASTSINCOS == 1
+            float los_i = gr::fxpt::cos(gr::fxpt::float_to_fixed(2*M_PI*d_fDTs*d_m*gr::fxpt::cos(gr::fxpt::float_to_fixed(d_theta_los)) + d_psi[0]));
+            float los_q = gr::fxpt::sin(gr::fxpt::float_to_fixed(2*M_PI*d_fDTs*d_m*gr::fxpt::cos(gr::fxpt::float_to_fixed(d_theta_los)) + d_psi[0]));
+#elif FASTSINCOS == 2
+            float los_i = d_table.cos(2*M_PI*d_fDTs*d_m*d_table.cos(d_theta_los) + d_psi[0]);
+            float los_q = d_table.sin(2*M_PI*d_fDTs*d_m*d_table.cos(d_theta_los) + d_psi[0]);
+#else
+            float los_i = cos(2*M_PI*d_fDTs*d_m*cos(d_theta_los) + d_psi[0]);
+            float los_q = sin(2*M_PI*d_fDTs*d_m*cos(d_theta_los) + d_psi[0]);
+#endif
+
+            H = H*scale_nlos + gr_complex(los_i,los_q)*scale_los;
+            }
+
+        //out[i] = in[i]*H;
+        d_m++;
+        update_theta();
+        return H;
+
+    }
+
+    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 */
+