changeset 554:d18ff10b5559

Adding code to AGC_coefficients(AGC_params*, float, int)
Function FIR_coeffs as private function in class AGC_coefficients.
FIR_coeffs returns a FloatArray and modify a boolean variable.

--- a/branches/carfac_cpp/src/AGC.cpp	Sun Apr 08 04:15:27 2012 +0000
+++ b/branches/carfac_cpp/src/AGC.cpp	Sun Apr 08 14:28:55 2012 +0000
@@ -1,10 +1,119 @@
 #include "AGC.h"
+#include <cmath>
+#include <stdlib.h>
+#include <stdio.h>  
 
 AGC_coefficients::AGC_coefficients(AGC_parameters* AGC_params,
                                    float fs, int n_ch){
-  // TODO stuff goes here
+  float decim = 1.0;
+  float total_DC_gain = 0.0;
+  float tau, ntimes, delay, spread_sq, u, p, dp;
+  int n_taps = 0, n_iterations = 1;
+  bool FIR_OK = false;
+  
+  n_ch_ = n_ch;
+  n_agc_stages_ = AGC_params->n_stages_;
+  agc_stage_gain_ = AGC_params->agc_stage_gain_;
+  
+  // FloatArray initialization using assign method - dont know if this is good enough
+  agc_epsilon_.assign(n_agc_stages_, 0.0); //the 1/(tau*fs) roughly
+  agc_polez1_ = agc_epsilon_;
+  agc_polez2_ = agc_epsilon_;
+  agc_spatial_iterations_ = agc_epsilon_;
+  agc_spatial_n_taps_ = agc_epsilon_;
+  agc_mix_coeffs_ = agc_epsilon_;
+  FloatArray agc1_scales = AGC_params->agc1_scales_;
+  FloatArray agc2_scales = AGC_params->agc2_scales_;
+  FloatArray agc_spatial_FIR;
+  decimation_ = AGC_params->decimation_;
+  
+  for(int stage=0; stage < n_agc_stages_; stage++){
+    tau = AGC_params->time_constants_[stage];
+    decim *= AGC_params->decimation_[stage];
+    agc_epsilon_[stage] = 1.0 - exp(-decim/(tau*fs));
+    ntimes = tau * (fs/decim);
+    delay = (agc2_scales[stage]-agc1_scales[stage])/ntimes;
+    spread_sq = (agc1_scales[stage]*agc1_scales[stage] + agc2_scales[stage]*agc2_scales[stage])/ntimes;
+    
+    u = 1.0 + 1.0/spread_sq;
+    p = u - sqrt(u*u-1);
+    dp = delay*(1 - 2*p + p*p)*0.5;
+    agc_polez1_[stage] = p - dp;
+    agc_polez2_[stage] = p + dp;
+    
+    while(!FIR_OK){
+      switch(n_taps){
+        case 0:
+          n_taps = 3;
+          break;
+        case 3:
+          n_taps = 5;
+          break;
+        case 5:
+          n_iterations++;
+          if(n_iterations > 16){
+            printf("Too many n_iterations in CARFAC_DesignAGC\n");
+            exit(1);
+          }
+          break;
+        default:
+          printf("Bad n_taps in CARFAC_DesignAGC\n");
+          exit(1);
+      }
+      agc_spatial_FIR = FIR_coeffs(n_taps, spread_sq, delay, n_iterations, &FIR_OK);
+    }
+    agc_spatial_iterations_[stage] = (float) n_iterations;
+    agc_spatial_n_taps_[stage] = (float) n_taps;
+    agc_spatial_fir_.push_back(FloatArray());
+    
+    for(int i =0; i < 3; i++)
+      agc_spatial_fir_[stage].push_back(agc_spatial_FIR[i]);
+      
+    total_DC_gain += pow(AGC_params->agc_stage_gain_,stage);
+    
+    if(stage == 0)
+      agc_mix_coeffs_[stage] = 0.0;
+    else
+      agc_mix_coeffs_[stage] = AGC_params->agc_mix_coeff_/(tau * (fs/decim));
+  }
+  agc_gain_ = total_DC_gain;
+  
+  // TODO Computation of the detect_scale_ member
 }
-
 AGC_coefficients::~AGC_coefficients(){
   // TODO Auto-generated destructor stub
 }
+
+FloatArray  AGC_coefficients::FIR_coeffs(int n_taps, float var, float mn, int n_iter, bool* ptr_FIR_OK)
+{
+  float a, b;
+  FloatArray FIR(3);
+  mn /= n_iter;
+  var /= n_iter;
+  
+  switch(n_taps){
+    case 3:
+      a = (var + mn*mn - mn)/2;
+      b = (var + mn*mn + mn)/2;
+      FIR[0] = a;
+      FIR[1] = 1.0 - a - b;
+      FIR[2] = b;
+      if(FIR[1] >= 0.2)
+        *ptr_FIR_OK = true;
+      break;
+    case 5:
+      a = ((var + mn*mn)*2/5 - mn*2/3)/2;
+      b = ((var + mn*mn)*2/5 + mn*2/3)/2;
+      FIR[0] = a/2;
+      FIR[1] = 1.0 - a - b;
+      FIR[2] = b;
+      if(FIR[1] >= 0.1)
+        *ptr_FIR_OK = true;
+      break;
+    default:
+      printf("Bad n_taps in AGC_spatial_FIR\n");
+      exit(1);
+  }
+  
+  return FIR;
+}

--- a/branches/carfac_cpp/src/AGC.h	Sun Apr 08 04:15:27 2012 +0000
+++ b/branches/carfac_cpp/src/AGC.h	Sun Apr 08 14:28:55 2012 +0000
@@ -36,10 +36,23 @@
   AGC_coefficients(AGC_parameters*, float, int);
   virtual ~AGC_coefficients();
 
+  int n_ch_;
+  int n_agc_stages_;
+  float agc_stage_gain_;
+  FloatArray agc_epsilon_;
+  FloatArray decimation_;
+  FloatArray agc_polez1_;
+  FloatArray agc_polez2_;
+  FloatArray agc_spatial_iterations_;
+  std::vector<FloatArray> agc_spatial_fir_;
+  FloatArray agc_spatial_n_taps_;
+  FloatArray agc_mix_coeffs_;
+  float agc_gain_;
   float detect_scale_;
-  float agc_gain_;
+  
 private:
   AGC_coefficients();
+  FloatArray FIR_coeffs(int, float, float, int, bool*);
 };
 
 #endif /* AGC_H_ */