Improved Notch Filter Lite

Updated version of the filter

src/algorithms/input_filter/adapters/notch_filter.cc

@@ -53,6 +53,10 @@ NotchFilter::NotchFilter(ConfigurationInterface* configuration, std::string role
     float default_p_c_factor = 0.9;
     int length_;
     int default_length_ = 32;
+    int n_segments_est;
+    int default_n_segments_est = 12500;
+    int n_segments_reset;
+    int default_n_segments_reset = 5000000;
     std::string default_item_type = "gr_complex";
     std::string default_dump_file = "./data/input_filter.dat";
     item_type_ = configuration->property(role + ".item_type", default_item_type);
@@ -62,10 +66,12 @@ NotchFilter::NotchFilter(ConfigurationInterface* configuration, std::string role
     pfa = configuration->property(role + ".pfa", default_pfa);
     p_c_factor = configuration->property(role + ".p_c_factor", default_p_c_factor);
     length_ = configuration->property(role + ".length", default_length_);
+    n_segments_est = configuration->property(role + ".segments_est", default_n_segments_est);
+    n_segments_reset = configuration->property(role + ".segments_reset", default_n_segments_reset);
     if (item_type_.compare("gr_complex") == 0)
         {
             item_size_ = sizeof(gr_complex);
-            notch_filter_ = make_notch_filter(pfa, p_c_factor, length_);
+            notch_filter_ = make_notch_filter(pfa, p_c_factor, length_, n_segments_est, n_segments_reset);
             DLOG(INFO) << "Item size " << item_size_;
             DLOG(INFO) << "input filter(" << notch_filter_->unique_id() << ")";
 

src/algorithms/input_filter/adapters/notch_filter_lite.cc

@@ -31,6 +31,7 @@
 
 #include "notch_filter_lite.h"
 #include <string>
+#include <cmath>
 #include <memory>
 #include <vector>
 #include <boost/lexical_cast.hpp>
@@ -49,6 +50,18 @@ NotchFilterLite::NotchFilterLite(ConfigurationInterface* configuration, std::str
     size_t item_size_;
     float p_c_factor;
     float default_p_c_factor = 0.9;
+    float pfa;
+    float default_pfa = 0.001;
+    int length_;
+    int default_length_ = 32;
+    int n_segments_est;
+    int default_n_segments_est = 12500;
+    int n_segments_reset;
+    int default_n_segments_reset = 5000000;
+    float default_samp_freq = 4000000;
+    float samp_freq = configuration->property("SignalSource.sampling_frequency", default_samp_freq);
+    float default_coeff_rate = samp_freq * 0.1; 
+    float coeff_rate;
     std::string default_item_type = "gr_complex";
     std::string default_dump_file = "./data/input_filter.dat";
     item_type_ = configuration->property(role + ".item_type", default_item_type);
@@ -56,13 +69,19 @@ NotchFilterLite::NotchFilterLite(ConfigurationInterface* configuration, std::str
     DLOG(INFO) << "dump_ is " << dump_;
     dump_filename_ = configuration->property(role + ".dump_filename", default_dump_file);
     p_c_factor = configuration->property(role + ".p_c_factor", default_p_c_factor);
+    pfa = configuration->property(role + ".pfa", default_pfa);
+    coeff_rate = configuration->property(role + ".coeff_rate", default_coeff_rate);
+    length_ = configuration->property(role + ".length", default_length_);
+    n_segments_est = configuration->property(role + ".segments_est", default_n_segments_est);
+    n_segments_reset = configuration->property(role + ".segments_reset", default_n_segments_reset);
+    int n_segments_coeff = (int) ((samp_freq / coeff_rate) / ((float) length_));
+    n_segments_coeff = std::max(1, n_segments_coeff);
     if (item_type_.compare("gr_complex") == 0)
         {
             item_size_ = sizeof(gr_complex);
-            notch_filter_lite_ = make_notch_filter_lite(p_c_factor);
+            notch_filter_lite_ = make_notch_filter_lite(p_c_factor, pfa, length_, n_segments_est, n_segments_reset, n_segments_coeff);
             DLOG(INFO) << "Item size " << item_size_;
             DLOG(INFO) << "input filter(" << notch_filter_lite_->unique_id() << ")";
-
         }
     else
         {

src/algorithms/input_filter/gnuradio_blocks/notch_cc.cc

@@ -43,12 +43,12 @@
 using google::LogMessage;
 
 notch_sptr make_notch_filter(float pfa, float p_c_factor, 
-                             int length_)
+                             int length_, int n_segments_est, int n_segments_reset)
 {
-    return notch_sptr(new Notch(pfa, p_c_factor, length_));
+    return notch_sptr(new Notch(pfa, p_c_factor, length_, n_segments_est, n_segments_reset));
 }
 
-Notch::Notch(float pfa, float p_c_factor, int length_) : gr::block("Notch",
+Notch::Notch(float pfa, float p_c_factor, int length_, int n_segments_est, int n_segments_reset) : gr::block("Notch",
                                                gr::io_signature::make (1, 1, sizeof(gr_complex)),
                                                gr::io_signature::make (1, 1, sizeof(gr_complex)))
 {
@@ -63,8 +63,8 @@ Notch::Notch(float pfa, float p_c_factor, int length_) : gr::block("Notch",
     filter_state_ = false; //Initial state of the filter
     n_deg_fred = 2 * length_; //Number of dregrees of freedom
     n_segments = 0; 
-    n_segments_est = 8; // Set the number of segments for noise power estimation
+    this->n_segments_est = n_segments_est; // Set the number of segments for noise power estimation
-    n_segments_reset = 10000; // Set the period (in segments) when the noise power is estimated
+    this->n_segments_reset = n_segments_reset; // Set the period (in segments) when the noise power is estimated
     z_0 = gr_complex(0 , 0);
     boost::math::chi_squared_distribution<float> my_dist_(n_deg_fred);
     thres_ = boost::math::quantile(boost::math::complement(my_dist_, pfa));

src/algorithms/input_filter/gnuradio_blocks/notch_cc.h

@@ -39,7 +39,7 @@ class Notch;
 typedef boost::shared_ptr<Notch> notch_sptr;
 
 notch_sptr make_notch_filter(float pfa, float p_c_factor, 
-                             int length_);
+                             int length_, int n_segments_est, int n_segments_reset);
 
 /*!
  * \brief This class implements a real-time software-defined multi state notch filter
@@ -67,7 +67,7 @@ private:
     
 public:
         
-    Notch(float pfa, float p_c_factor, int length_);
+    Notch(float pfa, float p_c_factor, int length_, int n_segments_est, int n_segments_reset);
     
     ~Notch();
     

src/algorithms/input_filter/gnuradio_blocks/notch_lite_cc.cc

@@ -37,15 +37,17 @@
 #include <volk/volk.h>
 #include <iostream>
 #include <glog/logging.h>
+#include <boost/math/distributions/chi_squared.hpp>
+#include <armadillo>
 
 using google::LogMessage;
 
-notch_lite_sptr make_notch_filter_lite(float p_c_factor)
+notch_lite_sptr make_notch_filter_lite(float p_c_factor, float pfa, int length_, int n_segments_est, int n_segments_reset, int n_segments_coeff)
 {
-    return notch_lite_sptr(new NotchLite(p_c_factor));
+    return notch_lite_sptr(new NotchLite(p_c_factor, pfa, length_, n_segments_est, n_segments_reset, n_segments_coeff));
 }
 
-NotchLite::NotchLite(float p_c_factor) : gr::block("NotchLite",
+NotchLite::NotchLite(float p_c_factor, float pfa, int length_, int n_segments_est, int n_segments_reset, int n_segments_coeff) : gr::block("NotchLite",
                                                    gr::io_signature::make (1, 1, sizeof(gr_complex)),
                                                    gr::io_signature::make (1, 1, sizeof(gr_complex)))
 {
@@ -53,28 +55,97 @@ NotchLite::NotchLite(float p_c_factor) : gr::block("NotchLite",
     set_alignment(std::max(1, alignment_multiple));
     set_history(2);
     this->p_c_factor = gr_complex(p_c_factor , 0);
+    this->n_segments_est = n_segments_est;
+    this->n_segments_reset = n_segments_reset;
+    this->n_segments_coeff_reset = n_segments_coeff;
+    this->n_segments_coeff = 0;
+    this->length_ = length_;
+    set_output_multiple(length_);
+    this->pfa = pfa;
+    n_segments = 0;
+    n_deg_fred = 2 * length_;
+    noise_pow_est = 0.0;
+    filter_state_ = false;
     z_0 = gr_complex(0 , 0);
-    last_out = gr_complex(0,0);
+    last_out = gr_complex(0, 0);
+    boost::math::chi_squared_distribution<float> my_dist_(n_deg_fred);
+    thres_ = boost::math::quantile(boost::math::complement(my_dist_, pfa));
+    c_samples = gr_complex(0, 0);
+    angle_ = 0.0;
+    power_spect = static_cast<float *>(volk_malloc(length_ * sizeof(float), volk_get_alignment()));
+    
 }
 
+NotchLite::~NotchLite()
+{
+    volk_free(power_spect);
+}
+
+
 int NotchLite::general_work(int noutput_items __attribute__((unused)), gr_vector_int &ninput_items __attribute__((unused)),
         gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
 {
+    int index_out = 0;
+    float sig2dB = 0.0;
+    float sig2lin = 0.0;
+    lv_32fc_t dot_prod_;
     gr_complex* in = (gr_complex *) input_items[0];
     gr_complex* out = (gr_complex *) output_items[0];
-    c_samples = static_cast<gr_complex *>(volk_malloc(noutput_items * sizeof(gr_complex), volk_get_alignment()));
+    in++;
-    angle_ = static_cast<float *>(volk_malloc(noutput_items * sizeof(float), volk_get_alignment()));
+    arma::cx_fvec signal_segment;
-        
+    arma::cx_fvec signal_segment_fft;
-    volk_32fc_x2_multiply_conjugate_32fc(c_samples, (in + 1), in, noutput_items);
+    while((index_out + length_) < noutput_items)
-    volk_32fc_s32f_atan2_32f(angle_, c_samples, ((float)1.0), noutput_items);
-    for (int aux = 0; aux < noutput_items; aux++)
     {
-        z_0 = std::exp(gr_complex(0,1) * (*(angle_ + aux)));
+        if((n_segments < n_segments_est) && (filter_state_ == false))
-        *(out + aux) = *(in + aux + 1) - z_0 * (*(in + aux)) + p_c_factor * z_0 * last_out;
+        {
-        last_out = *(out + aux);
+            signal_segment = arma::cx_fvec(in, length_, false, false);
+            signal_segment_fft = arma::fft(signal_segment);
+            volk_32fc_s32f_power_spectrum_32f(power_spect, signal_segment_fft.memptr(), 1.0, length_);
+            volk_32f_s32f_calc_spectral_noise_floor_32f(&sig2dB, power_spect, 15.0, length_);
+            sig2lin = std::pow(10.0, (sig2dB / 10.0)) / ((float) n_deg_fred);
+            noise_pow_est = (((float) n_segments) * noise_pow_est + sig2lin) / ((float)(n_segments + 1));
+            memcpy(out, in, sizeof(gr_complex) * length_);
+        }
+        else
+        {
+            volk_32fc_x2_conjugate_dot_prod_32fc(&dot_prod_, in, in, length_);
+            if( (lv_creal(dot_prod_) / noise_pow_est) > thres_)
+            {
+                if(filter_state_ == false)
+                {
+                    filter_state_ = true;
+                    last_out = gr_complex(0,0);
+                    n_segments_coeff = 0;
+                }
+                if(n_segments_coeff == 0)
+                {
+                    volk_32fc_x2_multiply_conjugate_32fc(&c_samples, in, (in - 1), 1);
+                    volk_32fc_s32f_atan2_32f(&angle_, &c_samples, ((float)1.0), 1);
+                    z_0 = std::exp(gr_complex(0,1) * angle_);
+                }
+                for(int aux = 0; aux < length_; aux++)
+                {
+                    *(out + aux) = *(in + aux) - z_0 * (*(in + aux - 1)) + p_c_factor * z_0 * last_out;
+                    last_out = *(out + aux);
+                }
+                n_segments_coeff++;
+                n_segments_coeff = n_segments_coeff % n_segments_coeff_reset;
+            }
+            else
+            {
+                if (n_segments > n_segments_reset)
+                {
+                    n_segments = 0;
+                }
+                filter_state_ = false;
+                memcpy(out, in, sizeof(gr_complex) * length_);
+            }
+        }
+        index_out += length_;
+        n_segments++;
+        in += length_;
+        out += length_;
     }
-    volk_free(c_samples);
+    consume_each(index_out);
-    volk_free(angle_);
+    return index_out;
-    consume_each(noutput_items);
-    return noutput_items;
 }

src/algorithms/input_filter/gnuradio_blocks/notch_lite_cc.h

@@ -38,7 +38,7 @@ class NotchLite;
 
 typedef boost::shared_ptr<NotchLite> notch_lite_sptr;
 
-notch_lite_sptr make_notch_filter_lite(float p_c_factor);
+notch_lite_sptr make_notch_filter_lite(float p_c_factor, float pfa, int length_, int n_segments_est, int n_segments_reset, int n_segments_coeff);
 
 /*!
  * \brief This class implements a real-time software-defined single state notch filter
@@ -48,15 +48,29 @@ class NotchLite : public gr::block
 {
 private:
     
+    int length_;
+    int n_segments;
+    int n_segments_est;
+    int n_segments_reset;
+    int n_segments_coeff_reset;
+    int n_segments_coeff;
+    int n_deg_fred;
+    float pfa;
+    float thres_;
+    float noise_pow_est;
+    bool filter_state_;
     gr_complex last_out;
     gr_complex z_0;
     gr_complex p_c_factor;
-    gr_complex* c_samples;
+    gr_complex c_samples;
-    float* angle_;
+    float angle_;
-        
+    float* power_spect;
+    
 public:
         
-    NotchLite(float p_c_factor);
+    NotchLite(float p_c_factor, float pfa, int length_, int n_segments_est, int n_segments_reset, int n_segments_coeff);
+    
+    ~NotchLite();
     
     int general_work (int noutput_items, gr_vector_int &ninput_items, 
                       gr_vector_const_void_star &input_items,