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New noise floor power estimation in notch filter

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In this version, the noise floor power is estimated via a VOLK Kernel
This commit is contained in:
Antonio Ramos
2017-07-10 09:48:38 +02:00
parent 119c8c1966
commit 0b8e3c9399
2 changed files with 24 additions and 14 deletions
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31
src/algorithms/input_filter/gnuradio_blocks/notch_cc.cc
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@@ -38,6 +38,7 @@
#include <volk/volk.h>
#include <iostream>
#include <glog/logging.h>
#include <armadillo>
using google::LogMessage;
@@ -63,12 +64,13 @@ Notch::Notch(float pfa, float p_c_factor, int length_) : gr::block("Notch",
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
n_segments_reset = 1000000; // Set the period (in segments) when the noise power is estimated
n_segments_reset = 10000; // 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));
c_samples = static_cast<gr_complex *>(volk_malloc(length_ * sizeof(gr_complex), volk_get_alignment()));
angle_ = static_cast<float *>(volk_malloc(length_ * sizeof(float), volk_get_alignment()));
power_spect = static_cast<float *>(volk_malloc(length_ * sizeof(float), volk_get_alignment()));
last_out = gr_complex(0,0);
}
@@ -76,6 +78,7 @@ Notch::~Notch()
{
volk_free(c_samples);
volk_free(angle_);
volk_free(power_spect);
}
int Notch::general_work(int noutput_items __attribute__((unused)), gr_vector_int &ninput_items __attribute__((unused)),
@@ -85,29 +88,35 @@ int Notch::general_work(int noutput_items __attribute__((unused)), gr_vector_int
int index_in = 1;
int index_out = 0;
int aux = 0;
lv_32fc_t magnitude;
float sig2 = 0.0;
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];
gr_complex* paux;
in++;
arma::cx_fvec signal_segment;
arma::cx_fvec signal_segment_fft;
while(((index_out + length_) < noutput_items) && (n_segments < n_segments_est) && (filter_state_ == false))
{
volk_32fc_x2_conjugate_dot_prod_32fc(&magnitude, in, in, length_);
sig2 = lv_creal(magnitude) / ((float) n_deg_fred);
noise_pow_est = (((float) n_segments) * noise_pow_est + sig2) / ((float)(n_segments + 1));
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_);
index_out += length_;
index_in += length_;
n_segments++;
memcpy(out, in, sizeof(gr_complex) * length_);
in += length_;
out += length_;
}
while((index_out + length_) < noutput_items)
{
n_segments++;
volk_32fc_x2_conjugate_dot_prod_32fc(&magnitude, in, in, length_);
if( (lv_creal(magnitude) / noise_pow_est) > thres_)
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)
{
@@ -120,7 +129,7 @@ int Notch::general_work(int noutput_items __attribute__((unused)), gr_vector_int
for(aux = 0; aux < length_; aux++)
{
z_0 = std::exp(gr_complex(0,1) * (*(angle_ + aux)));
*out = *in - z_0 * (*(in - 1))
*out = (*in) - z_0 * (*(in - 1))
+ p_c_factor * z_0 * last_out;
last_out = *out;
index_out++;
@@ -137,9 +146,9 @@ int Notch::general_work(int noutput_items __attribute__((unused)), gr_vector_int
n_segments = 0;
}
filter_state_ = false;
memcpy(out, in, sizeof(gr_complex) * length_);
index_out += length_;
index_in += length_;
memcpy(out, in, sizeof(gr_complex) * length_);
in += length_;
out += length_;
}

7
src/algorithms/input_filter/gnuradio_blocks/notch_cc.h
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@@ -51,18 +51,19 @@ private:
float pfa;
float noise_pow_est;
gr_complex p_c_factor;
float thres_;
int length_;
int n_deg_fred;
unsigned int n_segments;
unsigned int n_segments_est;
unsigned int n_segments_reset;
int n_deg_fred;
bool filter_state_;
gr_complex last_out;
gr_complex z_0;
gr_complex p_c_factor;
gr_complex* c_samples;
float* angle_;
float* angle_;
float* power_spect;
public: