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Added a non CFAR PCPS acquisition algorithm based on the estimation of

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the post correlation noise floor. If enabled
(.Acquisition_1C.use_CFAR_algorithm=true) as an option in the
acquisition configuration, it allows setting more stable thresholds in
the presence of non-gaussian front-end noise (which is the usual
behavior of front-ends....)
This commit is contained in:
Javier Arribas 2016-02-25 18:21:30 +01:00
parent 29a91e66bf
commit 4480c12d94
11 changed files with 117 additions and 54 deletions
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5
conf/gnss-sdr_Hybrid_byte_sim.conf
View File

@ -204,8 +204,11 @@ Acquisition_1C.if=0
Acquisition_1C.sampled_ms=1
;#implementation: Acquisition algorithm selection for this channel: [GPS_L1_CA_PCPS_Acquisition] or [Galileo_E1_PCPS_Ambiguous_Acquisition]
Acquisition_1C.implementation=GPS_L1_CA_PCPS_Acquisition
;#use_CFAR_algorithm: If enabled, acquisition estimates the input signal power to implement CFAR detection algorithms
;#notice that this affects the Acquisition threshold range!
Acquisition_1C.use_CFAR_algorithm=false;
;#threshold: Acquisition threshold
Acquisition_1C.threshold=0.045
Acquisition_1C.threshold=11
;#pfa: Acquisition false alarm probability. This option overrides the threshold option. Only use with implementations: [GPS_L1_CA_PCPS_Acquisition] or [Galileo_E1_PCPS_Ambiguous_Acquisition]
;Acquisition_1C.pfa=0.01
;#doppler_max: Maximum expected Doppler shift [Hz]

3
src/algorithms/acquisition/adapters/galileo_e1_pcps_ambiguous_acquisition.cc
View File

@ -70,6 +70,7 @@ GalileoE1PcpsAmbiguousAcquisition::GalileoE1PcpsAmbiguousAcquisition(
}
bit_transition_flag_ = configuration_->property(role + ".bit_transition_flag", false);
use_CFAR_algorithm_flag_=configuration_->property(role + ".use_CFAR_algorithm", true); //will be false in future versions
if (!bit_transition_flag_)
{
@ -107,7 +108,7 @@ GalileoE1PcpsAmbiguousAcquisition::GalileoE1PcpsAmbiguousAcquisition(
item_size_ = sizeof(gr_complex);
acquisition_cc_ = pcps_make_acquisition_cc(sampled_ms_, max_dwells_,
shift_resolution_, if_, fs_in_, samples_per_ms, code_length_,
bit_transition_flag_, queue_, dump_, dump_filename_);
bit_transition_flag_, use_CFAR_algorithm_flag_, queue_, dump_, dump_filename_);
stream_to_vector_ = gr::blocks::stream_to_vector::make(item_size_, vector_length_);
DLOG(INFO) << "stream_to_vector(" << stream_to_vector_->unique_id() << ")";
DLOG(INFO) << "acquisition(" << acquisition_cc_->unique_id() << ")";

1
src/algorithms/acquisition/adapters/galileo_e1_pcps_ambiguous_acquisition.h
View File

@ -143,6 +143,7 @@ private:
unsigned int vector_length_;
unsigned int code_length_;
bool bit_transition_flag_;
bool use_CFAR_algorithm_flag_;
unsigned int channel_;
float threshold_;
unsigned int doppler_max_;

5
src/algorithms/acquisition/adapters/gps_l1_ca_pcps_acquisition.cc
View File

@ -65,6 +65,7 @@ GpsL1CaPcpsAcquisition::GpsL1CaPcpsAcquisition(
sampled_ms_ = configuration_->property(role + ".coherent_integration_time_ms", 1);
bit_transition_flag_ = configuration_->property(role + ".bit_transition_flag", false);
use_CFAR_algorithm_flag_=configuration_->property(role + ".use_CFAR_algorithm", true); //will be false in future versions
if (!bit_transition_flag_)
{
@ -89,14 +90,14 @@ GpsL1CaPcpsAcquisition::GpsL1CaPcpsAcquisition(
item_size_ = sizeof(lv_16sc_t);
acquisition_sc_ = pcps_make_acquisition_sc(sampled_ms_, max_dwells_,
shift_resolution_, if_, fs_in_, code_length_, code_length_,
bit_transition_flag_, queue_, dump_, dump_filename_);
bit_transition_flag_, use_CFAR_algorithm_flag_, queue_, dump_, dump_filename_);
DLOG(INFO) << "acquisition(" << acquisition_cc_->unique_id() << ")";
}else{
item_size_ = sizeof(gr_complex);
acquisition_cc_ = pcps_make_acquisition_cc(sampled_ms_, max_dwells_,
shift_resolution_, if_, fs_in_, code_length_, code_length_,
bit_transition_flag_, queue_, dump_, dump_filename_);
bit_transition_flag_, use_CFAR_algorithm_flag_, queue_, dump_, dump_filename_);
DLOG(INFO) << "acquisition(" << acquisition_cc_->unique_id() << ")";
}

1
src/algorithms/acquisition/adapters/gps_l1_ca_pcps_acquisition.h
View File

@ -157,6 +157,7 @@ private:
unsigned int vector_length_;
unsigned int code_length_;
bool bit_transition_flag_;
bool use_CFAR_algorithm_flag_;
unsigned int channel_;
float threshold_;
unsigned int doppler_max_;

3
src/algorithms/acquisition/adapters/gps_l2_m_pcps_acquisition.cc
View File

@ -62,6 +62,7 @@ GpsL2MPcpsAcquisition::GpsL2MPcpsAcquisition(
shift_resolution_ = configuration_->property(role + ".doppler_max", 15);
bit_transition_flag_ = configuration_->property(role + ".bit_transition_flag", false);
use_CFAR_algorithm_flag_=configuration_->property(role + ".use_CFAR_algorithm", true); //will be false in future versions
if (!bit_transition_flag_)
{
@ -87,7 +88,7 @@ GpsL2MPcpsAcquisition::GpsL2MPcpsAcquisition(
item_size_ = sizeof(gr_complex);
acquisition_cc_ = pcps_make_acquisition_cc(1, max_dwells_,
shift_resolution_, if_, fs_in_, code_length_, code_length_,
bit_transition_flag_, queue_, dump_, dump_filename_);
bit_transition_flag_, use_CFAR_algorithm_flag_, queue_, dump_, dump_filename_);
stream_to_vector_ = gr::blocks::stream_to_vector::make(item_size_, vector_length_);

1
src/algorithms/acquisition/adapters/gps_l2_m_pcps_acquisition.h
View File

@ -152,6 +152,7 @@ private:
unsigned int vector_length_;
unsigned int code_length_;
bool bit_transition_flag_;
bool use_CFAR_algorithm_flag_;
unsigned int channel_;
float threshold_;
unsigned int doppler_max_;

44
src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_cc.cc
View File

@ -40,6 +40,8 @@
#include <volk/volk.h>
#include "gnss_signal_processing.h"
#include "control_message_factory.h"
#include <gnuradio/fxpt.h> // fixed point sine and cosine
#include "GPS_L1_CA.h" //GPS_TWO_PI
using google::LogMessage;
@ -48,21 +50,21 @@ pcps_acquisition_cc_sptr pcps_make_acquisition_cc(
unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename)
{
return pcps_acquisition_cc_sptr(
new pcps_acquisition_cc(sampled_ms, max_dwells, doppler_max, freq, fs_in, samples_per_ms,
samples_per_code, bit_transition_flag, queue, dump, dump_filename));
samples_per_code, bit_transition_flag, use_CFAR_algorithm_flag, queue, dump, dump_filename));
}
pcps_acquisition_cc::pcps_acquisition_cc(
unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename) :
gr::block("pcps_acquisition_cc",
@ -86,6 +88,7 @@ pcps_acquisition_cc::pcps_acquisition_cc(
d_input_power = 0.0;
d_num_doppler_bins = 0;
d_bit_transition_flag = bit_transition_flag;
d_use_CFAR_algorithm_flag=use_CFAR_algorithm_flag;
d_threshold = 0.0;
d_doppler_step = 250;
d_code_phase = 0;
@ -169,6 +172,22 @@ void pcps_acquisition_cc::set_local_code(std::complex<float> * code)
volk_32fc_conjugate_32fc(d_fft_codes, d_fft_if->get_outbuf(), d_fft_size);
}
void pcps_acquisition_cc::update_local_carrier(gr_complex* carrier_vector, int correlator_length_samples, float freq)
{
float sin_f, cos_f;
float phase_step_rad= GPS_TWO_PI * freq/ static_cast<float>(d_fs_in);
int phase_step_rad_i = gr::fxpt::float_to_fixed(phase_step_rad);
int phase_rad_i = 0;
for(int i = 0; i < correlator_length_samples; i++)
{
gr::fxpt::sincos(phase_rad_i, &sin_f, &cos_f);
carrier_vector[i] = gr_complex(cos_f, -sin_f);
phase_rad_i += phase_step_rad_i;
}
}
void pcps_acquisition_cc::init()
{
d_gnss_synchro->Acq_delay_samples = 0.0;
@ -186,7 +205,7 @@ void pcps_acquisition_cc::init()
{
d_grid_doppler_wipeoffs[doppler_index] = static_cast<gr_complex*>(volk_malloc(d_fft_size * sizeof(gr_complex), volk_get_alignment()));
int doppler = -static_cast<int>(d_doppler_max) + d_doppler_step * doppler_index;
complex_exp_gen(d_grid_doppler_wipeoffs[doppler_index], -d_freq - doppler, d_fs_in, d_fft_size);
update_local_carrier(d_grid_doppler_wipeoffs[doppler_index], d_fft_size, d_freq + doppler);
}
}
@ -281,10 +300,13 @@ int pcps_acquisition_cc::general_work(int noutput_items,
<< d_threshold << ", doppler_max: " << d_doppler_max
<< ", doppler_step: " << d_doppler_step;
// 1- Compute the input signal power estimation
if (d_use_CFAR_algorithm_flag==true)
{
// 1- (optional) Compute the input signal power estimation
volk_32fc_magnitude_squared_32f(d_magnitude, in, d_fft_size);
volk_32f_accumulator_s32f(&d_input_power, d_magnitude, d_fft_size);
d_input_power /= static_cast<float>(d_fft_size);
}
// 2- Doppler frequency search loop
for (unsigned int doppler_index=0; doppler_index < d_num_doppler_bins; doppler_index++)
{
@ -312,14 +334,23 @@ int pcps_acquisition_cc::general_work(int noutput_items,
volk_32fc_magnitude_squared_32f(d_magnitude, d_ifft->get_outbuf() + offset, effective_fft_size);
volk_32f_index_max_16u(&indext, d_magnitude, effective_fft_size);
if (d_use_CFAR_algorithm_flag==true)
{
// Normalize the maximum value to correct the scale factor introduced by FFTW
magt = d_magnitude[indext] / (fft_normalization_factor * fft_normalization_factor);
}
// 4- record the maximum peak and the associated synchronization parameters
if (d_mag < magt)
{
d_mag = magt;
if (d_use_CFAR_algorithm_flag==false)
{
// Search grid noise floor approximation for this doppler line
volk_32f_accumulator_s32f(&d_input_power, d_magnitude, effective_fft_size);
d_input_power=(d_input_power-d_mag)/(effective_fft_size-1);
}
// In case that d_bit_transition_flag = true, we compare the potentially
// new maximum test statistics (d_mag/d_input_power) with the value in
// d_test_statistics. When the second dwell is being processed, the value
@ -327,6 +358,7 @@ int pcps_acquisition_cc::general_work(int noutput_items,
// the maximum test statistics in the previous dwell is greater than
// current d_mag/d_input_power). Note that d_test_statistics is not
// restarted between consecutive dwells in multidwell operation.
if (d_test_statistics < (d_mag / d_input_power) || !d_bit_transition_flag)
{
d_gnss_synchro->Acq_delay_samples = static_cast<double>(indext % d_samples_per_code);

10
src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_cc.h
View File

@ -67,7 +67,7 @@ pcps_acquisition_cc_sptr
pcps_make_acquisition_cc(unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename);
@ -84,19 +84,18 @@ private:
pcps_make_acquisition_cc(unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename);
pcps_acquisition_cc(unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename);
void calculate_magnitudes(gr_complex* fft_begin, int doppler_shift,
int doppler_offset);
void update_local_carrier(gr_complex* carrier_vector, int correlator_length_samples, float freq);
long d_fs_in;
long d_freq;
@ -125,6 +124,7 @@ private:
float d_input_power;
float d_test_statistics;
bool d_bit_transition_flag;
bool d_use_CFAR_algorithm_flag;
gr::msg_queue::sptr d_queue;
concurrent_queue<int> *d_channel_internal_queue;
std::ofstream d_dump_file;

65
src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_sc.cc
View File

@ -41,6 +41,8 @@
#include "gnss_signal_processing.h"
#include "control_message_factory.h"
#include <volk_gnsssdr/volk_gnsssdr.h>
#include <gnuradio/fxpt.h> // fixed point sine and cosine
#include "GPS_L1_CA.h" //GPS_TWO_PI
using google::LogMessage;
@ -48,21 +50,21 @@ pcps_acquisition_sc_sptr pcps_make_acquisition_sc(
unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename)
{
return pcps_acquisition_sc_sptr(
new pcps_acquisition_sc(sampled_ms, max_dwells, doppler_max, freq, fs_in, samples_per_ms,
samples_per_code, bit_transition_flag, queue, dump, dump_filename));
samples_per_code, bit_transition_flag, use_CFAR_algorithm_flag, queue, dump, dump_filename));
}
pcps_acquisition_sc::pcps_acquisition_sc(
unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename) :
gr::block("pcps_acquisition_sc",
@ -86,6 +88,7 @@ pcps_acquisition_sc::pcps_acquisition_sc(
d_input_power = 0.0;
d_num_doppler_bins = 0;
d_bit_transition_flag = bit_transition_flag;
d_use_CFAR_algorithm_flag=use_CFAR_algorithm_flag;
d_threshold = 0.0;
d_doppler_step = 250;
d_code_phase = 0;
@ -172,6 +175,22 @@ void pcps_acquisition_sc::set_local_code(std::complex<float> * code)
volk_32fc_conjugate_32fc(d_fft_codes, d_fft_if->get_outbuf(), d_fft_size);
}
void pcps_acquisition_sc::update_local_carrier(gr_complex* carrier_vector, int correlator_length_samples, float freq)
{
float sin_f, cos_f;
float phase_step_rad= GPS_TWO_PI * freq/ static_cast<float>(d_fs_in);
int phase_step_rad_i = gr::fxpt::float_to_fixed(phase_step_rad);
int phase_rad_i = 0;
for(int i = 0; i < correlator_length_samples; i++)
{
gr::fxpt::sincos(phase_rad_i, &sin_f, &cos_f);
carrier_vector[i] = gr_complex(cos_f, -sin_f);
phase_rad_i += phase_step_rad_i;
}
}
void pcps_acquisition_sc::init()
{
d_gnss_synchro->Acq_delay_samples = 0.0;
@ -189,7 +208,7 @@ void pcps_acquisition_sc::init()
{
d_grid_doppler_wipeoffs[doppler_index] = static_cast<gr_complex*>(volk_malloc(d_fft_size * sizeof(gr_complex), volk_get_alignment()));
int doppler = -static_cast<int>(d_doppler_max) + d_doppler_step * doppler_index;
complex_exp_gen(d_grid_doppler_wipeoffs[doppler_index], -d_freq - doppler, d_fs_in, d_fft_size);
update_local_carrier(d_grid_doppler_wipeoffs[doppler_index], d_fft_size, d_freq + doppler);
}
}
@ -273,11 +292,9 @@ int pcps_acquisition_sc::general_work(int noutput_items,
float fft_normalization_factor = static_cast<float>(d_fft_size) * static_cast<float>(d_fft_size);
d_input_power = 0.0;
d_mag = 0.0;
d_sample_counter += d_fft_size; // sample counter
d_well_count++;
DLOG(INFO) << "Channel: " << d_channel
@ -286,10 +303,13 @@ int pcps_acquisition_sc::general_work(int noutput_items,
<< d_threshold << ", doppler_max: " << d_doppler_max
<< ", doppler_step: " << d_doppler_step;
// 1- Compute the input signal power estimation
if (d_use_CFAR_algorithm_flag==true)
{
// 1- (optional) Compute the input signal power estimation
volk_32fc_magnitude_squared_32f(d_magnitude, d_in_32fc, d_fft_size);
volk_32f_accumulator_s32f(&d_input_power, d_magnitude, d_fft_size);
d_input_power /= static_cast<float>(d_fft_size);
}
// 2- Doppler frequency search loop
for (unsigned int doppler_index=0; doppler_index < d_num_doppler_bins; doppler_index++)
{
@ -316,15 +336,27 @@ int pcps_acquisition_sc::general_work(int noutput_items,
size_t offset = ( d_bit_transition_flag ? effective_fft_size : 0 );
volk_32fc_magnitude_squared_32f(d_magnitude, d_ifft->get_outbuf() + offset, effective_fft_size);
volk_32f_index_max_16u(&indext, d_magnitude, effective_fft_size);
magt = d_magnitude[indext];
if (d_use_CFAR_algorithm_flag==true)
{
// Normalize the maximum value to correct the scale factor introduced by FFTW
magt = d_magnitude[indext] / (fft_normalization_factor * fft_normalization_factor);
}
// 4- record the maximum peak and the associated synchronization parameters
if (d_mag < magt)
{
d_mag = magt;
if (d_use_CFAR_algorithm_flag==false)
{
// Search grid noise floor approximation for this doppler line
volk_32f_accumulator_s32f(&d_input_power, d_magnitude, effective_fft_size);
d_input_power=(d_input_power-d_mag)/(effective_fft_size-1);
}
// In case that d_bit_transition_flag = true, we compare the potentially
// new maximum test statistics (d_mag/d_input_power) with the value in
// d_test_statistics. When the second dwell is being processed, the value
@ -332,6 +364,7 @@ int pcps_acquisition_sc::general_work(int noutput_items,
// the maximum test statistics in the previous dwell is greater than
// current d_mag/d_input_power). Note that d_test_statistics is not
// restarted between consecutive dwells in multidwell operation.
if (d_test_statistics < (d_mag / d_input_power) || !d_bit_transition_flag)
{
d_gnss_synchro->Acq_delay_samples = static_cast<double>(indext % d_samples_per_code);
@ -339,8 +372,9 @@ int pcps_acquisition_sc::general_work(int noutput_items,
d_gnss_synchro->Acq_samplestamp_samples = d_sample_counter;
// 5- Compute the test statistics and compare to the threshold
//d_test_statistics = 2 * d_fft_size * d_mag / d_input_power;
d_test_statistics = d_mag / d_input_power;
//std::cout<<"d_input_power="<<d_input_power<<" d_test_statistics="<<d_test_statistics<<" d_gnss_synchro->Acq_doppler_hz ="<<d_gnss_synchro->Acq_doppler_hz <<std::endl;
}
}
@ -455,18 +489,3 @@ int pcps_acquisition_sc::general_work(int noutput_items,
output_items.clear(); // removes a warning
return noutput_items;
}
//void pcps_acquisition_sc::forecast (int noutput_items, gr_vector_int &ninput_items_required)
//{
//// COD:
//// For zero-padded case we need one extra code period
//if( d_bit_transition_flag )
//{
//ninput_items_required[0] = noutput_items*(d_samples_per_code * d_max_dwells + d_samples_per_code);
//}
//else
//{
//ninput_items_required[0] = noutput_items*d_fft_size*d_max_dwells;
//}
//}

13
src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_sc.h
View File

@ -67,7 +67,7 @@ pcps_acquisition_sc_sptr
pcps_make_acquisition_sc(unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename);
@ -84,19 +84,21 @@ private:
pcps_make_acquisition_sc(unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename);
pcps_acquisition_sc(unsigned int sampled_ms, unsigned int max_dwells,
unsigned int doppler_max, long freq, long fs_in,
int samples_per_ms, int samples_per_code,
bool bit_transition_flag,
bool bit_transition_flag, bool use_CFAR_algorithm_flag,
gr::msg_queue::sptr queue, bool dump,
std::string dump_filename);
void calculate_magnitudes(gr_complex* fft_begin, int doppler_shift,
int doppler_offset);
void update_local_carrier(gr_complex* carrier_vector,
int correlator_length_samples,
float freq);
long d_fs_in;
long d_freq;
@ -126,6 +128,7 @@ private:
float d_input_power;
float d_test_statistics;
bool d_bit_transition_flag;
bool d_use_CFAR_algorithm_flag;
gr::msg_queue::sptr d_queue;
concurrent_queue<int> *d_channel_internal_queue;
std::ofstream d_dump_file;