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FEATURE FE02: Adding the function that calculates the threshold from false alarm probability. 

git-svn-id: https://svn.code.sf.net/p/gnss-sdr/code/trunk@357 64b25241-fba3-4117-9849-534c7e92360d
This commit is contained in:
Luis Esteve 2013-05-16 16:25:51 +00:00
parent 63c7f22e57
commit b9ac964654
7 changed files with 96 additions and 24 deletions
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14
conf/gnss-sdr.conf
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@ -247,42 +247,36 @@ Channel0.signal=1C
;#satellite: Satellite PRN ID for this channel. Disable this option to random search
Channel0.satellite=15
Channel0.repeat_satellite=false
;######### CHANNEL 1 CONFIG ############
Channel1.system=GPS
Channel1.signal=1C
Channel1.satellite=18
Channel1.repeat_satellite=false
;######### CHANNEL 2 CONFIG ############
Channel2.system=GPS
Channel2.signal=1C
Channel2.satellite=16
Channel2.repeat_satellite=false
;######### CHANNEL 3 CONFIG ############
Channel3.system=GPS
Channel3.signal=1C
Channel3.satellite=21
Channel3.repeat_satellite=false
;######### CHANNEL 4 CONFIG ############
Channel4.system=GPS
Channel4.signal=1C
Channel4.satellite=3
Channel4.repeat_satellite=false
;######### CHANNEL 5 CONFIG ############
Channel5.system=GPS
Channel5.signal=1C
;Channel5.satellite=21
;Channel5.repeat_satellite=false
;######### ACQUISITION GLOBAL CONFIG ############
@ -301,16 +295,18 @@ Acquisition.sampled_ms=1
;######### ACQUISITION CHANNELS CONFIG ######
;######### ACQUISITION CH 0 CONFIG ############
;#implementation: Acquisition algorithm selection for this channel: [GPS_L1_CA_PCPS_Acquisition]
;#implementation: Acquisition algorithm selection for this channel: [GPS_L1_CA_PCPS_Acquisition] or [Galileo_E1_PCPS_Ambiguous_Acquisition]
Acquisition0.implementation=GPS_L1_CA_PCPS_Acquisition
;#threshold: Acquisition threshold
Acquisition0.threshold=50
;#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]
Acquisition0.pfa=0.001
;#doppler_max: Maximum expected Doppler shift [Hz]
Acquisition0.doppler_max=10000
;#doppler_max: Doppler step in the grid search [Hz]
Acquisition0.doppler_step=250
;#repeat_satellite: Use only jointly with the satellte PRN ID option.
;#repeat_satellite: Use only jointly with the satellite PRN ID option.
Acquisition0.repeat_satellite = false
;######### ACQUISITION CH 1 CONFIG ############
Acquisition1.implementation=GPS_L1_CA_PCPS_Acquisition

39
src/algorithms/acquisition/adapters/galileo_e1_pcps_ambiguous_acquisition.cc
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@ -39,6 +39,8 @@
#include <gnuradio/gr_io_signature.h>
#include <glog/log_severity.h>
#include <glog/logging.h>
#include <boost/math/distributions/exponential.hpp>
using google::LogMessage;
@ -55,7 +57,7 @@ GalileoE1PcpsAmbiguousAcquisition::GalileoE1PcpsAmbiguousAcquisition(
DLOG(INFO) << "role " << role;
item_type_ = configuration->property(role + ".item_type",
item_type_ = configuration_->property(role + ".item_type",
default_item_type);
fs_in_ = configuration_->property("GNSS-SDR.internal_fs_hz", 4000000);
@ -118,8 +120,17 @@ GalileoE1PcpsAmbiguousAcquisition::set_channel(unsigned int channel)
void
GalileoE1PcpsAmbiguousAcquisition::set_threshold(float threshold)
{
threshold_ = threshold;
if (item_type_.compare("gr_complex") == 0)
float pfa = configuration_->property(role_+ boost::lexical_cast<std::string>(channel_) + ".pfa", 0.0);
if(pfa==0.0)
{
threshold_ = threshold;
}
else
{
threshold_ = calculate_threshold(pfa);
}
if (item_type_.compare("gr_complex") == 0)
{
acquisition_cc_->set_threshold(threshold_);
}
@ -214,6 +225,28 @@ GalileoE1PcpsAmbiguousAcquisition::reset()
}
}
float GalileoE1PcpsAmbiguousAcquisition::calculate_threshold(float pfa)
{
//Calculate the threshold
unsigned int frequency_bins = 0;
for (int doppler = (int)(-doppler_max_); doppler <= (int)doppler_max_; doppler += doppler_step_)
{
frequency_bins++;
}
DLOG(INFO) <<"Pfa = "<< pfa;
unsigned int ncells = vector_length_*frequency_bins;
double exponent = 1/(double)ncells;
double val = pow(1.0-pfa,exponent);
boost::math::exponential_distribution<double> mydist (0.5);
float threshold = (float)quantile(mydist,val);
DLOG(INFO) << "Threshold = " << threshold;
return threshold;
}
void

2
src/algorithms/acquisition/adapters/galileo_e1_pcps_ambiguous_acquisition.h
View File

@ -148,6 +148,8 @@ private:
unsigned int out_streams_;
gr_msg_queue_sptr queue_;
concurrent_queue<int> *channel_internal_queue_;
float calculate_threshold(float pfa);
};
#endif /* GNSS_SDR_GALILEO_E1_PCPS_AMBIGUOUS_ACQUISITION_H_ */

54
src/algorithms/acquisition/adapters/gps_l1_ca_pcps_acquisition.cc
View File

@ -40,6 +40,7 @@
#include <gnuradio/gr_io_signature.h>
#include <glog/log_severity.h>
#include <glog/logging.h>
#include <boost/math/distributions/exponential.hpp>
using google::LogMessage;
@ -47,26 +48,30 @@ GpsL1CaPcpsAcquisition::GpsL1CaPcpsAcquisition(
ConfigurationInterface* configuration, std::string role,
unsigned int in_streams, unsigned int out_streams,
gr_msg_queue_sptr queue) :
role_(role), in_streams_(in_streams), out_streams_(out_streams), queue_(
role_(role), in_streams_(in_streams), out_streams_(out_streams), queue_(
queue)
{
configuration_=configuration;
std::string default_item_type = "gr_complex";
std::string default_dump_filename = "./data/acquisition.dat";
DLOG(INFO) << "role " << role;
item_type_ = configuration->property(role + ".item_type",
// std::cout << "role " << role_ << std::endl;
item_type_ = configuration_->property(role + ".item_type",
default_item_type);
fs_in_ = configuration->property("GNSS-SDR.internal_fs_hz", 2048000);
if_ = configuration->property(role + ".ifreq", 0);
dump_ = configuration->property(role + ".dump", false);
shift_resolution_ = configuration->property(role + ".doppler_max", 15);
sampled_ms_ = configuration->property(role + ".sampled_ms", 1);
dump_filename_ = configuration->property(role + ".dump_filename",
fs_in_ = configuration_->property("GNSS-SDR.internal_fs_hz", 2048000);
if_ = configuration_->property(role + ".ifreq", 0);
dump_ = configuration_->property(role + ".dump", false);
shift_resolution_ = configuration_->property(role + ".doppler_max", 15);
sampled_ms_ = configuration_->property(role + ".sampled_ms", 1);
dump_filename_ = configuration_->property(role + ".dump_filename",
default_dump_filename);
//--- Find number of samples per spreading code -------------------------
vector_length_ = round(fs_in_
/ (GPS_L1_CA_CODE_RATE_HZ / GPS_L1_CA_CODE_LENGTH_CHIPS));
@ -113,7 +118,16 @@ void GpsL1CaPcpsAcquisition::set_channel(unsigned int channel)
void GpsL1CaPcpsAcquisition::set_threshold(float threshold)
{
threshold_ = threshold;
float pfa = configuration_->property(role_+ boost::lexical_cast<std::string>(channel_) + ".pfa", 0.0);
if(pfa==0.0)
{
threshold_ = threshold;
}
else
{
threshold_ = calculate_threshold(pfa);
}
if (item_type_.compare("gr_complex") == 0)
{
acquisition_cc_->set_threshold(threshold_);
@ -194,6 +208,28 @@ void GpsL1CaPcpsAcquisition::reset()
}
}
float GpsL1CaPcpsAcquisition::calculate_threshold(float pfa)
{
//Calculate the threshold
unsigned int frequency_bins = 0;
for (int doppler = (int)(-doppler_max_); doppler <= (int)doppler_max_; doppler += doppler_step_)
{
frequency_bins++;
}
DLOG(INFO) <<"Pfa = "<< pfa;
unsigned int ncells = vector_length_*frequency_bins;
double exponent = 1/(double)ncells;
double val = pow(1.0-pfa,exponent);
boost::math::exponential_distribution<double> mydist (0.5);
float threshold = (float)quantile(mydist,val);
DLOG(INFO) << "Threshold = " << threshold;
return threshold;
}
void GpsL1CaPcpsAcquisition::connect(gr_top_block_sptr top_block)
{

3
src/algorithms/acquisition/adapters/gps_l1_ca_pcps_acquisition.h
View File

@ -127,6 +127,7 @@ public:
void reset();
private:
ConfigurationInterface* configuration_;
pcps_acquisition_cc_sptr acquisition_cc_;
gr::blocks::stream_to_vector::sptr stream_to_vector_;
size_t item_size_;
@ -150,6 +151,8 @@ private:
unsigned int out_streams_;
gr_msg_queue_sptr queue_;
concurrent_queue<int> *channel_internal_queue_;
float calculate_threshold(float pfa);
};
#endif /* GNSS_SDR_GPS_L1_CA_PCPS_ACQUISITION_H_ */

2
src/algorithms/acquisition/gnuradio_blocks/pcps_acquisition_cc.cc
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@ -188,7 +188,7 @@ int pcps_acquisition_cc::general_work(int noutput_items,
d_input_power = d_input_power / (float)d_fft_size;
// 2- Doppler frequency search loop
for (doppler = (int)(-d_doppler_max); doppler < (int)d_doppler_max; doppler += d_doppler_step)
for (doppler = (int)(-d_doppler_max); doppler <= (int)d_doppler_max; doppler += d_doppler_step)
{
// doppler search steps
// Perform the carrier wipe-off

6
src/algorithms/channel/adapters/channel.cc
View File

@ -64,14 +64,16 @@ Channel::Channel(ConfigurationInterface *configuration, unsigned int channel,
acq_->set_gnss_synchro(&gnss_synchro_);
trk_->set_gnss_synchro(&gnss_synchro_);
acq_->set_threshold(configuration->property("Acquisition"
+ boost::lexical_cast<std::string>(channel_) + ".threshold", 0.0));
// IMPORTANT: Do not change the order of the following 3 methods
acq_->set_doppler_max(configuration->property("Acquisition"
+ boost::lexical_cast<std::string>(channel_) + ".doppler_max",
10000));
acq_->set_doppler_step(configuration->property("Acquisition"
+ boost::lexical_cast<std::string>(channel_) + ".doppler_step",
250));
acq_->set_threshold(configuration->property("Acquisition"
+ boost::lexical_cast<std::string>(channel_) + ".threshold", 0.0));
repeat_ = configuration->property("Acquisition" + boost::lexical_cast<
std::string>(channel_) + ".repeat_satellite", false);