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https://github.com/gnss-sdr/gnss-sdr
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Changed the "CN_estimators" library name by the more informative "lock_detectors". The CN0 estimators for GPS L1 C/A and Galileo E1 have been unified
git-svn-id: https://svn.code.sf.net/p/gnss-sdr/code/trunk@254 64b25241-fba3-4117-9849-534c7e92360d
This commit is contained in:
Carles Fernandez
@@ -1,7 +1,7 @@
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project : build-dir ../../../../build ;
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obj tracking_discriminators : tracking_discriminators.cc ;
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obj CN_estimators : CN_estimators.cc ;
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obj lock_detectors : lock_detectors.cc ;
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obj tracking_FLL_PLL_filter : tracking_FLL_PLL_filter.cc ;
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obj tracking_2nd_PLL_filter : tracking_2nd_PLL_filter.cc ;
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obj tracking_2nd_DLL_filter : tracking_2nd_DLL_filter.cc ;
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@@ -1,7 +1,6 @@
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/*!
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* \file CN_estimators.cc
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* \brief Implementation of a library with a set of Carrier to Noise
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* estimators and lock detectors.
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* \file lock_detectors.cc
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* \brief Implementation of a library with a set of code and carrier phase lock detectors.
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*
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* SNV_CN0 is a Carrier-to-Noise (CN0) estimator
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* based on the Signal-to-Noise Variance (SNV) estimator [1].
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@@ -46,7 +45,8 @@
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*
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* -------------------------------------------------------------------------
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*/
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#include "CN_estimators.h"
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#include "lock_detectors.h"
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#include "GPS_L1_CA.h"
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#include "Galileo_E1.h"
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#include <gnuradio/gr_complex.h>
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@@ -68,73 +68,28 @@
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* where \f$f_s\f$ is the sampling frequency and \f$L_{PRN}\f$ is the PRN sequence length.
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*
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*/
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float gps_l1_ca_CN0_SNV(gr_complex* Prompt_buffer, int length, long fs_in)
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float cn0_svn_estimator(gr_complex* Prompt_buffer, int length, long fs_in, double code_length)
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{
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// estimate CN0 using buffered values
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// MATLAB CODE
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// SNR_SNV(count)=Psig/(Ptot-Psig);
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// CN0_SNV_dB=10*log10(SNR_SNV)+10*log10(BW)-10*log10(PRN_length);
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float SNR, SNR_dB_Hz;
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float tmp_abs_real;
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float Psig, Ptot;
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Psig = 0;
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Ptot = 0;
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float SNR = 0;
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float SNR_dB_Hz = 0;
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float Psig = 0;
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float Ptot = 0;
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for (int i=0; i<length; i++)
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{
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tmp_abs_real = std::abs(Prompt_buffer[i].real());
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Psig += tmp_abs_real;
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Psig += std::abs(Prompt_buffer[i].real());
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Ptot += Prompt_buffer[i].imag() * Prompt_buffer[i].imag() + Prompt_buffer[i].real() * Prompt_buffer[i].real();
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}
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Psig = Psig / (float)length;
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Psig = Psig * Psig;
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SNR = Psig / (Ptot / (float)length - Psig);
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SNR_dB_Hz = 10 * log10(SNR) + 10 * log10(fs_in/2) - 10 * log10(GPS_L1_CA_CODE_LENGTH_CHIPS);
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return SNR_dB_Hz;
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}
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/*
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* Signal-to-Noise (SNR) (\f$\rho\f$) estimator using the Signal-to-Noise Variance (SNV) estimator:
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* \f{equation}
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* \hat{\rho}=\frac{\hat{P}_s}{\hat{P}_n}=\frac{\hat{P}_s}{\hat{P}_{tot}-\hat{P}_s},
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* \f}
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* where \f$\hat{P}_s=\left(\frac{1}{N}\sum^{N-1}_{i=0}|Re(Pc(i))|\right)^2\f$ is the estimation of the signal power,
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* \f$\hat{P}_{tot}=\frac{1}{N}\sum^{N-1}_{i=0}|Pc(i)|^2\f$ is the estimator of the total power, \f$|\cdot|\f$ is the absolute value,
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* \f$Re(\cdot)\f$ stands for the real part of the value, and \f$Pc(i)\f$ is the prompt correlator output for the sample index i.
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*
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* The SNR value is converted to CN0 [dB-Hz], taking to account the receiver bandwidth and the PRN code gain, using the following formula:
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* \f{equation}
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* CN0_{dB}=10*log(\hat{\rho})+10*log(\frac{f_s}{2})-10*log(L_{PRN}),
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* \f}
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* where \f$f_s\f$ is the sampling frequency and \f$L_{PRN}\f$ is the PRN sequence length.
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*
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*/
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float galileo_e1_CN0_SNV(gr_complex* Prompt_buffer, int length, long fs_in)
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{
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// estimate CN0 using buffered values
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// MATLAB CODE
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// SNR_SNV(count)=Psig/(Ptot-Psig);
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// CN0_SNV_dB=10*log10(SNR_SNV)+10*log10(BW)-10*log10(PRN_length);
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float SNR, SNR_dB_Hz;
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float tmp_abs_real;
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float Psig, Ptot;
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Psig = 0;
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Ptot = 0;
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for (int i=0; i<length; i++)
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{
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tmp_abs_real= std::abs(Prompt_buffer[i].real());
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Psig += tmp_abs_real;
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Ptot += Prompt_buffer[i].imag() * Prompt_buffer[i].imag() + Prompt_buffer[i].real() * Prompt_buffer[i].real();
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}
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Psig = Psig / (float)length;
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Psig = Psig * Psig;
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SNR = Psig / (Ptot / (float)length - Psig);
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SNR_dB_Hz = 10 * log10(SNR) + 10 * log10(fs_in/2) - 10 * log10(Galileo_E1_B_CODE_LENGTH_CHIPS);
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Ptot = Ptot / (float)length;
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SNR = Psig / (Ptot - Psig);
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SNR_dB_Hz = 10 * log10(SNR) + 10 * log10(fs_in/2) - 10 * log10((float)code_length);
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return SNR_dB_Hz;
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}
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/*
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* The Carrier Phase Lock Detector block uses the normalised estimate of the cosine of twice the carrier phase error is given by
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* The estimate of the cosine of twice the carrier phase error is given by
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* \f{equation}
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* \cos(2\phi)=\frac{NBD}{NBP},
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* \f}
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@@ -144,15 +99,10 @@ float galileo_e1_CN0_SNV(gr_complex* Prompt_buffer, int length, long fs_in)
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*/
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float carrier_lock_detector(gr_complex* Prompt_buffer, int length)
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{
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/*
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* carrier lock detector
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*/
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// estimate using buffered values
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float tmp_sum_I, tmp_sum_Q;
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tmp_sum_I = 0;
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tmp_sum_Q = 0;
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float NBD,NBP;
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float tmp_sum_I = 0;
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float tmp_sum_Q = 0;
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float NBD = 0;
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float NBP = 0;
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for (int i=0; i<length; i++)
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{
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tmp_sum_I += Prompt_buffer[i].real();
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@@ -162,4 +112,3 @@ float carrier_lock_detector(gr_complex* Prompt_buffer, int length)
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NBD = tmp_sum_I*tmp_sum_I - tmp_sum_Q*tmp_sum_Q;
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return NBD/NBP;
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}
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@@ -1,7 +1,6 @@
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/*!
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* \file CN_estimators.h
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* \brief Interface of a library with a set of Carrier to Noise
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* estimators and lock detectors.
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* \file lock_detectors.h
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* \brief Interface of a library with a set of code and carrier phase lock detectors.
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*
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* SNV_CN0 is a Carrier-to-Noise (CN0) estimator
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* based on the Signal-to-Noise Variance (SNV) estimator [1].
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@@ -23,7 +22,7 @@
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* </ul>
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* -------------------------------------------------------------------------
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*
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* Copyright (C) 2010-2011 (see AUTHORS file for a list of contributors)
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* Copyright (C) 2010-2012 (see AUTHORS file for a list of contributors)
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*
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* GNSS-SDR is a software defined Global Navigation
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* Satellite Systems receiver
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@@ -46,33 +45,12 @@
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* -------------------------------------------------------------------------
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*/
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#ifndef GNSS_SDR_CN_ESTIMATORS_H_
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#define GNSS_SDR_CN_ESTIMATORS_H_
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#ifndef GNSS_SDR_LOCK_DETECTORS_H_
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#define GNSS_SDR_LOCK_DETECTORS_H_
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#include <gnuradio/gr_complex.h>
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/*! \brief CN0_SNV is a Carrier-to-Noise (CN0) estimator
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* based on the Signal-to-Noise Variance (SNV) estimator
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*
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* Signal-to-Noise (SNR) (\f$\rho\f$) estimator using the Signal-to-Noise Variance (SNV) estimator:
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* \f{equation}
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* \hat{\rho}=\frac{\hat{P}_s}{\hat{P}_n}=\frac{\hat{P}_s}{\hat{P}_{tot}-\hat{P}_s},
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* \f}
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* where \f$\hat{P}_s=\left(\frac{1}{N}\sum^{N-1}_{i=0}|Re(Pc(i))|\right)^2\f$ is the estimation of the signal power,
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* \f$\hat{P}_{tot}=\frac{1}{N}\sum^{N-1}_{i=0}|Pc(i)|^2\f$ is the estimator of the total power, \f$|\cdot|\f$ is the absolute value,
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* \f$Re(\cdot)\f$ stands for the real part of the value, and \f$Pc(i)\f$ is the prompt correlator output for the sample index i.
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*
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* The SNR value is converted to CN0 [dB-Hz], taking to account the receiver bandwidth and the PRN code gain, using the following formula:
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* \f{equation}
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* CN0_{dB}=10*log(\hat{\rho})+10*log(\frac{f_s}{2})-10*log(L_{PRN}),
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* \f}
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* where \f$f_s\f$ is the sampling frequency and \f$L_{PRN}\f$ is the PRN sequence length.
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* Ref: Marco Pini, Emanuela Falletti and Maurizio Fantino, "Performance
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* Evaluation of C/N0 Estimators using a Real Time GNSS Software Receiver,"
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* IEEE 10th International Symposium on Spread Spectrum Techniques and
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* Applications, pp.28-30, August 2008.
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*/
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float gps_l1_ca_CN0_SNV(gr_complex* Prompt_buffer, int length, long fs_in);
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/*! \brief CN0_SNV is a Carrier-to-Noise (CN0) estimator
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* based on the Signal-to-Noise Variance (SNV) estimator
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*
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@@ -94,11 +72,13 @@ float gps_l1_ca_CN0_SNV(gr_complex* Prompt_buffer, int length, long fs_in);
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* IEEE 10th International Symposium on Spread Spectrum Techniques and
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* Applications, pp.28-30, August 2008.
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*/
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float galileo_e1_CN0_SNV(gr_complex* Prompt_buffer, int length, long fs_in);
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float cn0_svn_estimator(gr_complex* Prompt_buffer, int length, long fs_in, double code_length);
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/*! \brief A carrier lock detector
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*
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* The Carrier Phase Lock Detector block uses the normalised estimate of the cosine of twice the carrier phase error is given by
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* The Carrier Phase Lock Detector block uses the estimate of the cosine of twice the carrier phase error is given by
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* \f{equation}
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* C2\phi=\frac{NBD}{NBP},
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* \f}
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