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lock_detectors.h
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lock_detectors.h
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/*!
* \file lock_detectors.h
* \brief Interface of a library with a set of code and carrier phase lock detectors.
*
* SNV_CN0 is a Carrier-to-Noise (CN0) estimator
* based on the Signal-to-Noise Variance (SNV) estimator [1].
* Carrier lock detector using normalised estimate of the cosine
* of twice the carrier phase error [2].
*
* [1] Marco Pini, Emanuela Falletti and Maurizio Fantino, "Performance
* Evaluation of C/N0 Estimators using a Real Time GNSS Software Receiver,"
* IEEE 10th International Symposium on Spread Spectrum Techniques and
* Applications, pp.28-30, August 2008.
*
* [2] Van Dierendonck, A.J. (1996), Global Positioning System: Theory and
* Applications,
* Volume I, Chapter 8: GPS Receivers, AJ Systems, Los Altos, CA 94024.
* Inc.: 329-407.
* \authors <ul>
* <li> Javier Arribas, 2011. jarribas(at)cttc.es
* <li> Luis Esteve, 2012. luis(at)epsilon-formacion.com
* </ul>
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2015 (see AUTHORS file for a list of contributors)
*
* GNSS-SDR is a software defined Global Navigation
* Satellite Systems receiver
*
* This file is part of GNSS-SDR.
*
* GNSS-SDR is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GNSS-SDR is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNSS-SDR. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#ifndef GNSS_SDR_LOCK_DETECTORS_H_
#define GNSS_SDR_LOCK_DETECTORS_H_
#include <gnuradio/gr_complex.h>
/*! \brief CN0_SNV is a Carrier-to-Noise (CN0) estimator
* based on the Signal-to-Noise Variance (SNV) estimator
*
* Signal-to-Noise (SNR) (\f$\rho\f$) estimator using the Signal-to-Noise Variance (SNV) estimator:
* \f{equation}
* \hat{\rho}=\frac{\hat{P}_s}{\hat{P}_n}=\frac{\hat{P}_s}{\hat{P}_{tot}-\hat{P}_s},
* \f}
* 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,
* \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,
* \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.
*
* The SNR value is converted to CN0 [dB-Hz], taking to account the receiver bandwidth and the PRN code gain, using the following formula:
* \f{equation}
* CN0_{dB}=10*log(\hat{\rho})+10*log(\frac{f_s}{2})-10*log(L_{PRN}),
* \f}
* where \f$f_s\f$ is the sampling frequency and \f$L_{PRN}\f$ is the PRN sequence length.
* Ref: Marco Pini, Emanuela Falletti and Maurizio Fantino, "Performance
* Evaluation of C/N0 Estimators using a Real Time GNSS Software Receiver,"
* IEEE 10th International Symposium on Spread Spectrum Techniques and
* Applications, pp.28-30, August 2008.
*/
float cn0_svn_estimator(gr_complex* Prompt_buffer, int length, long fs_in, double code_length);
/*! \brief A carrier lock detector
*
* The Carrier Phase Lock Detector block uses the estimate of the cosine of twice the carrier phase error is given by
* \f{equation}
* C2\phi=\frac{NBD}{NBP},
* \f}
* where \f$NBD=(\sum^{N-1}_{i=0}|Im(Pc(i))|)^2+(\sum^{N-1}_{i=0}|Re(Pc(i))|)^2\f$,
* \f$NBP=\sum^{N-1}_{i=0}Im(Pc(i))^2-\sum^{N-1}_{i=0}Re(Pc(i))^2\f$, and
* \f$Pc(i)\f$ is the prompt correlator output for the sample index i.
* Ref: Van Dierendonck, A.J. (1996), Global Positioning System: Theory and
* Applications,
* Volume I, Chapter 8: GPS Receivers, AJ Systems, Los Altos, CA 94024.
* Inc.: 329-407.
*/
float carrier_lock_detector(gr_complex* Prompt_buffer, int length);
#endif