From 87e106ceacb32c8344a87d351ac976c22a1e3fa5 Mon Sep 17 00:00:00 2001 From: Carles Fernandez Date: Mon, 16 Sep 2019 21:03:04 +0200 Subject: [PATCH] Improve CN0 estimator --- .../gnuradio_blocks/dll_pll_veml_tracking.cc | 2 +- .../dll_pll_veml_tracking_fpga.cc | 2 +- .../galileo_e1_tcp_connector_tracking_cc.cc | 2 +- ...glonass_l1_ca_dll_pll_c_aid_tracking_cc.cc | 2 +- ...glonass_l1_ca_dll_pll_c_aid_tracking_sc.cc | 2 +- .../glonass_l1_ca_dll_pll_tracking_cc.cc | 2 +- ...glonass_l2_ca_dll_pll_c_aid_tracking_cc.cc | 2 +- ...glonass_l2_ca_dll_pll_c_aid_tracking_sc.cc | 2 +- .../glonass_l2_ca_dll_pll_tracking_cc.cc | 2 +- .../gps_l1_ca_dll_pll_tracking_gpu_cc.cc | 2 +- .../gps_l1_ca_kf_tracking_cc.cc | 2 +- .../gps_l1_ca_tcp_connector_tracking_cc.cc | 2 +- .../tracking/libs/lock_detectors.cc | 47 +++++++++++++++++++ src/algorithms/tracking/libs/lock_detectors.h | 25 +++++++++- 14 files changed, 83 insertions(+), 13 deletions(-) diff --git a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.cc b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.cc index c31751f1e..462728e58 100644 --- a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.cc +++ b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.cc @@ -849,7 +849,7 @@ bool dll_pll_veml_tracking::cn0_and_tracking_lock_status(double coh_integration_ d_Prompt_buffer[d_cn0_estimation_counter % trk_parameters.cn0_samples] = d_P_accu; d_cn0_estimation_counter++; // Code lock indicator - float d_CN0_SNV_dB_Hz_raw = cn0_svn_estimator(d_Prompt_buffer.data(), trk_parameters.cn0_samples, static_cast(coh_integration_time_s)); + float d_CN0_SNV_dB_Hz_raw = cn0_mm_estimator(d_Prompt_buffer.data(), trk_parameters.cn0_samples, static_cast(coh_integration_time_s)); d_CN0_SNV_dB_Hz = d_cn0_smoother.smooth(d_CN0_SNV_dB_Hz_raw); // Carrier lock indicator d_carrier_lock_test = d_carrier_lock_test_smoother.smooth(carrier_lock_detector(d_Prompt_buffer.data(), 1)); diff --git a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc index 0caffd514..24f72dd3a 100644 --- a/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc +++ b/src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc @@ -607,7 +607,7 @@ bool dll_pll_veml_tracking_fpga::cn0_and_tracking_lock_status(double coh_integra d_Prompt_buffer[d_cn0_estimation_counter % trk_parameters.cn0_samples] = d_P_accu; d_cn0_estimation_counter++; // Code lock indicator - float d_CN0_SNV_dB_Hz_raw = cn0_svn_estimator(d_Prompt_buffer.data(), trk_parameters.cn0_samples, static_cast(coh_integration_time_s)); + float d_CN0_SNV_dB_Hz_raw = cn0_mm_estimator(d_Prompt_buffer.data(), trk_parameters.cn0_samples, static_cast(coh_integration_time_s)); d_CN0_SNV_dB_Hz = d_cn0_smoother.smooth(d_CN0_SNV_dB_Hz_raw); // Carrier lock indicator d_carrier_lock_test = d_carrier_lock_test_smoother.smooth(carrier_lock_detector(d_Prompt_buffer.data(), 1)); diff --git a/src/algorithms/tracking/gnuradio_blocks/galileo_e1_tcp_connector_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/galileo_e1_tcp_connector_tracking_cc.cc index 4fc9b15d2..32eced1b6 100644 --- a/src/algorithms/tracking/gnuradio_blocks/galileo_e1_tcp_connector_tracking_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/galileo_e1_tcp_connector_tracking_cc.cc @@ -414,7 +414,7 @@ int Galileo_E1_Tcp_Connector_Tracking_cc::general_work(int noutput_items __attri d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GALILEO_E1_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GALILEO_E1_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), FLAGS_cn0_samples); diff --git a/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_cc.cc index f9bf06568..697502b15 100644 --- a/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_cc.cc @@ -762,7 +762,7 @@ int glonass_l1_ca_dll_pll_c_aid_tracking_cc::general_work(int noutput_items __at { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L1_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L1_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_sc.cc b/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_sc.cc index 6c3dc8cc6..1d0773764 100644 --- a/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_sc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_sc.cc @@ -753,7 +753,7 @@ int glonass_l1_ca_dll_pll_c_aid_tracking_sc::general_work(int noutput_items __at { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L1_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L1_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_tracking_cc.cc index f7f6a6012..8057b0a56 100644 --- a/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_tracking_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_tracking_cc.cc @@ -621,7 +621,7 @@ int Glonass_L1_Ca_Dll_Pll_Tracking_cc::general_work(int noutput_items __attribut { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L1_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L1_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_cc.cc index d5eaf07a1..8fa87bed3 100644 --- a/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_cc.cc @@ -760,7 +760,7 @@ int glonass_l2_ca_dll_pll_c_aid_tracking_cc::general_work(int noutput_items __at { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L2_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L2_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_sc.cc b/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_sc.cc index 7f357d5f6..4909aabcc 100644 --- a/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_sc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_sc.cc @@ -751,7 +751,7 @@ int glonass_l2_ca_dll_pll_c_aid_tracking_sc::general_work(int noutput_items __at { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L2_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L2_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_tracking_cc.cc index 732b51b5b..14fcfe63f 100644 --- a/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_tracking_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_tracking_cc.cc @@ -621,7 +621,7 @@ int Glonass_L2_Ca_Dll_Pll_Tracking_cc::general_work(int noutput_items __attribut { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L2_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES, GLONASS_L2_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), CN0_ESTIMATION_SAMPLES); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_tracking_gpu_cc.cc b/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_tracking_gpu_cc.cc index b2d18d8db..612b93364 100644 --- a/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_tracking_gpu_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_tracking_gpu_cc.cc @@ -436,7 +436,7 @@ int Gps_L1_Ca_Dll_Pll_Tracking_GPU_cc::general_work(int noutput_items __attribut { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GPS_L1_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GPS_L1_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), FLAGS_cn0_samples); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_kf_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_kf_tracking_cc.cc index d8e75cb64..93a481499 100644 --- a/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_kf_tracking_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_kf_tracking_cc.cc @@ -794,7 +794,7 @@ int Gps_L1_Ca_Kf_Tracking_cc::general_work(int noutput_items __attribute__((unus { d_cn0_estimation_counter = 0; // Code lock indicator - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GPS_L1_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GPS_L1_CA_CODE_PERIOD_S); // Carrier lock indicator d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), FLAGS_cn0_samples); // Loss of lock detection diff --git a/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_tcp_connector_tracking_cc.cc b/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_tcp_connector_tracking_cc.cc index 03076a35b..885c721aa 100644 --- a/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_tcp_connector_tracking_cc.cc +++ b/src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_tcp_connector_tracking_cc.cc @@ -450,7 +450,7 @@ int Gps_L1_Ca_Tcp_Connector_Tracking_cc::general_work(int noutput_items __attrib else { d_cn0_estimation_counter = 0; - d_CN0_SNV_dB_Hz = cn0_svn_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GPS_L1_CA_CODE_PERIOD_S); + d_CN0_SNV_dB_Hz = cn0_mm_estimator(d_Prompt_buffer.data(), FLAGS_cn0_samples, GPS_L1_CA_CODE_PERIOD_S); d_carrier_lock_test = carrier_lock_detector(d_Prompt_buffer.data(), FLAGS_cn0_samples); // ###### TRACKING UNLOCK NOTIFICATION ##### diff --git a/src/algorithms/tracking/libs/lock_detectors.cc b/src/algorithms/tracking/libs/lock_detectors.cc index 33e726781..a56d73bc8 100644 --- a/src/algorithms/tracking/libs/lock_detectors.cc +++ b/src/algorithms/tracking/libs/lock_detectors.cc @@ -85,6 +85,53 @@ float cn0_svn_estimator(const gr_complex* Prompt_buffer, int length, float coh_i } +/* + * Signal-to-Noise (SNR) (\f$\rho\f$) estimator using the Moments Method: + * \f{equation} + * \hat{\rho}=\frac{\hat{P}_s}{\hat{P}_n}=\frac{\sqrt{2*\hat{M}_2^2 - \hat{M}_4 }}{\hat{M}_2-\sqrt{2*\hat{M}_2^2 - \hat{M}_4 }}, + * \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{M}_2=\frac{1}{N}\sum^{N-1}_{i=0}|Pc(i)|^2 \f$, \f$\hat{M}_4 = \frac{1}{N}\sum^{N-1}_{i=0}|Pc(i)|^4 \f$, \f$|\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 coherent integration time, using the following formula: + * \f{equation} + * CN0_{dB}=10*log(\hat{\rho})-10*log(T_{int}), + * \f} + * where \f$T_{int}\f$ is the coherent integration time, in seconds. + * + */ +float cn0_mm_estimator(const gr_complex* Prompt_buffer, int length, float coh_integration_time_s) +{ + float SNR_aux = 0.0; + float SNR_dB_Hz = 0.0; + float Psig = 0.0; + float m_2 = 0.0; + float m_4 = 0.0; + float aux; + auto n = static_cast(length); + for (int i = 0; i < length; i++) + { + Psig += std::abs(Prompt_buffer[i].real()); + aux = Prompt_buffer[i].imag() * Prompt_buffer[i].imag() + Prompt_buffer[i].real() * Prompt_buffer[i].real(); + m_2 += aux; + m_4 += (aux * aux); + } + Psig /= n; + Psig = Psig * Psig; + m_2 /= n; + m_4 /= n; + aux = std::sqrt(2.0 * m_2 * m_2 - m_4); + SNR_aux = aux / (m_2 - aux); + SNR_dB_Hz = 10.0 * std::log10(SNR_aux) - 10.0 * std::log10(coh_integration_time_s); + if (std::isnan(SNR_dB_Hz)) + { + SNR_dB_Hz = Psig / (m_2 - Psig); + } + return SNR_dB_Hz; +} + + /* * The estimate of the cosine of twice the carrier phase error is given by * \f{equation} diff --git a/src/algorithms/tracking/libs/lock_detectors.h b/src/algorithms/tracking/libs/lock_detectors.h index d193f0c15..852ea4a6b 100644 --- a/src/algorithms/tracking/libs/lock_detectors.h +++ b/src/algorithms/tracking/libs/lock_detectors.h @@ -51,7 +51,7 @@ #include -/*! \brief CN0_SNV is a Carrier-to-Noise (CN0) estimator +/*! \brief cn0_svn_estimator 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: @@ -75,6 +75,29 @@ float cn0_svn_estimator(const gr_complex* Prompt_buffer, int length, float coh_integration_time_s); +/*! \brief cn0_mm_estimator is a Carrier-to-Noise (CN0) estimator + * based on the Moments Method (MM) + * + * Signal-to-Noise (SNR) (\f$\rho\f$) estimator using the Moments Method: + * \f{equation} + * \hat{\rho}=\frac{\hat{P}_s}{\hat{P}_n}=\frac{\sqrt{2*\hat{M}_2^2 - \hat{M}_4 }}{\hat{M}_2-\sqrt{2*\hat{M}_2^2 - \hat{M}_4 }}, + * \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{M}_2=\frac{1}{N}sum^{N-1}_{i=0}|Pc(i)|^2 \f$, \f$\hat{M}_4 = \frac{1}{N}sum^{N-1}_{i=0}|Pc(i)|^4 \f$, \f$|\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 coherent integration time, using the following formula: + * \f{equation} + * CN0_{dB}=10*log(\hat{\rho})-10*log(T_{int}), + * \f} + * where \f$T_{int}\f$ is the coherent integration time, in seconds. + * Ref: D. R. Pauluzzi, N. C. Beaulieu, "A comparison of SNR estimation + * techniques for the AWGN channel," IEEE Trans. on Comm., vol. 48, + * no. 10, pp. 1681–1691, Oct. 2000. + */ +float cn0_mm_estimator(const gr_complex* Prompt_buffer, int length, float coh_integration_time_s); + + /*! \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