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Merge remote-tracking branch 'cf/normalize-discriminator' into next

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Fix normalization of the non coherent DLL discriminator for BPSK (partially fixes #333)

Fixed non coherent DLL discriminator in BPSK modulations when spacing between discriminators was different from 0.5

Added unit test

Based on solution by @odrisci at #334
This commit is contained in:
Carles Fernandez 2020-02-17 19:01:55 +01:00
commit 0ec3ca0986
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GPG Key ID: 4C583C52B0C3877D
18 changed files with 353 additions and 16 deletions
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36
src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.cc
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@ -134,6 +134,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
// GPS L1 C/A does not have pilot component nor secondary code
d_secondary = false;
trk_parameters.track_pilot = false;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
// symbol integration: 20 trk symbols (20 ms) = 1 tlm bit
// set the preamble in the secondary code acquisition to obtain tlm symbol synchronization
d_secondary_code_length = static_cast<uint32_t>(GPS_CA_PREAMBLE_LENGTH_SYMBOLS);
@ -153,6 +156,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
// GPS L2 does not have pilot component nor secondary code
d_secondary = false;
trk_parameters.track_pilot = false;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
}
else if (signal_type == "L5")
{
@ -165,6 +171,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
d_code_samples_per_chip = 1;
d_code_length_chips = static_cast<uint32_t>(GPS_L5I_CODE_LENGTH_CHIPS);
d_secondary = true;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
if (trk_parameters.track_pilot)
{
// synchronize pilot secondary code
@ -213,6 +222,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
d_correlation_length_ms = 4;
d_code_samples_per_chip = 2; // CBOC disabled: 2 samples per chip. CBOC enabled: 12 samples per chip
d_veml = true;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.slope = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
trk_parameters.y_intercept = GetYInterceptAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
if (trk_parameters.track_pilot)
{
d_secondary = true;
@ -237,6 +249,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
d_code_samples_per_chip = 1;
d_code_length_chips = static_cast<uint32_t>(GALILEO_E5A_CODE_LENGTH_CHIPS);
d_secondary = true;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
if (trk_parameters.track_pilot)
{
// synchronize pilot secondary code
@ -283,6 +298,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
d_code_samples_per_chip = 1;
d_secondary = true;
trk_parameters.track_pilot = false;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
// synchronize and remove data secondary code
d_secondary_code_length = static_cast<uint32_t>(BEIDOU_B1I_SECONDARY_CODE_LENGTH);
d_secondary_code_string = const_cast<std::string *>(&BEIDOU_B1I_SECONDARY_CODE_STR);
@ -301,6 +319,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
d_code_samples_per_chip = 1;
d_secondary = false;
trk_parameters.track_pilot = false;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
d_secondary_code_length = static_cast<uint32_t>(BEIDOU_B3I_SECONDARY_CODE_LENGTH);
d_secondary_code_string = const_cast<std::string *>(&BEIDOU_B3I_SECONDARY_CODE_STR);
d_data_secondary_code_length = static_cast<uint32_t>(BEIDOU_B3I_SECONDARY_CODE_LENGTH);
@ -965,7 +986,7 @@ void dll_pll_veml_tracking::run_dll_pll()
}
else
{
d_code_error_chips = dll_nc_e_minus_l_normalized(d_E_accu, d_L_accu); // [chips/Ti]
d_code_error_chips = dll_nc_e_minus_l_normalized(d_E_accu, d_L_accu, trk_parameters.spc, trk_parameters.slope, trk_parameters.y_intercept); // [chips/Ti]
}
// Code discriminator filter
d_code_error_filt_chips = d_code_loop_filter.apply(d_code_error_chips); // [chips/second]
@ -1621,6 +1642,12 @@ int dll_pll_veml_tracking::general_work(int noutput_items __attribute__((unused)
d_E_accu = *d_Early;
d_P_accu = *d_Prompt;
d_L_accu = *d_Late;
trk_parameters.spc = trk_parameters.early_late_space_chips;
// if (std::string(trk_parameters.signal) == "E1")
// {
// trk_parameters.slope = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
// trk_parameters.y_intercept = GetYInterceptAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
// }
// fail-safe: check if the secondary code or bit synchronization has not succeeded in a limited time period
if (trk_parameters.bit_synchronization_time_limit_s < (d_sample_counter - d_acq_sample_stamp) / static_cast<int>(trk_parameters.fs_in))
@ -1722,11 +1749,18 @@ int dll_pll_veml_tracking::general_work(int noutput_items __attribute__((unused)
d_local_code_shift_chips[1] = -trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
d_local_code_shift_chips[3] = trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
d_local_code_shift_chips[4] = trk_parameters.very_early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
trk_parameters.spc = trk_parameters.early_late_space_narrow_chips;
// if (std::string(trk_parameters.signal) == "E1")
// {
// trk_parameters.slope = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
// trk_parameters.y_intercept = GetYInterceptAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
// }
}
else
{
d_local_code_shift_chips[0] = -trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
d_local_code_shift_chips[2] = trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
trk_parameters.spc = trk_parameters.early_late_space_narrow_chips;
}
}
else

27
src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking_fpga.cc
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@ -129,6 +129,9 @@ dll_pll_veml_tracking_fpga::dll_pll_veml_tracking_fpga(const Dll_Pll_Conf_Fpga &
// GPS L1 C/A does not have pilot component nor secondary code
d_secondary = false;
trk_parameters.track_pilot = false;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
// symbol integration: 20 trk symbols (20 ms) = 1 tlm bit
// set the preamble in the secondary code acquisition to obtain tlm symbol synchronization
d_secondary_code_length = static_cast<uint32_t>(GPS_CA_PREAMBLE_LENGTH_SYMBOLS);
@ -143,6 +146,9 @@ dll_pll_veml_tracking_fpga::dll_pll_veml_tracking_fpga(const Dll_Pll_Conf_Fpga &
// GPS L2C has 1 trk symbol (20 ms) per tlm bit, no symbol integration required
d_symbols_per_bit = GPS_L2_SAMPLES_PER_SYMBOL;
d_correlation_length_ms = 20;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
// GPS L2 does not have pilot component nor secondary code
d_secondary = false;
trk_parameters.track_pilot = false;
@ -156,6 +162,9 @@ dll_pll_veml_tracking_fpga::dll_pll_veml_tracking_fpga(const Dll_Pll_Conf_Fpga &
d_symbols_per_bit = GPS_L5_SAMPLES_PER_SYMBOL;
d_correlation_length_ms = 1;
d_secondary = true;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
if (d_extended_correlation_in_fpga == true)
{
if (trk_parameters.extend_correlation_symbols > 1)
@ -207,6 +216,9 @@ dll_pll_veml_tracking_fpga::dll_pll_veml_tracking_fpga(const Dll_Pll_Conf_Fpga &
d_symbols_per_bit = 1;
d_correlation_length_ms = 4;
d_veml = true;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.slope = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
trk_parameters.y_intercept = GetYInterceptAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
if (trk_parameters.track_pilot)
{
d_secondary = true;
@ -229,6 +241,9 @@ dll_pll_veml_tracking_fpga::dll_pll_veml_tracking_fpga(const Dll_Pll_Conf_Fpga &
d_symbols_per_bit = 20;
d_correlation_length_ms = 1;
d_secondary = true;
trk_parameters.slope = 1.0;
trk_parameters.spc = trk_parameters.early_late_space_chips;
trk_parameters.y_intercept = 1.0;
if (d_extended_correlation_in_fpga == true)
{
if (trk_parameters.extend_correlation_symbols > 1)
@ -718,7 +733,7 @@ void dll_pll_veml_tracking_fpga::run_dll_pll()
}
else
{
d_code_error_chips = dll_nc_e_minus_l_normalized(d_E_accu, d_L_accu); // [chips/Ti]
d_code_error_chips = dll_nc_e_minus_l_normalized(d_E_accu, d_L_accu, trk_parameters.spc, trk_parameters.slope, trk_parameters.y_intercept); // [chips/Ti]
}
// Code discriminator filter
d_code_error_filt_chips = d_code_loop_filter.apply(d_code_error_chips); // [chips/second]
@ -1581,6 +1596,12 @@ int dll_pll_veml_tracking_fpga::general_work(int noutput_items __attribute__((un
d_E_accu = *d_Early;
d_P_accu = *d_Prompt;
d_L_accu = *d_Late;
trk_parameters.spc = trk_parameters.early_late_space_chips;
// if (std::string(trk_parameters.signal) == "E1")
// {
// trk_parameters.slope = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
// trk_parameters.y_intercept = GetYInterceptAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
// }
// fail-safe: check if the secondary code or bit synchronization has not succeeded in a limited time period
if (trk_parameters.bit_synchronization_time_limit_s < (d_sample_counter - d_acq_sample_stamp) / static_cast<int>(trk_parameters.fs_in))
@ -1723,11 +1744,15 @@ int dll_pll_veml_tracking_fpga::general_work(int noutput_items __attribute__((un
d_local_code_shift_chips[1] = -trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
d_local_code_shift_chips[3] = trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
d_local_code_shift_chips[4] = trk_parameters.very_early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
trk_parameters.spc = trk_parameters.early_late_space_narrow_chips;
// trk_parameters.slope = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
// trk_parameters.y_intercept = GetYInterceptAbs(&SinBocCorrelationFunction<1, 1>, trk_parameters.spc);
}
else
{
d_local_code_shift_chips[0] = -trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
d_local_code_shift_chips[2] = trk_parameters.early_late_space_narrow_chips * static_cast<float>(d_code_samples_per_chip);
trk_parameters.spc = trk_parameters.early_late_space_narrow_chips;
}
}
else

2
src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_cc.cc
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@ -697,7 +697,7 @@ int glonass_l1_ca_dll_pll_c_aid_tracking_cc::general_work(int noutput_items __at
// ################## DLL ##########################################################
// DLL discriminator
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2]); // [chips/Ti] //early and late
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2], d_early_late_spc_chips, 1.0); // [chips/Ti] //early and late
// Code discriminator filter
d_code_error_filt_chips_s = d_code_loop_filter.get_code_nco(d_code_error_chips_Ti); // input [chips/Ti] -> output [chips/second]
d_code_error_filt_chips_Ti = d_code_error_filt_chips_s * CURRENT_INTEGRATION_TIME_S;

2
src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_c_aid_tracking_sc.cc
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@ -694,7 +694,7 @@ int glonass_l1_ca_dll_pll_c_aid_tracking_sc::general_work(int noutput_items __at
// ################## DLL ##########################################################
// DLL discriminator
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(std::complex<float>(d_correlator_outs_16sc[0].real(), d_correlator_outs_16sc[0].imag()), std::complex<float>(d_correlator_outs_16sc[2].real(), d_correlator_outs_16sc[2].imag())); // [chips/Ti] //early and late
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(std::complex<float>(d_correlator_outs_16sc[0].real(), d_correlator_outs_16sc[0].imag()), std::complex<float>(d_correlator_outs_16sc[2].real(), d_correlator_outs_16sc[2].imag()), d_early_late_spc_chips, 1.0); // [chips/Ti] //early and late
// Code discriminator filter
d_code_error_filt_chips_s = d_code_loop_filter.get_code_nco(d_code_error_chips_Ti); // input [chips/Ti] -> output [chips/second]
d_code_error_filt_chips_Ti = d_code_error_filt_chips_s * CURRENT_INTEGRATION_TIME_S;

2
src/algorithms/tracking/gnuradio_blocks/glonass_l1_ca_dll_pll_tracking_cc.cc
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@ -555,7 +555,7 @@ int Glonass_L1_Ca_Dll_Pll_Tracking_cc::general_work(int noutput_items __attribut
// ################## DLL ##########################################################
// DLL discriminator
code_error_chips = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2]); // [chips/Ti] //early and late
code_error_chips = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2], d_early_late_spc_chips, 1.0); // [chips/Ti] //early and late
// Code discriminator filter
code_error_filt_chips = d_code_loop_filter.get_code_nco(code_error_chips); // [chips/second]
double T_chip_seconds = 1.0 / static_cast<double>(d_code_freq_chips);

2
src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_cc.cc
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@ -693,7 +693,7 @@ int glonass_l2_ca_dll_pll_c_aid_tracking_cc::general_work(int noutput_items __at
// ################## DLL ##########################################################
// DLL discriminator
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2]); // [chips/Ti] //early and late
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2], d_early_late_spc_chips, 1.0); // [chips/Ti] //early and late
// Code discriminator filter
d_code_error_filt_chips_s = d_code_loop_filter.get_code_nco(d_code_error_chips_Ti); // input [chips/Ti] -> output [chips/second]
d_code_error_filt_chips_Ti = d_code_error_filt_chips_s * CURRENT_INTEGRATION_TIME_S;

2
src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_c_aid_tracking_sc.cc
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@ -692,7 +692,7 @@ int glonass_l2_ca_dll_pll_c_aid_tracking_sc::general_work(int noutput_items __at
// ################## DLL ##########################################################
// DLL discriminator
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(std::complex<float>(d_correlator_outs_16sc[0].real(), d_correlator_outs_16sc[0].imag()), std::complex<float>(d_correlator_outs_16sc[2].real(), d_correlator_outs_16sc[2].imag())); // [chips/Ti] //early and late
d_code_error_chips_Ti = dll_nc_e_minus_l_normalized(std::complex<float>(d_correlator_outs_16sc[0].real(), d_correlator_outs_16sc[0].imag()), std::complex<float>(d_correlator_outs_16sc[2].real(), d_correlator_outs_16sc[2].imag()), d_early_late_spc_chips, 1.0); // [chips/Ti] //early and late
// Code discriminator filter
d_code_error_filt_chips_s = d_code_loop_filter.get_code_nco(d_code_error_chips_Ti); // input [chips/Ti] -> output [chips/second]
d_code_error_filt_chips_Ti = d_code_error_filt_chips_s * CURRENT_INTEGRATION_TIME_S;

2
src/algorithms/tracking/gnuradio_blocks/glonass_l2_ca_dll_pll_tracking_cc.cc
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@ -556,7 +556,7 @@ int Glonass_L2_Ca_Dll_Pll_Tracking_cc::general_work(int noutput_items __attribut
// ################## DLL ##########################################################
// DLL discriminator
code_error_chips = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2]); // [chips/Ti] //early and late
code_error_chips = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2], d_early_late_spc_chips, 1.0); // [chips/Ti] //early and late
// Code discriminator filter
code_error_filt_chips = d_code_loop_filter.get_code_nco(code_error_chips); // [chips/second]
double T_chip_seconds = 1.0 / static_cast<double>(d_code_freq_chips);

2
src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_dll_pll_tracking_gpu_cc.cc
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@ -373,7 +373,7 @@ int Gps_L1_Ca_Dll_Pll_Tracking_GPU_cc::general_work(int noutput_items __attribut
// ################## DLL ##########################################################
// DLL discriminator
code_error_chips_Ti = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2]); // [chips/Ti] // early and late
code_error_chips_Ti = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2], d_early_late_spc_chips, 1.0); // [chips/Ti] // early and late
// Code discriminator filter
code_error_filt_chips = d_code_loop_filter.get_code_nco(code_error_chips_Ti); // input [chips/Ti] -> output [chips/second]
code_error_filt_secs_Ti = code_error_filt_chips * CURRENT_INTEGRATION_TIME_S / d_code_freq_chips; // [s/Ti]

2
src/algorithms/tracking/gnuradio_blocks/gps_l1_ca_kf_tracking_cc.cc
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@ -737,7 +737,7 @@ int Gps_L1_Ca_Kf_Tracking_cc::general_work(int noutput_items __attribute__((unus
// New code Doppler frequency estimation based on carrier frequency estimation
d_code_freq_chips = GPS_L1_CA_CODE_RATE_CPS + ((d_carrier_doppler_hz * GPS_L1_CA_CODE_RATE_CPS) / GPS_L1_FREQ_HZ);
// DLL discriminator
code_error_chips = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2]); // [chips/Ti] early and late
code_error_chips = dll_nc_e_minus_l_normalized(d_correlator_outs[0], d_correlator_outs[2], d_early_late_spc_chips, 1.0); // [chips/Ti] early and late
// Code discriminator filter
code_error_filt_chips = d_code_loop_filter.get_code_nco(code_error_chips); // [chips/second]
double T_chip_seconds = 1.0 / static_cast<double>(d_code_freq_chips);

3
src/algorithms/tracking/libs/dll_pll_conf.cc
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@ -50,6 +50,9 @@ Dll_Pll_Conf::Dll_Pll_Conf()
very_early_late_space_chips = 0.5;
early_late_space_narrow_chips = 0.1;
very_early_late_space_narrow_chips = 0.1;
slope = 1.0;
spc = 0.5;
y_intercept = 1.0;
extend_correlation_symbols = 5;
cn0_samples = FLAGS_cn0_samples;
cn0_smoother_samples = 200;

3
src/algorithms/tracking/libs/dll_pll_conf.h
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@ -52,6 +52,9 @@ public:
float very_early_late_space_chips;
float early_late_space_narrow_chips;
float very_early_late_space_narrow_chips;
float slope;
float spc;
float y_intercept;
int32_t extend_correlation_symbols;
bool high_dyn;
int32_t cn0_samples;

3
src/algorithms/tracking/libs/dll_pll_conf_fpga.cc
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@ -52,6 +52,9 @@ Dll_Pll_Conf_Fpga::Dll_Pll_Conf_Fpga()
very_early_late_space_chips = 0.5;
early_late_space_narrow_chips = 0.1;
very_early_late_space_narrow_chips = 0.1;
slope = 1.0;
spc = 0.5;
y_intercept = 1.0;
extend_correlation_symbols = 5;
cn0_samples = FLAGS_cn0_samples;
cn0_smoother_samples = 200;

3
src/algorithms/tracking/libs/dll_pll_conf_fpga.h
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@ -56,6 +56,9 @@ public:
float very_early_late_space_chips;
float early_late_space_narrow_chips;
float very_early_late_space_narrow_chips;
float slope;
float spc;
float y_intercept;
int32_t extend_correlation_symbols;
bool high_dyn;
int32_t cn0_samples;

7
src/algorithms/tracking/libs/tracking_discriminators.cc
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@ -23,7 +23,6 @@
#include "tracking_discriminators.h"
#include "MATH_CONSTANTS.h"
#include <cmath>
// All the outputs are in RADIANS
@ -114,12 +113,12 @@ double pll_cloop_two_quadrant_atan(gr_complex prompt_s1)
/*
* DLL Noncoherent Early minus Late envelope normalized discriminator:
* \f{equation}
* error=\frac{1}{2}\frac{E-L}{E+L},
* error = \frac{y_{intercept} - \text{slope} * \epsilon}{\text{slope}} \frac{E-L}{E+L},
* \f}
* where \f$E=\sqrt{I_{ES}^2+Q_{ES}^2}\f$ is the Early correlator output absolute value and
* \f$L=\sqrt{I_{LS}^2+Q_{LS}^2}\f$ is the Late correlator output absolute value. The output is in [chips].
*/
double dll_nc_e_minus_l_normalized(gr_complex early_s1, gr_complex late_s1)
double dll_nc_e_minus_l_normalized(gr_complex early_s1, gr_complex late_s1, float spc, float slope, float y_intercept)
{
double P_early = std::abs(early_s1);
double P_late = std::abs(late_s1);
@ -128,7 +127,7 @@ double dll_nc_e_minus_l_normalized(gr_complex early_s1, gr_complex late_s1)
{
return 0.0;
}
return 0.5 * (P_early - P_late) / E_plus_L;
return ((y_intercept - slope * spc) / slope) * (P_early - P_late) / E_plus_L;
}

92
src/algorithms/tracking/libs/tracking_discriminators.h
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@ -28,6 +28,7 @@
#define GNSS_SDR_TRACKING_DISCRIMINATORS_H
#include <gnuradio/gr_complex.h>
#include <cmath>
/*! brief FLL four quadrant arctan discriminator
*
@ -83,12 +84,12 @@ double pll_cloop_two_quadrant_atan(gr_complex prompt_s1);
*
* DLL Noncoherent Early minus Late envelope normalized discriminator:
* \f{equation}
* error=\frac{E-L}{E+L},
* error = \frac{y_{intercept} - \text{slope} * \epsilon}{\text{slope}} \frac{E-L}{E+L},
* \f}
* where \f$E=\sqrt{I_{ES}^2+Q_{ES}^2}\f$ is the Early correlator output absolute value and
* \f$L=\sqrt{I_{LS}^2+Q_{LS}^2}\f$ is the Late correlator output absolute value. The output is in [chips].
*/
double dll_nc_e_minus_l_normalized(gr_complex early_s1, gr_complex late_s1);
double dll_nc_e_minus_l_normalized(gr_complex early_s1, gr_complex late_s1, float spc = 0.5, float slope = 1.0, float y_intercept = 1.0);
/*! \brief DLL Noncoherent Very Early Minus Late Power (VEMLP) normalized discriminator
@ -104,4 +105,91 @@ double dll_nc_e_minus_l_normalized(gr_complex early_s1, gr_complex late_s1);
double dll_nc_vemlp_normalized(gr_complex very_early_s1, gr_complex early_s1, gr_complex late_s1, gr_complex very_late_s1);
template <typename Fun>
double CalculateSlope(Fun &&f, double x)
{
static constexpr double dx = 1e-6;
return (f(x + dx / 2.0) - f(x - dx / 2.0)) / dx;
}
template <typename Fun>
double CalculateSlopeAbs(Fun &&f, double x)
{
static constexpr double dx = 1e-6;
return (std::abs(f(x + dx / 2.0)) - std::abs(f(x - dx / 2.0))) / dx;
}
template <typename Fun>
double GetYIntercept(Fun &&f, double x)
{
double slope = CalculateSlope(f, x);
double y1 = f(x);
return y1 - slope * x;
}
template <typename Fun>
double GetYInterceptAbs(Fun &&f, double x)
{
double slope = CalculateSlopeAbs(f, x);
double y1 = std::abs(f(x));
return y1 - slope * x;
}
// SinBocCorrelationFunction and CosBocCorrelationFunction from
// Sousa, F. and Nunes, F., "New Expressions for the Autocorrelation
// Function of BOC GNSS Signals", NAVIGATION - Journal of the Institute
// of Navigation, March 2013.
//
template <int M = 1, int N = M>
double SinBocCorrelationFunction(double offset_in_chips)
{
static constexpr int TWO_P = 2 * M / N;
double abs_tau = std::abs(offset_in_chips);
if (abs_tau > 1.0)
{
return 0.0;
}
int k = static_cast<int>(std::ceil(TWO_P * abs_tau));
double sgn = ((k & 0x01) == 0 ? 1.0 : -1.0); // (-1)^k
return sgn * (2.0 * (k * k - k * TWO_P - k) / TWO_P + 1.0 +
(2 * TWO_P - 2 * k + 1) * abs_tau);
}
template <int M = 1, int N = M>
double CosBocCorrelationFunction(double offset_in_chips)
{
static constexpr int TWO_P = 2 * M / N;
double abs_tau = std::abs(offset_in_chips);
if (abs_tau > 1.0)
{
return 0.0;
}
int k = static_cast<int>(std::floor(2.0 * TWO_P * abs_tau));
if ((k & 0x01) == 0) // k is even
{
double sgn = ((k >> 1) & 0x01 ? -1.0 : 1.0); // (-1)^(k/2)
return sgn * ((2 * k * TWO_P + 2 * TWO_P - k * k) / (2.0 * TWO_P) + (-2 * TWO_P + k - 1) * abs_tau);
}
else
{
double sgn = (((k + 1) >> 1) & 0x01 ? -1.0 : 1.0); // (-1)^((k+1)/2)
return sgn * ((k * k + 2 * k - 2 * k * TWO_P + 1) / (2.0 * TWO_P) + (2 * TWO_P - k - 2) * abs_tau);
}
}
#endif

2
src/tests/test_main.cc
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@ -94,12 +94,14 @@ DECLARE_string(log_dir);
#endif
#include "unit-tests/signal-processing-blocks/tracking/cpu_multicorrelator_real_codes_test.cc"
#include "unit-tests/signal-processing-blocks/tracking/cpu_multicorrelator_test.cc"
#include "unit-tests/signal-processing-blocks/tracking/discriminator_test.cc"
#include "unit-tests/signal-processing-blocks/tracking/galileo_e1_dll_pll_veml_tracking_test.cc"
#include "unit-tests/signal-processing-blocks/tracking/galileo_e5a_tracking_test.cc"
#include "unit-tests/signal-processing-blocks/tracking/glonass_l1_ca_dll_pll_c_aid_tracking_test.cc"
#include "unit-tests/signal-processing-blocks/tracking/glonass_l1_ca_dll_pll_tracking_test.cc"
#include "unit-tests/signal-processing-blocks/tracking/tracking_loop_filter_test.cc"
#if CUDA_BLOCKS_TEST
#include "unit-tests/signal-processing-blocks/tracking/gpu_multicorrelator_test.cc"
#endif

177
src/tests/unit-tests/signal-processing-blocks/tracking/discriminator_test.cc Normal file
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@ -0,0 +1,177 @@
/*!
* \file discriminator_test.cc
* \brief This file implements tests for the tracking discriminators
* \author Cillian O'Driscoll, 2019. cillian.odriscoll(at)gmail.com
*
*
* -------------------------------------------------------------------------
*
* Copyright (C) 2010-2019 (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.
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
* -------------------------------------------------------------------------
*/
#include "tracking_discriminators.h"
#include <gtest/gtest.h>
#include <cmath>
#include <vector>
double BpskCorrelationFunction(double offset_in_chips)
{
double abs_tau = std::abs(offset_in_chips);
if (abs_tau > 1.0)
{
return 0.0;
}
return 1.0 - abs_tau;
}
TEST(DllNcEMinusLNormalizedTest, Bpsk)
{
std::vector<gr_complex> complex_amplitude_vector = {{1.0, 0.0}, {-1.0, 0.0}, {0.0, 1.0}, {1.0, 1.0}};
std::vector<double> spacing_vector = {0.5, 0.25, 0.1, 0.01};
std::vector<double> error_vector = {0.0, 0.01, 0.1, 0.25, -0.25, -0.1, -0.01};
for (auto A : complex_amplitude_vector)
{
for (auto spacing : spacing_vector)
{
for (auto err : error_vector)
{
gr_complex E = A * static_cast<float>(BpskCorrelationFunction(err - spacing));
gr_complex L = A * static_cast<float>(BpskCorrelationFunction(err + spacing));
double disc_out = dll_nc_e_minus_l_normalized(E, L, spacing);
if (std::abs(err) < 2.0 * spacing)
{
EXPECT_NEAR(disc_out, err, 1e-4) << " Spacing: " << spacing;
}
else
{
EXPECT_TRUE(err * disc_out >= 0.0);
}
if (spacing != 0.5 and err != 0.0)
{
double disc_out_old = dll_nc_e_minus_l_normalized(E, L);
EXPECT_NE(disc_out_old, err);
}
}
}
}
}
TEST(DllNcEMinusLNormalizedTest, SinBoc11)
{
std::vector<gr_complex> complex_amplitude_vector = {{1.0, 0.0}, {-1.0, 0.0}, {0.0, 1.0}, {1.0, 1.0}};
std::vector<double> spacing_vector = {0.75, 0.6666, 5.0 / 12.0, 0.25, 1.0 / 6.0, 0.01};
std::vector<double> error_vector = {0.0, 0.01, 0.1, 0.25, -0.25, -0.1, -0.01};
for (auto A : complex_amplitude_vector)
{
for (auto spacing : spacing_vector)
{
double corr_slope = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, spacing);
double y_intercept = GetYInterceptAbs(&SinBocCorrelationFunction<1, 1>, spacing);
for (auto err : error_vector)
{
gr_complex E = A * static_cast<float>(SinBocCorrelationFunction<1, 1>(err - spacing));
gr_complex L = A * static_cast<float>(SinBocCorrelationFunction<1, 1>(err + spacing));
double disc_out = dll_nc_e_minus_l_normalized(E, L, spacing, corr_slope, y_intercept);
double corr_slope_at_err = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, spacing + err);
double corr_slope_at_neg_err = -CalculateSlopeAbs(&SinBocCorrelationFunction<1, 1>, spacing - err);
bool in_linear_region = (std::abs(err) < spacing) and (std::abs(corr_slope_at_err - corr_slope_at_neg_err) < 0.01);
double norm_factor = (y_intercept - corr_slope * spacing) / spacing;
if (in_linear_region)
{
EXPECT_NEAR(disc_out, err, 1e-4) << " Spacing: " << spacing << ", slope : " << corr_slope << ", y_intercept: " << y_intercept << ", norm: " << norm_factor << " E: " << E << ", L: " << L;
if (norm_factor != 0.5 and err != 0.0)
{
double disc_out_old = dll_nc_e_minus_l_normalized(E, L);
EXPECT_NE(disc_out_old, err) << " Spacing: " << spacing << ", slope : " << corr_slope << ", y_intercept: " << y_intercept << ", norm: " << norm_factor << " E: " << E << ", L: " << L;
}
}
}
}
}
}
TEST(CosBocCorrelationFunction, FixedPoints)
{
double res = CosBocCorrelationFunction<1, 1>(0.0);
EXPECT_NEAR(res, 1.0, 1e-4);
res = CosBocCorrelationFunction<1, 1>(0.2);
EXPECT_NEAR(res, 0.0, 1e-4);
res = CosBocCorrelationFunction<1, 1>(0.25);
EXPECT_NEAR(res, -0.25, 1e-4);
res = CosBocCorrelationFunction<1, 1>(0.5);
EXPECT_NEAR(res, -0.5, 1e-4);
res = CosBocCorrelationFunction<1, 1>(0.75);
EXPECT_NEAR(res, 0.25, 1e-4);
res = CosBocCorrelationFunction<1, 1>(1.0);
EXPECT_NEAR(res, 0.0, 1e-4);
res = CosBocCorrelationFunction<1, 1>(-0.2);
EXPECT_NEAR(res, 0.0, 1e-4);
res = CosBocCorrelationFunction<1, 1>(-0.5);
EXPECT_NEAR(res, -0.5, 1e-4);
res = CosBocCorrelationFunction<1, 1>(-0.75);
EXPECT_NEAR(res, 0.25, 1e-4);
res = CosBocCorrelationFunction<1, 1>(-1.0);
EXPECT_NEAR(res, 0.0, 1e-4);
}
TEST(DllNcEMinusLNormalizedTest, CosBoc11)
{
std::vector<gr_complex> complex_amplitude_vector = {{1.0, 0.0}, {-1.0, 0.0}, {0.0, 1.0}, {1.0, 1.0}};
std::vector<double> spacing_vector = {0.875, 0.588, 0.1, 0.01};
std::vector<double> error_vector = {0.0, 0.01, 0.1, 0.25, -0.25, -0.1, -0.01};
for (auto A : complex_amplitude_vector)
{
for (auto spacing : spacing_vector)
{
double corr_slope = -CalculateSlopeAbs(&CosBocCorrelationFunction<1, 1>, spacing);
double y_intercept = GetYInterceptAbs(&CosBocCorrelationFunction<1, 1>, spacing);
for (auto err : error_vector)
{
gr_complex E = A * static_cast<float>(CosBocCorrelationFunction<1, 1>(err - spacing));
gr_complex L = A * static_cast<float>(CosBocCorrelationFunction<1, 1>(err + spacing));
double disc_out = dll_nc_e_minus_l_normalized(E, L, spacing, corr_slope, y_intercept);
double corr_slope_at_err = -CalculateSlopeAbs(&CosBocCorrelationFunction<1, 1>, spacing + err);
double corr_slope_at_neg_err = -CalculateSlopeAbs(&CosBocCorrelationFunction<1, 1>, spacing - err);
bool in_linear_region = (std::abs(err) < spacing) and (std::abs(corr_slope_at_err - corr_slope_at_neg_err) < 0.01);
double norm_factor = (y_intercept - corr_slope * spacing) / spacing;
if (in_linear_region)
{
EXPECT_NEAR(disc_out, err, 1e-4) << " Spacing: " << spacing << ", slope : " << corr_slope << ", y_intercept: " << y_intercept << ", norm: " << norm_factor << " E: " << E << ", L: " << L;
if (norm_factor != 0.5 and err != 0.0)
{
double disc_out_old = dll_nc_e_minus_l_normalized(E, L);
EXPECT_NE(disc_out_old, err) << " Spacing: " << spacing << ", slope : " << corr_slope << ", y_intercept: " << y_intercept << ", norm: " << norm_factor << " E: " << E << ", L: " << L;
}
}
}
}
}
}