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First draft of DPE for PRS

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Note this operates as a DPE but actually generates a full BOC
subcarrier. The next step will make it possible to actually generate the
local replica subcarrier as a cosine wave.
This commit is contained in:
Cillian O'Driscoll
2015-11-20 16:57:37 +00:00
parent 283d4fa9e5
commit c96bbaba01
5 changed files with 149 additions and 28 deletions
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5
src/algorithms/tracking/adapters/galileo_e1_prs_de_tracking.cc
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@@ -69,6 +69,7 @@ GalileoE1PrsDeTracking::GalileoE1PrsDeTracking(
float early_late_subcarrier_space_chips;
bool aid_subcarrier_with_carrier;
bool aid_code_with_subcarrier;
bool model_prs_subcarrier_as_sinusoid;
item_type = configuration->property(role + ".item_type", default_item_type);
fs_in = configuration->property("GNSS-SDR.internal_fs_hz", 2048000);
@@ -85,6 +86,7 @@ GalileoE1PrsDeTracking::GalileoE1PrsDeTracking(
early_late_subcarrier_space_chips = configuration->property(role + ".early_late_subcarrier_space_cycles", 0.125);
aid_subcarrier_with_carrier = configuration->property(role + ".aid_subcarrier_with_carrier", false );
aid_code_with_subcarrier = configuration->property(role + ".aid_code_with_subcarrier", false );
model_prs_subcarrier_as_sinusoid = configuration->property(role + ".model_prs_subcarrier_as_sinusoid", false );
pll_loop_order = configuration->property(role + ".pll_loop_order", 3);
sll_loop_order = configuration->property(role + ".sll_loop_order", 3);
@@ -131,7 +133,8 @@ GalileoE1PrsDeTracking::GalileoE1PrsDeTracking(
sll_loop_order, sll_initial_bw_hz, sll_final_bw_hz,
initial_early_late_code_space_chips, final_early_late_code_space_chips,
early_late_subcarrier_space_chips,
aid_subcarrier_with_carrier, aid_code_with_subcarrier, code_gen);
aid_subcarrier_with_carrier, aid_code_with_subcarrier,
model_prs_subcarrier_as_sinusoid, code_gen);
}
else
{

117
src/algorithms/tracking/gnuradio_blocks/galileo_e1_prs_de_tracking_cc.cc
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@@ -87,6 +87,7 @@ galileo_e1_prs_de_make_tracking_cc(
float early_late_subcarrier_space_cycles,
bool aid_subcarrier_with_carrier,
bool aid_code_with_subcarrier,
bool prs_sinusoidal_subcarrier,
LongCodeInterface_sptr prs_code_gen)
{
return galileo_e1_prs_de_tracking_cc_sptr(new galileo_e1_prs_de_tracking_cc(if_freq,
@@ -96,7 +97,8 @@ galileo_e1_prs_de_make_tracking_cc(
sll_loop_order, sll_initial_bw_hz, sll_final_bw_hz,
initial_early_late_code_space_chips, final_early_late_code_space_chips,
early_late_subcarrier_space_cycles,
aid_subcarrier_with_carrier, aid_code_with_subcarrier, prs_code_gen));
aid_subcarrier_with_carrier, aid_code_with_subcarrier,
prs_sinusoidal_subcarrier, prs_code_gen));
}
@@ -128,6 +130,7 @@ galileo_e1_prs_de_tracking_cc::galileo_e1_prs_de_tracking_cc(
float early_late_subcarrier_space_cycles,
bool aid_subcarrier_with_carrier,
bool aid_code_with_subcarrier,
bool prs_sinusoidal_subcarrier,
LongCodeInterface_sptr prs_code_gen):
gr::block("galileo_e1_prs_de_tracking_cc", gr::io_signature::make(1, 1, sizeof(gr_complex)),
gr::io_signature::make(1, 1, sizeof(Gnss_Synchro)))
@@ -208,6 +211,9 @@ galileo_e1_prs_de_tracking_cc::galileo_e1_prs_de_tracking_cc(
d_late_subcarrier_prs = static_cast<gr_complex*>(volk_malloc(2 * d_vector_length * sizeof(gr_complex), volk_get_alignment()));
d_carr_sign = static_cast<gr_complex*>(volk_malloc(2*d_vector_length * sizeof(gr_complex), volk_get_alignment()));
// Re-use the late subcarrier for the DPE
d_prompt_quadrature_subcarrier_prs = d_late_subcarrier_prs;
// correlator outputs (scalar)
d_Prompt_Subcarrier_Early_Code = static_cast<gr_complex*>(volk_malloc(sizeof(gr_complex), volk_get_alignment()));
d_Prompt_Subcarrier_Prompt_Code = static_cast<gr_complex*>(volk_malloc(sizeof(gr_complex), volk_get_alignment()));
@@ -222,6 +228,9 @@ galileo_e1_prs_de_tracking_cc::galileo_e1_prs_de_tracking_cc(
d_Prompt_Code_Early_Subcarrier_prs = static_cast<gr_complex*>(volk_malloc(sizeof(gr_complex), volk_get_alignment()));
d_Prompt_Code_Late_Subcarrier_prs= static_cast<gr_complex*>(volk_malloc(sizeof(gr_complex), volk_get_alignment()));
// Re-use the prompt code late subcarrier for the DPE
d_Prompt_Code_Quadrature_Subcarrier_prs = d_Prompt_Code_Late_Subcarrier_prs;
//--- Initializations ------------------------------
// Initial code frequency basis of NCO
d_code_freq_chips = static_cast<double>(Galileo_E1_CODE_CHIP_RATE_HZ);
@@ -292,6 +301,8 @@ galileo_e1_prs_de_tracking_cc::galileo_e1_prs_de_tracking_cc(
d_tow_received = false;
d_rx_time_set = false;
d_preamble_start_detected = false;
d_prs_sinusoidal_subcarrier = prs_sinusoidal_subcarrier;
}
void galileo_e1_prs_de_tracking_cc::start_tracking()
@@ -476,7 +487,14 @@ void galileo_e1_prs_de_tracking_cc::update_local_code_prs()
// Add 1/4 of a cyle here to account for cosine phasing:
tsubcarrier_phase_halfcyles = static_cast<double>(d_subcarrier_phase_halfcycles_prs) + 0.5;
early_late_subcarrier_spc_halfcycles = d_early_late_subcarrier_spc_cycles * 2.0;
if( d_prs_sinusoidal_subcarrier )
{
early_late_subcarrier_spc_halfcycles = 0.5; // DPE requires quarter cycle spacing
}
else
{
early_late_subcarrier_spc_halfcycles = d_early_late_subcarrier_spc_cycles * 2.0;
}
int64_t early_code_phase_fxp = double_to_fxpt64( tcode_chips + d_early_late_code_spc_chips );
int64_t prompt_code_phase_fxp = double_to_fxpt64( tcode_chips );
@@ -714,22 +732,47 @@ int galileo_e1_prs_de_tracking_cc::general_work (int noutput_items,gr_vector_int
-std::sin( carrier_doppler_inc_rad ) );
// perform carrier wipe-off and compute Very Early, Early, Prompt, Late and Very Late correlation
d_correlator.Carrier_rotate_and_DE_volk(d_current_prn_length_samples,
in,
&phase_as_complex,
phase_inc_as_complex,
d_early_code_prs,
d_prompt_code_prs,
d_late_code_prs,
d_early_subcarrier_prs,
d_prompt_subcarrier_prs,
d_late_subcarrier_prs,
d_Prompt_Subcarrier_Early_Code_prs,
d_Prompt_Subcarrier_Prompt_Code_prs,
d_Prompt_Subcarrier_Late_Code_prs,
d_Prompt_Code_Early_Subcarrier_prs,
d_Prompt_Code_Late_Subcarrier_prs );
// Two options: Double estimator or Double phase estimator
// In the double estimator the subcarrier is assumed to be a square wave
// In the double phase estiamtor the subcarrier is approximated by its fundamental
// Fourier component
//
if( d_prs_sinusoidal_subcarrier ){
d_correlator.Carrier_rotate_and_DPE_volk(d_current_prn_length_samples,
in,
&phase_as_complex,
phase_inc_as_complex,
d_early_code_prs,
d_prompt_code_prs,
d_late_code_prs,
d_prompt_quadrature_subcarrier_prs,
d_prompt_subcarrier_prs,
d_Prompt_Subcarrier_Early_Code_prs,
d_Prompt_Subcarrier_Prompt_Code_prs,
d_Prompt_Subcarrier_Late_Code_prs,
d_Prompt_Code_Quadrature_Subcarrier_prs );
}
else
{
// perform carrier wipe-off and compute Very Early, Early, Prompt, Late and Very Late correlation
d_correlator.Carrier_rotate_and_DE_volk(d_current_prn_length_samples,
in,
&phase_as_complex,
phase_inc_as_complex,
d_early_code_prs,
d_prompt_code_prs,
d_late_code_prs,
d_early_subcarrier_prs,
d_prompt_subcarrier_prs,
d_late_subcarrier_prs,
d_Prompt_Subcarrier_Early_Code_prs,
d_Prompt_Subcarrier_Prompt_Code_prs,
d_Prompt_Subcarrier_Late_Code_prs,
d_Prompt_Code_Early_Subcarrier_prs,
d_Prompt_Code_Late_Subcarrier_prs );
}
// Now update the code and carrier phase estimates:
double chips_to_halfcycles_prs = Galileo_E1_A_SUB_CARRIER_RATE_HZ /
@@ -892,13 +935,25 @@ int galileo_e1_prs_de_tracking_cc::general_work (int noutput_items,gr_vector_int
// ################## SLL ##########################################################
// SLL discriminator
subcarrier_error_cycles_prs = dll_nc_e_minus_l_normalized(
*d_Prompt_Code_Early_Subcarrier_prs,
*d_Prompt_Code_Late_Subcarrier_prs); //[chips/Ti]
// normalise the SLL discriminator by the slope of the
// BOC(1,1) at the origin:
corr_slope = 2.0;
subcarrier_error_cycles_prs *= ( 1 - corr_slope*d_early_late_subcarrier_spc_cycles) / corr_slope;
if( d_prs_sinusoidal_subcarrier )
{
gr_complex Z = (
*d_Prompt_Code_Quadrature_Subcarrier_prs /
*d_Prompt_Subcarrier_Prompt_Code_prs );
subcarrier_error_cycles_prs = std::atan( Z.real() ) / static_cast<float>(GPS_TWO_PI);
}
else
{
subcarrier_error_cycles_prs = dll_nc_e_minus_l_normalized(
*d_Prompt_Code_Early_Subcarrier_prs,
*d_Prompt_Code_Late_Subcarrier_prs); //[chips/Ti]
// normalise the SLL discriminator by the slope of the
// BOC(1,1) at the origin:
corr_slope = 2.0;
subcarrier_error_cycles_prs *= ( 1 - corr_slope*d_early_late_subcarrier_spc_cycles) / corr_slope;
}
// Subcarrier discriminator filter
subcarrier_error_filt_cycles_prs = d_subcarrier_loop_filter_prs.apply(subcarrier_error_cycles_prs); //[chips/second]
@@ -1206,11 +1261,19 @@ int galileo_e1_prs_de_tracking_cc::general_work (int noutput_items,gr_vector_int
// PRS Variables:
prompt_I = (*d_Prompt_Subcarrier_Prompt_Code_prs).real();
prompt_Q = (*d_Prompt_Subcarrier_Prompt_Code_prs).imag();
tmp_VE = std::abs<float>(*d_Prompt_Code_Early_Subcarrier_prs);
if( d_prs_sinusoidal_subcarrier )
{
tmp_VE = d_Prompt_Code_Quadrature_Subcarrier_prs->real();
tmp_VL = d_Prompt_Code_Quadrature_Subcarrier_prs->imag();
}
else
{
tmp_VE = std::abs<float>(*d_Prompt_Code_Early_Subcarrier_prs);
tmp_VL = std::abs<float>(*d_Prompt_Code_Late_Subcarrier_prs);
}
tmp_E = std::abs<float>(*d_Prompt_Subcarrier_Early_Code_prs);
tmp_P = std::abs<float>(*d_Prompt_Subcarrier_Prompt_Code_prs);
tmp_L = std::abs<float>(*d_Prompt_Subcarrier_Late_Code_prs);
tmp_VL = std::abs<float>(*d_Prompt_Code_Late_Subcarrier_prs);
// Dump correlators output
d_dump_file.write(reinterpret_cast<char*>(&tmp_VE), sizeof(float));
d_dump_file.write(reinterpret_cast<char*>(&tmp_E), sizeof(float));

9
src/algorithms/tracking/gnuradio_blocks/galileo_e1_prs_de_tracking_cc.h
View File

@@ -71,6 +71,7 @@ galileo_e1_prs_de_make_tracking_cc(long if_freq,
float early_late_subcarrier_space_cycles,
bool aid_subcarrier_with_carrier,
bool aid_code_with_subcarrier,
bool prs_sinusoidal_subcarrier,
LongCodeInterface_sptr prs_code_gen);
/*!
@@ -120,6 +121,7 @@ private:
float early_late_subcarrier_space_cycles,
bool aid_subcarrier_with_carrier,
bool aid_code_with_subcarrier,
bool prs_sinusoidal_subcarrier,
LongCodeInterface_sptr prs_code_gen);
galileo_e1_prs_de_tracking_cc(long if_freq,
@@ -142,6 +144,7 @@ private:
float early_late_subcarrier_space_cycles,
bool aid_subcarrier_with_carrier,
bool aid_code_with_subcarrier,
bool prs_sinusoidal_subcarrier,
LongCodeInterface_sptr prs_code_gen);
void update_local_code();
@@ -192,6 +195,8 @@ private:
gr_complex* d_prompt_subcarrier_prs;
gr_complex* d_late_subcarrier_prs;
gr_complex* d_prompt_quadrature_subcarrier_prs;
gr_complex *d_Prompt_Subcarrier_Early_Code;
gr_complex *d_Prompt_Subcarrier_Prompt_Code;
gr_complex *d_Prompt_Subcarrier_Late_Code;
@@ -204,6 +209,8 @@ private:
gr_complex *d_Prompt_Code_Early_Subcarrier_prs;
gr_complex *d_Prompt_Code_Late_Subcarrier_prs;
gr_complex *d_Prompt_Code_Quadrature_Subcarrier_prs;
// remaining code phase and carrier phase between tracking loops
double d_rem_code_phase_samples;
double d_rem_subcarrier_phase_samples;
@@ -301,6 +308,8 @@ private:
bool d_prs_tracking_enabled;
// Should we approximate the PRS subcarrier as a sinusoid?
bool d_prs_sinusoidal_subcarrier;
// file dump
std::string d_dump_filename;

32
src/algorithms/tracking/libs/correlator.cc
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@@ -290,3 +290,35 @@ void Correlator::Carrier_rotate_and_DE_volk(int signal_length_samples,
volk_free(subcarrier_wipeoff);
volk_free(code_wipeoff);
}
void Correlator::Carrier_rotate_and_DPE_volk(int signal_length_samples,
const gr_complex* input,
gr_complex *phase_as_complex,
gr_complex phase_inc_as_complex,
const gr_complex* E_code,
const gr_complex* P_code,
const gr_complex* L_code,
const gr_complex* P_subcarrier,
const gr_complex* PQ_subcarrier,
gr_complex* P_subcarrier_E_code_out,
gr_complex* P_subcarrier_P_code_out,
gr_complex* P_subcarrier_L_code_out,
gr_complex* P_code_PQ_subcarrier_out )
{
gr_complex* bb_signal = static_cast<gr_complex*>(volk_malloc(signal_length_samples * sizeof(gr_complex), volk_get_alignment()));
gr_complex* subcarrier_wipeoff = static_cast<gr_complex*>(volk_malloc(signal_length_samples * sizeof(gr_complex), volk_get_alignment()));
gr_complex* code_wipeoff = static_cast<gr_complex*>(volk_malloc(signal_length_samples * sizeof(gr_complex), volk_get_alignment()));
volk_32fc_s32fc_x2_rotator_32fc(bb_signal, input, phase_inc_as_complex, phase_as_complex, signal_length_samples);
volk_32fc_x2_multiply_32fc(subcarrier_wipeoff, bb_signal, P_subcarrier, signal_length_samples );
volk_32fc_x2_multiply_32fc(code_wipeoff, bb_signal, P_code, signal_length_samples );
volk_32fc_x2_dot_prod_32fc(P_subcarrier_E_code_out, subcarrier_wipeoff, E_code, signal_length_samples);
volk_32fc_x2_dot_prod_32fc(P_subcarrier_P_code_out, subcarrier_wipeoff, P_code, signal_length_samples);
volk_32fc_x2_dot_prod_32fc(P_subcarrier_L_code_out, subcarrier_wipeoff, L_code, signal_length_samples);
volk_32fc_x2_dot_prod_32fc(P_code_PQ_subcarrier_out, code_wipeoff, PQ_subcarrier, signal_length_samples);
volk_free(bb_signal);
volk_free(subcarrier_wipeoff);
volk_free(code_wipeoff);
}

14
src/algorithms/tracking/libs/correlator.h
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@@ -146,6 +146,20 @@ public:
gr_complex* P_code_E_subcarrier_out,
gr_complex* P_code_L_subcarrier_out );
void Carrier_rotate_and_DPE_volk(int signal_length_samples,
const gr_complex* input,
gr_complex *phase_as_complex,
gr_complex phase_inc_as_complex,
const gr_complex* E_code,
const gr_complex* P_code,
const gr_complex* L_code,
const gr_complex* P_subcarrier,
const gr_complex* PQ_subcarrier,
gr_complex* P_subcarrier_E_code_out,
gr_complex* P_subcarrier_P_code_out,
gr_complex* P_subcarrier_L_code_out,
gr_complex* P_code_PQ_subcarrier_out );
private:
unsigned long next_power_2(unsigned long v);
};