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TTFF reduction in GPS L1 and Galileo E1

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This commit is contained in:
Javier Arribas committed 2021-08-03 14:03:27 +02:00
1 parent b4b9c31182
commit 23a2d3ef89
8 files changed
+90 -54
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src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_telemetry_decoder_gs.cc
+15
View File
@@ -581,6 +581,11 @@ void galileo_telemetry_decoder_gs::set_satellite(const Gnss_Satellite &satellite
void galileo_telemetry_decoder_gs::reset()
{
gr::thread::scoped_lock lock(d_setlock);
d_flag_frame_sync = false;
d_TOW_at_current_symbol_ms = 0;
d_TOW_at_Preamble_ms = 0;
d_fnav_nav.set_flag_TOW_set(false);
d_inav_nav.set_flag_TOW_set(false);
d_last_valid_preamble = d_sample_counter;
d_sent_tlm_failed_msg = false;
d_stat = 0;
@@ -840,6 +845,15 @@ int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((
d_TOW_at_current_symbol_ms = d_TOW_at_Preamble_ms + static_cast<uint32_t>(GALILEO_INAV_PAGE_PART_MS + (d_required_symbols + 1) * d_PRN_code_period_ms);
d_inav_nav.set_TOW6_flag(false);
}
//warning: type 0 frame does not contain a valid TOW in some simulated signals, thus it is not safe to activate the following code:
// else if (d_inav_nav.is_TOW0_set() == true) // page 0 arrived and decoded
// {
// // TOW_0 refers to the even preamble, but when we decode it we are in the odd part, so 1 second later plus the decoding delay
// d_TOW_at_Preamble_ms = static_cast<uint32_t>(d_inav_nav.get_TOW0() * 1000.0);
// d_TOW_at_current_symbol_ms = d_TOW_at_Preamble_ms + static_cast<uint32_t>(GALILEO_INAV_PAGE_PART_MS + (d_required_symbols + 1) * d_PRN_code_period_ms);
// d_inav_nav.set_TOW0_flag(false);
// //std::cout << "FRAME 0 current tow: " << tmp_d_TOW_at_current_symbol_ms << " vs. " << d_TOW_at_current_symbol_ms + d_PRN_code_period_ms << "\n";
// }
else
{
// this page has no timing information
@@ -955,6 +969,7 @@ int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((
if (d_inav_nav.get_flag_TOW_set() == true or d_fnav_nav.get_flag_TOW_set() == true or d_cnav_nav.get_flag_CRC_test() == true)
{
//std::cout << "TOW is set\n";
current_symbol.TOW_at_current_symbol_ms = d_TOW_at_current_symbol_ms;
// todo: Galileo to GPS time conversion should be moved to observable block.
// current_symbol.TOW_at_current_symbol_ms -= d_delta_t; // Galileo to GPS TOW
src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_gs.cc
+40 -52
View File
@@ -294,6 +294,24 @@ bool gps_l1_ca_telemetry_decoder_gs::decode_subframe()
switch (subframe_ID)
{
case 1:
if (d_nav.satellite_validation() == true)
{
// get ephemeris object for this SV (mandatory)
const std::shared_ptr<Gps_Ephemeris> tmp_obj = std::make_shared<Gps_Ephemeris>(d_nav.get_ephemeris());
this->message_port_pub(pmt::mp("telemetry"), pmt::make_any(tmp_obj));
}
break;
case 2:
if (d_nav.satellite_validation() == true)
{
// get ephemeris object for this SV (mandatory)
const std::shared_ptr<Gps_Ephemeris> tmp_obj = std::make_shared<Gps_Ephemeris>(d_nav.get_ephemeris());
this->message_port_pub(pmt::mp("telemetry"), pmt::make_any(tmp_obj));
}
break;
case 3: // we have a new set of ephemeris data for the current SV
if (d_nav.satellite_validation() == true)
{
@@ -389,63 +407,33 @@ int gps_l1_ca_telemetry_decoder_gs::general_work(int noutput_items __attribute__
if (abs(corr_value) >= d_samples_per_preamble)
{
d_preamble_index = d_sample_counter; // record the preamble sample stamp
if (corr_value < 0)
{
d_flag_PLL_180_deg_phase_locked = true;
}
else
{
d_flag_PLL_180_deg_phase_locked = false;
}
DLOG(INFO) << "Preamble detection for GPS L1 satellite " << this->d_satellite;
decode_subframe();
d_stat = 1; // enter into frame pre-detection status
if (decode_subframe())
{
d_CRC_error_counter = 0;
d_flag_preamble = true; // valid preamble indicator (initialized to false every work())
gr::thread::scoped_lock lock(d_setlock);
d_last_valid_preamble = d_sample_counter;
if (!d_flag_frame_sync)
{
d_flag_frame_sync = true;
DLOG(INFO) << " Frame sync SAT " << this->d_satellite;
}
d_stat = 1; // preamble acquired
}
}
d_flag_TOW_set = false;
break;
}
case 1: // possible preamble lock
{
// correlate with preamble
int32_t corr_value = 0;
if (d_symbol_history.size() >= GPS_CA_PREAMBLE_LENGTH_BITS)
{
// ******* preamble correlation ********
for (int32_t i = 0; i < GPS_CA_PREAMBLE_LENGTH_BITS; i++)
{
if (d_symbol_history[i] < 0.0) // symbols clipping
{
corr_value -= d_preamble_samples[i];
}
else
{
corr_value += d_preamble_samples[i];
}
}
}
if (abs(corr_value) >= d_samples_per_preamble)
{
// check preamble separation
const auto preamble_diff = static_cast<int32_t>(d_sample_counter - d_preamble_index);
if (abs(preamble_diff - d_preamble_period_symbols) == 0)
{
DLOG(INFO) << "Preamble confirmation for SAT " << this->d_satellite;
d_preamble_index = d_sample_counter; // record the preamble sample stamp
if (corr_value < 0)
{
d_flag_PLL_180_deg_phase_locked = true;
}
else
{
d_flag_PLL_180_deg_phase_locked = false;
}
decode_subframe();
d_stat = 2;
}
else
{
if (preamble_diff > d_preamble_period_symbols)
{
d_stat = 0; // start again
d_flag_TOW_set = false;
}
}
}
break;
}
case 2: // preamble acquired
case 1: // preamble acquired
{
if (d_sample_counter >= d_preamble_index + static_cast<uint64_t>(d_preamble_period_symbols))
{