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optimization in Galileo E1/E5 TLM decoder state machine

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This commit is contained in:
Javier Arribas 2019-04-16 10:08:56 +02:00
parent 5e5c85ef99
commit 35b5ec1112
2 changed files with 40 additions and 21 deletions
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60
src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_telemetry_decoder_gs.cc
View File

@ -215,7 +215,7 @@ galileo_telemetry_decoder_gs::galileo_telemetry_decoder_gs(
d_flag_preamble = false;
d_channel = 0;
flag_TOW_set = false;
flag_PLL_180_deg_phase_locked = false;
d_symbol_history.set_capacity(d_required_symbols + 1);
// vars for Viterbi decoder
@ -488,9 +488,6 @@ void galileo_telemetry_decoder_gs::set_channel(int32_t channel)
int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((unused)), gr_vector_int &ninput_items __attribute__((unused)),
gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
{
int32_t corr_value = 0;
int32_t preamble_diff = 0;
auto **out = reinterpret_cast<Gnss_Synchro **>(&output_items[0]); // Get the output buffer pointer
const auto **in = reinterpret_cast<const Gnss_Synchro **>(&input_items[0]); // Get the input buffer pointer
@ -513,27 +510,29 @@ int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((
d_sent_tlm_failed_msg = true;
}
}
if (d_symbol_history.size() > d_required_symbols)
{
// ******* preamble correlation ********
for (int32_t i = 0; i < d_samples_per_preamble; i++)
{
if (d_symbol_history[i] < 0.0) // symbols clipping
{
corr_value -= d_preamble_samples[i];
}
else
{
corr_value += d_preamble_samples[i];
}
}
}
// ******* frame sync ******************
switch (d_stat)
{
case 0: // no preamble information
{
//correlate with preamble
int32_t corr_value = 0;
if (d_symbol_history.size() > d_required_symbols)
{
// ******* preamble correlation ********
for (int32_t i = 0; i < d_samples_per_preamble; 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)
{
d_preamble_index = d_sample_counter; // record the preamble sample stamp
@ -544,6 +543,24 @@ int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((
}
case 1: // possible preamble lock
{
//correlate with preamble
int32_t corr_value = 0;
int32_t preamble_diff = 0;
if (d_symbol_history.size() > d_required_symbols)
{
// ******* preamble correlation ********
for (int32_t i = 0; i < d_samples_per_preamble; 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
@ -554,6 +571,7 @@ int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((
DLOG(INFO) << "Starting page decoder for Galileo satellite " << this->d_satellite;
d_preamble_index = d_sample_counter; // record the preamble sample stamp
d_CRC_error_counter = 0;
if (corr_value < 0) flag_PLL_180_deg_phase_locked = true;
d_stat = 2;
}
else
@ -576,7 +594,7 @@ int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((
case 1: // INAV
// NEW Galileo page part is received
// 0. fetch the symbols into an array
if (corr_value > 0) // normal PLL lock
if (flag_PLL_180_deg_phase_locked == false) // normal PLL lock
{
for (uint32_t i = 0; i < d_frame_length_symbols; i++)
{
@ -595,7 +613,7 @@ int galileo_telemetry_decoder_gs::general_work(int noutput_items __attribute__((
case 2: // FNAV
// NEW Galileo page part is received
// 0. fetch the symbols into an array
if (corr_value > 0) // normal PLL lock
if (flag_PLL_180_deg_phase_locked == false) // normal PLL lock
{
int k = 0;
for (uint32_t i = 0; i < d_frame_length_symbols; i++)

1
src/algorithms/telemetry_decoder/gnuradio_blocks/galileo_telemetry_decoder_gs.h
View File

@ -102,6 +102,7 @@ private:
bool d_sent_tlm_failed_msg;
uint32_t d_stat;
bool d_flag_frame_sync;
bool flag_PLL_180_deg_phase_locked;
bool d_flag_parity;
bool d_flag_preamble;