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Code Issues Releases Wiki Activity

New correlation procedure

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This commit is contained in:
Antonio Ramos 2018-04-12 11:03:52 +02:00
parent 6de28277ed
commit f92dd4dc83
2 changed files with 13 additions and 2 deletions
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11
src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.cc
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@ -107,6 +107,8 @@ gps_l1_ca_telemetry_decoder_cc::gps_l1_ca_telemetry_decoder_cc(
d_TOW_at_current_symbol_ms = 0; d_TOW_at_current_symbol_ms = 0;
d_symbol_history.resize(GPS_CA_PREAMBLE_LENGTH_SYMBOLS + 1); // Change fixed buffer size d_symbol_history.resize(GPS_CA_PREAMBLE_LENGTH_SYMBOLS + 1); // Change fixed buffer size
d_symbol_history.clear(); // Clear all the elements in the buffer d_symbol_history.clear(); // Clear all the elements in the buffer
d_make_correlation = true;
d_symbol_counter_corr = 0;
} }
@ -170,7 +172,7 @@ int gps_l1_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__
unsigned int required_symbols = GPS_CA_PREAMBLE_LENGTH_SYMBOLS; unsigned int required_symbols = GPS_CA_PREAMBLE_LENGTH_SYMBOLS;
d_flag_preamble = false; d_flag_preamble = false;
if (d_symbol_history.size() > required_symbols) if (d_symbol_history.size() > required_symbols and d_make_correlation)
{ {
//******* preamble correlation ******** //******* preamble correlation ********
for (unsigned int i = 0; i < GPS_CA_PREAMBLE_LENGTH_SYMBOLS; i++) for (unsigned int i = 0; i < GPS_CA_PREAMBLE_LENGTH_SYMBOLS; i++)
@ -186,7 +188,12 @@ int gps_l1_ca_telemetry_decoder_cc::general_work(int noutput_items __attribute__
corr_value += d_preambles_symbols[i] * d_symbol_history.at(i).correlation_length_ms; corr_value += d_preambles_symbols[i] * d_symbol_history.at(i).correlation_length_ms;
} }
} }
if (corr_value >= GPS_CA_PREAMBLE_LENGTH_SYMBOLS) break; if (corr_value >= GPS_CA_PREAMBLE_LENGTH_SYMBOLS)
{
d_symbol_counter_corr = 0;
d_make_correlation = false;
break;
}
} }
} }

4
src/algorithms/telemetry_decoder/gnuradio_blocks/gps_l1_ca_telemetry_decoder_cc.h
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@ -84,6 +84,10 @@ private:
double d_symbol_accumulator; double d_symbol_accumulator;
short int d_symbol_accumulator_counter; short int d_symbol_accumulator_counter;
// symbol counting
bool d_make_correlation;
unsigned int d_symbol_counter_corr;
//bits and frame //bits and frame
unsigned short int d_frame_bit_index; unsigned short int d_frame_bit_index;
unsigned int d_GPS_frame_4bytes; unsigned int d_GPS_frame_4bytes;