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Optimizing GPS L1 CA bit transitiion detection by using a bit transition slope pattern

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This commit is contained in:
Javier Arribas 2021-09-27 16:11:17 +02:00
parent e9f7a36663
commit d6ed2698e6
2 changed files with 5 additions and 3 deletions
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6
src/algorithms/tracking/gnuradio_blocks/dll_pll_veml_tracking.cc
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@ -141,9 +141,9 @@ dll_pll_veml_tracking::dll_pll_veml_tracking(const Dll_Pll_Conf &conf_) : gr::bl
d_trk_parameters.spc = d_trk_parameters.early_late_space_chips; d_trk_parameters.spc = d_trk_parameters.early_late_space_chips;
d_trk_parameters.y_intercept = 1.0; d_trk_parameters.y_intercept = 1.0;
// symbol integration: 20 trk symbols (20 ms) = 1 tlm bit // symbol integration: 20 trk symbols (20 ms) = 1 tlm bit
// set the preamble in the secondary code acquisition to obtain tlm symbol synchronization // set the bit transition pattern in secondary code to obtain bit synchronization
d_secondary_code_length = static_cast<uint32_t>(GPS_CA_PREAMBLE_LENGTH_SYMBOLS); d_secondary_code_length = static_cast<uint32_t>(GPS_CA_BIT_TRANSITION_SYMBOLS_LENGTH_SYMBOLS);
d_secondary_code_string = GPS_CA_PREAMBLE_SYMBOLS_STR; d_secondary_code_string = GPS_CA_BIT_TRANSITION_SYMBOLS_STR;
d_symbols_per_bit = GPS_CA_TELEMETRY_SYMBOLS_PER_BIT; d_symbols_per_bit = GPS_CA_TELEMETRY_SYMBOLS_PER_BIT;
} }
else if (d_signal_type == "2S") else if (d_signal_type == "2S")

2
src/core/system_parameters/GPS_L1_CA.h
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@ -71,6 +71,8 @@ constexpr int32_t GPS_SUBFRAME_MS = 6000;
constexpr int32_t GPS_WORD_BITS = 30; //!< Number of bits per word in the NAV message [bits] constexpr int32_t GPS_WORD_BITS = 30; //!< Number of bits per word in the NAV message [bits]
constexpr char GPS_CA_PREAMBLE[9] = "10001011"; constexpr char GPS_CA_PREAMBLE[9] = "10001011";
constexpr char GPS_CA_PREAMBLE_SYMBOLS_STR[161] = "1111111111111111111100000000000000000000000000000000000000000000000000000000000011111111111111111111000000000000000000001111111111111111111111111111111111111111"; constexpr char GPS_CA_PREAMBLE_SYMBOLS_STR[161] = "1111111111111111111100000000000000000000000000000000000000000000000000000000000011111111111111111111000000000000000000001111111111111111111111111111111111111111";
constexpr int32_t GPS_CA_BIT_TRANSITION_SYMBOLS_LENGTH_SYMBOLS = 40;
constexpr char GPS_CA_BIT_TRANSITION_SYMBOLS_STR[41] = "1111111111111111111100000000000000000000";
// GPS NAVIGATION MESSAGE STRUCTURE // GPS NAVIGATION MESSAGE STRUCTURE
// NAVIGATION MESSAGE FIELDS POSITIONS (from IS-GPS-200M Appendix II) // NAVIGATION MESSAGE FIELDS POSITIONS (from IS-GPS-200M Appendix II)