kopia lustrzana https://github.com/f4exb/sdrangel
92 wiersze
3.3 KiB
C
92 wiersze
3.3 KiB
C
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#ifndef P25P1_HEURISTICS_H_030dd3530b7546abbb56f8dd1e66a2f6
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#define P25P1_HEURISTICS_H_030dd3530b7546abbb56f8dd1e66a2f6
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#define HEURISTICS_SIZE 200
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typedef struct
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{
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int values[HEURISTICS_SIZE];
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float means[HEURISTICS_SIZE];
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int index;
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int count;
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float sum;
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float var_sum;
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} SymbolHeuristics;
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typedef struct
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{
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unsigned int bit_count;
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unsigned int bit_error_count;
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SymbolHeuristics symbols[4][4];
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} P25Heuristics;
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typedef struct
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{
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int value;
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int dibit;
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int corrected_dibit;
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int sequence_broken;
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} AnalogSignal;
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#ifdef __cplusplus
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extern "C"{
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#endif
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/**
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* Initializes the heuristics state.
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* \param heuristics The P25Heuristics structure to initialize.
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*/
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void initialize_p25_heuristics(P25Heuristics* heuristics);
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/**
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* Important method that estimates the most likely symbol for a given analog signal value and previous dibit.
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* This is called by the digitizer.
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* \param rf_mod Indicates the modulation used. The previous dibit is only used on C4FM.
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* \param heuristics Pointer to the P25Heuristics module with all the needed state information.
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* \param previous_dibit The previous dibit.
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* \param analog_value The signal's analog value we want to interpret as a dibit.
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* \param dibit Address were to store the estimated dibit.
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* \return A boolean set to true if we are able to estimate a dibit. The reason why we might not be able
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* to estimate it is because we don't have enough information to model the Gaussians (not enough data
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* has been passed to contribute_to_heuristics).
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*/
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int estimate_symbol(int rf_mod, P25Heuristics* heuristics, int previous_dibit, int analog_value, int* dibit);
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/**
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* Log some useful information on the heuristics state.
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*/
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void debug_print_heuristics(P25Heuristics* heuristics);
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/**
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* This method contributes valuable information from dibits whose value we are confident is correct. We take
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* the dibits and corresponding analog signal values to model the Gaussians for each dibit (and previous
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* dibit if enabled).
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* \param rf_mod Indicates the modulation used. The previous dibit is only used on C4FM.
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* \param heuristics Pointer to the P25Heuristics module with all the needed state information.
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* \param analog_signal_array Sequence of AnalogSignal which contain the cleared dibits and analog values.
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* \param count number of cleared dibits passed (= number of elements to use from analog_signal_array).
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*/
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void contribute_to_heuristics(int rf_mod, P25Heuristics* heuristics, AnalogSignal* analog_signal_array, int count);
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/**
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* Updates the estimate for the BER (bit error rate). Mind this is method is not called for every single
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* bit in the data stream but only for those bits over which we have an estimate of its error rate,
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* specifically the bits that are protected by Reed-Solomon codes.
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* \param heuristics The heuristics state.
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* \param bits The number of bits we have read.
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* \param errors The number of errors we estimate in those bits.
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*/
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void update_error_stats(P25Heuristics* heuristics, int bits, int errors);
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/**
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* Returns the estimate for the BER (bit error rate).
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* \return The estimated BER. This is just the percentage of errors over the processed bits.
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*/
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float get_P25_BER_estimate(P25Heuristics* heuristics);
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#ifdef __cplusplus
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}
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#endif
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#endif // P25P1_HEURISTICS_H_030dd3530b7546abbb56f8dd1e66a2f6
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