diff options
Diffstat (limited to 'src/lib/gsm_receiver_cf.h')
| -rw-r--r-- | src/lib/gsm_receiver_cf.h | 246 |
1 files changed, 134 insertions, 112 deletions
diff --git a/src/lib/gsm_receiver_cf.h b/src/lib/gsm_receiver_cf.h index d35e4da..b937f76 100644 --- a/src/lib/gsm_receiver_cf.h +++ b/src/lib/gsm_receiver_cf.h @@ -37,8 +37,9 @@ typedef std::vector<gr_complex> vector_complex; gsm_receiver_cf_sptr gsm_make_receiver_cf(gr_feval_dd *tuner, int osr); /** GSM Receiver GNU Radio block + * * GSM Receiver class supports frequency correction, synchronisation and - * MLSE (Maximum Likelihood Sequence Estimation) estimation of synchronisation + * MLSE (Maximum Likelihood Sequence Estimation) estimation of synchronisation * bursts and normal bursts. * \ingroup block */ @@ -46,148 +47,169 @@ gsm_receiver_cf_sptr gsm_make_receiver_cf(gr_feval_dd *tuner, int osr); class gsm_receiver_cf : public gr_block { private: - - const int d_OSR; - const int d_chan_imp_length; + + /**@name Configuration of the receiver */ + //@{ + const int d_OSR; ///< oversampling ratio + const int d_chan_imp_length; ///< channel impulse length + //@} gr_complex d_sch_training_seq[N_SYNC_BITS]; ///<encoded training sequence of a SCH burst gr_complex d_norm_training_seq[TRAIN_SEQ_NUM][N_TRAIN_BITS]; ///<encoded training sequences of a normal bursts and dummy bursts gr_feval_dd *d_tuner; ///<callback to a python object which is used for frequency tunning - unsigned d_samples_counter; ///<samples counter - this is used in beetween find_fcch_burst and find_sch_burst - - //variables used to store result of the find_fcch_burst fuction -// unsigned d_fcch_start_pos; - float d_freq_offset; - - burst_counter d_burst_nr; - channel_configuration d_channel_conf; - - vector_complex d_channel_imp_resp; - - int d_ncc; - int d_bcc; + /** Countes samples consumed by the receiver + * + * It is used in beetween find_fcch_burst and find_sch_burst calls. + * My intention was to synchronize this counter with some internal sample + * counter of the USRP. Simple access to such USRP's counter isn't possible + * so this variable isn't used in the "synchronized" state of the receiver yet. + */ + unsigned d_counter; + + /**@name Variables used to store result of the find_fcch_burst fuction */ + //@{ + unsigned d_fcch_start_pos; ///< position of the first sample of the fcch burst + float d_freq_offset; ///< frequency offset of the received signal + //@} + + /**@name Identifiers of the BTS extracted from the SCH burst */ + //@{ + int d_ncc; ///< network color code + int d_bcc; ///< base station color code + //@} + + /**@name Internal state of the gsm receiver */ + //@{ enum states { - first_fcch_search, next_fcch_search, sch_search, //synchronization search part - synchronized //receiver is synchronized in this state + first_fcch_search, next_fcch_search, sch_search, // synchronization search part + synchronized // receiver is synchronized in this state } d_state; + //@} + + /**@name Variables which make internal state in the "synchronized" state */ + //@{ + burst_counter d_burst_nr; ///< frame number and timeslot number + channel_configuration d_channel_conf; ///< mapping of burst_counter to burst_type + //@} friend gsm_receiver_cf_sptr gsm_make_receiver_cf(gr_feval_dd *tuner, int osr); gsm_receiver_cf(gr_feval_dd *tuner, int osr); - - /** - * - * @param in - * @param nitems - * @return + /** Function whis is used to search a FCCH burst and to compute frequency offset before + * "synchronized" state of the receiver + * + * TODO: Describe the FCCH search algorithm in the documentation + * @param input vector with input signal + * @param nitems number of samples in the input vector + * @return */ - bool find_fcch_burst(const gr_complex *in, const int nitems); - - /** - * - * @param best_sum - * @param denominator - * @return + bool find_fcch_burst(const gr_complex *input, const int nitems); + + /** Computes frequency offset from FCCH burst samples + * + * @param input vector with input samples + * @param first_sample number of the first sample of the FCCH busrt + * @param last_sample number of the last sample of the FCCH busrt + * @return frequency offset */ - double compute_freq_offset(double best_sum, unsigned denominator); - - /** - * - * @param freq_offset + double compute_freq_offset(const gr_complex * input, unsigned first_sample, unsigned last_sample); + + /** Calls d_tuner's method to set frequency offset from Python level + * + * @param freq_offset absolute frequency offset of the received signal */ void set_frequency(double freq_offset); - - /** - * - * @param val1 - * @param val2 - * @return + + /** Computes angle between two complex numbers + * + * @param val1 first complex number + * @param val2 second complex number + * @return */ inline float compute_phase_diff(gr_complex val1, gr_complex val2); - /** - * - * @param in - * @param nitems - * @param out - * @return + /** Function whis is used to get near to SCH burst + * + * @param nitems number of samples in the gsm_receiver's buffer + * @return true if SCH burst is near, false otherwise */ - bool find_sch_burst(const gr_complex *in, const int nitems , float *out); - - /** - * - * @param in - * @param chan_imp_resp - * @return + bool find_sch_burst(const int nitems); + + /** Extracts channel impulse response from a SCH burst and computes first sample number of this burst + * + * @param input vector with input samples + * @param chan_imp_resp complex vector where channel impulse response will be stored + * @return number of first sample of the burst */ - int get_sch_chan_imp_resp(const gr_complex *in, gr_complex * chan_imp_resp); - - /** - * - * @param in - * @param chan_imp_resp - * @param burst_start - * @param output_binary + int get_sch_chan_imp_resp(const gr_complex *input, gr_complex * chan_imp_resp); + + /** MLSE detection of a burst bits + * + * Detects bits of burst using viterbi algorithm. + * @param input vector with input samples + * @param chan_imp_resp vector with the channel impulse response + * @param burst_start number of the first sample of the burst + * @param output_binary vector with output bits */ - void detect_burst(const gr_complex * in, gr_complex * chan_imp_resp, int burst_start, unsigned char * output_binary); - - /** - * - * @param input - * @param ninput - * @param gmsk_output - * @param start_point + void detect_burst(const gr_complex * input, gr_complex * chan_imp_resp, int burst_start, unsigned char * output_binary); + + /** Encodes differentially input bits and maps them into MSK states + * + * @param input vector with input bits + * @param nitems number of samples in the "input" vector + * @param gmsk_output bits mapped into MSK states + * @param start_point first state */ - void gmsk_mapper(const unsigned char * input, int ninput, gr_complex * gmsk_output, gr_complex start_point); - - /** - * - * @param sequence - * @param input_signal - * @param ninput - * @return + void gmsk_mapper(const unsigned char * input, int nitems, gr_complex * gmsk_output, gr_complex start_point); + + /** Correlates MSK mapped sequence with input signal + * + * @param sequence MKS mapped sequence + * @param length length of the sequence + * @param input_signal vector with input samples + * @return correlation value */ - gr_complex correlate_sequence(const gr_complex * sequence, const gr_complex * input_signal, int ninput); - - /** - * - * @param input - * @param out - * @param length + gr_complex correlate_sequence(const gr_complex * sequence, int length, const gr_complex * input); + + /** Computes autocorrelation of input vector for positive arguments + * + * @param input vector with input samples + * @param out output vector + * @param nitems length of the input vector */ - inline void autocorrelation(const gr_complex * input, gr_complex * out, int length); - - /** - * - * @param input - * @param input_length - * @param filter - * @param filter_length - * @param output + inline void autocorrelation(const gr_complex * input, gr_complex * out, int nitems); + + /** Filters input signal through channel impulse response + * + * @param input vector with input samples + * @param nitems number of samples to pass through filter + * @param filter filter taps - channel impulse response + * @param filter_length nember of filter taps + * @param output vector with filtered samples */ - inline void mafi(const gr_complex * input, int input_length, gr_complex * filter, int filter_length, gr_complex * output); - - /** - * - * @param in - * @param chan_imp_resp - * @param search_range - * @param bcc - * @return + inline void mafi(const gr_complex * input, int nitems, gr_complex * filter, int filter_length, gr_complex * output); + + /** Extracts channel impulse response from a normal burst and computes first sample number of this burst + * + * @param input vector with input samples + * @param chan_imp_resp complex vector where channel impulse response will be stored + * @param search_range possible absolute offset of a channel impulse response start + * @param bcc base station color code - number of a training sequence + * @return first sample number of normal burst */ - int get_norm_chan_imp_resp(const gr_complex *in, gr_complex * chan_imp_resp, unsigned search_range, int bcc); - + int get_norm_chan_imp_resp(const gr_complex * input, gr_complex * chan_imp_resp, unsigned search_range, int bcc); + /** - * - * @param burst_nr - * @param pakiet + * + * @param burst_nr + * @param pakiet */ void przetwarzaj_normalny_pakiet(burst_counter burst_nr, unsigned char * pakiet); - + /** - * + * */ void konfiguruj_odbiornik(); |