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-rw-r--r--src/lib/gsm_receiver_cf.h246
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();
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