v17rx.h

传真通信V27 V29 V17 T38解调与解码

/* We can store more trellis depth that we look back over, so that we can push out a group
   of symbols in one go, giving greater processing efficiency, at the expense of a bit more
   latency through the modem. */
/* Right now we don't take advantage of this optimisation. */
#define V17_TRELLIS_STORAGE_DEPTH   16
#define V17_TRELLIS_LOOKBACK_DEPTH  16

/*!
    V.17 modem receive side descriptor. This defines the working state for a
    single instance of a V.17 modem receiver.
*/
typedef struct
{
    /*! \brief The bit rate of the modem. Valid values are 7200 9600, 12000 and 14400. */
    int bit_rate;
    /*! \brief The callback function used to put each bit received. */
    put_bit_func_t put_bit;
    /*! \brief A user specified opaque pointer passed to the put_but routine. */
    void *user_data;
    /*! \brief A callback function which may be enabled to report every symbol's
               constellation position. */
    qam_report_handler_t *qam_report;
    /*! \brief A user specified opaque pointer passed to the qam_report callback
               routine. */
    void *qam_user_data;

    /*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */
#if defined(USE_FIXED_POINTx)
    int32_t rrc_filter[2*V17_RX_FILTER_STEPS];
#else
    float rrc_filter[2*V17_RX_FILTER_STEPS];
#endif
    /*! \brief Current offset into the RRC pulse shaping filter buffer. */
    int rrc_filter_step;

    /*! \brief The state of the differential decoder */
    int diff;
    /*! \brief The register for the data scrambler. */
    unsigned int scramble_reg;
    /*! \brief TRUE if the short training sequence is to be used. */
    int short_train;
    /*! \brief The section of the training data we are currently in. */
    int training_stage;
    int training_count;
    float training_error;
    /*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */
    int16_t last_sample;
    /*! \brief >0 if a signal above the minimum is present. It may or may not be a V.17 signal. */
    int signal_present;

    /*! \brief The current phase of the carrier (i.e. the DDS parameter). */
    uint32_t carrier_phase;
    /*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
    int32_t carrier_phase_rate;
    /*! \brief The carrier update rate saved for reuse when using short training. */
    int32_t carrier_phase_rate_save;
    float carrier_track_p;
    float carrier_track_i;

    /*! \brief The received signal power monitor. */
    power_meter_t power;
    int32_t carrier_on_power;
    int32_t carrier_off_power;
    float agc_scaling;
    float agc_scaling_save;

    float eq_delta;
    /*! \brief The adaptive equalizer coefficients */
#if defined(USE_FIXED_POINTx)
    complexi_t eq_coeff[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
    complexi_t eq_coeff_save[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
    complexi_t eq_buf[V17_EQUALIZER_MASK + 1];
#else
    complexf_t eq_coeff[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
    complexf_t eq_coeff_save[V17_EQUALIZER_PRE_LEN + 1 + V17_EQUALIZER_POST_LEN];
    complexf_t eq_buf[V17_EQUALIZER_MASK + 1];
#endif
    /*! \brief Current offset into equalizer buffer. */
    int eq_step;
    int eq_put_step;

    /*! \brief The current half of the baud. */
    int baud_half;
    /*! \brief Band edge symbol sync. filter state. */
#if defined(USE_FIXED_POINTx)
    int32_t symbol_sync_low[2];
    int32_t symbol_sync_high[2];
    int32_t symbol_sync_dc_filter[2];
    int32_t baud_phase;
#else
    float symbol_sync_low[2];
    float symbol_sync_high[2];
    float symbol_sync_dc_filter[2];
    float baud_phase;
#endif
    /*! \brief The total symbol timing correction since the carrier came up.
               This is only for performance analysis purposes. */
    int total_baud_timing_correction;

    /*! \brief Starting phase angles for the coarse carrier aquisition step. */
    int32_t start_angles[2];
    /*! \brief History list of phase angles for the coarse carrier aquisition step. */
    int32_t angles[16];
    /*! \brief A pointer to the current constellation. */
#if defined(USE_FIXED_POINTx)
    const complexi_t *constellation;
#else
    const complexf_t *constellation;
#endif
    /*! \brief A pointer to the current space map. There is a space map for
               each trellis state. */
    int space_map;
    /*! \brief The number of bits in each symbol at the current bit rate. */
    int bits_per_symbol;

    /*! \brief Current pointer to the trellis buffers */
    int trellis_ptr;
    /*! \brief The trellis. */
    int full_path_to_past_state_locations[V17_TRELLIS_STORAGE_DEPTH][8];
    /*! \brief The trellis. */
    int past_state_locations[V17_TRELLIS_STORAGE_DEPTH][8];
    /*! \brief Euclidean distances (actually the sqaures of the distances)
               from the last states of the trellis. */
#if defined(USE_FIXED_POINTx)
    int32_t distances[8];
#else
    float distances[8];
#endif
    /*! \brief Error and flow logging control */
    logging_state_t logging;
} v17_rx_state_t;

#ifdef __cplusplus
extern "C"
{
#endif

/*! Initialise a V.17 modem receive context.
    \brief Initialise a V.17 modem receive context.
    \param s The modem context.
    \param rate The bit rate of the modem. Valid values are 7200, 9600, 12000 and 14400.
    \param put_bit The callback routine used to put the received data.
    \param user_data An opaque pointer passed to the put_bit routine.
    \return A pointer to the modem context, or NULL if there was a problem. */
v17_rx_state_t *v17_rx_init(v17_rx_state_t *s, int rate, put_bit_func_t put_bit, void *user_data);

/*! Reinitialise an existing V.17 modem receive context.
    \brief Reinitialise an existing V.17 modem receive context.
    \param s The modem context.
    \param rate The bit rate of the modem. Valid values are 7200, 9600, 12000 and 14400.
    \param short_train TRUE if a short training sequence is expected.
    \return 0 for OK, -1 for bad parameter */
int v17_rx_restart(v17_rx_state_t *s, int rate, int short_train);

/*! Release a V.17 modem receive context.
    \brief Release a V.17 modem receive context.
    \param s The modem context.
    \return 0 for OK */
int v17_rx_release(v17_rx_state_t *s);

/*! Change the put_bit function associated with a V.17 modem receive context.
    \brief Change the put_bit function associated with a V.17 modem receive context.
    \param s The modem context.
    \param put_bit The callback routine used to handle received bits.
    \param user_data An opaque pointer. */
void v17_rx_set_put_bit(v17_rx_state_t *s, put_bit_func_t put_bit, void *user_data);

/*! Process a block of received V.17 modem audio samples.
    \brief Process a block of received V.17 modem audio samples.
    \param s The modem context.
    \param amp The audio sample buffer.
    \param len The number of samples in the buffer.
*/
void v17_rx(v17_rx_state_t *s, const int16_t amp[], int len);

/*! Get a snapshot of the current equalizer coefficients.
    \brief Get a snapshot of the current equalizer coefficients.
    \param s The modem context.
    \param coeffs The vector of complex coefficients.
    \return The number of coefficients in the vector. */
#if defined(USE_FIXED_POINTx)
int v17_rx_equalizer_state(v17_rx_state_t *s, complexi_t **coeffs);
#else
int v17_rx_equalizer_state(v17_rx_state_t *s, complexf_t **coeffs);
#endif

/*! Get the current received carrier frequency.
    \param s The modem context.
    \return The frequency, in Hertz. */
float v17_rx_carrier_frequency(v17_rx_state_t *s);

/*! Get the current symbol timing correction since startup.
    \param s The modem context.
    \return The correction. */
float v17_rx_symbol_timing_correction(v17_rx_state_t *s);

/*! Get a current received signal power.
    \param s The modem context.
    \return The signal power, in dBm0. */
float v17_rx_signal_power(v17_rx_state_t *s);

/*! Set the power level at which the carrier detection will cut in
    \param s The modem context.
    \param cutoff The signal cutoff power, in dBm0. */
void v17_rx_signal_cutoff(v17_rx_state_t *s, float cutoff);

/*! Set a handler routine to process QAM status reports
    \param s The modem context.
    \param handler The handler routine.
    \param user_data An opaque pointer passed to the handler routine. */
void v17_rx_set_qam_report_handler(v17_rx_state_t *s, qam_report_handler_t *handler, void *user_data);

#ifdef __cplusplus
}
#endif

#endif
/*- End of file ------------------------------------------------------------*/