diff options
Diffstat (limited to 'src/fsk.h')
| -rw-r--r-- | src/fsk.h | 171 |
1 files changed, 90 insertions, 81 deletions
@@ -4,7 +4,8 @@ AUTHOR......: Brady O'Brien DATE CREATED: 6 January 2016 - C Implementation of 2FSK/4FSK modulator/demodulator, based on octave/fsk_horus.m + C Implementation of 2FSK/4FSK modulator/demodulator, based on +octave/fsk_horus.m \*---------------------------------------------------------------------------*/ @@ -25,11 +26,11 @@ along with this program; if not, see <http://www.gnu.org/licenses/>. */ - #ifndef __C2FSK_H #define __C2FSK_H #include <stdint.h> + #include "comp.h" #include "kiss_fftr.h" #include "modem_stats.h" @@ -42,92 +43,99 @@ #define FSK_SCALE 16383 /* default internal parameters */ -#define FSK_DEFAULT_P 8 /* Number of timing offsets we have to choose from, try to keep P >= 8 */ -#define FSK_DEFAULT_NSYM 50 /* See Nsym below */ -#define FSK_NONE -1 /* unused parameter */ +#define FSK_DEFAULT_P \ + 8 /* Number of timing offsets we have to choose from, try to keep P >= 8 */ +#define FSK_DEFAULT_NSYM 50 /* See Nsym below */ +#define FSK_NONE -1 /* unused parameter */ struct FSK { - /* Static parameters set up by fsk_init */ - int Ndft; /* freq offset est fft */ - int Fs; /* sample freq */ - int N; /* processing buffer size */ - int Rs; /* symbol rate */ - int Ts; /* samples per symbol */ - int Nmem; /* size of extra mem for timing adj */ - int P; /* oversample rate for timing est/adj */ - int Nsym; /* Number of symbols processed by demodulator in each call, also the timing estimator window */ - int Nbits; /* Number of bits spat out in a processing frame */ - int f1_tx; /* f1 for modulator */ - int tone_spacing; /* Space between TX freqs for modulator (and option mask freq estimator) */ - int mode; /* 2FSK or 4FSK */ - float tc; /* time constant for smoothing FFTs */ - int est_min; /* Minimum frequency for freq. estimator */ - int est_max; /* Maximum frequency for freq. estimator */ - int est_space; /* Minimum frequency spacing for freq. estimator */ - float* hann_table; /* Precomputed or runtime computed hann window table */ - - /* Parameters used by demod */ - float* Sf; /* Average of magnitude spectrum */ - COMP phi_c[MODE_M_MAX]; /* phase of each demod local oscillator */ - COMP *f_dc; /* down converted samples */ - - kiss_fft_cfg fft_cfg; /* Config for KISS FFT, used in freq est */ - float norm_rx_timing; /* Normalized RX timing */ - - /* Parameters used by mod */ - COMP tx_phase_c; /* TX phase, but complex */ - - /* Statistics generated by demod */ - float EbNodB; /* Estimated EbNo in dB */ - float f_est[MODE_M_MAX]; /* Estimated frequencies (peak method) */ - float f2_est[MODE_M_MAX];/* Estimated frequencies (mask method) */ - int freq_est_type; /* which estimator to use */ - float ppm; /* Estimated PPM clock offset */ - float SNRest; /* used for LLRs */ - float v_est; /* used for LLRs */ - float rx_sig_pow; - float rx_nse_pow; - - /* Parameters used by mod/demod and driving code */ - int nin; /* Number of samples to feed the next demod cycle */ - int burst_mode; /* enables/disables 'burst' mode */ - int lock_nin; /* locks nin during testing */ - - /* modem statistics struct */ - struct MODEM_STATS *stats; - int normalise_eye; /* enables/disables normalisation of eye diagram */ + /* Static parameters set up by fsk_init */ + int Ndft; /* freq offset est fft */ + int Fs; /* sample freq */ + int N; /* processing buffer size */ + int Rs; /* symbol rate */ + int Ts; /* samples per symbol */ + int Nmem; /* size of extra mem for timing adj */ + int P; /* oversample rate for timing est/adj */ + int Nsym; /* Number of symbols processed by demodulator in each call, also the + timing estimator window */ + int Nbits; /* Number of bits spat out in a processing frame */ + int f1_tx; /* f1 for modulator */ + int tone_spacing; /* Space between TX freqs for modulator (and option mask + freq estimator) */ + int mode; /* 2FSK or 4FSK */ + float tc; /* time constant for smoothing FFTs */ + int est_min; /* Minimum frequency for freq. estimator */ + int est_max; /* Maximum frequency for freq. estimator */ + int est_space; /* Minimum frequency spacing for freq. estimator */ + float *hann_table; /* Precomputed or runtime computed hann window table */ + + /* Parameters used by demod */ + float *Sf; /* Average of magnitude spectrum */ + COMP phi_c[MODE_M_MAX]; /* phase of each demod local oscillator */ + COMP *f_dc; /* down converted samples */ + + kiss_fft_cfg fft_cfg; /* Config for KISS FFT, used in freq est */ + float norm_rx_timing; /* Normalized RX timing */ + + /* Parameters used by mod */ + COMP tx_phase_c; /* TX phase, but complex */ + + /* Statistics generated by demod */ + float EbNodB; /* Estimated EbNo in dB */ + float f_est[MODE_M_MAX]; /* Estimated frequencies (peak method) */ + float f2_est[MODE_M_MAX]; /* Estimated frequencies (mask method) */ + int freq_est_type; /* which estimator to use */ + float ppm; /* Estimated PPM clock offset */ + float SNRest; /* used for LLRs */ + float v_est; /* used for LLRs */ + float rx_sig_pow; + float rx_nse_pow; + + /* Parameters used by mod/demod and driving code */ + int nin; /* Number of samples to feed the next demod cycle */ + int burst_mode; /* enables/disables 'burst' mode */ + int lock_nin; /* locks nin during testing */ + + /* modem statistics struct */ + struct MODEM_STATS *stats; + int normalise_eye; /* enables/disables normalisation of eye diagram */ }; /* * Create a FSK modem - * + * * int Fs - Sample frequency * int Rs - Symbol rate * int M - 2 for 2FSK, 4 for 4FSK * int f1_tx - first tone frequency - * int tone_spacing - frequency spacing (for modulator and optional "mask" freq estimator) + * int tone_spacing - frequency spacing (for modulator and optional "mask" freq + * estimator) */ -struct FSK * fsk_create(int Fs, int Rs, int M, int f1_tx, int tone_spacing); +struct FSK *fsk_create(int Fs, int Rs, int M, int f1_tx, int tone_spacing); /* * Create a FSK modem - advanced version - * + * * int Fs - Sample frequency * int Rs - Symbol rate * int M - 2 for 2FSK, 4 for 4FSK * int P - number of timing offsets to choose from (suggest >= 8) * int Nsym - windows size for timing estimator * int f1_tx - first tone frequency - * int tone_spacing - frequency spacing (for modulator and optional "mask" freq estimator) + * int tone_spacing - frequency spacing (for modulator and optional "mask" freq + * estimator) */ -struct FSK * fsk_create_hbr(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, int tone_spacing); +struct FSK *fsk_create_hbr(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, + int tone_spacing); /* - * Set the minimum and maximum frequencies at which the freq. estimator can find tones + * Set the minimum and maximum frequencies at which the freq. estimator can find + * tones */ -void fsk_set_freq_est_limits(struct FSK *fsk,int fmin, int fmax); +void fsk_set_freq_est_limits(struct FSK *fsk, int fmin, int fmax); -/* +/* * Clear the estimator states */ void fsk_clear_estimators(struct FSK *fsk); @@ -139,39 +147,41 @@ void fsk_get_demod_stats(struct FSK *fsk, struct MODEM_STATS *stats); /* * Destroy an FSK state struct and free it's memory - * + * * struct FSK *fsk - FSK config/state struct to be destroyed */ void fsk_destroy(struct FSK *fsk); /* * Modulates Nsym bits into N samples - * + * * struct FSK *fsk - FSK config/state struct, set up by fsk_create - * float fsk_out[] - Buffer for samples of modulated FSK, fsk->Ts*(nbits/(M>>1)) in length - * uint8_t tx_bits[] - Buffer containing Nbits unpacked bits - * int nbits - number of bits to transmit + * float fsk_out[] - Buffer for samples of modulated FSK, + * fsk->Ts*(nbits/(M>>1)) in length uint8_t tx_bits[] - Buffer containing Nbits + * unpacked bits int nbits - number of bits to transmit */ void fsk_mod(struct FSK *fsk, float fsk_out[], uint8_t tx_bits[], int nbits); /* * Modulates Nsym bits into N samples - * + * * struct FSK *fsk - FSK config/state struct, set up by fsk_create - * float fsk_out[] - Buffer for samples of "voltage" used to modulate an external VCO + * float fsk_out[] - Buffer for samples of "voltage" used to modulate an + * external VCO * - fsk->Ts*(nbits/(M>>1)) in length * uint8_t tx_bits[] - Buffer containing Nbits unpacked bits * int nbits - number of bits to transmit */ -void fsk_mod_ext_vco(struct FSK *fsk, float vco_out[], uint8_t tx_bits[], int nbits); +void fsk_mod_ext_vco(struct FSK *fsk, float vco_out[], uint8_t tx_bits[], + int nbits); /* * Modulates Nsym bits into N complex samples - * + * * struct FSK *fsk - FSK config/state struct, set up by fsk_create - * comp fsk_out[] - Buffer for samples of modulated FSK, fsk->Ts*(nbits/(M>>1)) in length - * uint8_t tx_bits[] - Buffer containing Nbits unpacked bits - * int nbits - number of bits to transmit + * comp fsk_out[] - Buffer for samples of modulated FSK, + * fsk->Ts*(nbits/(M>>1)) in length uint8_t tx_bits[] - Buffer containing Nbits + * unpacked bits int nbits - number of bits to transmit */ void fsk_mod_c(struct FSK *fsk, COMP fsk_out[], uint8_t tx_bits[], int nbits); @@ -179,15 +189,14 @@ void fsk_mod_c(struct FSK *fsk, COMP fsk_out[], uint8_t tx_bits[], int nbits); * Returns the number of samples needed for the next fsk_demod() cycle * * struct FSK *fsk - FSK config/state struct, set up by fsk_create - * returns - number of samples to be fed into fsk_demod next cycle + * returns - number of samples to be fed into fsk_demod next cycle */ uint32_t fsk_nin(struct FSK *fsk); - /* - * Demodulate some number of FSK samples. The number of samples to be + * Demodulate some number of FSK samples. The number of samples to be * demodulated can be found by calling fsk_nin(). - * + * * struct FSK *fsk - FSK config/state struct, set up by fsk_create * uint8_t rx_bits[] - Buffer for fsk->Nbits unpacked bits to be written * float fsk_in[] - nin samples of modulated FSK @@ -196,7 +205,7 @@ void fsk_demod(struct FSK *fsk, uint8_t rx_bits[], COMP fsk_in[]); /* * Soft decision demodulation - * + * * struct FSK *fsk - FSK config/state struct, set up by fsk_create * float rx_flit[] - M x Nsym array of filtermagnitude outputs * float fsk_in[] - nin samples of modualted FSK @@ -204,7 +213,7 @@ void fsk_demod(struct FSK *fsk, uint8_t rx_bits[], COMP fsk_in[]); void fsk_demod_sd(struct FSK *fsk, float rx_filt[], COMP fsk_in[]); /* enables/disables normalisation of eye diagram samples */ - + void fsk_stats_normalise_eye(struct FSK *fsk, int normalise_enable); /* Set the FSK modem into burst demod mode */ |