diff options
Diffstat (limited to 'src/fsk.c')
| -rw-r--r-- | src/fsk.c | 1578 |
1 files changed, 793 insertions, 785 deletions
@@ -35,18 +35,18 @@ /* This needs square roots, may take more cpu time than it's worth */ #define EST_EBNO -/* This is a flag for the freq. estimator to use a precomputed/rt computed hann window table - On platforms with slow cosf, this will produce a substantial speedup at the cost of a small - amount of memory +/* This is a flag for the freq. estimator to use a precomputed/rt computed hann + window table On platforms with slow cosf, this will produce a substantial + speedup at the cost of a small amount of memory */ #define USE_HANN_TABLE -/* This flag turns on run-time hann table generation. If USE_HANN_TABLE is unset, - this flag has no effect. If USE_HANN_TABLE is set and this flag is set, the - hann table will be allocated and generated when fsk_init or fsk_init_hbr is - called. If this flag is not set, a hann function table of size fsk->Ndft MUST - be provided. On small platforms, this can be used with a precomputed table to - save memory at the cost of flash space. +/* This flag turns on run-time hann table generation. If USE_HANN_TABLE is + unset, this flag has no effect. If USE_HANN_TABLE is set and this flag is + set, the hann table will be allocated and generated when fsk_init or + fsk_init_hbr is called. If this flag is not set, a hann function table of + size fsk->Ndft MUST be provided. On small platforms, this can be used with a + precomputed table to save memory at the cost of flash space. */ #define GENERATE_HANN_TABLE_RUNTIME @@ -61,12 +61,13 @@ \*---------------------------------------------------------------------------*/ +#include "fsk.h" + #include <assert.h> -#include <stdlib.h> -#include <stdint.h> #include <math.h> +#include <stdint.h> +#include <stdlib.h> -#include "fsk.h" #include "comp_prim.h" #include "kiss_fftr.h" #include "modem_probe.h" @@ -84,13 +85,14 @@ static void stats_init(struct FSK *fsk); This is used by fsk_create and fsk_create_hbr to generate a hann function table */ -static void fsk_generate_hann_table(struct FSK* fsk){ - int Ndft = fsk->Ndft; - size_t i; - - for(i=0; i<Ndft; i++){ - fsk->hann_table[i] = 0.5 - 0.5 * cosf(2.0 * M_PI * (float)i / (float) (Ndft-1)); - } +static void fsk_generate_hann_table(struct FSK *fsk) { + int Ndft = fsk->Ndft; + size_t i; + + for (i = 0; i < Ndft; i++) { + fsk->hann_table[i] = + 0.5 - 0.5 * cosf(2.0 * M_PI * (float)i / (float)(Ndft - 1)); + } } #endif @@ -99,7 +101,7 @@ static void fsk_generate_hann_table(struct FSK* fsk){ FUNCTION....: fsk_create_core AUTHOR......: Brady O'Brien DATE CREATED: 7 January 2016 - + In this version of the demod the standard/hbr modes have been largely combined at they shared so much common code. The fsk_create/fsk_create_hbr function interface has been retained to @@ -107,94 +109,99 @@ static void fsk_generate_hann_table(struct FSK* fsk){ \*---------------------------------------------------------------------------*/ -struct FSK * fsk_create_core(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, int tone_spacing) -{ - struct FSK *fsk; - int i; - - /* Check configuration validity */ - assert(Fs > 0); - assert(Rs > 0); - assert(P > 0); - assert(Nsym > 0); - /* Ts (Fs/Rs) must be an integer */ - assert( (Fs%Rs) == 0 ); - /* Ts/P (Fs/Rs/P) must be an integer */ - assert( ((Fs/Rs)%P) == 0 ); - /* If P is too low we don't have a good choice of timing offsets to choose from */ - assert( P >= 4 ); - assert( M==2 || M==4); - - fsk = (struct FSK*) calloc(1, sizeof(struct FSK)); assert(fsk != NULL); - - // Need enough bins to within 10% of tone centre - float bin_width_Hz = 0.1*Rs; - float Ndft = (float)Fs/bin_width_Hz; - Ndft = pow(2.0, ceil(log2(Ndft))); - - /* Set constant config parameters */ - fsk->Fs = Fs; - fsk->Rs = Rs; - fsk->Ts = Fs/Rs; - fsk->burst_mode = 0; - fsk->P = P; - fsk->Nsym = Nsym; - fsk->N = fsk->Ts*fsk->Nsym; - fsk->Ndft = Ndft; - fsk->tc = 0.1; - fsk->Nmem = fsk->N+(2*fsk->Ts); - fsk->f1_tx = f1_tx; - fsk->tone_spacing = tone_spacing; - fsk->nin = fsk->N; - fsk->lock_nin = 0; - fsk->mode = M==2 ? MODE_2FSK : MODE_4FSK; - fsk->Nbits = M==2 ? fsk->Nsym : fsk->Nsym*2; - fsk->est_min = 0; - fsk->est_max = Fs; - fsk->est_space = 0.75*Rs; - fsk->freq_est_type = 0; - - //printf("C.....: M: %d Fs: %d Rs: %d Ts: %d nsym: %d nbit: %d N: %d Ndft: %d fmin: %d fmax: %d\n", - // M, fsk->Fs, fsk->Rs, fsk->Ts, fsk->Nsym, fsk->Nbits, fsk->N, fsk->Ndft, fsk->est_min, fsk->est_max); - /* Set up rx state */ - for(i=0; i<M; i++) - fsk->phi_c[i] = comp_exp_j(0); - fsk->f_dc = (COMP*)malloc(M*fsk->Nmem*sizeof(COMP)); assert(fsk->f_dc != NULL); - for(i=0; i<M*fsk->Nmem; i++) - fsk->f_dc[i] = comp0(); - - fsk->fft_cfg = kiss_fft_alloc(Ndft,0,NULL,NULL); assert(fsk->fft_cfg != NULL); - fsk->Sf = (float*)malloc(sizeof(float)*fsk->Ndft); assert(fsk->Sf != NULL); - for(i=0;i<Ndft;i++)fsk->Sf[i] = 0; - - #ifdef USE_HANN_TABLE - #ifdef GENERATE_HANN_TABLE_RUNTIME - fsk->hann_table = (float*)malloc(sizeof(float)*fsk->Ndft); assert(fsk->hann_table != NULL); - fsk_generate_hann_table(fsk); - #else - fsk->hann_table = NULL; - #endif - #endif - - - fsk->norm_rx_timing = 0; - - /* Set up tx state */ - fsk->tx_phase_c = comp_exp_j(0); - - /* Set up demod stats */ - fsk->EbNodB = 0; - - for( i=0; i<M; i++) - fsk->f_est[i] = 0; - - fsk->ppm = 0; - - fsk->stats = (struct MODEM_STATS*)malloc(sizeof(struct MODEM_STATS)); assert(fsk->stats != NULL); - stats_init(fsk); - fsk->normalise_eye = 1; - - return fsk; +struct FSK *fsk_create_core(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, + int tone_spacing) { + struct FSK *fsk; + int i; + + /* Check configuration validity */ + assert(Fs > 0); + assert(Rs > 0); + assert(P > 0); + assert(Nsym > 0); + /* Ts (Fs/Rs) must be an integer */ + assert((Fs % Rs) == 0); + /* Ts/P (Fs/Rs/P) must be an integer */ + assert(((Fs / Rs) % P) == 0); + /* If P is too low we don't have a good choice of timing offsets to choose + * from */ + assert(P >= 4); + assert(M == 2 || M == 4); + + fsk = (struct FSK *)calloc(1, sizeof(struct FSK)); + assert(fsk != NULL); + + // Need enough bins to within 10% of tone centre + float bin_width_Hz = 0.1 * Rs; + float Ndft = (float)Fs / bin_width_Hz; + Ndft = pow(2.0, ceil(log2(Ndft))); + + /* Set constant config parameters */ + fsk->Fs = Fs; + fsk->Rs = Rs; + fsk->Ts = Fs / Rs; + fsk->burst_mode = 0; + fsk->P = P; + fsk->Nsym = Nsym; + fsk->N = fsk->Ts * fsk->Nsym; + fsk->Ndft = Ndft; + fsk->tc = 0.1; + fsk->Nmem = fsk->N + (2 * fsk->Ts); + fsk->f1_tx = f1_tx; + fsk->tone_spacing = tone_spacing; + fsk->nin = fsk->N; + fsk->lock_nin = 0; + fsk->mode = M == 2 ? MODE_2FSK : MODE_4FSK; + fsk->Nbits = M == 2 ? fsk->Nsym : fsk->Nsym * 2; + fsk->est_min = 0; + fsk->est_max = Fs; + fsk->est_space = 0.75 * Rs; + fsk->freq_est_type = 0; + + // printf("C.....: M: %d Fs: %d Rs: %d Ts: %d nsym: %d nbit: %d N: %d Ndft: %d + // fmin: %d fmax: %d\n", + // M, fsk->Fs, fsk->Rs, fsk->Ts, fsk->Nsym, fsk->Nbits, fsk->N, + // fsk->Ndft, fsk->est_min, fsk->est_max); + /* Set up rx state */ + for (i = 0; i < M; i++) fsk->phi_c[i] = comp_exp_j(0); + fsk->f_dc = (COMP *)malloc(M * fsk->Nmem * sizeof(COMP)); + assert(fsk->f_dc != NULL); + for (i = 0; i < M * fsk->Nmem; i++) fsk->f_dc[i] = comp0(); + + fsk->fft_cfg = kiss_fft_alloc(Ndft, 0, NULL, NULL); + assert(fsk->fft_cfg != NULL); + fsk->Sf = (float *)malloc(sizeof(float) * fsk->Ndft); + assert(fsk->Sf != NULL); + for (i = 0; i < Ndft; i++) fsk->Sf[i] = 0; + +#ifdef USE_HANN_TABLE +#ifdef GENERATE_HANN_TABLE_RUNTIME + fsk->hann_table = (float *)malloc(sizeof(float) * fsk->Ndft); + assert(fsk->hann_table != NULL); + fsk_generate_hann_table(fsk); +#else + fsk->hann_table = NULL; +#endif +#endif + + fsk->norm_rx_timing = 0; + + /* Set up tx state */ + fsk->tx_phase_c = comp_exp_j(0); + + /* Set up demod stats */ + fsk->EbNodB = 0; + + for (i = 0; i < M; i++) fsk->f_est[i] = 0; + + fsk->ppm = 0; + + fsk->stats = (struct MODEM_STATS *)malloc(sizeof(struct MODEM_STATS)); + assert(fsk->stats != NULL); + stats_init(fsk); + fsk->normalise_eye = 1; + + return fsk; } /*---------------------------------------------------------------------------* \ @@ -202,7 +209,7 @@ struct FSK * fsk_create_core(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, FUNCTION....: fsk_create AUTHOR......: Brady O'Brien DATE CREATED: 7 January 2016 - + Create and initialize an instance of the FSK modem. Returns a pointer to the modem state/config struct. One modem config struct may be used for both mod and demod. @@ -212,8 +219,9 @@ struct FSK * fsk_create_core(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, \*---------------------------------------------------------------------------*/ -struct FSK * fsk_create(int Fs, int Rs, int M, int tx_f1, int tx_fs) { - return fsk_create_core(Fs, Rs, M, FSK_DEFAULT_P, FSK_DEFAULT_NSYM, tx_f1, tx_fs); +struct FSK *fsk_create(int Fs, int Rs, int M, int tx_f1, int tx_fs) { + return fsk_create_core(Fs, Rs, M, FSK_DEFAULT_P, FSK_DEFAULT_NSYM, tx_f1, + tx_fs); } /*---------------------------------------------------------------------------*\ @@ -221,7 +229,7 @@ struct FSK * fsk_create(int Fs, int Rs, int M, int tx_f1, int tx_fs) { FUNCTION....: fsk_create_hbr AUTHOR......: Brady O'Brien DATE CREATED: 11 February 2016 - + Alternate version of create allows user defined oversampling P and averaging window Nsym. In the current version of the demod it's simply an alias for the default core function. @@ -237,8 +245,9 @@ struct FSK * fsk_create(int Fs, int Rs, int M, int tx_f1, int tx_fs) { \*---------------------------------------------------------------------------*/ -struct FSK * fsk_create_hbr(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, int tone_spacing) { - return fsk_create_core(Fs, Rs, M, P, Nsym, f1_tx, tone_spacing); +struct FSK *fsk_create_hbr(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, + int tone_spacing) { + return fsk_create_core(Fs, Rs, M, P, Nsym, f1_tx, tone_spacing); } /*---------------------------------------------------------------------------*\ @@ -246,18 +255,18 @@ struct FSK * fsk_create_hbr(int Fs, int Rs, int M, int P, int Nsym, int f1_tx, i FUNCTION....: fsk_destroy AUTHOR......: Brady O'Brien DATE CREATED: 11 February 2016 - + Call this to free all memory and shut down the modem. \*---------------------------------------------------------------------------*/ -void fsk_destroy(struct FSK *fsk){ - free(fsk->Sf); - free(fsk->f_dc); - free(fsk->fft_cfg); - free(fsk->stats); - free(fsk->hann_table); - free(fsk); +void fsk_destroy(struct FSK *fsk) { + free(fsk->Sf); + free(fsk->f_dc); + free(fsk->fft_cfg); + free(fsk->stats); + free(fsk->hann_table); + free(fsk); } /*---------------------------------------------------------------------------*\ @@ -265,58 +274,57 @@ void fsk_destroy(struct FSK *fsk){ FUNCTION....: fsk_mod AUTHOR......: Brady O'Brien DATE CREATED: 11 February 2016 - + FSK modulator function, real valued output samples with amplitude 2. \*---------------------------------------------------------------------------*/ -void fsk_mod(struct FSK *fsk,float fsk_out[], uint8_t tx_bits[], int nbits) { - COMP tx_phase_c = fsk->tx_phase_c; /* Current complex TX phase */ - int f1_tx = fsk->f1_tx; /* '0' frequency */ - int tone_spacing = fsk->tone_spacing; /* space between frequencies */ - int Ts = fsk->Ts; /* samples-per-symbol */ - int Fs = fsk->Fs; /* sample freq */ - int M = fsk->mode; - COMP dosc_f[M]; /* phase shift per sample */ - COMP dph; /* phase shift of current bit */ - size_t i,j,m,bit_i,sym; - - /* trap these parameters being set to FSK_UNUSED, then calling mod */ - assert(f1_tx > 0); - assert(tone_spacing > 0); - - /* Init the per sample phase shift complex numbers */ - for( m=0; m<M; m++){ - dosc_f[m] = comp_exp_j(2*M_PI*((float)(f1_tx+(tone_spacing*m))/(float)(Fs))); +void fsk_mod(struct FSK *fsk, float fsk_out[], uint8_t tx_bits[], int nbits) { + COMP tx_phase_c = fsk->tx_phase_c; /* Current complex TX phase */ + int f1_tx = fsk->f1_tx; /* '0' frequency */ + int tone_spacing = fsk->tone_spacing; /* space between frequencies */ + int Ts = fsk->Ts; /* samples-per-symbol */ + int Fs = fsk->Fs; /* sample freq */ + int M = fsk->mode; + COMP dosc_f[M]; /* phase shift per sample */ + COMP dph; /* phase shift of current bit */ + size_t i, j, m, bit_i, sym; + + /* trap these parameters being set to FSK_UNUSED, then calling mod */ + assert(f1_tx > 0); + assert(tone_spacing > 0); + + /* Init the per sample phase shift complex numbers */ + for (m = 0; m < M; m++) { + dosc_f[m] = comp_exp_j(2 * M_PI * + ((float)(f1_tx + (tone_spacing * m)) / (float)(Fs))); + } + + bit_i = 0; + int nsym = nbits / (M >> 1); + for (i = 0; i < nsym; i++) { + sym = 0; + /* Pack the symbol number from the bit stream */ + for (m = M; m >>= 1;) { + uint8_t bit = tx_bits[bit_i]; + bit = (bit == 1) ? 1 : 0; + sym = (sym << 1) | bit; + bit_i++; } - - bit_i = 0; - int nsym = nbits/(M>>1); - for(i=0; i<nsym; i++) { - sym = 0; - /* Pack the symbol number from the bit stream */ - for( m=M; m>>=1; ){ - uint8_t bit = tx_bits[bit_i]; - bit = (bit==1)?1:0; - sym = (sym<<1)|bit; - bit_i++; - } - /* Look up symbol phase shift */ - dph = dosc_f[sym]; - /* Spin the oscillator for a symbol period */ - for(j=0; j<Ts; j++){ - tx_phase_c = cmult(tx_phase_c,dph); - fsk_out[i*Ts+j] = 2*tx_phase_c.real; - } - + /* Look up symbol phase shift */ + dph = dosc_f[sym]; + /* Spin the oscillator for a symbol period */ + for (j = 0; j < Ts; j++) { + tx_phase_c = cmult(tx_phase_c, dph); + fsk_out[i * Ts + j] = 2 * tx_phase_c.real; } - - /* Normalize TX phase to prevent drift */ - tx_phase_c = comp_normalize(tx_phase_c); - - /* save TX phase */ - fsk->tx_phase_c = tx_phase_c; - + } + + /* Normalize TX phase to prevent drift */ + tx_phase_c = comp_normalize(tx_phase_c); + + /* save TX phase */ + fsk->tx_phase_c = tx_phase_c; } /*---------------------------------------------------------------------------*\ @@ -324,110 +332,111 @@ void fsk_mod(struct FSK *fsk,float fsk_out[], uint8_t tx_bits[], int nbits) { FUNCTION....: fsk_mod_c AUTHOR......: Brady O'Brien DATE CREATED: 11 February 2016 - + FSK modulator function, complex valued output samples with magnitude 1. \*---------------------------------------------------------------------------*/ -void fsk_mod_c(struct FSK *fsk,COMP fsk_out[], uint8_t tx_bits[], int nbits) { - COMP tx_phase_c = fsk->tx_phase_c; /* Current complex TX phase */ - int f1_tx = fsk->f1_tx; /* '0' frequency */ - int tone_spacing = fsk->tone_spacing; /* space between frequencies */ - int Ts = fsk->Ts; /* samples-per-symbol */ - int Fs = fsk->Fs; /* sample freq */ - int M = fsk->mode; - COMP dosc_f[M]; /* phase shift per sample */ - COMP dph; /* phase shift of current bit */ - size_t i,j,bit_i,sym; - int m; - - /* trap these parameters being set to FSK_UNUSED, then calling mod */ - assert(f1_tx > 0); - assert(tone_spacing > 0); - - /* Init the per sample phase shift complex numbers */ - for( m=0; m<M; m++){ - dosc_f[m] = comp_exp_j(2*M_PI*((float)(f1_tx+(tone_spacing*m))/(float)(Fs))); +void fsk_mod_c(struct FSK *fsk, COMP fsk_out[], uint8_t tx_bits[], int nbits) { + COMP tx_phase_c = fsk->tx_phase_c; /* Current complex TX phase */ + int f1_tx = fsk->f1_tx; /* '0' frequency */ + int tone_spacing = fsk->tone_spacing; /* space between frequencies */ + int Ts = fsk->Ts; /* samples-per-symbol */ + int Fs = fsk->Fs; /* sample freq */ + int M = fsk->mode; + COMP dosc_f[M]; /* phase shift per sample */ + COMP dph; /* phase shift of current bit */ + size_t i, j, bit_i, sym; + int m; + + /* trap these parameters being set to FSK_UNUSED, then calling mod */ + assert(f1_tx > 0); + assert(tone_spacing > 0); + + /* Init the per sample phase shift complex numbers */ + for (m = 0; m < M; m++) { + dosc_f[m] = comp_exp_j(2 * M_PI * + ((float)(f1_tx + (tone_spacing * m)) / (float)(Fs))); + } + + bit_i = 0; + int nsym = nbits / (M >> 1); + for (i = 0; i < nsym; i++) { + sym = 0; + /* Pack the symbol number from the bit stream */ + for (m = M; m >>= 1;) { + uint8_t bit = tx_bits[bit_i]; + bit = (bit == 1) ? 1 : 0; + sym = (sym << 1) | bit; + bit_i++; } - - bit_i = 0; - int nsym = nbits/(M>>1); - for(i=0; i<nsym; i++) { - sym = 0; - /* Pack the symbol number from the bit stream */ - for( m=M; m>>=1; ){ - uint8_t bit = tx_bits[bit_i]; - bit = (bit==1)?1:0; - sym = (sym<<1)|bit; - bit_i++; - } - /* Look up symbol phase shift */ - dph = dosc_f[sym]; - /* Spin the oscillator for a symbol period */ - for(j=0; j<Ts; j++){ - tx_phase_c = cmult(tx_phase_c,dph); - fsk_out[i*Ts+j] = tx_phase_c; - } + /* Look up symbol phase shift */ + dph = dosc_f[sym]; + /* Spin the oscillator for a symbol period */ + for (j = 0; j < Ts; j++) { + tx_phase_c = cmult(tx_phase_c, dph); + fsk_out[i * Ts + j] = tx_phase_c; } - - /* Normalize TX phase to prevent drift */ - tx_phase_c = comp_normalize(tx_phase_c); - - /* save TX phase */ - fsk->tx_phase_c = tx_phase_c; - -} + } + /* Normalize TX phase to prevent drift */ + tx_phase_c = comp_normalize(tx_phase_c); + + /* save TX phase */ + fsk->tx_phase_c = tx_phase_c; +} /*---------------------------------------------------------------------------*\ FUNCTION....: fsk_mod_ext_vco AUTHOR......: David Rowe DATE CREATED: February 2018 - + Modulator that assume an external VCO. The output is a voltage that changes for each symbol. \*---------------------------------------------------------------------------*/ -void fsk_mod_ext_vco(struct FSK *fsk, float vco_out[], uint8_t tx_bits[], int nbits) { - int f1_tx = fsk->f1_tx; /* '0' frequency */ - int tone_spacing = fsk->tone_spacing; /* space between frequencies */ - int Ts = fsk->Ts; /* samples-per-symbol */ - int M = fsk->mode; - int i, j, m, sym, bit_i; - - /* trap these parameters being set to FSK_UNUSED, then calling mod */ - assert(f1_tx > 0); - assert(tone_spacing > 0); - - bit_i = 0; - int nsym = nbits/(M>>1); - for(i=0; i<nsym; i++) { - /* generate the symbol number from the bit stream, - e.g. 0,1 for 2FSK, 0,1,2,3 for 4FSK */ - - sym = 0; - - /* unpack the symbol number from the bit stream */ - - for( m=M; m>>=1; ){ - uint8_t bit = tx_bits[bit_i]; - bit = (bit==1)?1:0; - sym = (sym<<1)|bit; - bit_i++; - } - - /* - Map 'sym' to VCO frequency - Note: drive is inverted, a higher tone drives VCO voltage lower - */ - - //fprintf(stderr, "i: %d sym: %d freq: %f\n", i, sym, f1_tx + tone_spacing*(float)sym); - for(j=0; j<Ts; j++) { - vco_out[i*Ts+j] = f1_tx + tone_spacing*(float)sym; - } +void fsk_mod_ext_vco(struct FSK *fsk, float vco_out[], uint8_t tx_bits[], + int nbits) { + int f1_tx = fsk->f1_tx; /* '0' frequency */ + int tone_spacing = fsk->tone_spacing; /* space between frequencies */ + int Ts = fsk->Ts; /* samples-per-symbol */ + int M = fsk->mode; + int i, j, m, sym, bit_i; + + /* trap these parameters being set to FSK_UNUSED, then calling mod */ + assert(f1_tx > 0); + assert(tone_spacing > 0); + + bit_i = 0; + int nsym = nbits / (M >> 1); + for (i = 0; i < nsym; i++) { + /* generate the symbol number from the bit stream, + e.g. 0,1 for 2FSK, 0,1,2,3 for 4FSK */ + + sym = 0; + + /* unpack the symbol number from the bit stream */ + + for (m = M; m >>= 1;) { + uint8_t bit = tx_bits[bit_i]; + bit = (bit == 1) ? 1 : 0; + sym = (sym << 1) | bit; + bit_i++; + } + + /* + Map 'sym' to VCO frequency + Note: drive is inverted, a higher tone drives VCO voltage lower + */ + + // fprintf(stderr, "i: %d sym: %d freq: %f\n", i, sym, f1_tx + + // tone_spacing*(float)sym); + for (j = 0; j < Ts; j++) { + vco_out[i * Ts + j] = f1_tx + tone_spacing * (float)sym; } + } } /*---------------------------------------------------------------------------*\ @@ -435,492 +444,498 @@ void fsk_mod_ext_vco(struct FSK *fsk, float vco_out[], uint8_t tx_bits[], int nb FUNCTION....: fsk_nin AUTHOR......: Brady O'Brien DATE CREATED: 11 February 2016 - + Call me before each call to fsk_demod() to determine how many new samples you should pass in. the number of samples will vary due to timing variations. \*---------------------------------------------------------------------------*/ -uint32_t fsk_nin(struct FSK *fsk){ - return (uint32_t)fsk->nin; -} +uint32_t fsk_nin(struct FSK *fsk) { return (uint32_t)fsk->nin; } /* * Internal function to estimate the frequencies of the FSK tones. - * This is split off because it is fairly complicated, needs a bunch of memory, and probably - * takes more cycles than the rest of the demod. - * Parameters: - * fsk - FSK struct from demod containing FSK config - * fsk_in - block of samples in this demod cycles, must be nin long - * freqs - Array for the estimated frequencies - * M - number of frequency peaks to find + * This is split off because it is fairly complicated, needs a bunch of memory, + * and probably takes more cycles than the rest of the demod. Parameters: fsk - + * FSK struct from demod containing FSK config fsk_in - block of samples in this + * demod cycles, must be nin long freqs - Array for the estimated frequencies M + * - number of frequency peaks to find */ void fsk_demod_freq_est(struct FSK *fsk, COMP fsk_in[], float *freqs, int M) { - int Ndft = fsk->Ndft; - int Fs = fsk->Fs; - int nin = fsk->nin; - size_t i,j; - float hann; - float max; - int imax; - kiss_fft_cfg fft_cfg = fsk->fft_cfg; - int freqi[M]; - int st,en,f_zero; - - kiss_fft_cpx *fftin = (kiss_fft_cpx*)malloc(sizeof(kiss_fft_cpx)*Ndft); - kiss_fft_cpx *fftout = (kiss_fft_cpx*)malloc(sizeof(kiss_fft_cpx)*Ndft); - - st = (fsk->est_min*Ndft)/Fs + Ndft/2; if (st < 0) st = 0; - en = (fsk->est_max*Ndft)/Fs + Ndft/2; if (en > Ndft) en = Ndft; - //fprintf(stderr, "min: %d max: %d st: %d en: %d\n", fsk->est_min, fsk->est_max, st, en); - - f_zero = (fsk->est_space*Ndft)/Fs; - //fprintf(stderr, "fsk->est_space: %d f_zero = %d\n", fsk->est_space, f_zero); - - int numffts = floor((float)nin/(Ndft/2)) - 1; - for(j=0; j<numffts; j++){ - int a = j*Ndft/2; - //fprintf(stderr, "numffts: %d j: %d a: %d\n", numffts, (int)j, a); - /* Copy FSK buffer into reals of FFT buffer and apply a hann window */ - for(i=0; i<Ndft; i++){ - #ifdef USE_HANN_TABLE - hann = fsk->hann_table[i]; - #else - hann = 0.5 - 0.5 * cosf(2.0 * M_PI * (float)i / (float) (fft_samps-1)); - #endif - fftin[i].r = hann*fsk_in[i+a].real; - fftin[i].i = hann*fsk_in[i+a].imag; - } - - /* Do the FFT */ - kiss_fft(fft_cfg,fftin,fftout); - - /* FFT shift to put DC bin at Ndft/2 */ - kiss_fft_cpx tmp; - for(i=0; i<Ndft/2; i++) { - tmp = fftout[i]; - fftout[i] = fftout[i+Ndft/2]; - fftout[i+Ndft/2] = tmp; - } - - /* Find the magnitude^2 of each freq slot */ - for(i=0; i<Ndft; i++) { - fftout[i].r = (fftout[i].r*fftout[i].r) + (fftout[i].i*fftout[i].i) ; - } - - /* Mix back in with the previous fft block */ - /* Copy new fft est into imag of fftout for frequency divination below */ - float tc = fsk->tc; - for(i=0; i<Ndft; i++){ - fsk->Sf[i] = (fsk->Sf[i]*(1-tc)) + (sqrtf(fftout[i].r)*tc); - fftout[i].i = fsk->Sf[i]; - } + int Ndft = fsk->Ndft; + int Fs = fsk->Fs; + int nin = fsk->nin; + size_t i, j; + float hann; + float max; + int imax; + kiss_fft_cfg fft_cfg = fsk->fft_cfg; + int freqi[M]; + int st, en, f_zero; + + kiss_fft_cpx *fftin = (kiss_fft_cpx *)malloc(sizeof(kiss_fft_cpx) * Ndft); + kiss_fft_cpx *fftout = (kiss_fft_cpx *)malloc(sizeof(kiss_fft_cpx) * Ndft); + + st = (fsk->est_min * Ndft) / Fs + Ndft / 2; + if (st < 0) st = 0; + en = (fsk->est_max * Ndft) / Fs + Ndft / 2; + if (en > Ndft) en = Ndft; + // fprintf(stderr, "min: %d max: %d st: %d en: %d\n", fsk->est_min, + // fsk->est_max, st, en); + + f_zero = (fsk->est_space * Ndft) / Fs; + // fprintf(stderr, "fsk->est_space: %d f_zero = %d\n", fsk->est_space, + // f_zero); + + int numffts = floor((float)nin / (Ndft / 2)) - 1; + for (j = 0; j < numffts; j++) { + int a = j * Ndft / 2; + // fprintf(stderr, "numffts: %d j: %d a: %d\n", numffts, (int)j, a); + /* Copy FSK buffer into reals of FFT buffer and apply a hann window */ + for (i = 0; i < Ndft; i++) { +#ifdef USE_HANN_TABLE + hann = fsk->hann_table[i]; +#else + hann = 0.5 - 0.5 * cosf(2.0 * M_PI * (float)i / (float)(fft_samps - 1)); +#endif + fftin[i].r = hann * fsk_in[i + a].real; + fftin[i].i = hann * fsk_in[i + a].imag; } - - modem_probe_samp_f("t_Sf",fsk->Sf,Ndft); - - max = 0; - /* Find the M frequency peaks here */ - for(i=0; i<M; i++){ - imax = 0; - max = 0; - for(j=st;j<en;j++){ - if(fftout[j].i > max){ - max = fftout[j].i; - imax = j; - } - } - /* Blank out FMax +/-Fspace/2 */ - int f_min, f_max; - f_min = imax - f_zero; - f_min = f_min < 0 ? 0 : f_min; - f_max = imax + f_zero; - f_max = f_max > Ndft ? Ndft : f_max; - for(j=f_min; j<f_max; j++) - fftout[j].i = 0; - - /* Stick the freq index on the list */ - freqi[i] = imax - Ndft/2; + + /* Do the FFT */ + kiss_fft(fft_cfg, fftin, fftout); + + /* FFT shift to put DC bin at Ndft/2 */ + kiss_fft_cpx tmp; + for (i = 0; i < Ndft / 2; i++) { + tmp = fftout[i]; + fftout[i] = fftout[i + Ndft / 2]; + fftout[i + Ndft / 2] = tmp; } - - /* Gnome sort the freq list */ - /* My favorite sort of sort*/ - i = 1; - while(i<M){ - if(freqi[i] >= freqi[i-1]) i++; - else{ - j = freqi[i]; - freqi[i] = freqi[i-1]; - freqi[i-1] = j; - if(i>1) i--; - } + + /* Find the magnitude^2 of each freq slot */ + for (i = 0; i < Ndft; i++) { + fftout[i].r = (fftout[i].r * fftout[i].r) + (fftout[i].i * fftout[i].i); } - /* Convert freqs from indices to frequencies */ - for(i=0; i<M; i++){ - freqs[i] = (float)(freqi[i])*((float)Fs/(float)Ndft); + /* Mix back in with the previous fft block */ + /* Copy new fft est into imag of fftout for frequency divination below */ + float tc = fsk->tc; + for (i = 0; i < Ndft; i++) { + fsk->Sf[i] = (fsk->Sf[i] * (1 - tc)) + (sqrtf(fftout[i].r) * tc); + fftout[i].i = fsk->Sf[i]; } + } - /* Search for each tone method 2 - correlate with mask with non-zero entries at tone spacings ----- */ + modem_probe_samp_f("t_Sf", fsk->Sf, Ndft); - /* construct mask */ - float mask[Ndft]; - for(i=0; i<Ndft; i++) mask[i] = 0.0; - for(i=0;i<3; i++) mask[i] = 1.0; - int bin=0; - for(int m=1; m<=M-1; m++) { - bin = round((float)m*fsk->tone_spacing*Ndft/Fs)-1; - for(i=bin; i<=bin+2; i++) mask[i] = 1.0; + max = 0; + /* Find the M frequency peaks here */ + for (i = 0; i < M; i++) { + imax = 0; + max = 0; + for (j = st; j < en; j++) { + if (fftout[j].i > max) { + max = fftout[j].i; + imax = j; + } } - int len_mask = bin+2+1; - - #ifdef MODEMPROBE_ENABLE - modem_probe_samp_f("t_mask",mask,len_mask); - #endif - - /* drag mask over Sf, looking for peak in correlation */ - int b_max = st; float corr_max = 0.0; - float *Sf = fsk->Sf; - for (int b=st; b<en-len_mask; b++) { - float corr = 0.0; - for(i=0; i<len_mask; i++) - corr += mask[i] * Sf[b+i]; - if (corr > corr_max) { - corr_max = corr; - b_max = b; - } + /* Blank out FMax +/-Fspace/2 */ + int f_min, f_max; + f_min = imax - f_zero; + f_min = f_min < 0 ? 0 : f_min; + f_max = imax + f_zero; + f_max = f_max > Ndft ? Ndft : f_max; + for (j = f_min; j < f_max; j++) fftout[j].i = 0; + + /* Stick the freq index on the list */ + freqi[i] = imax - Ndft / 2; + } + + /* Gnome sort the freq list */ + /* My favorite sort of sort*/ + i = 1; + while (i < M) { + if (freqi[i] >= freqi[i - 1]) + i++; + else { + j = freqi[i]; + freqi[i] = freqi[i - 1]; + freqi[i - 1] = j; + if (i > 1) i--; + } + } + + /* Convert freqs from indices to frequencies */ + for (i = 0; i < M; i++) { + freqs[i] = (float)(freqi[i]) * ((float)Fs / (float)Ndft); + } + + /* Search for each tone method 2 - correlate with mask with non-zero entries + * at tone spacings ----- */ + + /* construct mask */ + float mask[Ndft]; + for (i = 0; i < Ndft; i++) mask[i] = 0.0; + for (i = 0; i < 3; i++) mask[i] = 1.0; + int bin = 0; + for (int m = 1; m <= M - 1; m++) { + bin = round((float)m * fsk->tone_spacing * Ndft / Fs) - 1; + for (i = bin; i <= bin + 2; i++) mask[i] = 1.0; + } + int len_mask = bin + 2 + 1; + +#ifdef MODEMPROBE_ENABLE + modem_probe_samp_f("t_mask", mask, len_mask); +#endif + + /* drag mask over Sf, looking for peak in correlation */ + int b_max = st; + float corr_max = 0.0; + float *Sf = fsk->Sf; + for (int b = st; b < en - len_mask; b++) { + float corr = 0.0; + for (i = 0; i < len_mask; i++) corr += mask[i] * Sf[b + i]; + if (corr > corr_max) { + corr_max = corr; + b_max = b; } - float foff = (b_max-Ndft/2)*Fs/Ndft; - //fprintf(stderr, "fsk->tone_spacing: %d\n",fsk->tone_spacing); - for (int m=0; m<M; m++) - fsk->f2_est[m] = foff + m*fsk->tone_spacing; + } + float foff = (b_max - Ndft / 2) * Fs / Ndft; + // fprintf(stderr, "fsk->tone_spacing: %d\n",fsk->tone_spacing); + for (int m = 0; m < M; m++) fsk->f2_est[m] = foff + m * fsk->tone_spacing; - #ifdef MODEMPROBE_ENABLE - modem_probe_samp_f("t_f2_est",fsk->f2_est,M); - #endif +#ifdef MODEMPROBE_ENABLE + modem_probe_samp_f("t_f2_est", fsk->f2_est, M); +#endif - free(fftin); - free(fftout); + free(fftin); + free(fftout); } /* core demodulator function */ -void fsk_demod_core(struct FSK *fsk, uint8_t rx_bits[], float rx_filt[], COMP fsk_in[]){ - int N = fsk->N; - int Ts = fsk->Ts; - int Rs = fsk->Rs; - int Fs = fsk->Fs; - int nsym = fsk->Nsym; - int nin = fsk->nin; - int P = fsk->P; - int Nmem = fsk->Nmem; - int M = fsk->mode; - size_t i,j,m; - float ft1; - - COMP t[M]; /* complex number temps */ - COMP t_c; /* another complex temp */ - COMP *phi_c = fsk->phi_c; - COMP *f_dc = fsk->f_dc; - COMP phi_ft; - int nold = Nmem-nin; - - COMP dphift; - float rx_timing,norm_rx_timing,old_norm_rx_timing,d_norm_rx_timing,appm; - - float fc_avg,fc_tx; - float meanebno,stdebno,eye_max; - int neyesamp,neyeoffset; - - #ifdef MODEMPROBE_ENABLE - #define NMP_NAME 26 - char mp_name_tmp[NMP_NAME+1]; /* Temporary string for modem probe trace names */ - #endif - - /* Estimate tone frequencies */ - fsk_demod_freq_est(fsk,fsk_in,fsk->f_est,M); - #ifdef MODEMPROBE_ENABLE - modem_probe_samp_f("t_f_est",fsk->f_est,M); - #endif - float *f_est; - if (fsk->freq_est_type) - f_est = fsk->f2_est; - else - f_est = fsk->f_est; - - /* update filter (integrator) memory by shifting in nin samples */ - for(m=0; m<M; m++) { - for(i=0,j=Nmem-nold; i<nold; i++,j++) - f_dc[m*Nmem+i] = f_dc[m*Nmem+j]; +void fsk_demod_core(struct FSK *fsk, uint8_t rx_bits[], float rx_filt[], + COMP fsk_in[]) { + int N = fsk->N; + int Ts = fsk->Ts; + int Rs = fsk->Rs; + int Fs = fsk->Fs; + int nsym = fsk->Nsym; + int nin = fsk->nin; + int P = fsk->P; + int Nmem = fsk->Nmem; + int M = fsk->mode; + size_t i, j, m; + float ft1; + + COMP t[M]; /* complex number temps */ + COMP t_c; /* another complex temp */ + COMP *phi_c = fsk->phi_c; + COMP *f_dc = fsk->f_dc; + COMP phi_ft; + int nold = Nmem - nin; + + COMP dphift; + float rx_timing, norm_rx_timing, old_norm_rx_timing, d_norm_rx_timing, appm; + + float fc_avg, fc_tx; + float meanebno, stdebno, eye_max; + int neyesamp, neyeoffset; + +#ifdef MODEMPROBE_ENABLE +#define NMP_NAME 26 + char mp_name_tmp[NMP_NAME + + 1]; /* Temporary string for modem probe trace names */ +#endif + + /* Estimate tone frequencies */ + fsk_demod_freq_est(fsk, fsk_in, fsk->f_est, M); +#ifdef MODEMPROBE_ENABLE + modem_probe_samp_f("t_f_est", fsk->f_est, M); +#endif + float *f_est; + if (fsk->freq_est_type) + f_est = fsk->f2_est; + else + f_est = fsk->f_est; + + /* update filter (integrator) memory by shifting in nin samples */ + for (m = 0; m < M; m++) { + for (i = 0, j = Nmem - nold; i < nold; i++, j++) + f_dc[m * Nmem + i] = f_dc[m * Nmem + j]; + } + + /* freq shift down to around DC, ensuring continuous phase from last frame */ + COMP dphi_m; + for (m = 0; m < M; m++) { + dphi_m = comp_exp_j(2 * M_PI * ((f_est[m]) / (float)(Fs))); + for (i = nold, j = 0; i < Nmem; i++, j++) { + phi_c[m] = cmult(phi_c[m], dphi_m); + f_dc[m * Nmem + i] = cmult(fsk_in[j], cconj(phi_c[m])); } - - /* freq shift down to around DC, ensuring continuous phase from last frame */ - COMP dphi_m; - for(m=0; m<M; m++) { - dphi_m = comp_exp_j(2*M_PI*((f_est[m])/(float)(Fs))); - for(i=nold,j=0; i<Nmem; i++,j++) { - phi_c[m] = cmult(phi_c[m],dphi_m); - f_dc[m*Nmem+i] = cmult(fsk_in[j],cconj(phi_c[m])); - } - phi_c[m] = comp_normalize(phi_c[m]); - #ifdef MODEMPROBE_ENABLE - snprintf(mp_name_tmp,NMP_NAME,"t_f%zd_dc",m+1); - modem_probe_samp_c(mp_name_tmp,&f_dc[m*Nmem],Nmem); - #endif + phi_c[m] = comp_normalize(phi_c[m]); +#ifdef MODEMPROBE_ENABLE + snprintf(mp_name_tmp, NMP_NAME, "t_f%zd_dc", m + 1); + modem_probe_samp_c(mp_name_tmp, &f_dc[m * Nmem], Nmem); +#endif + } + + /* integrate over symbol period at a variety of offsets */ + COMP f_int[M][(nsym + 1) * P]; + for (i = 0; i < (nsym + 1) * P; i++) { + int st = i * Ts / P; + int en = st + Ts - 1; + for (m = 0; m < M; m++) { + f_int[m][i] = comp0(); + for (j = st; j <= en; j++) + f_int[m][i] = cadd(f_int[m][i], f_dc[m * Nmem + j]); } + } - /* integrate over symbol period at a variety of offsets */ - COMP f_int[M][(nsym+1)*P]; - for(i=0; i<(nsym+1)*P; i++) { - int st = i*Ts/P; - int en = st+Ts-1; - for(m=0; m<M; m++) { - f_int[m][i] = comp0(); - for(j=st; j<=en; j++) - f_int[m][i] = cadd(f_int[m][i], f_dc[m*Nmem+j]); - } - } +#ifdef MODEMPROBE_ENABLE + for (m = 0; m < M; m++) { + snprintf(mp_name_tmp, NMP_NAME, "t_f%zd_int", m + 1); + modem_probe_samp_c(mp_name_tmp, &f_int[m][0], (nsym + 1) * P); + } +#endif - #ifdef MODEMPROBE_ENABLE - for(m=0; m<M; m++) { - snprintf(mp_name_tmp,NMP_NAME,"t_f%zd_int",m+1); - modem_probe_samp_c(mp_name_tmp,&f_int[m][0],(nsym+1)*P); - } - #endif - - /* Fine Timing Estimation */ - /* Apply magic nonlinearity to f1_int and f2_int, shift down to 0, - * extract angle */ - - /* Figure out how much to spin the oscillator to extract magic spectral line */ - dphift = comp_exp_j(2*M_PI*((float)(Rs)/(float)(P*Rs))); - phi_ft.real = 1; - phi_ft.imag = 0; - t_c=comp0(); - for(i=0; i<(nsym+1)*P; i++){ - /* Get abs^2 of fx_int[i], and add 'em */ - ft1 = 0; - for( m=0; m<M; m++){ - ft1 += (f_int[m][i].real*f_int[m][i].real) + (f_int[m][i].imag*f_int[m][i].imag); - } - - /* Down shift and accumulate magic line */ - t_c = cadd(t_c,fcmult(ft1,phi_ft)); - - /* Spin the oscillator for the magic line shift */ - phi_ft = cmult(phi_ft,dphift); + /* Fine Timing Estimation */ + /* Apply magic nonlinearity to f1_int and f2_int, shift down to 0, + * extract angle */ + + /* Figure out how much to spin the oscillator to extract magic spectral line + */ + dphift = comp_exp_j(2 * M_PI * ((float)(Rs) / (float)(P * Rs))); + phi_ft.real = 1; + phi_ft.imag = 0; + t_c = comp0(); + for (i = 0; i < (nsym + 1) * P; i++) { + /* Get abs^2 of fx_int[i], and add 'em */ + ft1 = 0; + for (m = 0; m < M; m++) { + ft1 += (f_int[m][i].real * f_int[m][i].real) + + (f_int[m][i].imag * f_int[m][i].imag); } - /* Check for NaNs in the fine timing estimate, return if found */ - /* otherwise segfaults happen */ - if( isnan(t_c.real) || isnan(t_c.imag)){ - return; - } - - /* Get the magic angle */ - norm_rx_timing = atan2f(t_c.imag,t_c.real)/(2*M_PI); - rx_timing = norm_rx_timing*(float)P; - - old_norm_rx_timing = fsk->norm_rx_timing; - fsk->norm_rx_timing = norm_rx_timing; - - /* Estimate sample clock offset */ - d_norm_rx_timing = norm_rx_timing - old_norm_rx_timing; - - /* Filter out big jumps in due to nin change */ - if(fabsf(d_norm_rx_timing) < .2){ - appm = 1e6*d_norm_rx_timing/(float)nsym; - fsk->ppm = .9*fsk->ppm + .1*appm; - } - - /* Figure out how many samples are needed the next modem cycle */ - /* Unless we're in burst mode or nin locked */ - if(!fsk->burst_mode && !fsk->lock_nin) { - if(norm_rx_timing > 0.25) - fsk->nin = N+Ts/4; - else if(norm_rx_timing < -0.25) - fsk->nin = N-Ts/4; - else - fsk->nin = N; + /* Down shift and accumulate magic line */ + t_c = cadd(t_c, fcmult(ft1, phi_ft)); + + /* Spin the oscillator for the magic line shift */ + phi_ft = cmult(phi_ft, dphift); + } + + /* Check for NaNs in the fine timing estimate, return if found */ + /* otherwise segfaults happen */ + if (isnan(t_c.real) || isnan(t_c.imag)) { + return; + } + + /* Get the magic angle */ + norm_rx_timing = atan2f(t_c.imag, t_c.real) / (2 * M_PI); + rx_timing = norm_rx_timing * (float)P; + + old_norm_rx_timing = fsk->norm_rx_timing; + fsk->norm_rx_timing = norm_rx_timing; + + /* Estimate sample clock offset */ + d_norm_rx_timing = norm_rx_timing - old_norm_rx_timing; + + /* Filter out big jumps in due to nin change */ + if (fabsf(d_norm_rx_timing) < .2) { + appm = 1e6 * d_norm_rx_timing / (float)nsym; + fsk->ppm = .9 * fsk->ppm + .1 * appm; + } + + /* Figure out how many samples are needed the next modem cycle */ + /* Unless we're in burst mode or nin locked */ + if (!fsk->burst_mode && !fsk->lock_nin) { + if (norm_rx_timing > 0.25) + fsk->nin = N + Ts / 4; + else if (norm_rx_timing < -0.25) + fsk->nin = N - Ts / 4; + else + fsk->nin = N; + } + + modem_probe_samp_f("t_norm_rx_timing", &(norm_rx_timing), 1); + modem_probe_samp_i("t_nin", &(fsk->nin), 1); + + /* Re-sample the integrators with linear interpolation magic */ + int low_sample = (int)floorf(rx_timing); + float fract = rx_timing - (float)low_sample; + int high_sample = (int)ceilf(rx_timing); + + /* Vars for finding the max-of-4 for each bit */ + float tmax[M]; + +#ifdef EST_EBNO + meanebno = 0; + stdebno = 0; +#endif + + float rx_nse_pow = 1E-12; + float rx_sig_pow = 0.0; + for (i = 0; i < nsym; i++) { + /* resample at ideal sampling instant */ + int st = (i + 1) * P; + for (m = 0; m < M; m++) { + t[m] = fcmult(1 - fract, f_int[m][st + low_sample]); + t[m] = cadd(t[m], fcmult(fract, f_int[m][st + high_sample])); + /* Figure mag^2 of each resampled fx_int */ + tmax[m] = (t[m].real * t[m].real) + (t[m].imag * t[m].imag); } - modem_probe_samp_f("t_norm_rx_timing",&(norm_rx_timing),1); - modem_probe_samp_i("t_nin",&(fsk->nin),1); - - /* Re-sample the integrators with linear interpolation magic */ - int low_sample = (int)floorf(rx_timing); - float fract = rx_timing - (float)low_sample; - int high_sample = (int)ceilf(rx_timing); - - /* Vars for finding the max-of-4 for each bit */ - float tmax[M]; - - #ifdef EST_EBNO - meanebno = 0; - stdebno = 0; - #endif - - float rx_nse_pow = 1E-12; float rx_sig_pow = 0.0; - for(i=0; i<nsym; i++) { - - /* resample at ideal sampling instant */ - int st = (i+1)*P; - for( m=0; m<M; m++) { - t[m] = fcmult(1-fract,f_int[m][st+low_sample]); - t[m] = cadd(t[m],fcmult( fract,f_int[m][st+high_sample])); - /* Figure mag^2 of each resampled fx_int */ - tmax[m] = (t[m].real*t[m].real) + (t[m].imag*t[m].imag); - } - - /* hard decision decoding of bits */ - float max = tmax[0]; /* Maximum for figuring correct symbol */ - float min = tmax[0]; - int sym = 0; /* Index of maximum */ - for( m=0; m<M; m++){ - if(tmax[m]>max){ - max = tmax[m]; - sym = m; - } - if(tmax[m]<min){ - min = tmax[m]; - } - } - - if(rx_bits != NULL){ - /* Get bits for 2FSK and 4FSK */ - if(M==2){ - rx_bits[i] = sym==1; /* 2FSK. 1 bit per symbol */ - }else if(M==4){ - rx_bits[(i*2)+1] = (sym&0x1); /* 4FSK. 2 bits per symbol */ - rx_bits[(i*2) ] = (sym&0x2)>>1; - } - } - - /* Optionally output filter magnitudes for soft decision/LLR - calculation. Update SNRest always as this is a useful - alternative to the earlier EbNo estimator below */ - float sum = 0.0; - for(m=0; m<M; m++) { - if (rx_filt != NULL) rx_filt[m*nsym+i] = sqrtf(tmax[m]); - sum += tmax[m]; - } - rx_sig_pow += max; - rx_nse_pow += (sum-max)/(M-1); - - /* Accumulate resampled int magnitude for EbNodB estimation */ - /* Standard deviation is calculated by algorithm devised by crafty soviets */ - #ifdef EST_EBNO - /* Accumulate the square of the sampled value */ - ft1 = max; - stdebno += ft1; - - /* Figure the abs value of the max tone */ - meanebno += sqrtf(ft1); - #endif + /* hard decision decoding of bits */ + float max = tmax[0]; /* Maximum for figuring correct symbol */ + float min = tmax[0]; + int sym = 0; /* Index of maximum */ + for (m = 0; m < M; m++) { + if (tmax[m] > max) { + max = tmax[m]; + sym = m; + } + if (tmax[m] < min) { + min = tmax[m]; + } } - fsk->rx_sig_pow = rx_sig_pow = rx_sig_pow/nsym; - fsk->rx_nse_pow = rx_nse_pow = rx_nse_pow/nsym; - fsk->v_est = sqrt(rx_sig_pow-rx_nse_pow); - fsk->SNRest = rx_sig_pow/rx_nse_pow; - - #ifdef EST_EBNO - /* Calculate mean for EbNodB estimation */ - meanebno = meanebno/(float)nsym; - - /* Calculate the std. dev for EbNodB estimate */ - stdebno = (stdebno/(float)nsym) - (meanebno*meanebno); - /* trap any negative numbers to avoid NANs flowing through */ - if (stdebno > 0.0) { - stdebno = sqrt(stdebno); - } else { - stdebno = 0.0; + if (rx_bits != NULL) { + /* Get bits for 2FSK and 4FSK */ + if (M == 2) { + rx_bits[i] = sym == 1; /* 2FSK. 1 bit per symbol */ + } else if (M == 4) { + rx_bits[(i * 2) + 1] = (sym & 0x1); /* 4FSK. 2 bits per symbol */ + rx_bits[(i * 2)] = (sym & 0x2) >> 1; + } } - - fsk->EbNodB = -6+(20*log10f((1e-6+meanebno)/(1e-6+stdebno))); - #else - fsk->EbNodB = 1; - #endif - - /* Write some statistics to the stats struct */ - - /* Save clock offset in ppm */ - fsk->stats->clock_offset = fsk->ppm; - - /* Calculate and save SNR from EbNodB estimate */ - - fsk->stats->snr_est = .5*fsk->stats->snr_est + .5*fsk->EbNodB;//+ 10*log10f(((float)Rs)/((float)Rs*M)); - - /* Save rx timing */ - fsk->stats->rx_timing = (float)rx_timing; - - /* Estimate and save frequency offset */ - fc_avg = fc_tx = 0.0; - for(int m=0; m<M; m++) { - fc_avg += f_est[m]/M; - fc_tx += (fsk->f1_tx + m*fsk->tone_spacing)/M; + + /* Optionally output filter magnitudes for soft decision/LLR + calculation. Update SNRest always as this is a useful + alternative to the earlier EbNo estimator below */ + float sum = 0.0; + for (m = 0; m < M; m++) { + if (rx_filt != NULL) rx_filt[m * nsym + i] = sqrtf(tmax[m]); + sum += tmax[m]; } - fsk->stats->foff = fc_avg-fc_tx; - - /* Take a sample for the eye diagrams ---------------------------------- */ + rx_sig_pow += max; + rx_nse_pow += (sum - max) / (M - 1); + +/* Accumulate resampled int magnitude for EbNodB estimation */ +/* Standard deviation is calculated by algorithm devised by crafty soviets */ +#ifdef EST_EBNO + /* Accumulate the square of the sampled value */ + ft1 = max; + stdebno += ft1; + + /* Figure the abs value of the max tone */ + meanebno += sqrtf(ft1); +#endif + } + + fsk->rx_sig_pow = rx_sig_pow = rx_sig_pow / nsym; + fsk->rx_nse_pow = rx_nse_pow = rx_nse_pow / nsym; + fsk->v_est = sqrt(rx_sig_pow - rx_nse_pow); + fsk->SNRest = rx_sig_pow / rx_nse_pow; + +#ifdef EST_EBNO + /* Calculate mean for EbNodB estimation */ + meanebno = meanebno / (float)nsym; + + /* Calculate the std. dev for EbNodB estimate */ + stdebno = (stdebno / (float)nsym) - (meanebno * meanebno); + /* trap any negative numbers to avoid NANs flowing through */ + if (stdebno > 0.0) { + stdebno = sqrt(stdebno); + } else { + stdebno = 0.0; + } + + fsk->EbNodB = -6 + (20 * log10f((1e-6 + meanebno) / (1e-6 + stdebno))); +#else + fsk->EbNodB = 1; +#endif + + /* Write some statistics to the stats struct */ + + /* Save clock offset in ppm */ + fsk->stats->clock_offset = fsk->ppm; + + /* Calculate and save SNR from EbNodB estimate */ - /* due to oversample rate P, we have too many samples for eye - trace. So lets output a decimated version. We use 2P - as we want two symbols worth of samples in trace */ + fsk->stats->snr_est = + .5 * fsk->stats->snr_est + + .5 * fsk->EbNodB; //+ 10*log10f(((float)Rs)/((float)Rs*M)); + + /* Save rx timing */ + fsk->stats->rx_timing = (float)rx_timing; + + /* Estimate and save frequency offset */ + fc_avg = fc_tx = 0.0; + for (int m = 0; m < M; m++) { + fc_avg += f_est[m] / M; + fc_tx += (fsk->f1_tx + m * fsk->tone_spacing) / M; + } + fsk->stats->foff = fc_avg - fc_tx; + + /* Take a sample for the eye diagrams ---------------------------------- */ + + /* due to oversample rate P, we have too many samples for eye + trace. So lets output a decimated version. We use 2P + as we want two symbols worth of samples in trace */ #ifndef __EMBEDDED__ - int neyesamp_dec = ceil(((float)P*2)/MODEM_STATS_EYE_IND_MAX); - neyesamp = (P*2)/neyesamp_dec; - assert(neyesamp <= MODEM_STATS_EYE_IND_MAX); - fsk->stats->neyesamp = neyesamp; - - neyeoffset = high_sample+1; - - int eye_traces = MODEM_STATS_ET_MAX/M; - int ind; - - fsk->stats->neyetr = fsk->mode*eye_traces; - for( i=0; i<eye_traces; i++){ - for ( m=0; m<M; m++){ - for(j=0; j<neyesamp; j++) { - /* - 2*P*i...........: advance two symbols for next trace - neyeoffset......: centre trace on ideal timing offset, peak eye opening - j*neweyesamp_dec: For 2*P>MODEM_STATS_EYE_IND_MAX advance through integrated - samples newamp_dec at a time so we dont overflow rx_eye[][] - */ - ind = 2*P*(i+1) + neyeoffset + j*neyesamp_dec; - assert((i*M+m) < MODEM_STATS_ET_MAX); - assert(ind >= 0); - assert(ind < (nsym+1)*P); - fsk->stats->rx_eye[i*M+m][j] = cabsolute(f_int[m][ind]); - } - } - } - - if (fsk->normalise_eye) { - eye_max = 0; - /* Normalize eye to +/- 1 */ - for(i=0; i<M*eye_traces; i++) - for(j=0; j<neyesamp; j++) - if(fabsf(fsk->stats->rx_eye[i][j])>eye_max) - eye_max = fabsf(fsk->stats->rx_eye[i][j]); - - for(i=0; i<M*eye_traces; i++) - for(j=0; j<neyesamp; j++) - fsk->stats->rx_eye[i][j] = fsk->stats->rx_eye[i][j]/eye_max; + int neyesamp_dec = ceil(((float)P * 2) / MODEM_STATS_EYE_IND_MAX); + neyesamp = (P * 2) / neyesamp_dec; + assert(neyesamp <= MODEM_STATS_EYE_IND_MAX); + fsk->stats->neyesamp = neyesamp; + + neyeoffset = high_sample + 1; + + int eye_traces = MODEM_STATS_ET_MAX / M; + int ind; + + fsk->stats->neyetr = fsk->mode * eye_traces; + for (i = 0; i < eye_traces; i++) { + for (m = 0; m < M; m++) { + for (j = 0; j < neyesamp; j++) { + /* + 2*P*i...........: advance two symbols for next trace + neyeoffset......: centre trace on ideal timing offset, peak eye + opening j*neweyesamp_dec: For 2*P>MODEM_STATS_EYE_IND_MAX advance + through integrated samples newamp_dec at a time so we dont overflow + rx_eye[][] + */ + ind = 2 * P * (i + 1) + neyeoffset + j * neyesamp_dec; + assert((i * M + m) < MODEM_STATS_ET_MAX); + assert(ind >= 0); + assert(ind < (nsym + 1) * P); + fsk->stats->rx_eye[i * M + m][j] = cabsolute(f_int[m][ind]); + } } - - fsk->stats->nr = 0; - fsk->stats->Nc = 0; - - for(i=0; i<M; i++) - fsk->stats->f_est[i] = f_est[i]; -#endif // !__EMBEDDED__ - - /* Dump some internal samples */ - modem_probe_samp_f("t_EbNodB",&(fsk->EbNodB),1); - modem_probe_samp_f("t_ppm",&(fsk->ppm),1); - modem_probe_samp_f("t_rx_timing",&(rx_timing),1); + } + + if (fsk->normalise_eye) { + eye_max = 0; + /* Normalize eye to +/- 1 */ + for (i = 0; i < M * eye_traces; i++) + for (j = 0; j < neyesamp; j++) + if (fabsf(fsk->stats->rx_eye[i][j]) > eye_max) + eye_max = fabsf(fsk->stats->rx_eye[i][j]); + + for (i = 0; i < M * eye_traces; i++) + for (j = 0; j < neyesamp; j++) + fsk->stats->rx_eye[i][j] = fsk->stats->rx_eye[i][j] / eye_max; + } + + fsk->stats->nr = 0; + fsk->stats->Nc = 0; + + for (i = 0; i < M; i++) fsk->stats->f_est[i] = f_est[i]; +#endif // !__EMBEDDED__ + + /* Dump some internal samples */ + modem_probe_samp_f("t_EbNodB", &(fsk->EbNodB), 1); + modem_probe_samp_f("t_ppm", &(fsk->ppm), 1); + modem_probe_samp_f("t_rx_timing", &(rx_timing), 1); } /*---------------------------------------------------------------------------*\ @@ -928,7 +943,7 @@ void fsk_demod_core(struct FSK *fsk, uint8_t rx_bits[], float rx_filt[], COMP fs FUNCTION....: fsk_demod AUTHOR......: Brady O'Brien DATE CREATED: 11 February 2016 - + FSK demodulator functions: fsk_demod...: complex samples in, bits out @@ -937,116 +952,109 @@ void fsk_demod_core(struct FSK *fsk, uint8_t rx_bits[], float rx_filt[], COMP fs \*---------------------------------------------------------------------------*/ void fsk_demod(struct FSK *fsk, uint8_t rx_bits[], COMP fsk_in[]) { - fsk_demod_core(fsk,rx_bits,NULL,fsk_in); + fsk_demod_core(fsk, rx_bits, NULL, fsk_in); } -void fsk_demod_sd(struct FSK *fsk, float rx_filt[], COMP fsk_in[]){ - fsk_demod_core(fsk,NULL,rx_filt,fsk_in); +void fsk_demod_sd(struct FSK *fsk, float rx_filt[], COMP fsk_in[]) { + fsk_demod_core(fsk, NULL, rx_filt, fsk_in); } -/* make sure stats have known values in case monitoring process reads stats before they are set */ +/* make sure stats have known values in case monitoring process reads stats + * before they are set */ static void stats_init(struct FSK *fsk) { - /* Take a sample for the eye diagrams */ - int i,j,m; - int P = fsk->P; - int M = fsk->mode; - - /* due to oversample rate P, we have too many samples for eye - trace. So lets output a decimated version */ - - /* asserts below as we found some problems over-running eye matrix */ - - /* TODO: refactor eye tracing code here and in fsk_demod */ -#ifndef __EMBEDDED__ - int neyesamp_dec = ceil(((float)P*2)/MODEM_STATS_EYE_IND_MAX); - int neyesamp = (P*2)/neyesamp_dec; - assert(neyesamp <= MODEM_STATS_EYE_IND_MAX); - fsk->stats->neyesamp = neyesamp; - - int eye_traces = MODEM_STATS_ET_MAX/M; - - fsk->stats->neyetr = fsk->mode*eye_traces; - for(i=0; i<eye_traces; i++) { - for (m=0; m<M; m++){ - for(j=0; j<neyesamp; j++) { - assert((i*M+m) < MODEM_STATS_ET_MAX); - fsk->stats->rx_eye[i*M+m][j] = 0; - } - } + /* Take a sample for the eye diagrams */ + int i, j, m; + int P = fsk->P; + int M = fsk->mode; + + /* due to oversample rate P, we have too many samples for eye + trace. So lets output a decimated version */ + + /* asserts below as we found some problems over-running eye matrix */ + + /* TODO: refactor eye tracing code here and in fsk_demod */ +#ifndef __EMBEDDED__ + int neyesamp_dec = ceil(((float)P * 2) / MODEM_STATS_EYE_IND_MAX); + int neyesamp = (P * 2) / neyesamp_dec; + assert(neyesamp <= MODEM_STATS_EYE_IND_MAX); + fsk->stats->neyesamp = neyesamp; + + int eye_traces = MODEM_STATS_ET_MAX / M; + + fsk->stats->neyetr = fsk->mode * eye_traces; + for (i = 0; i < eye_traces; i++) { + for (m = 0; m < M; m++) { + for (j = 0; j < neyesamp; j++) { + assert((i * M + m) < MODEM_STATS_ET_MAX); + fsk->stats->rx_eye[i * M + m][j] = 0; + } } -#endif // !__EMBEDDED__ + } +#endif // !__EMBEDDED__ - fsk->stats->rx_timing = fsk->stats->snr_est = 0; - + fsk->stats->rx_timing = fsk->stats->snr_est = 0; } - /* Set the FSK modem into burst demod mode */ -void fsk_enable_burst_mode(struct FSK *fsk){ - fsk->nin = fsk->N; - fsk->burst_mode = 1; +void fsk_enable_burst_mode(struct FSK *fsk) { + fsk->nin = fsk->N; + fsk->burst_mode = 1; } -void fsk_clear_estimators(struct FSK *fsk){ - int i; - /* Clear freq estimator state */ - for(i=0; i < (fsk->Ndft); i++){ - fsk->Sf[i] = 0; - } - /* Reset timing diff correction */ - fsk->nin = fsk->N; +void fsk_clear_estimators(struct FSK *fsk) { + int i; + /* Clear freq estimator state */ + for (i = 0; i < (fsk->Ndft); i++) { + fsk->Sf[i] = 0; + } + /* Reset timing diff correction */ + fsk->nin = fsk->N; } -void fsk_get_demod_stats(struct FSK *fsk, struct MODEM_STATS *stats){ - /* copy from internal stats, note we can't overwrite stats completely - as it has other states rqd by caller, also we want a consistent - interface across modem types for the freedv_api. - */ +void fsk_get_demod_stats(struct FSK *fsk, struct MODEM_STATS *stats) { + /* copy from internal stats, note we can't overwrite stats completely + as it has other states rqd by caller, also we want a consistent + interface across modem types for the freedv_api. + */ - stats->clock_offset = fsk->stats->clock_offset; - stats->snr_est = fsk->stats->snr_est; // TODO: make this SNR not Eb/No - stats->rx_timing = fsk->stats->rx_timing; - stats->foff = fsk->stats->foff; + stats->clock_offset = fsk->stats->clock_offset; + stats->snr_est = fsk->stats->snr_est; // TODO: make this SNR not Eb/No + stats->rx_timing = fsk->stats->rx_timing; + stats->foff = fsk->stats->foff; #ifndef __EMBEDDED__ - stats->neyesamp = fsk->stats->neyesamp; - stats->neyetr = fsk->stats->neyetr; - memcpy(stats->rx_eye, fsk->stats->rx_eye, sizeof(stats->rx_eye)); - memcpy(stats->f_est, fsk->stats->f_est, fsk->mode*sizeof(float)); -#endif // !__EMBEDDED__ - - /* these fields not used for FSK so set to something sensible */ - - stats->sync = 0; - stats->nr = fsk->stats->nr; - stats->Nc = fsk->stats->Nc; + stats->neyesamp = fsk->stats->neyesamp; + stats->neyetr = fsk->stats->neyetr; + memcpy(stats->rx_eye, fsk->stats->rx_eye, sizeof(stats->rx_eye)); + memcpy(stats->f_est, fsk->stats->f_est, fsk->mode * sizeof(float)); +#endif // !__EMBEDDED__ + + /* these fields not used for FSK so set to something sensible */ + + stats->sync = 0; + stats->nr = fsk->stats->nr; + stats->Nc = fsk->stats->Nc; } /* - * 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 est_min, int est_max){ - assert(fsk != NULL); - assert(est_min >= -fsk->Fs/2); - assert(est_max <= fsk->Fs/2); - assert(est_max > est_min); - fsk->est_min = est_min; - fsk->est_max = est_max; +void fsk_set_freq_est_limits(struct FSK *fsk, int est_min, int est_max) { + assert(fsk != NULL); + assert(est_min >= -fsk->Fs / 2); + assert(est_max <= fsk->Fs / 2); + assert(est_max > est_min); + fsk->est_min = est_min; + fsk->est_max = est_max; } void fsk_stats_normalise_eye(struct FSK *fsk, int normalise_enable) { - assert(fsk != NULL); - fsk->normalise_eye = normalise_enable; + assert(fsk != NULL); + fsk->normalise_eye = normalise_enable; } void fsk_set_freq_est_alg(struct FSK *fsk, int est_type) { - assert(fsk != NULL); - fsk->freq_est_type = est_type; + assert(fsk != NULL); + fsk->freq_est_type = est_type; } - - - - - - - |