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fsk: cleanup

This commit is contained in:
Kamal Mostafa 2011-06-04 09:57:33 -07:00
parent 80c8a62073
commit b73f7fb5b8
1 changed files with 50 additions and 25 deletions
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75
src/fsk.c
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@ -30,6 +30,8 @@ struct fsk_plan {
float f_space;
float filter_bw;
unsigned int n_data_bits;
unsigned int n_frame_bits;
#ifdef USE_FFT
int fftsize; // fftw wants this to be signed. why?
unsigned int b_mark;
@ -60,6 +62,9 @@ fsk_plan_new(
fskp->filter_bw = filter_bw;
fskp->n_data_bits = n_data_bits;
/* 1 prev_stop + n_data_bits + 1 start + 1 stop == n_data_bits + 3 */
fskp->n_frame_bits = fskp->n_data_bits + 3;
#ifdef USE_FFT
unsigned int fft_bw = filter_bw;
@ -152,8 +157,7 @@ fsk_frame_decode( fsk_plan *fskp, float *samples, unsigned int frame_nsamples,
{
float v = 0;
/* 1 prev_stop + n_data_bits + 1 start + 1 stop == n_data_bits + 3 */
float samples_per_bit = (float)frame_nsamples / (fskp->n_data_bits + 3);
float samples_per_bit = (float)frame_nsamples / fskp->n_frame_bits;
unsigned int bit_nsamples = (float)(samples_per_bit + 0.5);
@ -218,11 +222,13 @@ debug_log( "v=%f\n", v );
}
int
/* returns confidence value [0.0 to 1.0] */
float
fsk_find_frame( fsk_plan *fskp, float *samples, unsigned int frame_nsamples,
unsigned int try_max_nsamples,
unsigned int try_step_nsamples,
unsigned int *bits_outp
unsigned int *bits_outp,
unsigned int *frame_start_outp
)
{
unsigned int t;
@ -241,19 +247,18 @@ fsk_find_frame( fsk_plan *fskp, float *samples, unsigned int frame_nsamples,
best_bits = bits_out;
}
}
#define FSK_MINV (11 * 0.2)
if ( best_v <= FSK_MINV ) {
debug_log( "no frame\n" );
return -1;
}
debug_log("DATA '%c' @ v=%f t=%d\n",
isprint(best_bits)||isspace(best_bits) ? best_bits : '.',
best_v, best_t);
*bits_outp = best_bits;
*frame_start_outp = best_t;
return best_t;
float confidence = best_v / fskp->n_frame_bits;
debug_log("FSK_FRAME datum='%c' (0x%02x) c=%f t=%d\n",
isprint(best_bits)||isspace(best_bits) ? best_bits : '.',
best_bits,
confidence, best_t);
return confidence;
}
/****************************************************************************/
@ -366,8 +371,10 @@ main( int argc, char*argv[] )
size_t read_nsamples = fill_nsamples;
float *read_bufptr = samples;
int carrier = 0;
float confidence_total = 0;
unsigned int nbytes_decoded = 0;
int carrier = 0;
while ( 1 ) {
debug_log( "@read samples+%ld n=%lu\n",
@ -388,24 +395,42 @@ main( int argc, char*argv[] )
debug_log( "--------------------------\n");
int t =
fsk_find_frame(fskp, samples, frame_nsamples,
unsigned int t = 0;
float confidence;
confidence = fsk_find_frame(fskp, samples, frame_nsamples,
/*try_max_nsamples*/ nsamples_per_bit,
try_step_nsamples,
&bits
&bits,
&t
);
if ( t <= 0 ) {
if ( carrier )
fprintf(stderr, "\n### NOCARRIER ###\n");
carrier = 0;
#define FSK_MIN_CONFIDENCE 0.41
if ( confidence <= FSK_MIN_CONFIDENCE ) {
if ( carrier ) {
fprintf(stderr, "### NOCARRIER nbytes=%u confidence=%f ###\n",
nbytes_decoded,
confidence_total / nbytes_decoded );
carrier = 0;
confidence_total = 0;
nbytes_decoded = 0;
}
t = nsamples_per_bit;
} else {
if ( !carrier )
fprintf(stderr, "\n### CARRIER ###\n");
carrier = 1;
if ( !carrier ) {
fprintf(stderr, "### CARRIER ###\n");
carrier = 1;
}
confidence_total += confidence;
nbytes_decoded++;
// t += nsamples_per_bit * 10;
t += nsamples_per_bit * 9.5;