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minimodem: less aggressive refine on acquisition

This commit is contained in:
Kamal Mostafa 2012-09-05 23:22:27 -07:00
parent 2612aba0e2
commit fabd47ba99
1 changed files with 28 additions and 16 deletions
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44
src/minimodem.c
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@ -948,7 +948,7 @@ main( int argc, char*argv[] )
// fast/slow signals (at decreased performance). Note also
// FSK_ANALYZE_NSTEPS_CARRIER_LOCK below, which refines the frame
// position upon first acquiring carrier.
#define FSK_ANALYZE_NSTEPS 4
#define FSK_ANALYZE_NSTEPS 3
unsigned int try_step_nsamples = try_max_nsamples / FSK_ANALYZE_NSTEPS;
if ( try_step_nsamples == 0 )
try_step_nsamples = 1;
@ -1032,39 +1032,51 @@ main( int argc, char*argv[] )
// We just acquired carrier.
if ( !quiet_mode ) {
if ( bfsk_data_rate >= 100 )
fprintf(stderr, "### CARRIER %u @ %.1f Hz ",
(unsigned int)(bfsk_data_rate + 0.5),
fskp->b_mark * fskp->band_width);
else
fprintf(stderr, "### CARRIER %.2f @ %.1f Hz ",
bfsk_data_rate,
fskp->b_mark * fskp->band_width);
}
if ( confidence < INFINITY && try_step_nsamples > 1 ) {
// FSK_ANALYZE_NSTEPS_CARRIER_LOCK:
// Scan again, but try harder to find the best frame upon
// acquiring carrier. Since we found a valid confidence frame
// in the "sloppy" fsk_find_frame() call already, we're sure
// to find one at least as good this time.
#define FSK_ANALYZE_NSTEPS_CARRIER_LOCK 100
#define FSK_ANALYZE_NSTEPS_CARRIER_LOCK 8
try_step_nsamples = try_max_nsamples / FSK_ANALYZE_NSTEPS_CARRIER_LOCK;
if ( try_step_nsamples == 0 )
try_step_nsamples = 1;
try_confidence_search_limit = INFINITY;
confidence = fsk_find_frame(fskp, samplebuf, expect_nsamples,
float confidence2, amplitude2;
unsigned int bits2;
unsigned int frame_start_sample2;
confidence2 = fsk_find_frame(fskp, samplebuf, expect_nsamples,
try_first_sample,
try_max_nsamples,
try_step_nsamples,
try_confidence_search_limit,
expect_bits_string,
&bits,
&amplitude,
&frame_start_sample
&bits2,
&amplitude2,
&frame_start_sample2
);
if ( confidence2 > confidence ) {
bits = bits2;
amplitude = amplitude2;
frame_start_sample = frame_start_sample2;
}
}
if ( !quiet_mode ) {
if ( bfsk_data_rate >= 100 )
fprintf(stderr, "### CARRIER %u @ %.1f Hz ###\n",
(unsigned int)(bfsk_data_rate + 0.5),
fskp->b_mark * fskp->band_width);
else
fprintf(stderr, "### CARRIER %.2f @ %.1f Hz ###\n",
bfsk_data_rate,
fskp->b_mark * fskp->band_width);
}
if ( !quiet_mode )
fprintf(stderr, "###\n");
carrier = 1;
bfsk_databits_decode(0, 0, 0, 0); // reset the frame processor
}