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minimodem: restrict try_max_nsamples to 75% of a bit-width 

... actually 125% of a bit width before acquiring carrier.
This commit is contained in:
Kamal Mostafa 2012-09-02 14:27:04 -07:00
parent 7b0e47ac4e
commit fd45b5571c
1 changed files with 10 additions and 2 deletions
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12
src/minimodem.c
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@ -771,6 +771,9 @@ main( int argc, char*argv[] )
// for optimal analysis:
// should be >= 0.5 (half a bit width) or we may not find the optimal bit
// should be < 1.0 (a full bit width) or we may skip over whole bits
// for encodings without start/stop bits:
// MUST be <= 0.5 or we may accidentally skip a bit
//
assert( fsk_frame_overscan >= 0.0 && fsk_frame_overscan < 1.0 );
// ensure that we overscan at least a single sample
@ -914,11 +917,16 @@ main( int argc, char*argv[] )
if ( samples_nvalid < expect_nsamples )
break;
// try_max_nsamples = nsamples_per_bit + nsamples_overscan;
// try_max_nsamples
// serves two purposes
// 1. avoids finding a non-optimal first frame
// 2. allows us to track slightly slow signals
unsigned int try_max_nsamples = nsamples_per_bit + nsamples_overscan;
unsigned int try_max_nsamples;
if ( carrier )
try_max_nsamples = nsamples_per_bit * 0.75 + 0.5;
else
try_max_nsamples = nsamples_per_bit;
try_max_nsamples += nsamples_overscan;
#define FSK_ANALYZE_NSTEPS 10 /* accuracy vs. performance */
// Note: FSK_ANALYZE_NSTEPS has subtle effects on the