yafox
/
minimodem-mirror
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

minimodem decode_filter_width = decode_rate 

This doesn't really seem to help anything.
This commit is contained in:
Kamal Mostafa 2011-05-30 20:23:32 -07:00
parent e5fb5f4b75
commit d93537d128
1 changed files with 36 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
src/minimodem.c
View File

@ -31,8 +31,23 @@ band_mag( fftwf_complex * const cplx, unsigned int band, float scalar )
{
float re = cplx[band][0];
float im = cplx[band][1];
float mag = hypot(re, im) * scalar;
return mag;
float mag = hypot(re, im);
return mag * scalar;
}
static inline
float
band_mag_bw( fftwf_complex * const cplx, unsigned int band, unsigned int bw_nbands, float scalar )
{
float mag = 0;
unsigned int i;
for ( i=0; i<bw_nbands; i++ ) {
float re, im;
re = cplx[band+i][0];
im = cplx[band+i][1];
mag += hypot(re, im);
}
return mag * scalar / bw_nbands;
}
int main(int argc, char*argv[]) {
@ -94,16 +109,27 @@ int main(int argc, char*argv[]) {
band_width = 200;
}
// unsigned int decode_filter_width = decode_rate / 2;
// unsigned int decode_filter_width = decode_rate * 1.5;
unsigned int decode_filter_width = decode_rate;
if ( argi < argc ) {
assert(argc-argi == 2);
bfsk_mark_f = atoi(argv[argi++]);
bfsk_space_f = atoi(argv[argi++]);
}
unsigned int bfsk_bw_nbands = (decode_filter_width + (float)band_width/2) / band_width;
unsigned int bfsk_bw_nbands_half = bfsk_bw_nbands / 2;
unsigned int bfsk_mark_band = (bfsk_mark_f +(float)band_width/2) / band_width;
unsigned int bfsk_space_band = (bfsk_space_f +(float)band_width/2) / band_width;
fprintf(stderr, "### mark_band=%u space_band=%u bw_nbands=%u\n",
bfsk_mark_band, bfsk_space_band, bfsk_bw_nbands);
// FIXME -- need to account for bfsk_bw_nbands
if ( bfsk_mark_band == 0 || bfsk_space_band == 0 ) {
fprintf(stderr, __FILE__": mark or space band is at dsp DC\n");
// return 1;
@ -222,8 +248,12 @@ reprocess_audio:
fftwf_execute(fftplan);
/* examine channel 0 only */
float mag_mark = band_mag(fftout, bfsk_mark_band, magscalar);
float mag_space = band_mag(fftout, bfsk_space_band, magscalar);
float mag_mark = band_mag_bw(fftout,
bfsk_mark_band - bfsk_bw_nbands_half,
bfsk_bw_nbands, magscalar);
float mag_space = band_mag_bw(fftout,
bfsk_space_band - bfsk_bw_nbands_half,
bfsk_bw_nbands, magscalar);
static unsigned char lastbit;
@ -248,9 +278,9 @@ reprocess_audio:
float cd_ms_delta;
if ( decode_rate > 600 ) // HORRIBLE HACK
cd_ms_delta = 0.55;
cd_ms_delta = 0.3;
else
cd_ms_delta = 0.2;
cd_ms_delta = 0.1;
/* Detect bfsk carrier */
int carrier_detect /*boolean*/ =