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minimodem: --inverted switches the mark/space freqs

This commit is contained in:
Kamal Mostafa 2012-09-04 16:26:10 -07:00
parent 8731b54bc2
commit 30de59026b
2 changed files with 22 additions and 3 deletions
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7
src/minimodem.1.in
View File

@ -46,7 +46,12 @@ receive mode: decode audio tones
.SH OPTIONS
.TP
.B \-a, \-\-auto-carrier
automatically detect mark and space frequences from carrier
Automatically detect mark and space frequences from carrier.
.TP
.B \-i, \-\-inverted
Invert the mark and space frequencies (applies whether the
frequencies are defaults, discovered by \-\-auto-carrier,
or specified manually).
.TP
.B \-c, \-\-confidence min-confidence-threshold
Set receive confidence minimum threshold (default 1.5).

18
src/minimodem.c
View File

@ -280,6 +280,7 @@ usage()
" -r, --rx, --receive, --read (default)\n"
" [options]\n"
" -a, --auto-carrier\n"
" -i, --inverted\n"
" -c, --confidence {min-confidence-threshold}\n"
" -l, --limit {max-confidence-search-limit}\n"
" -8, --ascii ASCII 8-N-1\n"
@ -319,6 +320,7 @@ main( int argc, char*argv[] )
float band_width = 0;
unsigned int bfsk_mark_f = 0;
unsigned int bfsk_space_f = 0;
unsigned int bfsk_inverted_freqs = 0;
int bfsk_nstartbits = -1; // actually only supports 0 or 1 startbit
float bfsk_nstopbits = -1;
unsigned int bfsk_sync_on_data = 0;
@ -399,6 +401,7 @@ main( int argc, char*argv[] )
{ "confidence", 1, 0, 'c' },
{ "limit", 1, 0, 'l' },
{ "auto-carrier", 0, 0, 'a' },
{ "inverted", 0, 0, 'i' },
{ "ascii", 0, 0, '8' },
{ "baudot", 0, 0, '5' },
{ "file", 1, 0, 'f' },
@ -420,7 +423,7 @@ main( int argc, char*argv[] )
{ "Xrxnoise", 1, 0, MINIMODEM_OPT_XRXNOISE },
{ 0 }
};
c = getopt_long(argc, argv, "Vtrc:l:a85f:b:v:M:S:T:qAR:",
c = getopt_long(argc, argv, "Vtrc:l:ai85f:b:v:M:S:T:qAR:",
long_options, &option_index);
if ( c == -1 )
break;
@ -447,6 +450,9 @@ main( int argc, char*argv[] )
case 'a':
carrier_autodetect_threshold = 0.001;
break;
case 'i':
bfsk_inverted_freqs = 1;
break;
case 'f':
filename = optarg;
break;
@ -646,6 +652,12 @@ main( int argc, char*argv[] )
if ( bfsk_nstopbits < 0 )
bfsk_nstopbits = 1.0;
if ( bfsk_inverted_freqs ) {
float t = bfsk_mark_f;
bfsk_mark_f = bfsk_space_f;
bfsk_space_f = t;
}
/* restrict band_width to <= data rate (FIXME?) */
if ( band_width > bfsk_data_rate )
band_width = bfsk_data_rate;
@ -853,9 +865,11 @@ main( int argc, char*argv[] )
continue;
}
// FIXME: hardcoded negative shift
// default negative shift -- reasonable?
int b_shift = - (float)(autodetect_shift + fskp->band_width/2.0)
/ fskp->band_width;
if ( bfsk_inverted_freqs )
b_shift *= -1;
/* only accept a carrier as b_mark if it will not result
* in a b_space band which is "too low". */
if ( carrier_band + b_shift < 1 ) {