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minimodem: --sync-byte {0xXX}

This commit is contained in:
Kamal Mostafa 2012-09-01 14:54:32 -07:00
parent 82c72352ab
commit 04cc215640
2 changed files with 27 additions and 0 deletions
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7
src/minimodem.1.in
View File

@ -92,6 +92,13 @@ Sets the number of start bits (default is 1 for most baudmodes).
.B \-\-stopbits {n.n}
Sets the number of stop bits (default is 1.0 for most baudmodes).
.TP
.B \-\-sync-byte {0xXX}
If this option is used, initial carrier acquisition will be suppressed
until after one or more consecutive data frame(s) containing this value
are received. This can be used to synchronize the stream for protocols
which include a fixed preamble byte.
(This option applies to \-\-rx mode only).
.TP
.B \-q, \-\-quiet
Do not report CARRIER / NOCARRIER or signal analysis metrics.
.TP

20
src/minimodem.c
View File

@ -291,6 +291,7 @@ usage()
" -S, --space {space_freq}\n"
" --startbits {n}\n"
" --stopbits {n.n}\n"
" --sync-byte {0xXX}\n"
" -q, --quiet\n"
" -R, --samplerate {rate}\n"
" -V, --version\n"
@ -319,6 +320,8 @@ main( int argc, char*argv[] )
unsigned int bfsk_space_f = 0;
int bfsk_nstartbits = -1; // actually only supports 0 or 1 startbit
float bfsk_nstopbits = -1;
unsigned int bfsk_sync_on_data = 0;
unsigned int bfsk_sync_byte = -1;
unsigned int bfsk_n_data_bits = 0;
int autodetect_shift;
char *filename = NULL;
@ -372,6 +375,7 @@ main( int argc, char*argv[] )
MINIMODEM_OPT_UNUSED=256, // placeholder
MINIMODEM_OPT_STARTBITS,
MINIMODEM_OPT_STOPBITS,
MINIMODEM_OPT_SYNC_BYTE,
MINIMODEM_OPT_LUT,
MINIMODEM_OPT_FLOAT_SAMPLES,
MINIMODEM_OPT_RX_ONE,
@ -400,6 +404,7 @@ main( int argc, char*argv[] )
{ "space", 1, 0, 'S' },
{ "startbits", 1, 0, MINIMODEM_OPT_STARTBITS },
{ "stopbits", 1, 0, MINIMODEM_OPT_STOPBITS },
{ "sync-byte", 1, 0, MINIMODEM_OPT_SYNC_BYTE },
{ "quiet", 0, 0, 'q' },
{ "alsa", 0, 0, 'A' },
{ "samplerate", 1, 0, 'R' },
@ -473,6 +478,10 @@ main( int argc, char*argv[] )
bfsk_nstopbits = atof(optarg);
assert( bfsk_nstopbits >= 0 );
break;
case MINIMODEM_OPT_SYNC_BYTE:
bfsk_sync_on_data = 1;
bfsk_sync_byte = strtol(optarg, NULL, 0);
break;
case 'q':
quiet_mode = 1;
break;
@ -927,6 +936,11 @@ main( int argc, char*argv[] )
confidence, amplitude, track_amplitude );
}
if ( bfsk_sync_on_data ) {
if ( ! carrier && bits != bfsk_sync_byte )
confidence = 0.0;
}
#define FSK_MAX_NOCONFIDENCE_BITS 20
if ( confidence <= fsk_confidence_threshold ) {
@ -1020,6 +1034,12 @@ main( int argc, char*argv[] )
char dataoutbuf[4096];
unsigned int dataout_nbytes = 0;
// suppress printing of bfsk_sync_byte bytes
if ( bfsk_sync_on_data ) {
if ( dataout_nbytes == 0 && bits == bfsk_sync_byte )
continue;
}
dataout_nbytes += bfsk_databits_decode(dataoutbuf + dataout_nbytes,
dataout_size - dataout_nbytes,
bits, (int)bfsk_n_data_bits);