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minimodem: --stopbits replaces --txstopbits; better bps metric 

RX metrics account for fractional number of stop bits (e.g 1.5);
RX bps metric slightly more accurate (?).
This commit is contained in:
Kamal Mostafa 2012-08-30 15:05:33 -07:00
parent becf16761e
commit 7b34e89433
3 changed files with 31 additions and 28 deletions
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5
src/minimodem.1.in
View File

@ -86,7 +86,8 @@ FLT_EPSILON. (This option applies to \-\-tx mode only).
.TP .TP
.B \-S, \-\-space {space_freq} .B \-S, \-\-space {space_freq}
.TP .TP
.B \-T, \-\-txstopbits {m.n} .B \-T, \-\-stopbits {m.n}
Sets the number of stop bits (default is 1.0, or 1.5 for rtty).
.TP .TP
.B \-q, \-\-quiet .B \-q, \-\-quiet
Do not report CARRIER / NOCARRIER or signal analysis metrics. Do not report CARRIER / NOCARRIER or signal analysis metrics.
@ -130,7 +131,7 @@ default mark and space tone frequencies.
: Bell103 300 bps \-\-ascii : Bell103 300 bps \-\-ascii
.TP .TP
.B rtty .B rtty
: RTTY 45.45 bps \-\-baudot \-\-txstopbits 1.5 : RTTY 45.45 bps \-\-baudot \-\-stopbits 1.5
.TP .TP
.B {any floating point value N} .B {any floating point value N}
: Bell-like N bps \-\-ascii : Bell-like N bps \-\-ascii

52
src/minimodem.c
View File

@ -127,7 +127,7 @@ static void fsk_transmit_stdin(
float bfsk_mark_f, float bfsk_mark_f,
float bfsk_space_f, float bfsk_space_f,
int n_data_bits, int n_data_bits,
float bfsk_txstopbits, float bfsk_nstopbits,
int (*framebits_encoder)( unsigned int *databits_outp, char char_out ) int (*framebits_encoder)( unsigned int *databits_outp, char char_out )
) )
{ {
@ -176,7 +176,7 @@ static void fsk_transmit_stdin(
simpleaudio_tone(sa_out, tone_freq, bit_nsamples); simpleaudio_tone(sa_out, tone_freq, bit_nsamples);
} }
simpleaudio_tone(sa_out, bfsk_mark_f, simpleaudio_tone(sa_out, bfsk_mark_f,
bit_nsamples * bfsk_txstopbits); // stop bit_nsamples * bfsk_nstopbits); // stop
} }
if ( tx_interactive ) if ( tx_interactive )
@ -197,18 +197,17 @@ static void
report_no_carrier( fsk_plan *fskp, report_no_carrier( fsk_plan *fskp,
unsigned int sample_rate, unsigned int sample_rate,
float bfsk_data_rate, float bfsk_data_rate,
float nsamples_per_bit, float frame_n_bits,
unsigned int nframes_decoded, unsigned int nframes_decoded,
unsigned long long nbits_decoded,
size_t carrier_nsamples, size_t carrier_nsamples,
float confidence_total, float confidence_total,
float amplitude_total ) float amplitude_total )
{ {
float nbits_decoded = nframes_decoded * frame_n_bits;
#if 0 #if 0
fprintf(stderr, "nframes_decoded=%u\n", nframes_decoded); fprintf(stderr, "nframes_decoded=%u\n", nframes_decoded);
fprintf(stderr, "nbits_decoded=%llu\n", nbits_decoded); fprintf(stderr, "nbits_decoded=%f\n", nbits_decoded);
fprintf(stderr, "carrier_nsamples=%lu\n", carrier_nsamples); fprintf(stderr, "carrier_nsamples=%lu\n", carrier_nsamples);
fprintf(stderr, "nsamples_per_bit=%f\n", nsamples_per_bit);
#endif #endif
float throughput_rate = float throughput_rate =
nbits_decoded * sample_rate / (float)carrier_nsamples; nbits_decoded * sample_rate / (float)carrier_nsamples;
@ -217,7 +216,12 @@ report_no_carrier( fsk_plan *fskp,
confidence_total / nframes_decoded, confidence_total / nframes_decoded,
amplitude_total / nframes_decoded, amplitude_total / nframes_decoded,
throughput_rate); throughput_rate);
if ( (size_t)(nbits_decoded * nsamples_per_bit + 0.5) == carrier_nsamples ) { #if 0
fprintf(stderr, " bits*sr=%llu rate*nsamp=%llu",
(unsigned long long)(nbits_decoded * sample_rate + 0.5),
(unsigned long long)(bfsk_data_rate * carrier_nsamples) );
#endif
if ( (unsigned long long)(nbits_decoded * sample_rate + 0.5) == (unsigned long long)(bfsk_data_rate * carrier_nsamples) ) {
fprintf(stderr, " (rate perfect) ###\n"); fprintf(stderr, " (rate perfect) ###\n");
} else { } else {
float throughput_skew = (throughput_rate - bfsk_data_rate) float throughput_skew = (throughput_rate - bfsk_data_rate)
@ -334,7 +338,7 @@ usage()
" -v, --volume {amplitude or 'E'}\n" " -v, --volume {amplitude or 'E'}\n"
" -M, --mark {mark_freq}\n" " -M, --mark {mark_freq}\n"
" -S, --space {space_freq}\n" " -S, --space {space_freq}\n"
" -T, --txstopbits {m.n}\n" " -T, --stopbits {m.n}\n"
" -q, --quiet\n" " -q, --quiet\n"
" -R, --samplerate {rate}\n" " -R, --samplerate {rate}\n"
" -V, --version\n" " -V, --version\n"
@ -361,7 +365,7 @@ main( int argc, char*argv[] )
float band_width = 0; float band_width = 0;
unsigned int bfsk_mark_f = 0; unsigned int bfsk_mark_f = 0;
unsigned int bfsk_space_f = 0; unsigned int bfsk_space_f = 0;
float bfsk_txstopbits = 0; float bfsk_nstopbits = 0;
unsigned int bfsk_n_data_bits = 0; unsigned int bfsk_n_data_bits = 0;
int autodetect_shift; int autodetect_shift;
char *filename = NULL; char *filename = NULL;
@ -439,7 +443,7 @@ main( int argc, char*argv[] )
{ "volume", 1, 0, 'v' }, { "volume", 1, 0, 'v' },
{ "mark", 1, 0, 'M' }, { "mark", 1, 0, 'M' },
{ "space", 1, 0, 'S' }, { "space", 1, 0, 'S' },
{ "txstopbits", 1, 0, 'T' }, { "stopbits", 1, 0, 'T' },
{ "quiet", 0, 0, 'q' }, { "quiet", 0, 0, 'q' },
{ "alsa", 0, 0, 'A' }, { "alsa", 0, 0, 'A' },
{ "samplerate", 1, 0, 'R' }, { "samplerate", 1, 0, 'R' },
@ -506,8 +510,8 @@ main( int argc, char*argv[] )
assert( bfsk_space_f > 0 ); assert( bfsk_space_f > 0 );
break; break;
case 'T': case 'T':
bfsk_txstopbits = atof(optarg); bfsk_nstopbits = atof(optarg);
assert( bfsk_txstopbits > 0 ); assert( bfsk_nstopbits > 0 );
break; break;
case 'q': case 'q':
quiet_mode = 1; quiet_mode = 1;
@ -590,8 +594,8 @@ main( int argc, char*argv[] )
bfsk_data_rate = 45.45; bfsk_data_rate = 45.45;
if ( bfsk_n_data_bits == 0 ) if ( bfsk_n_data_bits == 0 )
bfsk_n_data_bits = 5; bfsk_n_data_bits = 5;
if ( bfsk_txstopbits == 0 ) if ( bfsk_nstopbits == 0 )
bfsk_txstopbits = 1.5; bfsk_nstopbits = 1.5;
} else { } else {
bfsk_data_rate = atof(modem_mode); bfsk_data_rate = atof(modem_mode);
if ( bfsk_n_data_bits == 0 ) if ( bfsk_n_data_bits == 0 )
@ -647,8 +651,8 @@ main( int argc, char*argv[] )
} }
} }
if ( bfsk_txstopbits == 0 ) if ( bfsk_nstopbits == 0 )
bfsk_txstopbits = 1.0; bfsk_nstopbits = 1.0;
/* restrict band_width to <= data rate (FIXME?) */ /* restrict band_width to <= data rate (FIXME?) */
if ( band_width > bfsk_data_rate ) if ( band_width > bfsk_data_rate )
@ -689,7 +693,7 @@ main( int argc, char*argv[] )
bfsk_data_rate, bfsk_data_rate,
bfsk_mark_f, bfsk_space_f, bfsk_mark_f, bfsk_space_f,
bfsk_n_data_bits, bfsk_n_data_bits,
bfsk_txstopbits, bfsk_nstopbits,
bfsk_framebits_encode bfsk_framebits_encode
); );
@ -759,7 +763,6 @@ main( int argc, char*argv[] )
float confidence_total = 0; float confidence_total = 0;
float amplitude_total = 0; float amplitude_total = 0;
unsigned int nframes_decoded = 0; unsigned int nframes_decoded = 0;
unsigned long long nbits_decoded = 0;
size_t carrier_nsamples = 0; size_t carrier_nsamples = 0;
unsigned int noconfidence = 0; unsigned int noconfidence = 0;
@ -784,6 +787,10 @@ main( int argc, char*argv[] )
debug_log("fsk_frame_overscan=%f nsamples_overscan=%u\n", debug_log("fsk_frame_overscan=%f nsamples_overscan=%u\n",
fsk_frame_overscan, nsamples_overscan); fsk_frame_overscan, nsamples_overscan);
// n databits plus one start bit plus bfsk_nstopbits stop bit(s):
float frame_n_bits = bfsk_n_data_bits + 1 + bfsk_nstopbits;
unsigned int frame_nsamples = nsamples_per_bit * frame_n_bits + 0.5;
float track_amplitude = 0.0; float track_amplitude = 0.0;
while ( 1 ) { while ( 1 ) {
@ -892,15 +899,12 @@ main( int argc, char*argv[] )
char expect_bits_string[33] = "10dddddddddddddddddddddddddddddd"; char expect_bits_string[33] = "10dddddddddddddddddddddddddddddd";
expect_bits_string[bfsk_n_data_bits + 2] = '1'; expect_bits_string[bfsk_n_data_bits + 2] = '1';
expect_bits_string[bfsk_n_data_bits + 3] = 0; expect_bits_string[bfsk_n_data_bits + 3] = 0;
unsigned int frame_n_bits = bfsk_n_data_bits + 2;
unsigned int frame_bits_shift = 2; // prev_stop + start unsigned int frame_bits_shift = 2; // prev_stop + start
// FIXME - weird hardcode: // FIXME - weird hardcode:
unsigned int frame_bits_mask = 0xFF; unsigned int frame_bits_mask = 0xFF;
if ( bfsk_n_data_bits == 5 ) if ( bfsk_n_data_bits == 5 )
frame_bits_mask = 0x1F; frame_bits_mask = 0x1F;
unsigned int frame_nsamples = nsamples_per_bit * frame_n_bits;
unsigned int expect_n_bits = strlen(expect_bits_string); unsigned int expect_n_bits = strlen(expect_bits_string);
unsigned int expect_nsamples = nsamples_per_bit * expect_n_bits; unsigned int expect_nsamples = nsamples_per_bit * expect_n_bits;
@ -975,14 +979,13 @@ main( int argc, char*argv[] )
if ( carrier ) { if ( carrier ) {
if ( !quiet_mode ) if ( !quiet_mode )
report_no_carrier(fskp, sample_rate, bfsk_data_rate, report_no_carrier(fskp, sample_rate, bfsk_data_rate,
nsamples_per_bit, nframes_decoded, nbits_decoded, frame_n_bits, nframes_decoded,
carrier_nsamples, confidence_total, amplitude_total); carrier_nsamples, confidence_total, amplitude_total);
carrier = 0; carrier = 0;
carrier_nsamples = 0; carrier_nsamples = 0;
confidence_total = 0; confidence_total = 0;
amplitude_total = 0; amplitude_total = 0;
nframes_decoded = 0; nframes_decoded = 0;
nbits_decoded = 0;
track_amplitude = 0.0; track_amplitude = 0.0;
} }
@ -1025,7 +1028,6 @@ main( int argc, char*argv[] )
confidence_total += confidence; confidence_total += confidence;
amplitude_total += amplitude; amplitude_total += amplitude;
nframes_decoded++; nframes_decoded++;
nbits_decoded += frame_n_bits;
noconfidence = 0; noconfidence = 0;
// Advance the sample stream forward past the junk before the // Advance the sample stream forward past the junk before the
@ -1071,7 +1073,7 @@ main( int argc, char*argv[] )
if ( carrier ) { if ( carrier ) {
if ( !quiet_mode ) if ( !quiet_mode )
report_no_carrier(fskp, sample_rate, bfsk_data_rate, report_no_carrier(fskp, sample_rate, bfsk_data_rate,
nsamples_per_bit, nframes_decoded, nbits_decoded, frame_n_bits, nframes_decoded,
carrier_nsamples, confidence_total, amplitude_total); carrier_nsamples, confidence_total, amplitude_total);
} }

2
tests/self-test
View File

@ -49,7 +49,7 @@ set -e
#echo "$MINIMODEM --tx ... $minimodem_tx_args" #echo "$MINIMODEM --tx ... $minimodem_tx_args"
#echo "$MINIMODEM --rx ... $minimodem_rx_args" #echo "$MINIMODEM --rx ... $minimodem_rx_args"
$MINIMODEM --tx -T 1 --file $TMPF.wav $minimodem_tx_args < "$textfile" $MINIMODEM --tx --file $TMPF.wav $minimodem_tx_args < "$textfile"
# cp $TMPF.wav /tmp/x.wav # cp $TMPF.wav /tmp/x.wav