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authorKyle Keen <keenerd@gmail.com>2012-12-02 23:50:03 -0500
committerSteve Markgraf <steve@steve-m.de>2012-12-09 17:15:01 +0100
commitd6107bb059ad32c5787646dfe37dc87b68bc8758 (patch)
tree6851e023a7a325af281cbd621739fcaa20d51477 /src/rtl_fm.c
parente4e8ef55fc7d96a5de215512259f9f5751ba6053 (diff)
rtl_fm: frequency ranges, flexible squelch
Signed-off-by: Steve Markgraf <steve@steve-m.de>
Diffstat (limited to 'src/rtl_fm.c')
-rw-r--r--src/rtl_fm.c113
1 files changed, 75 insertions, 38 deletions
diff --git a/src/rtl_fm.c b/src/rtl_fm.c
index b1dc76a..81a4071 100644
--- a/src/rtl_fm.c
+++ b/src/rtl_fm.c
@@ -25,16 +25,14 @@
* based on rtl_sdr.c and rtl_tcp.c
* todo: realtime ARMv5
* remove float math (disqualifies complex.h)
- * replace atan2 with a fast approximation
* in-place array operations
- * better wide band support
* sanity checks
* nicer FIR than square
* scale squelch to other input parameters
* test all the demodulations
- * sci notation parsing
* pad output on hop
* nearest gain approx
+ * frequency ranges could be stored better
*/
#include <errno.h>
@@ -66,7 +64,6 @@
#define DEFAULT_BUF_LENGTH (1 * 16384)
#define MAXIMUM_OVERSAMPLE 16
#define MAXIMUM_BUF_LENGTH (MAXIMUM_OVERSAMPLE * DEFAULT_BUF_LENGTH)
-#define CONSEQ_SQUELCH 20
#define AUTO_GAIN -100
static pthread_t demod_thread;
@@ -86,8 +83,10 @@ struct fm_state
int post_downsample;
int output_scale;
int squelch_level;
+ int conseq_squelch;
int squelch_hits;
- int term_squelch_hits;
+ int terminate_on_squelch;
+ int exit_flag;
uint8_t buf[MAXIMUM_BUF_LENGTH];
uint32_t buf_len;
int signal[MAXIMUM_BUF_LENGTH]; /* 16 bit signed i/q pairs */
@@ -96,7 +95,7 @@ struct fm_state
int signal2_len;
FILE *file;
int edge;
- uint32_t freqs[100];
+ uint32_t freqs[1000];
int freq_len;
int freq_now;
uint32_t sample_rate;
@@ -116,24 +115,26 @@ void usage(void)
{
fprintf(stderr,
"rtl_fm, a simple narrow band FM demodulator for RTL2832 based DVB-T receivers\n\n"
- "Use:\trtl_fm -f freq [-options] filename\n"
- "\t-f frequency_to_tune_to [Hz]\n"
- "\t (use multiple -f for scanning)\n"
- "\t[-s samplerate (default: 24k Hz)]\n"
+ "Use:\trtl_fm -f freq [-options] [filename]\n"
+ "\t-f frequency_to_tune_to [Hz]\n"
+ "\t (use multiple -f for scanning, requires squelch)\n"
+ "\t (ranges supported, -f 118M:137M:25k)\n"
+ "\t[-s sample_rate (default: 24k)]\n"
"\t[-d device_index (default: 0)]\n"
"\t[-g tuner_gain (default: automatic)]\n"
"\t[-l squelch_level (default: 0/off)]\n"
- "\t[-o oversampling (default: 1)]\n"
+ "\t[-o oversampling (default: 1, 4 recommended)]\n"
"\t[-p ppm_error (default: 0)]\n"
"\t[-E sets lower edge tuning (default: center)]\n"
"\t[-N enables NBFM mode (default: on)]\n"
"\t[-W enables WBFM mode (default: off)]\n"
"\t (-N -s 170k -o 4 -A -r 32k -l 0 -D)\n"
- "\tfilename (a '-' dumps samples to stdout)\n\n"
+ "\tfilename (a '-' dumps samples to stdout)\n"
+ "\t (omitting the filename also uses stdout)\n\n"
"Experimental options:\n"
- "\t[-r output rate (default: same as -s)]\n"
- "\t[-t terminate_hits (default: 0/off)]\n"
- "\t (requires squelch on and scanning off)\n"
+ "\t[-r output_rate (default: same as -s)]\n"
+ "\t[-t squelch_delay (default: 20)]\n"
+ "\t (+values will mute/scan, -values will exit)\n"
"\t[-M enables AM mode (default: off)]\n"
"\t[-L enables LSB mode (default: off)]\n"
"\t[-U enables USB mode (default: off)]\n"
@@ -369,7 +370,7 @@ void am_demod(struct fm_state *fm)
int i, pcm;
for (i = 0; i < (fm->signal_len); i += 2) {
// hypot uses floats but won't overflow
- //pcm = (int)hypot(fm->signal[i], fm->signal[i+1]);
+ //fm->signal2[i/2] = (int16_t)hypot(fm->signal[i], fm->signal[i+1]);
pcm = fm->signal[i] * fm->signal[i];
pcm += fm->signal[i+1] * fm->signal[i+1];
fm->signal2[i/2] = (int16_t)sqrt(pcm); // * fm->output_scale;
@@ -445,7 +446,7 @@ int mad(int *samples, int len, int step)
int post_squelch(struct fm_state *fm)
/* returns 1 for active signal, 0 for no signal */
{
- int i, i2, dev_r, dev_j, len, sq_l;
+ int dev_r, dev_j, len, sq_l;
/* only for small samples, big samples need chunk processing */
len = fm->signal_len;
sq_l = fm->squelch_level;
@@ -456,12 +457,6 @@ int post_squelch(struct fm_state *fm)
return 1;
}
fm->squelch_hits++;
- if (fm->term_squelch_hits) {
- return 0;}
- /* weak signal, kill it entirely */
- for (i=0; i<len; i++) {
- fm->signal2[i] = 0;
- }
return 0;
}
@@ -504,7 +499,7 @@ static void optimal_settings(struct fm_state *fm, int freq, int hopping)
void full_demod(struct fm_state *fm)
{
- int sr, freq_next;
+ int i, sr, freq_next, hop = 0;
rotate_90(fm->buf, fm->buf_len);
if (fm->fir_enable) {
low_pass_fir(fm, fm->buf, fm->buf_len);
@@ -517,6 +512,16 @@ void full_demod(struct fm_state *fm)
return;
}
sr = post_squelch(fm);
+ if (!sr && fm->squelch_hits > fm->conseq_squelch) {
+ if (fm->terminate_on_squelch) {
+ fm->exit_flag = 1;}
+ if (fm->freq_len == 1) { /* mute */
+ for (i=0; i<fm->signal_len; i++) {
+ fm->signal2[i] = 0;}
+ }
+ else {
+ hop = 1;}
+ }
if (fm->post_downsample > 1) {
fm->signal2_len = low_pass_simple(fm->signal2, fm->signal2_len, fm->post_downsample);}
if (fm->output_rate > 0) {
@@ -526,11 +531,11 @@ void full_demod(struct fm_state *fm)
deemph_filter(fm);}
/* ignore under runs for now */
fwrite(fm->signal2, 2, fm->signal2_len, fm->file);
- if (fm->freq_len > 1 && !sr && fm->squelch_hits > CONSEQ_SQUELCH) {
+ if (hop) {
freq_next = (fm->freq_now + 1) % fm->freq_len;
optimal_settings(fm, freq_next, 1);
- fm->squelch_hits = CONSEQ_SQUELCH + 1; /* hair trigger */
- /* wait for settling and dump buffer */
+ fm->squelch_hits = fm->conseq_squelch + 1; /* hair trigger */
+ /* wait for settling and flush buffer */
usleep(5000);
rtlsdr_read_sync(dev, NULL, 4096, NULL);
}
@@ -559,16 +564,14 @@ static void *demod_thread_fn(void *arg)
while (!do_exit) {
sem_wait(&data_ready);
full_demod(fm2);
- if (!fm2->term_squelch_hits) {
- continue;}
- if (fm2->squelch_hits > fm2->term_squelch_hits) {
+ if (fm2->exit_flag) {
do_exit = 1;
rtlsdr_cancel_async(dev);}
}
return 0;
}
-int atofs(char* f)
+double atofs(char* f)
/* standard suffixes */
{
char* chop;
@@ -584,8 +587,26 @@ int atofs(char* f)
suff *= atof(chop);}
free(chop);
if (suff != 1.0) {
- return (int)suff;}
- return (int)atof(f);
+ return suff;}
+ return atof(f);
+}
+
+void frequency_range(struct fm_state *fm, char *arg)
+{
+ char *start, *stop, *step;
+ int i;
+ start = arg;
+ stop = strchr(start, ':') + 1;
+ stop[-1] = '\0';
+ step = strchr(stop, ':') + 1;
+ step[-1] = '\0';
+ for(i=(int)atofs(start); i<=(int)atofs(stop); i+=(int)atofs(step))
+ {
+ fm->freqs[fm->freq_len] = (uint32_t)i;
+ fm->freq_len++;
+ }
+ stop[-1] = ':';
+ step[-1] = ':';
}
int main(int argc, char **argv)
@@ -605,7 +626,8 @@ int main(int argc, char **argv)
fm.freqs[0] = 100000000;
fm.sample_rate = DEFAULT_SAMPLE_RATE;
fm.squelch_level = 0;
- fm.term_squelch_hits = 0;
+ fm.conseq_squelch = 20;
+ fm.terminate_on_squelch = 0;
fm.freq_len = 0;
fm.edge = 0;
fm.fir_enable = 0;
@@ -623,8 +645,13 @@ int main(int argc, char **argv)
dev_index = atoi(optarg);
break;
case 'f':
- fm.freqs[fm.freq_len] = (uint32_t)atofs(optarg);
- fm.freq_len++;
+ if (strchr(optarg, ':'))
+ {frequency_range(&fm, optarg);}
+ else
+ {
+ fm.freqs[fm.freq_len] = (uint32_t)atofs(optarg);
+ fm.freq_len++;
+ }
break;
case 'g':
gain = (int)(atof(optarg) * 10);
@@ -644,10 +671,15 @@ int main(int argc, char **argv)
fprintf(stderr, "Oversample must be between 1 and %i\n", MAXIMUM_OVERSAMPLE);}
break;
case 't':
- fm.term_squelch_hits = (int)atof(optarg);
+ fm.conseq_squelch = (int)atof(optarg);
+ if (fm.conseq_squelch < 0) {
+ fm.conseq_squelch = -fm.conseq_squelch;
+ fm.terminate_on_squelch = 1;
+ }
break;
case 'p':
ppm_error = atoi(optarg);
+ break;
case 'E':
fm.edge = 1;
break;
@@ -693,8 +725,13 @@ int main(int argc, char **argv)
/* quadruple sample_rate to limit to Δθ to ±π/2 */
fm.sample_rate *= fm.post_downsample;
+ if (fm.freq_len > 1) {
+ fm.terminate_on_squelch = 0;
+ }
+
if (argc <= optind) {
- usage();
+ //usage();
+ filename = "-";
} else {
filename = argv[optind];
}