sdr
/
rtl-sdr
8
1
Fork 5
Code Issues Pull Requests Projects Releases Wiki Activity

rtl_fm: tweaks for nicer scanning 

Signed-off-by: Steve Markgraf <steve@steve-m.de>
This commit is contained in:
Kyle Keen 2012-05-30 11:17:21 -04:00 committed by Steve Markgraf
parent c3dde1db91
commit d56267a42f
1 changed files with 20 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
src/rtl_fm.c
View File

@ -51,9 +51,10 @@
#define DEFAULT_SAMPLE_RATE 24000 #define DEFAULT_SAMPLE_RATE 24000
#define DEFAULT_ASYNC_BUF_NUMBER 32 #define DEFAULT_ASYNC_BUF_NUMBER 32
#define DEFAULT_BUF_LENGTH 1024 #define DEFAULT_BUF_LENGTH (1 * 16384)
#define MINIMAL_BUF_LENGTH 512 #define MINIMAL_BUF_LENGTH 512
#define MAXIMAL_BUF_LENGTH (256 * 16384) #define MAXIMAL_BUF_LENGTH (256 * 16384)
#define CONSEQ_SQUELCH 4
static pthread_t demod_thread; static pthread_t demod_thread;
static sem_t data_ready; static sem_t data_ready;
@ -70,10 +71,11 @@ struct fm_state
int downsample; /* min 4, max 256 */ int downsample; /* min 4, max 256 */
int output_scale; int output_scale;
int squelch_level; int squelch_level;
int squelch_hits;
uint8_t buf[DEFAULT_BUF_LENGTH]; uint8_t buf[DEFAULT_BUF_LENGTH];
uint32_t buf_len; uint32_t buf_len;
int signal[2048]; /* 16 bit signed i/q pairs */ int signal[DEFAULT_BUF_LENGTH]; /* 16 bit signed i/q pairs */
int16_t signal2[2048]; /* signal has lowpass, signal2 has demod */ int16_t signal2[DEFAULT_BUF_LENGTH]; /* signal has lowpass, signal2 has demod */
int signal_len; int signal_len;
FILE *file; FILE *file;
int edge; int edge;
@ -101,7 +103,7 @@ void usage(void)
"\t[-E freq sets lower edge (default: center)]\n" "\t[-E freq sets lower edge (default: center)]\n"
"\tfilename (a '-' dumps samples to stdout)\n\n" "\tfilename (a '-' dumps samples to stdout)\n\n"
"Produces signed 16 bit ints, use Sox to hear them.\n" "Produces signed 16 bit ints, use Sox to hear them.\n"
"\trtl_fm ... | play -t raw -r 24k -e signed-integer -b 16 -c 1 -\n\n"); "\trtl_fm ... | play -t raw -r 24k -e signed-integer -b 16 -c 1 -V1 -\n\n");
#endif #endif
exit(1); exit(1);
} }
@ -228,12 +230,14 @@ int post_squelch(struct fm_state *fm)
dev_r = mad(&(fm->signal[0]), len, 2); dev_r = mad(&(fm->signal[0]), len, 2);
dev_j = mad(&(fm->signal[1]), len, 2); dev_j = mad(&(fm->signal[1]), len, 2);
if ((dev_r > sq_l) || (dev_j > sq_l)) { if ((dev_r > sq_l) || (dev_j > sq_l)) {
fm->squelch_hits = 0;
return 1; return 1;
} }
/* weak signal, kill it entirely */ /* weak signal, kill it entirely */
for (i=0; i<len; i++) { for (i=0; i<len; i++) {
fm->signal2[i/2] = 0; fm->signal2[i/2] = 0;
} }
fm->squelch_hits++;
return 0; return 0;
} }
@ -266,19 +270,20 @@ static void optimal_settings(struct fm_state *fm, int freq, int hopping)
} }
void full_demod(unsigned char *buf, uint32_t len, struct fm_state *fm2) void full_demod(unsigned char *buf, uint32_t len, struct fm_state *fm)
{ {
int sr, freq_next; int sr, freq_next;
rotate_90(buf, len); rotate_90(buf, len);
low_pass(fm2, buf, len); low_pass(fm, buf, len);
fm_demod(fm2); fm_demod(fm);
sr = post_squelch(fm2); sr = post_squelch(fm);
/* ignore under runs for now */ /* ignore under runs for now */
fwrite(fm2->signal2, 2, fm2->signal_len/2, fm2->file); fwrite(fm->signal2, 2, fm->signal_len/2, fm->file);
if (fm2->freq_len > 1 && !sr) { if (fm->freq_len > 1 && !sr && fm->squelch_hits > CONSEQ_SQUELCH) {
freq_next = (fm2->freq_now + 1) % fm2->freq_len; freq_next = (fm->freq_now + 1) % fm->freq_len;
optimal_settings(fm2, freq_next, 1); optimal_settings(fm, freq_next, 1);
// wait for settling and dump buffer fm->squelch_hits = CONSEQ_SQUELCH + 1; /* hair trigger */
/* wait for settling and dump buffer */
usleep(5000); usleep(5000);
rtlsdr_read_sync(dev, NULL, 4096, NULL); rtlsdr_read_sync(dev, NULL, 4096, NULL);
} }
@ -293,7 +298,8 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
if (!ctx) { if (!ctx) {
return;} return;}
fm2 = (struct fm_struct*)(ctx); // warning? fm2 = (struct fm_struct*)(ctx); // warning?
//full_demod(buf, len, fm2); /* single threaded uses 25% less CPU? */
/* full_demod(buf, len, fm2); */
memcpy(fm2->buf, buf, len); memcpy(fm2->buf, buf, len);
fm2->buf_len = len; fm2->buf_len = len;
sem_getvalue(&data_ready, &dr_val); sem_getvalue(&data_ready, &dr_val);
@ -377,7 +383,6 @@ int main(int argc, char **argv)
#endif #endif
buffer = malloc(DEFAULT_BUF_LENGTH * sizeof(uint8_t)); buffer = malloc(DEFAULT_BUF_LENGTH * sizeof(uint8_t));
//buffer = fm.buf;
device_count = rtlsdr_get_device_count(); device_count = rtlsdr_get_device_count();
if (!device_count) { if (!device_count) {