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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
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35
src/rtl_fm.c
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@ -51,9 +51,10 @@
#define DEFAULT_SAMPLE_RATE 24000
#define DEFAULT_ASYNC_BUF_NUMBER 32
#define DEFAULT_BUF_LENGTH 1024
#define DEFAULT_BUF_LENGTH (1 * 16384)
#define MINIMAL_BUF_LENGTH 512
#define MAXIMAL_BUF_LENGTH (256 * 16384)
#define CONSEQ_SQUELCH 4
static pthread_t demod_thread;
static sem_t data_ready;
@ -70,10 +71,11 @@ struct fm_state
int downsample; /* min 4, max 256 */
int output_scale;
int squelch_level;
int squelch_hits;
uint8_t buf[DEFAULT_BUF_LENGTH];
uint32_t buf_len;
int signal[2048]; /* 16 bit signed i/q pairs */
int16_t signal2[2048]; /* signal has lowpass, signal2 has demod */
int signal[DEFAULT_BUF_LENGTH]; /* 16 bit signed i/q pairs */
int16_t signal2[DEFAULT_BUF_LENGTH]; /* signal has lowpass, signal2 has demod */
int signal_len;
FILE *file;
int edge;
@ -101,7 +103,7 @@ void usage(void)
"\t[-E freq sets lower edge (default: center)]\n"
"\tfilename (a '-' dumps samples to stdout)\n\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
exit(1);
}
@ -228,12 +230,14 @@ int post_squelch(struct fm_state *fm)
dev_r = mad(&(fm->signal[0]), len, 2);
dev_j = mad(&(fm->signal[1]), len, 2);
if ((dev_r > sq_l) || (dev_j > sq_l)) {
fm->squelch_hits = 0;
return 1;
}
/* weak signal, kill it entirely */
for (i=0; i<len; i++) {
fm->signal2[i/2] = 0;
}
fm->squelch_hits++;
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;
rotate_90(buf, len);
low_pass(fm2, buf, len);
fm_demod(fm2);
sr = post_squelch(fm2);
low_pass(fm, buf, len);
fm_demod(fm);
sr = post_squelch(fm);
/* ignore under runs for now */
fwrite(fm2->signal2, 2, fm2->signal_len/2, fm2->file);
if (fm2->freq_len > 1 && !sr) {
freq_next = (fm2->freq_now + 1) % fm2->freq_len;
optimal_settings(fm2, freq_next, 1);
// wait for settling and dump buffer
fwrite(fm->signal2, 2, fm->signal_len/2, fm->file);
if (fm->freq_len > 1 && !sr && fm->squelch_hits > CONSEQ_SQUELCH) {
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 */
usleep(5000);
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) {
return;}
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);
fm2->buf_len = len;
sem_getvalue(&data_ready, &dr_val);
@ -377,7 +383,6 @@ int main(int argc, char **argv)
#endif
buffer = malloc(DEFAULT_BUF_LENGTH * sizeof(uint8_t));
//buffer = fm.buf;
device_count = rtlsdr_get_device_count();
if (!device_count) {