mirror of
https://github.com/rtlsdrblog/rtl-sdr-blog.git
synced 2024-11-10 04:37:37 +01:00
rtl_fm: frequency ranges, flexible squelch
Signed-off-by: Steve Markgraf <steve@steve-m.de>
This commit is contained in:
Kyle Keen
Steve Markgraf
parent
e4e8ef55fc
commit
d6107bb059
113
src/rtl_fm.c
113
src/rtl_fm.c
@ -25,16 +25,14 @@
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* based on rtl_sdr.c and rtl_tcp.c
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* todo: realtime ARMv5
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* remove float math (disqualifies complex.h)
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* replace atan2 with a fast approximation
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* in-place array operations
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* better wide band support
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* sanity checks
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* nicer FIR than square
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* scale squelch to other input parameters
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* test all the demodulations
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* sci notation parsing
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* pad output on hop
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* nearest gain approx
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* frequency ranges could be stored better
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*/
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#include <errno.h>
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@ -66,7 +64,6 @@
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#define DEFAULT_BUF_LENGTH (1 * 16384)
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#define MAXIMUM_OVERSAMPLE 16
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#define MAXIMUM_BUF_LENGTH (MAXIMUM_OVERSAMPLE * DEFAULT_BUF_LENGTH)
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#define CONSEQ_SQUELCH 20
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#define AUTO_GAIN -100
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static pthread_t demod_thread;
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@ -86,8 +83,10 @@ struct fm_state
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int post_downsample;
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int output_scale;
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int squelch_level;
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int conseq_squelch;
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int squelch_hits;
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int term_squelch_hits;
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int terminate_on_squelch;
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int exit_flag;
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uint8_t buf[MAXIMUM_BUF_LENGTH];
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uint32_t buf_len;
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int signal[MAXIMUM_BUF_LENGTH]; /* 16 bit signed i/q pairs */
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@ -96,7 +95,7 @@ struct fm_state
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int signal2_len;
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FILE *file;
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int edge;
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uint32_t freqs[100];
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uint32_t freqs[1000];
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int freq_len;
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int freq_now;
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uint32_t sample_rate;
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@ -116,24 +115,26 @@ void usage(void)
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{
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fprintf(stderr,
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"rtl_fm, a simple narrow band FM demodulator for RTL2832 based DVB-T receivers\n\n"
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"Use:\trtl_fm -f freq [-options] filename\n"
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"\t-f frequency_to_tune_to [Hz]\n"
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"\t (use multiple -f for scanning)\n"
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"\t[-s samplerate (default: 24k Hz)]\n"
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"Use:\trtl_fm -f freq [-options] [filename]\n"
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"\t-f frequency_to_tune_to [Hz]\n"
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"\t (use multiple -f for scanning, requires squelch)\n"
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"\t (ranges supported, -f 118M:137M:25k)\n"
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"\t[-s sample_rate (default: 24k)]\n"
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"\t[-d device_index (default: 0)]\n"
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"\t[-g tuner_gain (default: automatic)]\n"
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"\t[-l squelch_level (default: 0/off)]\n"
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"\t[-o oversampling (default: 1)]\n"
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"\t[-o oversampling (default: 1, 4 recommended)]\n"
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"\t[-p ppm_error (default: 0)]\n"
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"\t[-E sets lower edge tuning (default: center)]\n"
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"\t[-N enables NBFM mode (default: on)]\n"
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"\t[-W enables WBFM mode (default: off)]\n"
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"\t (-N -s 170k -o 4 -A -r 32k -l 0 -D)\n"
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"\tfilename (a '-' dumps samples to stdout)\n\n"
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"\tfilename (a '-' dumps samples to stdout)\n"
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"\t (omitting the filename also uses stdout)\n\n"
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"Experimental options:\n"
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"\t[-r output rate (default: same as -s)]\n"
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"\t[-t terminate_hits (default: 0/off)]\n"
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"\t (requires squelch on and scanning off)\n"
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"\t[-r output_rate (default: same as -s)]\n"
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"\t[-t squelch_delay (default: 20)]\n"
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"\t (+values will mute/scan, -values will exit)\n"
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"\t[-M enables AM mode (default: off)]\n"
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"\t[-L enables LSB mode (default: off)]\n"
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"\t[-U enables USB mode (default: off)]\n"
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@ -369,7 +370,7 @@ void am_demod(struct fm_state *fm)
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int i, pcm;
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for (i = 0; i < (fm->signal_len); i += 2) {
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// hypot uses floats but won't overflow
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//pcm = (int)hypot(fm->signal[i], fm->signal[i+1]);
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//fm->signal2[i/2] = (int16_t)hypot(fm->signal[i], fm->signal[i+1]);
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pcm = fm->signal[i] * fm->signal[i];
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pcm += fm->signal[i+1] * fm->signal[i+1];
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fm->signal2[i/2] = (int16_t)sqrt(pcm); // * fm->output_scale;
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@ -445,7 +446,7 @@ int mad(int *samples, int len, int step)
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int post_squelch(struct fm_state *fm)
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/* returns 1 for active signal, 0 for no signal */
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{
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int i, i2, dev_r, dev_j, len, sq_l;
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int dev_r, dev_j, len, sq_l;
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/* only for small samples, big samples need chunk processing */
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len = fm->signal_len;
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sq_l = fm->squelch_level;
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@ -456,12 +457,6 @@ int post_squelch(struct fm_state *fm)
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return 1;
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}
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fm->squelch_hits++;
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if (fm->term_squelch_hits) {
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return 0;}
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/* weak signal, kill it entirely */
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for (i=0; i<len; i++) {
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fm->signal2[i] = 0;
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}
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return 0;
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}
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@ -504,7 +499,7 @@ static void optimal_settings(struct fm_state *fm, int freq, int hopping)
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void full_demod(struct fm_state *fm)
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{
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int sr, freq_next;
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int i, sr, freq_next, hop = 0;
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rotate_90(fm->buf, fm->buf_len);
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if (fm->fir_enable) {
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low_pass_fir(fm, fm->buf, fm->buf_len);
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@ -517,6 +512,16 @@ void full_demod(struct fm_state *fm)
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return;
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}
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sr = post_squelch(fm);
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if (!sr && fm->squelch_hits > fm->conseq_squelch) {
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if (fm->terminate_on_squelch) {
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fm->exit_flag = 1;}
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if (fm->freq_len == 1) { /* mute */
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for (i=0; i<fm->signal_len; i++) {
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fm->signal2[i] = 0;}
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}
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else {
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hop = 1;}
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}
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if (fm->post_downsample > 1) {
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fm->signal2_len = low_pass_simple(fm->signal2, fm->signal2_len, fm->post_downsample);}
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if (fm->output_rate > 0) {
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@ -526,11 +531,11 @@ void full_demod(struct fm_state *fm)
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deemph_filter(fm);}
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/* ignore under runs for now */
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fwrite(fm->signal2, 2, fm->signal2_len, fm->file);
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if (fm->freq_len > 1 && !sr && fm->squelch_hits > CONSEQ_SQUELCH) {
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if (hop) {
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freq_next = (fm->freq_now + 1) % fm->freq_len;
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optimal_settings(fm, freq_next, 1);
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fm->squelch_hits = CONSEQ_SQUELCH + 1; /* hair trigger */
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/* wait for settling and dump buffer */
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fm->squelch_hits = fm->conseq_squelch + 1; /* hair trigger */
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/* wait for settling and flush buffer */
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usleep(5000);
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rtlsdr_read_sync(dev, NULL, 4096, NULL);
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}
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@ -559,16 +564,14 @@ static void *demod_thread_fn(void *arg)
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while (!do_exit) {
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sem_wait(&data_ready);
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full_demod(fm2);
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if (!fm2->term_squelch_hits) {
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continue;}
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if (fm2->squelch_hits > fm2->term_squelch_hits) {
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if (fm2->exit_flag) {
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do_exit = 1;
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rtlsdr_cancel_async(dev);}
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}
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return 0;
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}
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int atofs(char* f)
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double atofs(char* f)
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/* standard suffixes */
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{
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char* chop;
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@ -584,8 +587,26 @@ int atofs(char* f)
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suff *= atof(chop);}
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free(chop);
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if (suff != 1.0) {
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return (int)suff;}
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return (int)atof(f);
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return suff;}
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return atof(f);
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}
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void frequency_range(struct fm_state *fm, char *arg)
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{
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char *start, *stop, *step;
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int i;
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start = arg;
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stop = strchr(start, ':') + 1;
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stop[-1] = '\0';
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step = strchr(stop, ':') + 1;
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step[-1] = '\0';
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for(i=(int)atofs(start); i<=(int)atofs(stop); i+=(int)atofs(step))
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{
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fm->freqs[fm->freq_len] = (uint32_t)i;
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fm->freq_len++;
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}
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stop[-1] = ':';
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step[-1] = ':';
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}
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int main(int argc, char **argv)
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@ -605,7 +626,8 @@ int main(int argc, char **argv)
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fm.freqs[0] = 100000000;
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fm.sample_rate = DEFAULT_SAMPLE_RATE;
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fm.squelch_level = 0;
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fm.term_squelch_hits = 0;
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fm.conseq_squelch = 20;
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fm.terminate_on_squelch = 0;
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fm.freq_len = 0;
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fm.edge = 0;
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fm.fir_enable = 0;
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@ -623,8 +645,13 @@ int main(int argc, char **argv)
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dev_index = atoi(optarg);
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break;
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case 'f':
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fm.freqs[fm.freq_len] = (uint32_t)atofs(optarg);
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fm.freq_len++;
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if (strchr(optarg, ':'))
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{frequency_range(&fm, optarg);}
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else
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{
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fm.freqs[fm.freq_len] = (uint32_t)atofs(optarg);
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fm.freq_len++;
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}
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break;
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case 'g':
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gain = (int)(atof(optarg) * 10);
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@ -644,10 +671,15 @@ int main(int argc, char **argv)
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fprintf(stderr, "Oversample must be between 1 and %i\n", MAXIMUM_OVERSAMPLE);}
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break;
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case 't':
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fm.term_squelch_hits = (int)atof(optarg);
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fm.conseq_squelch = (int)atof(optarg);
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if (fm.conseq_squelch < 0) {
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fm.conseq_squelch = -fm.conseq_squelch;
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fm.terminate_on_squelch = 1;
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}
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break;
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case 'p':
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ppm_error = atoi(optarg);
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break;
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case 'E':
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fm.edge = 1;
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break;
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@ -693,8 +725,13 @@ int main(int argc, char **argv)
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/* quadruple sample_rate to limit to Δθ to ±π/2 */
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fm.sample_rate *= fm.post_downsample;
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if (fm.freq_len > 1) {
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fm.terminate_on_squelch = 0;
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}
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if (argc <= optind) {
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usage();
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//usage();
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filename = "-";
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} else {
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filename = argv[optind];
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}
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