diff options
Diffstat (limited to 'src/rtl_fm.c')
| -rw-r--r-- | src/rtl_fm.c | 113 |
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]; } |