/* * rtl-sdr, turns your Realtek RTL2832 based DVB dongle into a SDR receiver * Copyright (C) 2012 by Steve Markgraf <steve@steve-m.de> * Copyright (C) 2012 by Hoernchen <la@tfc-server.de> * Copyright (C) 2012 by Kyle Keen <keenerd@gmail.com> * Copyright (C) 2013 by Elias Oenal <EliasOenal@gmail.com> * Copyright (C) 2016, 2017 Konsulko Group * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ /* * Note that this version replaces the standalone main() with separate * init/start/stop API calls to allow building into another application. * Other than removing the separate controller thread and adding an output * function callback, other changes have been kept to a minimum to * potentially allow using other rtl_fm features by modifying rtl_fm_init. * * December 2016, Scott Murray <scott.murray@konsulko.com> */ /* * written because people could not do real time * FM demod on Atom hardware with GNU radio * based on rtl_sdr.c and rtl_tcp.c * * lots of locks, but that is okay * (no many-to-many locks) * * todo: * sanity checks * scale squelch to other input parameters * test all the demodulations * pad output on hop * frequency ranges could be stored better * scaled AM demod amplification * auto-hop after time limit * peak detector to tune onto stronger signals * fifo for active hop frequency * clips * noise squelch * merge stereo patch * merge soft agc patch * merge udp patch * testmode to detect overruns * watchdog to reset bad dongle * fix oversampling */ #include <errno.h> #include <signal.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <math.h> #include <pthread.h> #include "rtl-sdr.h" #include "rtl_fm.h" #include "convenience/convenience.h" #define DEFAULT_SAMPLE_RATE 24000 #define DEFAULT_BUF_LENGTH RTL_FM_DEFAULT_BUF_LENGTH #define MAXIMUM_OVERSAMPLE RTL_FM_MAXIMUM_OVERSAMPLE #define MAXIMUM_BUF_LENGTH RTL_FM_MAXIMUM_BUF_LENGTH #define AUTO_GAIN -100 #define BUFFER_DUMP 4096 #define FREQUENCIES_LIMIT 1000 #define DEFAULT_SQUELCH_LEVEL 140 #define DEFAULT_CONSEQ_SQUELCH 10 static volatile int do_exit = 0; static int lcm_post[17] = {1,1,1,3,1,5,3,7,1,9,5,11,3,13,7,15,1}; static int ACTUAL_BUF_LENGTH; static int *atan_lut = NULL; static int atan_lut_size = 131072; /* 512 KB */ static int atan_lut_coef = 8; struct dongle_state { int exit_flag; pthread_t thread; rtlsdr_dev_t *dev; int dev_index; uint32_t freq; uint32_t rate; int gain; uint16_t buf16[MAXIMUM_BUF_LENGTH]; uint32_t buf_len; int ppm_error; int offset_tuning; int direct_sampling; int mute; struct demod_state *demod_target; }; struct demod_state { int exit_flag; pthread_t thread; int16_t lowpassed[MAXIMUM_BUF_LENGTH]; int lp_len; int16_t lp_i_hist[10][6]; int16_t lp_q_hist[10][6]; int16_t result[MAXIMUM_BUF_LENGTH]; int16_t droop_i_hist[9]; int16_t droop_q_hist[9]; int result_len; int rate_in; int rate_out; int rate_out2; int now_r, now_j; int pre_r, pre_j; int prev_index; int downsample; /* min 1, max 256 */ int post_downsample; int output_scale; int squelch_level, conseq_squelch, squelch_hits, terminate_on_squelch; int downsample_passes; int comp_fir_size; int custom_atan; int deemph, deemph_a; int now_lpr; int prev_lpr_index; int dc_block, dc_avg; void (*mode_demod)(struct demod_state*); pthread_rwlock_t rw; pthread_cond_t ready; pthread_mutex_t ready_m; struct output_state *output_target; }; struct output_state { int exit_flag; pthread_t thread; rtl_fm_output_fn_t output_fn; void *output_fn_data; int16_t result[MAXIMUM_BUF_LENGTH]; int result_len; int rate; pthread_rwlock_t rw; pthread_cond_t ready; pthread_mutex_t ready_m; }; struct controller_state { int exit_flag; pthread_t thread; uint32_t freqs[FREQUENCIES_LIMIT]; int freq_len; int freq_now; int edge; int wb_mode; pthread_cond_t hop; pthread_mutex_t hop_m; void (*freq_callback)(uint32_t, void*); void *freq_callback_data; int scanning; int scan_direction; void (*scan_callback)(uint32_t, void*); void *scan_callback_data; uint32_t scan_step; uint32_t scan_min; uint32_t scan_max; int scan_squelch_level; int scan_squelch_count; }; // multiple of these, eventually struct dongle_state dongle; struct demod_state demod; struct output_state output; struct controller_state controller; #if 0 static void sighandler(int signum) { fprintf(stderr, "Signal caught, exiting!\n"); do_exit = 1; rtlsdr_cancel_async(dongle.dev); } #endif /* more cond dumbness */ #define safe_cond_signal(n, m) pthread_mutex_lock(m); pthread_cond_signal(n); pthread_mutex_unlock(m) #define safe_cond_wait(n, m) pthread_mutex_lock(m); pthread_cond_wait(n, m); pthread_mutex_unlock(m) /* {length, coef, coef, coef} and scaled by 2^15 for now, only length 9, optimal way to get +85% bandwidth */ #define CIC_TABLE_MAX 10 int cic_9_tables[][10] = { {0,}, {9, -156, -97, 2798, -15489, 61019, -15489, 2798, -97, -156}, {9, -128, -568, 5593, -24125, 74126, -24125, 5593, -568, -128}, {9, -129, -639, 6187, -26281, 77511, -26281, 6187, -639, -129}, {9, -122, -612, 6082, -26353, 77818, -26353, 6082, -612, -122}, {9, -120, -602, 6015, -26269, 77757, -26269, 6015, -602, -120}, {9, -120, -582, 5951, -26128, 77542, -26128, 5951, -582, -120}, {9, -119, -580, 5931, -26094, 77505, -26094, 5931, -580, -119}, {9, -119, -578, 5921, -26077, 77484, -26077, 5921, -578, -119}, {9, -119, -577, 5917, -26067, 77473, -26067, 5917, -577, -119}, {9, -199, -362, 5303, -25505, 77489, -25505, 5303, -362, -199}, }; void rotate_90(unsigned char *buf, uint32_t len) /* 90 rotation is 1+0j, 0+1j, -1+0j, 0-1j or [0, 1, -3, 2, -4, -5, 7, -6] */ { uint32_t i; unsigned char tmp; for (i=0; i<len; i+=8) { /* uint8_t negation = 255 - x */ tmp = 255 - buf[i+3]; buf[i+3] = buf[i+2]; buf[i+2] = tmp; buf[i+4] = 255 - buf[i+4]; buf[i+5] = 255 - buf[i+5]; tmp = 255 - buf[i+6]; buf[i+6] = buf[i+7]; buf[i+7] = tmp; } } void low_pass(struct demod_state *d) /* simple square window FIR */ { int i=0, i2=0; while (i < d->lp_len) { d->now_r += d->lowpassed[i]; d->now_j += d->lowpassed[i+1]; i += 2; d->prev_index++; if (d->prev_index < d->downsample) { continue; } d->lowpassed[i2] = d->now_r; // * d->output_scale; d->lowpassed[i2+1] = d->now_j; // * d->output_scale; d->prev_index = 0; d->now_r = 0; d->now_j = 0; i2 += 2; } d->lp_len = i2; } int low_pass_simple(int16_t *signal2, int len, int step) // no wrap around, length must be multiple of step { int i, i2, sum; for(i=0; i < len; i+=step) { sum = 0; for(i2=0; i2<step; i2++) { sum += (int)signal2[i + i2]; } //signal2[i/step] = (int16_t)(sum / step); signal2[i/step] = (int16_t)(sum); } signal2[i/step + 1] = signal2[i/step]; return len / step; } void low_pass_real(struct demod_state *s) /* simple square window FIR */ // add support for upsampling? { int i=0, i2=0; int fast = (int)s->rate_out; int slow = s->rate_out2; while (i < s->result_len) { s->now_lpr += s->result[i]; i++; s->prev_lpr_index += slow; if (s->prev_lpr_index < fast) { continue; } s->result[i2] = (int16_t)(s->now_lpr / (fast/slow)); s->prev_lpr_index -= fast; s->now_lpr = 0; i2 += 1; } s->result_len = i2; } void fifth_order(int16_t *data, int length, int16_t *hist) /* for half of interleaved data */ { int i; int16_t a, b, c, d, e, f; a = hist[1]; b = hist[2]; c = hist[3]; d = hist[4]; e = hist[5]; f = data[0]; /* a downsample should improve resolution, so don't fully shift */ data[0] = (a + (b+e)*5 + (c+d)*10 + f) >> 4; for (i=4; i<length; i+=4) { a = c; b = d; c = e; d = f; e = data[i-2]; f = data[i]; data[i/2] = (a + (b+e)*5 + (c+d)*10 + f) >> 4; } /* archive */ hist[0] = a; hist[1] = b; hist[2] = c; hist[3] = d; hist[4] = e; hist[5] = f; } void generic_fir(int16_t *data, int length, int *fir, int16_t *hist) /* Okay, not at all generic. Assumes length 9, fix that eventually. */ { int d, temp, sum; for (d=0; d<length; d+=2) { temp = data[d]; sum = 0; sum += (hist[0] + hist[8]) * fir[1]; sum += (hist[1] + hist[7]) * fir[2]; sum += (hist[2] + hist[6]) * fir[3]; sum += (hist[3] + hist[5]) * fir[4]; sum += hist[4] * fir[5]; data[d] = sum >> 15 ; hist[0] = hist[1]; hist[1] = hist[2]; hist[2] = hist[3]; hist[3] = hist[4]; hist[4] = hist[5]; hist[5] = hist[6]; hist[6] = hist[7]; hist[7] = hist[8]; hist[8] = temp; } } /* define our own complex math ops because ARMv5 has no hardware float */ void multiply(int ar, int aj, int br, int bj, int *cr, int *cj) { *cr = ar*br - aj*bj; *cj = aj*br + ar*bj; } int polar_discriminant(int ar, int aj, int br, int bj) { int cr, cj; double angle; multiply(ar, aj, br, -bj, &cr, &cj); angle = atan2((double)cj, (double)cr); return (int)(angle / 3.14159 * (1<<14)); } int fast_atan2(int y, int x) /* pre scaled for int16 */ { int yabs, angle; int pi4=(1<<12), pi34=3*(1<<12); // note pi = 1<<14 if (x==0 && y==0) { return 0; } yabs = y; if (yabs < 0) { yabs = -yabs; } if (x >= 0) { angle = pi4 - pi4 * (x-yabs) / (x+yabs); } else { angle = pi34 - pi4 * (x+yabs) / (yabs-x); } if (y < 0) { return -angle; } return angle; } int polar_disc_fast(int ar, int aj, int br, int bj) { int cr, cj; multiply(ar, aj, br, -bj, &cr, &cj); return fast_atan2(cj, cr); } int atan_lut_init(void) { int i = 0; atan_lut = malloc(atan_lut_size * sizeof(int)); for (i = 0; i < atan_lut_size; i++) { atan_lut[i] = (int) (atan((double) i / (1<<atan_lut_coef)) / 3.14159 * (1<<14)); } return 0; } int polar_disc_lut(int ar, int aj, int br, int bj) { int cr, cj, x, x_abs; multiply(ar, aj, br, -bj, &cr, &cj); /* special cases */ if (cr == 0 || cj == 0) { if (cr == 0 && cj == 0) {return 0;} if (cr == 0 && cj > 0) {return 1 << 13;} if (cr == 0 && cj < 0) {return -(1 << 13);} if (cj == 0 && cr > 0) {return 0;} if (cj == 0 && cr < 0) {return 1 << 14;} } /* real range -32768 - 32768 use 64x range -> absolute maximum: 2097152 */ x = (cj << atan_lut_coef) / cr; x_abs = abs(x); if (x_abs >= atan_lut_size) { /* we can use linear range, but it is not necessary */ return (cj > 0) ? 1<<13 : -1<<13; } if (x > 0) { return (cj > 0) ? atan_lut[x] : atan_lut[x] - (1<<14); } else { return (cj > 0) ? (1<<14) - atan_lut[-x] : -atan_lut[-x]; } return 0; } void fm_demod(struct demod_state *fm) { int i, pcm; int16_t *lp = fm->lowpassed; pcm = polar_discriminant(lp[0], lp[1], fm->pre_r, fm->pre_j); fm->result[0] = (int16_t)pcm; for (i = 2; i < (fm->lp_len-1); i += 2) { switch (fm->custom_atan) { case 0: pcm = polar_discriminant(lp[i], lp[i+1], lp[i-2], lp[i-1]); break; case 1: pcm = polar_disc_fast(lp[i], lp[i+1], lp[i-2], lp[i-1]); break; case 2: pcm = polar_disc_lut(lp[i], lp[i+1], lp[i-2], lp[i-1]); break; } fm->result[i/2] = (int16_t)pcm; } fm->pre_r = lp[fm->lp_len - 2]; fm->pre_j = lp[fm->lp_len - 1]; fm->result_len = fm->lp_len/2; } void am_demod(struct demod_state *fm) // todo, fix this extreme laziness { int i, pcm; int16_t *lp = fm->lowpassed; int16_t *r = fm->result; for (i = 0; i < fm->lp_len; i += 2) { // hypot uses floats but won't overflow //r[i/2] = (int16_t)hypot(lp[i], lp[i+1]); pcm = lp[i] * lp[i]; pcm += lp[i+1] * lp[i+1]; r[i/2] = (int16_t)sqrt(pcm) * fm->output_scale; } fm->result_len = fm->lp_len/2; // lowpass? (3khz) highpass? (dc) } void usb_demod(struct demod_state *fm) { int i, pcm; int16_t *lp = fm->lowpassed; int16_t *r = fm->result; for (i = 0; i < fm->lp_len; i += 2) { pcm = lp[i] + lp[i+1]; r[i/2] = (int16_t)pcm * fm->output_scale; } fm->result_len = fm->lp_len/2; } void lsb_demod(struct demod_state *fm) { int i, pcm; int16_t *lp = fm->lowpassed; int16_t *r = fm->result; for (i = 0; i < fm->lp_len; i += 2) { pcm = lp[i] - lp[i+1]; r[i/2] = (int16_t)pcm * fm->output_scale; } fm->result_len = fm->lp_len/2; } void raw_demod(struct demod_state *fm) { int i; for (i = 0; i < fm->lp_len; i++) { fm->result[i] = (int16_t)fm->lowpassed[i]; } fm->result_len = fm->lp_len; } void deemph_filter(struct demod_state *fm) { static int avg; // cheating... int i, d; // de-emph IIR // avg = avg * (1 - alpha) + sample * alpha; for (i = 0; i < fm->result_len; i++) { d = fm->result[i] - avg; if (d > 0) { avg += (d + fm->deemph_a/2) / fm->deemph_a; } else { avg += (d - fm->deemph_a/2) / fm->deemph_a; } fm->result[i] = (int16_t)avg; } } void dc_block_filter(struct demod_state *fm) { int i, avg; int64_t sum = 0; for (i=0; i < fm->result_len; i++) { sum += fm->result[i]; } avg = sum / fm->result_len; avg = (avg + fm->dc_avg * 9) / 10; for (i=0; i < fm->result_len; i++) { fm->result[i] -= avg; } fm->dc_avg = avg; } int mad(int16_t *samples, int len, int step) /* mean average deviation */ { int i=0, sum=0, ave=0; if (len == 0) {return 0;} for (i=0; i<len; i+=step) { sum += samples[i]; } ave = sum / (len * step); sum = 0; for (i=0; i<len; i+=step) { sum += abs(samples[i] - ave); } return sum / (len / step); } int rms(int16_t *samples, int len, int step) /* largely lifted from rtl_power */ { int i; long p, t, s; double dc, err; p = t = 0L; for (i=0; i<len; i+=step) { s = (long)samples[i]; t += s; p += s * s; } /* correct for dc offset in squares */ dc = (double)(t*step) / (double)len; err = t * 2 * dc - dc * dc * len; return (int)sqrt((p-err) / len); } void arbitrary_upsample(int16_t *buf1, int16_t *buf2, int len1, int len2) /* linear interpolation, len1 < len2 */ { int i = 1; int j = 0; int tick = 0; double frac; // use integers... while (j < len2) { frac = (double)tick / (double)len2; buf2[j] = (int16_t)(buf1[i-1]*(1-frac) + buf1[i]*frac); j++; tick += len1; if (tick > len2) { tick -= len2; i++; } if (i >= len1) { i = len1 - 1; tick = len2; } } } void arbitrary_downsample(int16_t *buf1, int16_t *buf2, int len1, int len2) /* fractional boxcar lowpass, len1 > len2 */ { int i = 1; int j = 0; int tick = 0; double remainder = 0; double frac; // use integers... buf2[0] = 0; while (j < len2) { frac = 1.0; if ((tick + len2) > len1) { frac = (double)(len1 - tick) / (double)len2;} buf2[j] += (int16_t)((double)buf1[i] * frac + remainder); remainder = (double)buf1[i] * (1.0-frac); tick += len2; i++; if (tick > len1) { j++; buf2[j] = 0; tick -= len1; } if (i >= len1) { i = len1 - 1; tick = len1; } } for (j=0; j<len2; j++) { buf2[j] = buf2[j] * len2 / len1;} } void arbitrary_resample(int16_t *buf1, int16_t *buf2, int len1, int len2) /* up to you to calculate lengths and make sure it does not go OOB * okay for buffers to overlap, if you are downsampling */ { if (len1 < len2) { arbitrary_upsample(buf1, buf2, len1, len2); } else { arbitrary_downsample(buf1, buf2, len1, len2); } } void full_demod(struct demod_state *d) { int i, ds_p; int sr = 0; ds_p = d->downsample_passes; if (ds_p) { for (i=0; i < ds_p; i++) { fifth_order(d->lowpassed, (d->lp_len >> i), d->lp_i_hist[i]); fifth_order(d->lowpassed+1, (d->lp_len >> i) - 1, d->lp_q_hist[i]); } d->lp_len = d->lp_len >> ds_p; /* droop compensation */ if (d->comp_fir_size == 9 && ds_p <= CIC_TABLE_MAX) { generic_fir(d->lowpassed, d->lp_len, cic_9_tables[ds_p], d->droop_i_hist); generic_fir(d->lowpassed+1, d->lp_len-1, cic_9_tables[ds_p], d->droop_q_hist); } } else { low_pass(d); } /* power squelch */ if (d->squelch_level) { sr = rms(d->lowpassed, d->lp_len, 1); if (sr < d->squelch_level) { d->squelch_hits++; for (i=0; i< d->lp_len; i++) { d->lowpassed[i] = 0; } } else { d->squelch_hits = 0; } } d->mode_demod(d); /* lowpassed -> result */ if (d->mode_demod == &raw_demod) { return; } /* todo, fm noise squelch */ // use nicer filter here too? if (d->post_downsample > 1) { d->result_len = low_pass_simple(d->result, d->result_len, d->post_downsample);} if (d->deemph) { deemph_filter(d);} if (d->dc_block) { dc_block_filter(d);} if (d->rate_out2 > 0) { low_pass_real(d); //arbitrary_resample(d->result, d->result, d->result_len, d->result_len * d->rate_out2 / d->rate_out); } } static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx) { int i; struct dongle_state *s = ctx; struct demod_state *d = s->demod_target; if (do_exit) { return;} if (!ctx) { return;} if (s->mute) { for (i=0; i<s->mute; i++) { buf[i] = 127;} s->mute = 0; } if (!s->offset_tuning) { rotate_90(buf, len);} for (i=0; i<(int)len; i++) { s->buf16[i] = (int16_t)buf[i] - 127;} pthread_rwlock_wrlock(&d->rw); memcpy(d->lowpassed, s->buf16, 2*len); d->lp_len = len; pthread_rwlock_unlock(&d->rw); safe_cond_signal(&d->ready, &d->ready_m); } static void *dongle_thread_fn(void *arg) { struct dongle_state *s = arg; fprintf(stderr, "dongle_thread_fn running\n"); rtlsdr_read_async(s->dev, rtlsdr_callback, s, 0, s->buf_len); fprintf(stderr, "dongle_thread_fn exited!\n"); return 0; } static void rtl_fm_scan_callback(void) { struct controller_state *s = &controller; uint32_t frequency = rtl_fm_get_freq(); if(!s->scanning) return; if(!s->scan_direction) { frequency += s->scan_step; if(frequency > s->scan_max) frequency = s->scan_min; } else { frequency -= s->scan_step; if(frequency < s->scan_min) frequency = s->scan_max; } rtl_fm_set_freq(frequency); } static void rtl_fm_scan_end_callback(void) { struct controller_state *s = &controller; if(!s->scanning) return; rtl_fm_scan_stop(); if(s->scan_callback) s->scan_callback(rtl_fm_get_freq(), s->scan_callback_data); } static void *demod_thread_fn(void *arg) { struct demod_state *d = arg; struct output_state *o = d->output_target; fprintf(stderr, "demod_thread_fn running\n"); while (!do_exit) { safe_cond_wait(&d->ready, &d->ready_m); pthread_rwlock_wrlock(&d->rw); full_demod(d); pthread_rwlock_unlock(&d->rw); if (d->exit_flag) { do_exit = 1; } if (d->squelch_level) { if(d->squelch_hits > d->conseq_squelch) { d->squelch_hits = d->conseq_squelch + 1; /* hair trigger */ //safe_cond_signal(&controller.hop, &controller.hop_m); rtl_fm_scan_callback(); continue; } else if(!d->squelch_hits) { rtl_fm_scan_end_callback(); } } pthread_rwlock_wrlock(&o->rw); memcpy(o->result, d->result, 2*d->result_len); o->result_len = d->result_len; pthread_rwlock_unlock(&o->rw); safe_cond_signal(&o->ready, &o->ready_m); } fprintf(stderr, "demod_thread_fn exited!\n"); return 0; } static void *output_thread_fn(void *arg) { struct output_state *s = arg; fprintf(stderr, "output_thread_fn running\n"); while (!do_exit) { // use timedwait and pad out under runs safe_cond_wait(&s->ready, &s->ready_m); pthread_rwlock_rdlock(&s->rw); if(s->output_fn) { s->output_fn(s->result, s->result_len, s->output_fn_data); } pthread_rwlock_unlock(&s->rw); } fprintf(stderr, "output_thread_fn exited!\n"); return 0; } static void optimal_settings(int freq, int rate) { // giant ball of hacks // seems unable to do a single pass, 2:1 int capture_freq, capture_rate; struct dongle_state *d = &dongle; struct demod_state *dm = &demod; struct controller_state *cs = &controller; dm->downsample = (1000000 / dm->rate_in) + 1; if (dm->downsample_passes) { dm->downsample_passes = (int)log2(dm->downsample) + 1; dm->downsample = 1 << dm->downsample_passes; } capture_freq = freq; capture_rate = dm->downsample * dm->rate_in; if (!d->offset_tuning) { capture_freq = freq + capture_rate/4;} capture_freq += cs->edge * dm->rate_in / 2; dm->output_scale = (1<<15) / (128 * dm->downsample); if (dm->output_scale < 1) { dm->output_scale = 1;} if (dm->mode_demod == &fm_demod) { dm->output_scale = 1;} d->freq = (uint32_t)capture_freq; d->rate = (uint32_t)capture_rate; } void frequency_range(struct controller_state *s, 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)) { s->freqs[s->freq_len] = (uint32_t)i; s->freq_len++; if (s->freq_len >= FREQUENCIES_LIMIT) { break;} } stop[-1] = ':'; step[-1] = ':'; } void dongle_init(struct dongle_state *s) { s->rate = DEFAULT_SAMPLE_RATE; s->gain = AUTO_GAIN; // tenths of a dB s->mute = 0; s->direct_sampling = 0; s->offset_tuning = 0; s->demod_target = &demod; } void demod_init(struct demod_state *s) { s->rate_in = DEFAULT_SAMPLE_RATE; s->rate_out = DEFAULT_SAMPLE_RATE; s->squelch_level = 0; s->conseq_squelch = DEFAULT_CONSEQ_SQUELCH; s->terminate_on_squelch = 0; s->squelch_hits = DEFAULT_CONSEQ_SQUELCH + 1; s->downsample_passes = 0; s->comp_fir_size = 0; s->prev_index = 0; s->post_downsample = 1; // once this works, default = 4 s->custom_atan = 0; s->deemph = 0; s->rate_out2 = -1; // flag for disabled s->mode_demod = &fm_demod; s->pre_j = s->pre_r = s->now_r = s->now_j = 0; s->prev_lpr_index = 0; s->deemph_a = 0; s->now_lpr = 0; s->dc_block = 0; s->dc_avg = 0; pthread_rwlock_init(&s->rw, NULL); pthread_cond_init(&s->ready, NULL); pthread_mutex_init(&s->ready_m, NULL); s->output_target = &output; } void demod_cleanup(struct demod_state *s) { pthread_rwlock_destroy(&s->rw); pthread_cond_destroy(&s->ready); pthread_mutex_destroy(&s->ready_m); } void output_init(struct output_state *s) { s->rate = DEFAULT_SAMPLE_RATE; s->output_fn = NULL; s->output_fn_data = NULL; pthread_rwlock_init(&s->rw, NULL); pthread_cond_init(&s->ready, NULL); pthread_mutex_init(&s->ready_m, NULL); } void output_cleanup(struct output_state *s) { pthread_rwlock_destroy(&s->rw); pthread_cond_destroy(&s->ready); pthread_mutex_destroy(&s->ready_m); } void controller_init(struct controller_state *s) { s->freqs[0] = 100000000; s->freq_len = 0; s->edge = 0; s->wb_mode = 0; pthread_cond_init(&s->hop, NULL); pthread_mutex_init(&s->hop_m, NULL); } void controller_cleanup(struct controller_state *s) { pthread_cond_destroy(&s->hop); pthread_mutex_destroy(&s->hop_m); } int sanity_checks(void) { int r = 1; if (controller.freq_len == 0) { fprintf(stderr, "Please specify a frequency.\n"); r = 0; } if (controller.freq_len >= FREQUENCIES_LIMIT) { fprintf(stderr, "Too many channels, maximum %i.\n", FREQUENCIES_LIMIT); r = 0; } if (controller.freq_len > 1 && demod.squelch_level == 0) { fprintf(stderr, "Please specify a squelch level. Required for scanning multiple frequencies.\n"); r = 0; } return r; } int rtl_fm_init(uint32_t freq, uint32_t sample_rate, uint32_t resample_rate, rtl_fm_output_fn_t output_fn, void *output_fn_data) { int r = 0; dongle_init(&dongle); demod_init(&demod); output_init(&output); controller_init(&controller); /* * Simulate the effects of command line arguments: * * -W wbfm -s <sample rate> -r <resample rate> */ /* Set initial frequency */ controller.freqs[0] = freq; controller.freq_len++; /* Set mode to wbfm */ controller.wb_mode = 1; demod.mode_demod = &fm_demod; demod.rate_in = 170000; demod.rate_out = 170000; demod.rate_out2 = 32000; demod.custom_atan = 1; //demod.post_downsample = 4; demod.deemph = 1; controller.scan_squelch_count = DEFAULT_CONSEQ_SQUELCH; controller.scan_squelch_level = DEFAULT_SQUELCH_LEVEL; demod.squelch_level = 0; /* Adjust frequency for wb mode */ controller.freqs[0] += 16000; /* Set sample rate */ demod.rate_in = sample_rate; demod.rate_out = sample_rate; /* Set resample rate */ output.rate = (int) resample_rate; demod.rate_out2 = (int) resample_rate; /* Set output function pointer */ if(output_fn) { output.output_fn = output_fn; output.output_fn_data = output_fn_data; } /* quadruple sample_rate to limit to Δθ to ±π/2 */ demod.rate_in *= demod.post_downsample; if (!output.rate) { output.rate = demod.rate_out; } if (!sanity_checks()) return -1; if (controller.freq_len > 1) { demod.terminate_on_squelch = 0; } ACTUAL_BUF_LENGTH = lcm_post[demod.post_downsample] * DEFAULT_BUF_LENGTH; dongle.dev_index = verbose_device_search("0"); if (dongle.dev_index < 0) { return -1; } r = rtlsdr_open(&dongle.dev, (uint32_t)dongle.dev_index); if (r < 0) { fprintf(stderr, "Failed to open rtlsdr device #%d.\n", dongle.dev_index); return r; } if (demod.deemph) { demod.deemph_a = (int)round(1.0/((1.0-exp(-1.0/(demod.rate_out * 75e-6))))); } /* Set the tuner gain */ if (dongle.gain == AUTO_GAIN) { verbose_auto_gain(dongle.dev); } else { dongle.gain = nearest_gain(dongle.dev, dongle.gain); verbose_gain_set(dongle.dev, dongle.gain); } verbose_ppm_set(dongle.dev, dongle.ppm_error); //r = rtlsdr_set_testmode(dongle.dev, 1); return r; } void rtl_fm_start(void) { struct controller_state *s = &controller; /* * A bunch of the following is pulled from the controller_thread_fn, * which has been removed. */ /* Reset endpoint before we start reading from it (mandatory) */ verbose_reset_buffer(dongle.dev); /* set up primary channel */ optimal_settings(s->freqs[0], demod.rate_in); if (dongle.direct_sampling) { verbose_direct_sampling(dongle.dev, 1);} if (dongle.offset_tuning) { verbose_offset_tuning(dongle.dev);} /* Set the frequency */ verbose_set_frequency(dongle.dev, dongle.freq); fprintf(stderr, "Oversampling input by: %ix.\n", demod.downsample); fprintf(stderr, "Oversampling output by: %ix.\n", demod.post_downsample); fprintf(stderr, "Buffer size: %0.2fms\n", 1000 * 0.5 * (float)ACTUAL_BUF_LENGTH / (float)dongle.rate); /* Set the sample rate */ verbose_set_sample_rate(dongle.dev, dongle.rate); fprintf(stderr, "Output at %u Hz.\n", demod.rate_in/demod.post_downsample); usleep(100000); rtl_fm_scan_stop(); do_exit = 0; pthread_create(&output.thread, NULL, output_thread_fn, (void *)(&output)); pthread_create(&demod.thread, NULL, demod_thread_fn, (void *)(&demod)); pthread_create(&dongle.thread, NULL, dongle_thread_fn, (void *)(&dongle)); } void rtl_fm_set_freq(uint32_t freq) { struct controller_state *s = &controller; if(s->freqs[0] == freq) return; s->freqs[0] = freq; s->freq_len = 1; if (s->wb_mode) { s->freqs[0] += 16000; } optimal_settings(s->freqs[0], demod.rate_in); if (dongle.offset_tuning) { verbose_offset_tuning(dongle.dev); } rtlsdr_set_center_freq(dongle.dev, dongle.freq); // It does not look like refreshing the sample rate is desirable // (e.g. the scanning code in the removed controller thread function // did not do it), and behavior seemed a bit less robust with it // present. However, I am leaving this here as a reminder to revisit // via some more testing. //rtlsdr_set_sample_rate(dongle.dev, dongle.rate); // This triggers a mute during the frequency change dongle.mute = BUFFER_DUMP; if(s->freq_callback) s->freq_callback(freq, s->freq_callback_data); } void rtl_fm_set_freq_callback(void (*callback)(uint32_t, void *), void *data) { struct controller_state *s = &controller; s->freq_callback = callback; s->freq_callback_data = data; } uint32_t rtl_fm_get_freq(void) { struct controller_state *s = &controller; uint32_t frequency = s->freqs[0]; if (s->wb_mode) frequency -= 16000; return frequency; } void rtl_fm_stop(void) { rtl_fm_scan_stop(); rtlsdr_cancel_async(dongle.dev); do_exit = 1; pthread_join(dongle.thread, NULL); safe_cond_signal(&demod.ready, &demod.ready_m); pthread_join(demod.thread, NULL); safe_cond_signal(&output.ready, &output.ready_m); pthread_join(output.thread, NULL); } void rtl_fm_scan_start(int direction, void (*callback)(uint32_t, void *), void *data, uint32_t step, uint32_t min, uint32_t max) { struct controller_state *s = &controller; struct demod_state *dm = &demod; uint32_t frequency = rtl_fm_get_freq(); if(s->scanning && s->scan_direction == direction) return; s->scanning = 1; s->scan_direction = direction; s->scan_callback = callback; s->scan_callback_data = data; s->scan_step = step; s->scan_min = min; s->scan_max = max; /* Start scan by stepping in the desired direction */ if(!direction) { frequency += s->scan_step; if(frequency > s->scan_max) frequency = s->scan_min; } else { frequency -= s->scan_step; if(frequency < s->scan_min) frequency = s->scan_max; } rtl_fm_set_freq(frequency); dm->conseq_squelch = s->scan_squelch_count; dm->squelch_hits = s->scan_squelch_count + 1; dm->squelch_level = s->scan_squelch_level; } void rtl_fm_scan_stop(void) { struct controller_state *s = &controller; struct demod_state *dm = &demod; s->scanning = 0; dm->squelch_hits = s->scan_squelch_count + 1; dm->squelch_level = 0; } void rtl_fm_scan_set_squelch_level(int level) { struct controller_state *s = &controller; s->scan_squelch_level = level; } void rtl_fm_scan_set_squelch_limit(int count) { struct controller_state *s = &controller; s->scan_squelch_count = count; } void rtl_fm_cleanup(void) { //dongle_cleanup(&dongle); demod_cleanup(&demod); output_cleanup(&output); controller_cleanup(&controller); rtlsdr_close(dongle.dev); } // vim: tabstop=8:softtabstop=8:shiftwidth=8:noexpandtab