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rtl-sdr/src/rtl_fm.c

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/*
* 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>
*
* 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/>.
*/
/*
* 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
* todo: realtime ARMv5
* remove float math (disqualifies complex.h)
* in-place array operations
* sanity checks
* nicer FIR than square
* 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
* use slower sample rates (250k) for nbfm
* offset tuning
* fifo for active hop frequency
* clips
* real squelch math
*/
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#ifndef _WIN32
#include <unistd.h>
#else
#include <windows.h>
#include <fcntl.h>
#include <io.h>
#include "getopt/getopt.h"
#define usleep(x) Sleep(x/1000)
#define round(x) (x > 0.0 ? floor(x + 0.5): ceil(x - 0.5))
#define _USE_MATH_DEFINES
#endif
#include <math.h>
#include <pthread.h>
#include <libusb.h>
#include "rtl-sdr.h"
#define DEFAULT_SAMPLE_RATE 24000
#define DEFAULT_ASYNC_BUF_NUMBER 32
#define DEFAULT_BUF_LENGTH (1 * 16384)
#define MAXIMUM_OVERSAMPLE 16
#define MAXIMUM_BUF_LENGTH (MAXIMUM_OVERSAMPLE * DEFAULT_BUF_LENGTH)
#define AUTO_GAIN -100
#define BUFFER_DUMP 4096
#define FREQUENCIES_LIMIT 1000
static pthread_t demod_thread;
static pthread_cond_t data_ready; /* shared buffer filled */
static pthread_rwlock_t data_rw; /* lock for shared buffer */
static pthread_mutex_t data_mutex; /* because conds are dumb */
static volatile int do_exit = 0;
static rtlsdr_dev_t *dev = NULL;
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 fm_state
{
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 exit_flag;
uint8_t buf[MAXIMUM_BUF_LENGTH];
uint32_t buf_len;
int signal[MAXIMUM_BUF_LENGTH]; /* 16 bit signed i/q pairs */
int16_t signal2[MAXIMUM_BUF_LENGTH]; /* signal has lowpass, signal2 has demod */
int signal_len;
int signal2_len;
FILE *file;
int edge;
uint32_t freqs[FREQUENCIES_LIMIT];
int freq_len;
int freq_now;
uint32_t sample_rate;
int output_rate;
int fir_enable;
int fir[256]; /* fir_len == downsample */
int fir_sum;
int custom_atan;
int deemph, deemph_a;
int now_lpr;
int prev_lpr_index;
int dc_block, dc_avg;
void (*mode_demod)(struct fm_state*);
};
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, 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, 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 fast -r 32k -l 0 -D)\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 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"
//"\t[-D enables DSB mode (default: off)]\n"
"\t[-R enables raw mode (default: off, 2x16 bit output)]\n"
"\t[-F enables Hamming FIR (default: off/square)]\n"
"\t[-D enables de-emphasis (default: off)]\n"
"\t[-C enables DC blocking of output (default: off)]\n"
"\t[-A std/fast/lut choose atan math (default: std)]\n"
//"\t[-C clip_path (default: off)\n"
//"\t (create time stamped raw clips, requires squelch)\n"
//"\t (path must have '\%s' and will expand to date_time_freq)\n"
//"\t[-H hop_fifo (default: off)\n"
//"\t (fifo will contain the active frequency)\n"
"\n"
"Produces signed 16 bit ints, use Sox or aplay to hear them.\n"
"\trtl_fm ... - | play -t raw -r 24k -es -b 16 -c 1 -V1 -\n"
"\t | aplay -r 24k -f S16_LE -t raw -c 1\n"
"\t -s 22.5k - | multimon -t raw /dev/stdin\n\n");
exit(1);
}
#ifdef _WIN32
BOOL WINAPI
sighandler(int signum)
{
if (CTRL_C_EVENT == signum) {
fprintf(stderr, "Signal caught, exiting!\n");
do_exit = 1;
//rtlsdr_cancel_async(dev);
return TRUE;
}
return FALSE;
}
#else
static void sighandler(int signum)
{
fprintf(stderr, "Signal caught, exiting!\n");
do_exit = 1;
//rtlsdr_cancel_async(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)
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 fm_state *fm, unsigned char *buf, uint32_t len)
/* simple square window FIR */
{
int i=0, i2=0;
while (i < (int)len) {
fm->now_r += ((int)buf[i] - 127);
fm->now_j += ((int)buf[i+1] - 127);
i += 2;
fm->prev_index++;
if (fm->prev_index < fm->downsample) {
continue;
}
fm->signal[i2] = fm->now_r; // * fm->output_scale;
fm->signal[i2+1] = fm->now_j; // * fm->output_scale;
fm->prev_index = 0;
fm->now_r = 0;
fm->now_j = 0;
i2 += 2;
}
fm->signal_len = i2;
}
void build_fir(struct fm_state *fm)
/* hamming */
/* point = sum(sample[i] * fir[i] * fir_len / fir_sum) */
{
double a, b, w, N1;
int i, len;
len = fm->downsample;
a = 25.0/46.0;
b = 21.0/46.0;
N1 = (double)(len-1);
for(i = 0; i < len; i++) {
w = a - b*cos(2*i*M_PI/N1);
fm->fir[i] = (int)(w * 255);
}
fm->fir_sum = 0;
for(i = 0; i < len; i++) {
fm->fir_sum += fm->fir[i];
}
}
void low_pass_fir(struct fm_state *fm, unsigned char *buf, uint32_t len)
/* perform an arbitrary FIR, doubles CPU use */
// possibly bugged, or overflowing
{
int i=0, i2=0, i3=0;
while (i < (int)len) {
i3 = fm->prev_index;
fm->now_r += ((int)buf[i] - 127) * fm->fir[i3];
fm->now_j += ((int)buf[i+1] - 127) * fm->fir[i3];
i += 2;
fm->prev_index++;
if (fm->prev_index < fm->downsample) {
continue;
}
fm->now_r *= fm->downsample;
fm->now_j *= fm->downsample;
fm->now_r /= fm->fir_sum;
fm->now_j /= fm->fir_sum;
fm->signal[i2] = fm->now_r; //* fm->output_scale;
fm->signal[i2+1] = fm->now_j; //* fm->output_scale;
fm->prev_index = 0;
fm->now_r = 0;
fm->now_j = 0;
i2 += 2;
}
fm->signal_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 fm_state *fm)
/* simple square window FIR */
// add support for upsampling?
{
int i=0, i2=0;
int fast = (int)fm->sample_rate / fm->post_downsample;
int slow = fm->output_rate;
while (i < fm->signal2_len) {
fm->now_lpr += fm->signal2[i];
i++;
fm->prev_lpr_index += slow;
if (fm->prev_lpr_index < fast) {
continue;
}
fm->signal2[i2] = (int16_t)(fm->now_lpr / (fast/slow));
fm->prev_lpr_index -= fast;
fm->now_lpr = 0;
i2 += 1;
}
fm->signal2_len = i2;
}
/* 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()
{
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 fm_state *fm)
{
int i, pcm;
pcm = polar_discriminant(fm->signal[0], fm->signal[1],
fm->pre_r, fm->pre_j);
fm->signal2[0] = (int16_t)pcm;
for (i = 2; i < (fm->signal_len); i += 2) {
switch (fm->custom_atan) {
case 0:
pcm = polar_discriminant(fm->signal[i], fm->signal[i+1],
fm->signal[i-2], fm->signal[i-1]);
break;
case 1:
pcm = polar_disc_fast(fm->signal[i], fm->signal[i+1],
fm->signal[i-2], fm->signal[i-1]);
break;
case 2:
pcm = polar_disc_lut(fm->signal[i], fm->signal[i+1],
fm->signal[i-2], fm->signal[i-1]);
break;
}
fm->signal2[i/2] = (int16_t)pcm;
}
fm->pre_r = fm->signal[fm->signal_len - 2];
fm->pre_j = fm->signal[fm->signal_len - 1];
fm->signal2_len = fm->signal_len/2;
}
void am_demod(struct fm_state *fm)
// todo, fix this extreme laziness
{
int i, pcm;
for (i = 0; i < (fm->signal_len); i += 2) {
// hypot uses floats but won't overflow
//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;
}
fm->signal2_len = fm->signal_len/2;
// lowpass? (3khz) highpass? (dc)
}
void usb_demod(struct fm_state *fm)
{
int i, pcm;
for (i = 0; i < (fm->signal_len); i += 2) {
pcm = fm->signal[i] + fm->signal[i+1];
fm->signal2[i/2] = (int16_t)pcm * fm->output_scale;
}
fm->signal2_len = fm->signal_len/2;
}
void lsb_demod(struct fm_state *fm)
{
int i, pcm;
for (i = 0; i < (fm->signal_len); i += 2) {
pcm = fm->signal[i] - fm->signal[i+1];
fm->signal2[i/2] = (int16_t)pcm * fm->output_scale;
}
fm->signal2_len = fm->signal_len/2;
}
void raw_demod(struct fm_state *fm)
{
/* hacky and pointless code */
int i;
for (i = 0; i < (fm->signal_len); i++) {
fm->signal2[i] = (int16_t)fm->signal[i];
}
fm->signal2_len = fm->signal_len;
}
void deemph_filter(struct fm_state *fm)
{
static int avg; // cheating...
int i, d;
// de-emph IIR
// avg = avg * (1 - alpha) + sample * alpha;
for (i = 0; i < fm->signal2_len; i++) {
d = fm->signal2[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->signal2[i] = (int16_t)avg;
}
}
void dc_block_filter(struct fm_state *fm)
{
int i, avg;
int64_t sum = 0;
for (i=0; i < fm->signal2_len; i++) {
sum += fm->signal2[i];
}
avg = sum / fm->signal2_len;
avg = (avg + fm->dc_avg * 9) / 10;
for (i=0; i < fm->signal2_len; i++) {
fm->signal2[i] -= avg;
}
fm->dc_avg = avg;
}
int mad(int *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 post_squelch(struct fm_state *fm)
/* returns 1 for active signal, 0 for no signal */
{
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;
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;
}
fm->squelch_hits++;
return 0;
}
static void optimal_settings(struct fm_state *fm, int freq, int hopping)
{
int r, capture_freq, capture_rate;
fm->downsample = (1000000 / fm->sample_rate) + 1;
fm->freq_now = freq;
capture_rate = fm->downsample * fm->sample_rate;
capture_freq = fm->freqs[freq] + capture_rate/4;
capture_freq += fm->edge * fm->sample_rate / 2;
fm->output_scale = (1<<15) / (128 * fm->downsample);
if (fm->output_scale < 1) {
fm->output_scale = 1;}
if (fm->mode_demod == &fm_demod) {
fm->output_scale = 1;}
/* Set the frequency */
r = rtlsdr_set_center_freq(dev, (uint32_t)capture_freq);
if (hopping) {
return;}
fprintf(stderr, "Oversampling input by: %ix.\n", fm->downsample);
fprintf(stderr, "Oversampling output by: %ix.\n", fm->post_downsample);
fprintf(stderr, "Buffer size: %0.2fms\n",
1000 * 0.5 * (float)ACTUAL_BUF_LENGTH / (float)capture_rate);
if (r < 0) {
fprintf(stderr, "WARNING: Failed to set center freq.\n");}
else {
fprintf(stderr, "Tuned to %u Hz.\n", capture_freq);}
/* Set the sample rate */
fprintf(stderr, "Sampling at %u Hz.\n", capture_rate);
if (fm->output_rate > 0) {
fprintf(stderr, "Output at %u Hz.\n", fm->output_rate);
} else {
fprintf(stderr, "Output at %u Hz.\n", fm->sample_rate/fm->post_downsample);}
r = rtlsdr_set_sample_rate(dev, (uint32_t)capture_rate);
if (r < 0) {
fprintf(stderr, "WARNING: Failed to set sample rate.\n");}
}
void full_demod(struct fm_state *fm)
{
uint8_t dump[BUFFER_DUMP];
int i, sr, freq_next, n_read, hop = 0;
pthread_rwlock_wrlock(&data_rw);
rotate_90(fm->buf, fm->buf_len);
if (fm->fir_enable) {
low_pass_fir(fm, fm->buf, fm->buf_len);
} else {
low_pass(fm, fm->buf, fm->buf_len);
}
pthread_rwlock_unlock(&data_rw);
fm->mode_demod(fm);
if (fm->mode_demod == &raw_demod) {
fwrite(fm->signal2, 2, fm->signal2_len, fm->file);
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) {
low_pass_real(fm);
}
if (fm->deemph) {
deemph_filter(fm);}
if (fm->dc_block) {
dc_block_filter(fm);}
/* ignore under runs for now */
fwrite(fm->signal2, 2, fm->signal2_len, fm->file);
if (hop) {
freq_next = (fm->freq_now + 1) % fm->freq_len;
optimal_settings(fm, freq_next, 1);
fm->squelch_hits = fm->conseq_squelch + 1; /* hair trigger */
/* wait for settling and flush buffer */
usleep(5000);
rtlsdr_read_sync(dev, &dump, BUFFER_DUMP, &n_read);
if (n_read != BUFFER_DUMP) {
fprintf(stderr, "Error: bad retune.\n");}
}
}
static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
{
struct fm_state *fm2 = ctx;
if (do_exit) {
return;}
if (!ctx) {
return;}
pthread_rwlock_wrlock(&data_rw);
memcpy(fm2->buf, buf, len);
fm2->buf_len = len;
pthread_rwlock_unlock(&data_rw);
safe_cond_signal(&data_ready, &data_mutex);
/* single threaded uses 25% less CPU? */
/* full_demod(fm2); */
}
static void sync_read(unsigned char *buf, uint32_t len, struct fm_state *fm)
{
int r, n_read;
r = rtlsdr_read_sync(dev, buf, len, &n_read);
if (r < 0) {
fprintf(stderr, "WARNING: sync read failed.\n");
return;
}
pthread_rwlock_wrlock(&data_rw);
memcpy(fm->buf, buf, len);
fm->buf_len = len;
pthread_rwlock_unlock(&data_rw);
safe_cond_signal(&data_ready, &data_mutex);
//full_demod(fm);
}
static void *demod_thread_fn(void *arg)
{
struct fm_state *fm2 = arg;
while (!do_exit) {
safe_cond_wait(&data_ready, &data_mutex);
full_demod(fm2);
if (fm2->exit_flag) {
do_exit = 1;
//rtlsdr_cancel_async(dev);
}
}
return 0;
}
double atofs(char *f)
/* standard suffixes */
{
char last;
int len;
double suff = 1.0;
len = strlen(f);
last = f[len-1];
f[len-1] = '\0';
switch (last) {
case 'g':
case 'G':
suff *= 1e3;
case 'm':
case 'M':
suff *= 1e3;
case 'k':
case 'K':
suff *= 1e3;
suff *= atof(f);
f[len-1] = last;
return suff;
}
f[len-1] = last;
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++;
if (fm->freq_len >= FREQUENCIES_LIMIT) {
break;}
}
stop[-1] = ':';
step[-1] = ':';
}
int nearest_gain(int target_gain)
{
int i, err1, err2, count, close_gain;
int* gains;
count = rtlsdr_get_tuner_gains(dev, NULL);
if (count <= 0) {
return 0;
}
gains = malloc(sizeof(int) * count);
count = rtlsdr_get_tuner_gains(dev, gains);
close_gain = gains[0];
for (i=0; i<count; i++) {
err1 = abs(target_gain - close_gain);
err2 = abs(target_gain - gains[i]);
if (err2 < err1) {
close_gain = gains[i];
}
}
free(gains);
return close_gain;
}
void fm_init(struct fm_state *fm)
{
fm->freqs[0] = 100000000;
fm->sample_rate = DEFAULT_SAMPLE_RATE;
fm->squelch_level = 0;
fm->conseq_squelch = 20;
fm->terminate_on_squelch = 0;
fm->squelch_hits = 0;
fm->freq_len = 0;
fm->edge = 0;
fm->fir_enable = 0;
fm->prev_index = 0;
fm->post_downsample = 1; // once this works, default = 4
fm->custom_atan = 0;
fm->deemph = 0;
fm->output_rate = -1; // flag for disabled
fm->mode_demod = &fm_demod;
fm->pre_j = fm->pre_r = fm->now_r = fm->now_j = 0;
fm->prev_lpr_index = 0;
fm->deemph_a = 0;
fm->now_lpr = 0;
fm->dc_block = 0;
fm->dc_avg = 0;
}
int main(int argc, char **argv)
{
#ifndef _WIN32
struct sigaction sigact;
#endif
struct fm_state fm;
char *filename = NULL;
int n_read, r, opt, wb_mode = 0;
int i, gain = AUTO_GAIN; // tenths of a dB
uint8_t *buffer;
uint32_t dev_index = 0;
int device_count;
int ppm_error = 0;
char vendor[256], product[256], serial[256];
fm_init(&fm);
pthread_cond_init(&data_ready, NULL);
pthread_rwlock_init(&data_rw, NULL);
pthread_mutex_init(&data_mutex, NULL);
while ((opt = getopt(argc, argv, "d:f:g:s:b:l:o:t:r:p:EFA:NWMULRDCh")) != -1) {
switch (opt) {
case 'd':
dev_index = atoi(optarg);
break;
case 'f':
if (fm.freq_len >= FREQUENCIES_LIMIT) {
break;}
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);
break;
case 'l':
fm.squelch_level = (int)atof(optarg);
break;
case 's':
fm.sample_rate = (uint32_t)atofs(optarg);
break;
case 'r':
fm.output_rate = (int)atofs(optarg);
break;
case 'o':
fm.post_downsample = (int)atof(optarg);
if (fm.post_downsample < 1 || fm.post_downsample > MAXIMUM_OVERSAMPLE) {
fprintf(stderr, "Oversample must be between 1 and %i\n", MAXIMUM_OVERSAMPLE);}
break;
case 't':
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;
case 'F':
fm.fir_enable = 1;
break;
case 'A':
if (strcmp("std", optarg) == 0) {
fm.custom_atan = 0;}
if (strcmp("fast", optarg) == 0) {
fm.custom_atan = 1;}
if (strcmp("lut", optarg) == 0) {
atan_lut_init();
fm.custom_atan = 2;}
break;
case 'D':
fm.deemph = 1;
break;
case 'C':
fm.dc_block = 1;
break;
case 'N':
fm.mode_demod = &fm_demod;
break;
case 'W':
wb_mode = 1;
fm.mode_demod = &fm_demod;
fm.sample_rate = 170000;
fm.output_rate = 32000;
fm.custom_atan = 1;
fm.post_downsample = 4;
fm.deemph = 1;
fm.squelch_level = 0;
break;
case 'M':
fm.mode_demod = &am_demod;
break;
case 'U':
fm.mode_demod = &usb_demod;
break;
case 'L':
fm.mode_demod = &lsb_demod;
break;
case 'R':
fm.mode_demod = &raw_demod;
break;
case 'h':
default:
usage();
break;
}
}
/* quadruple sample_rate to limit to Δθ to ±π/2 */
fm.sample_rate *= fm.post_downsample;
if (fm.freq_len == 0) {
fprintf(stderr, "Please specify a frequency.\n");
exit(1);
}
if (fm.freq_len >= FREQUENCIES_LIMIT) {
fprintf(stderr, "Too many channels, maximum %i.\n", FREQUENCIES_LIMIT);
exit(1);
}
if (fm.freq_len > 1 && fm.squelch_level == 0) {
fprintf(stderr, "Please specify a squelch level. Required for scanning multiple frequencies.\n");
exit(1);
}
if (fm.freq_len > 1) {
fm.terminate_on_squelch = 0;
}
if (argc <= optind) {
filename = "-";
} else {
filename = argv[optind];
}
ACTUAL_BUF_LENGTH = lcm_post[fm.post_downsample] * DEFAULT_BUF_LENGTH;
buffer = malloc(ACTUAL_BUF_LENGTH * sizeof(uint8_t));
device_count = rtlsdr_get_device_count();
if (!device_count) {
fprintf(stderr, "No supported devices found.\n");
exit(1);
}
fprintf(stderr, "Found %d device(s):\n", device_count);
for (i = 0; i < device_count; i++) {
rtlsdr_get_device_usb_strings(i, vendor, product, serial);
fprintf(stderr, " %d: %s, %s, SN: %s\n", i, vendor, product, serial);
}
fprintf(stderr, "\n");
fprintf(stderr, "Using device %d: %s\n",
dev_index, rtlsdr_get_device_name(dev_index));
r = rtlsdr_open(&dev, dev_index);
if (r < 0) {
fprintf(stderr, "Failed to open rtlsdr device #%d.\n", dev_index);
exit(1);
}
#ifndef _WIN32
sigact.sa_handler = sighandler;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = 0;
sigaction(SIGINT, &sigact, NULL);
sigaction(SIGTERM, &sigact, NULL);
sigaction(SIGQUIT, &sigact, NULL);
sigaction(SIGPIPE, &sigact, NULL);
#else
SetConsoleCtrlHandler( (PHANDLER_ROUTINE) sighandler, TRUE );
#endif
/* WBFM is special */
// I really should loop over everything
// but you are more wrong for scanning broadcast FM
if (wb_mode) {
fm.freqs[0] += 16000;
}
if (fm.deemph) {
fm.deemph_a = (int)round(1.0/((1.0-exp(-1.0/(fm.output_rate * 75e-6)))));
}
optimal_settings(&fm, 0, 0);
build_fir(&fm);
/* Set the tuner gain */
if (gain == AUTO_GAIN) {
r = rtlsdr_set_tuner_gain_mode(dev, 0);
} else {
r = rtlsdr_set_tuner_gain_mode(dev, 1);
gain = nearest_gain(gain);
r = rtlsdr_set_tuner_gain(dev, gain);
}
if (r != 0) {
fprintf(stderr, "WARNING: Failed to set tuner gain.\n");
} else if (gain == AUTO_GAIN) {
fprintf(stderr, "Tuner gain set to automatic.\n");
} else {
fprintf(stderr, "Tuner gain set to %0.2f dB.\n", gain/10.0);
}
r = rtlsdr_set_freq_correction(dev, ppm_error);
if (strcmp(filename, "-") == 0) { /* Write samples to stdout */
fm.file = stdout;
#ifdef _WIN32
_setmode(_fileno(fm.file), _O_BINARY);
#endif
} else {
fm.file = fopen(filename, "wb");
if (!fm.file) {
fprintf(stderr, "Failed to open %s\n", filename);
exit(1);
}
}
/* Reset endpoint before we start reading from it (mandatory) */
r = rtlsdr_reset_buffer(dev);
if (r < 0) {
fprintf(stderr, "WARNING: Failed to reset buffers.\n");}
pthread_create(&demod_thread, NULL, demod_thread_fn, (void *)(&fm));
/*rtlsdr_read_async(dev, rtlsdr_callback, (void *)(&fm),
DEFAULT_ASYNC_BUF_NUMBER,
ACTUAL_BUF_LENGTH);*/
while (!do_exit) {
sync_read(buffer, ACTUAL_BUF_LENGTH, &fm);
}
if (do_exit) {
fprintf(stderr, "\nUser cancel, exiting...\n");}
else {
fprintf(stderr, "\nLibrary error %d, exiting...\n", r);}
//rtlsdr_cancel_async(dev);
safe_cond_signal(&data_ready, &data_mutex);
pthread_join(demod_thread, NULL);
pthread_cond_destroy(&data_ready);
pthread_rwlock_destroy(&data_rw);
pthread_mutex_destroy(&data_mutex);
if (fm.file != stdout) {
fclose(fm.file);}
rtlsdr_close(dev);
free (buffer);
return r >= 0 ? r : -r;
}
// vim: tabstop=8:softtabstop=8:shiftwidth=8:noexpandtab
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