forked from pinkavaj/rtl-sdr
/
rtl_fm.c
1428 lines (1307 loc) · 35.1 KB
/
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
*
* lots of locks, but that is okay
* (no many-to-many locks)
*
* todo:
* sanity checks
* scale squelch to other input parameters
* pad output on hop
* frequency ranges could be stored better
* auto-hop after time limit
* peak detector to tune onto stronger signals
* fifo for active hop frequency
* clips
* noise squelch
* merge stereo 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>
#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)
#ifdef _MSC_VER
#define round(x) (x > 0.0 ? floor(x + 0.5): ceil(x - 0.5))
#endif
#define _USE_MATH_DEFINES
#endif
#include <math.h>
#include <pthread.h>
#include <libusb.h>
#include "rtl-sdr.h"
#include "convenience/convenience.h"
#define DEFAULT_SAMPLE_RATE 24000
#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 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 agc_state
{
int64_t gain_num;
int64_t gain_den;
int64_t gain_max;
int gain_int;
int peak_target;
int attack_step;
int decay_step;
};
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;
int agc_enable;
struct agc_state *agc;
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;
FILE *file;
char *filename;
int16_t result[MAXIMUM_BUF_LENGTH];
int result_len;
int rate;
int wav_format;
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;
};
// multiple of these, eventually
struct dongle_state dongle;
struct demod_state demod;
struct output_state output;
struct controller_state controller;
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[-M modulation (default: fm)]\n"
"\t fm, wbfm, raw, am, usb, lsb\n"
"\t wbfm == -M fm -s 170k -o 4 -A fast -r 32k -l 0 -E deemp\n"
"\t raw mode outputs 2x16 bit IQ pairs\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 for fm squelch is inverted\n"
//"\t[-o oversampling (default: 1, 4 recommended)]\n"
"\t[-p ppm_error (default: 0)]\n"
"\t[-E enable_option (default: none)]\n"
"\t use multiple -E to enable multiple options\n"
"\t edge: enable lower edge tuning\n"
"\t dc: enable dc blocking filter\n"
"\t deemp: enable de-emphasis filter\n"
"\t swagc: enable software agc (only for AM)\n"
"\t direct: enable direct sampling\n"
"\t no-mod: enable no-mod direct sampling\n"
"\t offset: enable offset tuning\n"
"\t wav: generate WAV header\n"
"\tfilename ('-' means stdout)\n"
"\t omitting the filename also uses stdout\n\n"
"Experimental options:\n"
"\t[-r resample_rate (default: none / same as -s)]\n"
"\t[-t squelch_delay (default: 10)]\n"
"\t +values will mute/scan, -values will exit\n"
"\t[-F fir_size (default: off)]\n"
"\t enables low-leakage downsample filter\n"
"\t size can be 0 or 9. 0 has bad roll off\n"
"\t[-A std/fast/lut/ale 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 -M wbfm | play -r 32k ... \n"
"\t -E wav | play -t wav - \n"
"\t -s 22050 | 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(dongle.dev);
return TRUE;
}
return FALSE;
}
#else
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},
};
#ifdef _MSC_VER
double log2(double n)
{
return log(n) / log(2.0);
}
#endif
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;
}
int esbensen(int ar, int aj, int br, int bj)
/*
input signal: s(t) = a*exp(-i*w*t+p)
a = amplitude, w = angular freq, p = phase difference
solve w
s' = -i(w)*a*exp(-i*w*t+p)
s'*conj(s) = -i*w*a*a
s'*conj(s) / |s|^2 = -i*w
*/
{
int cj, dr, dj;
int scaled_pi = 2608; /* 1<<14 / (2*pi) */
dr = (br - ar) * 2;
dj = (bj - aj) * 2;
cj = bj*dr - br*dj; /* imag(ds*conj(s)) */
return (scaled_pi * cj / (ar*ar+aj*aj+1));
}
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;
case 3:
pcm = esbensen(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);
}
int squelch_to_rms(int db, struct dongle_state *dongle, struct demod_state *demod)
/* 0 dB = 1 rms at 50dB gain and 1024 downsample */
{
double linear, gain, downsample;
if (db == 0) {
return 0;}
linear = pow(10.0, (double)db/20.0);
gain = 50.0;
if (dongle->gain != AUTO_GAIN) {
gain = (double)(dongle->gain) / 10.0;
}
gain = 50.0 - gain;
gain = pow(10.0, gain/20.0);
downsample = 1024.0 / (double)demod->downsample;
linear = linear / gain;
linear = linear / downsample;
return (int)linear + 1;
}
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 software_agc(struct demod_state *d)
/* ignores complex pairs, indirectly calculates power squelching */
{
int i = 0;
int output;
struct agc_state *agc = d->agc;
for (i=0; i < d->result_len; i++) {
output = (int)((int64_t)d->result[i] * agc->gain_num / agc->gain_den);
if (abs(output) < agc->peak_target) {
agc->gain_num += agc->decay_step;
} else {
agc->gain_num -= agc->attack_step;
}
if (agc->gain_num < agc->gain_den) {
agc->gain_num = agc->gain_den;}
if (agc->gain_num > agc->gain_max) {
agc->gain_num = agc->gain_max;}
agc->gain_int = (int)(agc->gain_num / agc->gain_den);
d->result[i] = output;
}
}
void full_demod(struct demod_state *d)
{
int i, ds_p;
int do_squelch = 0;
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);
}
if (d->agc_enable) {
software_agc(d);
if(d->squelch_level && d->agc->gain_int > d->squelch_level) {
do_squelch = 1;}
/* power squelch */
} else if (d->squelch_level) {
sr = rms(d->lowpassed, d->lp_len, 1);
if (sr < d->squelch_level) {
do_squelch = 1;}
}
if (do_squelch) {
d->squelch_hits++;
for (i=0; i<d->lp_len; i++) {
d->lowpassed[i] = 0;
}
} else {
d->squelch_hits = 0;
}
if (d->squelch_level && d->squelch_hits > d->conseq_squelch) {
d->agc->gain_num = d->agc->gain_den;
}
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;
rtlsdr_read_async(s->dev, rtlsdr_callback, s, 0, s->buf_len);
return 0;
}
static void *demod_thread_fn(void *arg)
{
struct demod_state *d = arg;
struct output_state *o = d->output_target;
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 && d->squelch_hits > d->conseq_squelch) {
d->squelch_hits = d->conseq_squelch + 1; /* hair trigger */
safe_cond_signal(&controller.hop, &controller.hop_m);
continue;
}
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);
}
return 0;
}
static void *output_thread_fn(void *arg)
{
struct output_state *s = arg;
while (!do_exit) {
// use timedwait and pad out under runs
safe_cond_wait(&s->ready, &s->ready_m);
pthread_rwlock_rdlock(&s->rw);
fwrite(s->result, 2, s->result_len, s->file);
pthread_rwlock_unlock(&s->rw);
}
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;
}
static void *controller_thread_fn(void *arg)
{
// thoughts for multiple dongles
// might be no good using a controller thread if retune/rate blocks
int i;
struct controller_state *s = arg;
if (s->wb_mode) {
for (i=0; i < s->freq_len; i++) {
s->freqs[i] += 16000;}
}
/* set up primary channel */
optimal_settings(s->freqs[0], demod.rate_in);
demod.squelch_level = squelch_to_rms(demod.squelch_level, &dongle, &demod);
if (dongle.direct_sampling) {
verbose_direct_sampling(dongle.dev, dongle.direct_sampling);}
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);