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rtl_fm_streamer.c
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rtl_fm_streamer.c
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/*
* rtl_fm_streamer, turns your Realtek RTL2832 based DVB dongle into a SDR receiver
* Based on "rtl_fm", see http://sdr.osmocom.org/trac/wiki/rtl-sdr for details
*
* Copyright (C) 2012 by Steve Markgraf <[email protected]>
* Copyright (C) 2012 by Hoernchen <[email protected]>
* Copyright (C) 2012 by Kyle Keen <[email protected]>
* Copyright (C) 2013 by Elias Oenal <[email protected]>
* Copyright (C) 2015 by Miroslav Slugen <[email protected]>
* Copyright (C) 2015 by Albrecht Lohoefener <[email protected]>
*
* 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_fm.c, 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 into stronger signals
* fifo for active hop frequency
* clips
* noise squelch
* merge soft agc 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>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#else
#include <windows.h>
#include <fcntl.h>
#include <io.h>
#include "getopt/getopt.h"
#define msleep(x) Sleep(x)
#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"
#include "jsonrpc-c/jsonrpc-c.h"
#define VERSION "0.0.6"
#define DEFAULT_SAMPLE_RATE 240000
#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
#define PI2_F 6.28318531f
#define PI_F 3.14159265f
#define PI_2_F 1.5707963f
#define PI_4_F 0.78539816f
#define DEEMPHASIS_NONE 0
#define DEEMPHASIS_FM_EU 0.000050
#define DEEMPHASIS_FM_USA 0.000075
typedef enum
{
false = 0,
true
}bool;
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;
/* 8 MB */
static char input_buffer[16 * MAXIMUM_BUF_LENGTH];
static char output_buffer[16 * MAXIMUM_BUF_LENGTH];
uint32_t input_buffer_rpos = 0,
input_buffer_wpos = 0,
input_buffer_size = 0,
input_buffer_size_max = 16 * MAXIMUM_BUF_LENGTH;
uint32_t output_buffer_rpos = 0,
output_buffer_wpos = 0,
output_buffer_size = 0,
output_buffer_size_max = 16 * MAXIMUM_BUF_LENGTH;
static int ConnectionDesc;
bool isStartStream;
bool isReading;
struct lp_real
{
float *br;
float *bm;
float *bs;
float *fm;
float *fp;
float *fs;
float swf;
float cwf;
float pp;
int pos;
int size;
int rsize;
int mode;
};
struct dongle_state
{
int exit_flag;
pthread_t thread;
rtlsdr_dev_t *dev;
int dev_index;
uint32_t freq;
uint32_t rate;
int gain;
int ppm_error;
int direct_sampling;
int mute;
struct demod_state *demod_target;
};
struct demod_state
{
int exit_flag;
pthread_t thread;
uint8_t buf[MAXIMUM_BUF_LENGTH];
uint32_t buf_len;
/* required 4 bytes for F32 part */
int16_t lowpassed[MAXIMUM_BUF_LENGTH << 1];
int lp_len;
/* tmp buffer for low pass filter F32 */
float lowpass_tb[48];
int16_t lp_i_hist[10][6];
int16_t lp_q_hist[10][6];
/* result buffer fo FM will be always 1/2 of lowpassed or less, so no need to shift */
int16_t result[MAXIMUM_BUF_LENGTH];
int result_len;
int16_t droop_i_hist[9];
int16_t droop_q_hist[9];
int offset_tuning;
int rate_in;
int rate_out;
int rate_out2;
int now_r, now_j;
int pre_r, pre_j;
float pre_r_f32, pre_j_f32;
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;
double deemph;
int deemph_a;
int deemph_l;
int deemph_r;
float deemph_l_f32;
float deemph_r_f32;
float deemph_lambda;
float volume;
int now_lpr;
int prev_lpr_index;
struct lp_real lpr;
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;
int rate;
int16_t *result;
int result_len;
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;
};
typedef struct
{
// Two socket descriptors which are just integer numbers used to access a socket
int SocketDesc;
// Two socket address structures - One for the server itself and the other for client
struct sockaddr_in serv_addr, client_addr;
socklen_t size;
pthread_t ConnectionThread;
} connection_state;
typedef struct
{
// Socket which is JSON-RPC is listening
int Port;
struct jrpc_server Server;
float RMSShadowBuf[MAXIMUM_BUF_LENGTH << 1];
int RMSShadowBuf_len;
pthread_t thread;
} json_rpc_state;
// multiple of these, eventually
struct dongle_state dongle;
struct demod_state demod;
struct output_state output;
struct controller_state controller;
connection_state connection;
json_rpc_state json_rpc;
void usage(void)
{
fprintf(
stderr, "rtl_fm_streamer, a simple narrow band FM demodulator for RTL2832 based DVB-T receivers\n\n"
"Use:\trtl_fm_streamer -f freq [-options] [filename]\n"
"\t[-M modulation (default: wbfm)]\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[-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 direct: enable direct sampling\n"
"\t offset: enable offset tuning\n"
"\t[-P Listen IP port]\n"
"\tfilename ('-' means stdout)\n"
"\t omitting the filename also uses stdout\n\n"
"Experimental options:\n"
"\t[-r resample_rate (default: 48000)]\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 choose atan math (default: std)]\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 }, };
/* table for u8 -> f32 conversion, 0 = positive, 1 = negative */
static float u8_f32_table[2][256] =
{
{ 0 },
{ 0 } };
/* table with low pass filter coeficients */
static float lp_filter_f32[16] =
{ 0 };
#ifdef _MSC_VER
double log2(double n)
{
return log(n) / log(2.0);
}
#endif
void init_u8_f32_table()
{
int i;
for (i = 0; i < 256; i++)
{
u8_f32_table[0][i] = ((float) i - 127.5f) / 128.0f;
u8_f32_table[1][i] = ((float) i - 127.5f) / -128.0f;
}
}
void rotate_90_u8_f32(struct demod_state *d)
/* 90 rotation is 1+0j, 0+1j, -1+0j, 0-1j
or [0, 1, -3, 2, -4, -5, 7, -6] */
{
float *ob = (float*) d->lowpassed;
uint32_t i;
for (i = 0; i < d->buf_len; i += 8)
{
ob[i] = u8_f32_table[0][d->buf[i]];
ob[i + 1] = u8_f32_table[0][d->buf[i + 1]];
ob[i + 2] = u8_f32_table[1][d->buf[i + 3]];
ob[i + 3] = u8_f32_table[0][d->buf[i + 2]];
ob[i + 4] = u8_f32_table[1][d->buf[i + 4]];
ob[i + 5] = u8_f32_table[1][d->buf[i + 5]];
ob[i + 6] = u8_f32_table[0][d->buf[i + 7]];
ob[i + 7] = u8_f32_table[1][d->buf[i + 6]];
}
d->lp_len = d->buf_len;
}
void u8_f32(struct demod_state *d)
{
float *ob = (float*) d->lowpassed;
uint32_t i;
for (i = 0; i < d->buf_len; i++)
{
ob[i] = u8_f32_table[0][d->buf[i]];
}
d->lp_len = d->buf_len;
}
void init_lp_f32()
{
int i;
float j;
for (i = 0; i < 16; i++)
{
j = (float) i - 15.5f;
lp_filter_f32[i] = (sinf(0.125f * PI_F * j) / (PI_F * j)) * (0.54f - 0.46f * cosf(PI_F * (float) i / 15.5f));
}
}
void lp_f32(struct demod_state *d)
{
int i, j;
float xb[6] =
{ 0 }, *ob = (float*) d->lowpassed, *tb = d->lowpass_tb, *fb = lp_filter_f32;
/* first three reads needs data from tmp buffer */
/* I - 0 */
xb[0] = (tb[ 0] + ob[14]) * fb[0] +
(tb[ 2] + ob[12]) * fb[1] +
(tb[ 4] + ob[10]) * fb[2] +
(tb[ 6] + ob[ 8]) * fb[3] +
(tb[ 8] + ob[ 6]) * fb[4] +
(tb[10] + ob[ 4]) * fb[5] +
(tb[12] + ob[ 2]) * fb[6] +
(tb[14] + ob[ 0]) * fb[7] +
(tb[16] + tb[46]) * fb[8] +
(tb[18] + tb[44]) * fb[9] +
(tb[20] + tb[42]) * fb[10] +
(tb[22] + tb[40]) * fb[11] +
(tb[24] + tb[38]) * fb[12] +
(tb[26] + tb[36]) * fb[13] +
(tb[28] + tb[34]) * fb[14] +
(tb[30] + tb[32]) * fb[15];
/* Q - 0 */
xb[1] = (tb[ 1] + ob[15]) * fb[0] +
(tb[ 3] + ob[13]) * fb[1] +
(tb[ 5] + ob[11]) * fb[2] +
(tb[ 7] + ob[ 9]) * fb[3] +
(tb[ 9] + ob[ 7]) * fb[4] +
(tb[11] + ob[ 5]) * fb[5] +
(tb[13] + ob[ 3]) * fb[6] +
(tb[15] + ob[ 1]) * fb[7] +
(tb[17] + tb[47]) * fb[8] +
(tb[19] + tb[45]) * fb[9] +
(tb[21] + tb[43]) * fb[10] +
(tb[23] + tb[41]) * fb[11] +
(tb[25] + tb[39]) * fb[12] +
(tb[27] + tb[37]) * fb[13] +
(tb[29] + tb[35]) * fb[14] +
(tb[31] + tb[33]) * fb[15];
/* I - 1 */
xb[2] = (tb[16] + ob[30]) * fb[0] +
(tb[18] + ob[28]) * fb[1] +
(tb[20] + ob[26]) * fb[2] +
(tb[22] + ob[24]) * fb[3] +
(tb[24] + ob[22]) * fb[4] +
(tb[26] + ob[20]) * fb[5] +
(tb[28] + ob[18]) * fb[6] +
(tb[30] + ob[16]) * fb[7] +
(tb[32] + ob[14]) * fb[8] +
(tb[34] + ob[12]) * fb[9] +
(tb[36] + ob[10]) * fb[10] +
(tb[38] + ob[ 8]) * fb[11] +
(tb[40] + ob[ 6]) * fb[12] +
(tb[42] + ob[ 4]) * fb[13] +
(tb[44] + ob[ 2]) * fb[14] +
(tb[46] + ob[ 0]) * fb[15];
/* Q - 1 */
xb[3] = (tb[17] + ob[31]) * fb[0] +
(tb[19] + ob[29]) * fb[1] +
(tb[21] + ob[27]) * fb[2] +
(tb[23] + ob[25]) * fb[3] +
(tb[25] + ob[23]) * fb[4] +
(tb[27] + ob[21]) * fb[5] +
(tb[29] + ob[19]) * fb[6] +
(tb[31] + ob[17]) * fb[7] +
(tb[33] + ob[15]) * fb[8] +
(tb[35] + ob[13]) * fb[9] +
(tb[37] + ob[11]) * fb[10] +
(tb[39] + ob[ 9]) * fb[11] +
(tb[41] + ob[ 7]) * fb[12] +
(tb[43] + ob[ 5]) * fb[13] +
(tb[45] + ob[ 3]) * fb[14] +
(tb[47] + ob[ 1]) * fb[15];
/* I - 2 */
xb[4] = (tb[32] + ob[46]) * fb[0] +
(tb[34] + ob[44]) * fb[1] +
(tb[36] + ob[42]) * fb[2] +
(tb[38] + ob[40]) * fb[3] +
(tb[40] + ob[38]) * fb[4] +
(tb[42] + ob[36]) * fb[5] +
(tb[44] + ob[34]) * fb[6] +
(tb[46] + ob[32]) * fb[7] +
(ob[ 0] + ob[30]) * fb[8] +
(ob[ 2] + ob[28]) * fb[9] +
(ob[ 4] + ob[26]) * fb[10] +
(ob[ 6] + ob[24]) * fb[11] +
(ob[ 8] + ob[22]) * fb[12] +
(ob[10] + ob[20]) * fb[13] +
(ob[12] + ob[18]) * fb[14] +
(ob[14] + ob[16]) * fb[15];
/* Q - 2 */
xb[5] = (tb[33] + ob[47]) * fb[0] +
(tb[35] + ob[45]) * fb[1] +
(tb[37] + ob[43]) * fb[2] +
(tb[39] + ob[41]) * fb[3] +
(tb[41] + ob[39]) * fb[4] +
(tb[43] + ob[37]) * fb[5] +
(tb[45] + ob[35]) * fb[6] +
(tb[47] + ob[33]) * fb[7] +
(ob[ 1] + ob[31]) * fb[8] +
(ob[ 3] + ob[29]) * fb[9] +
(ob[ 5] + ob[27]) * fb[10] +
(ob[ 7] + ob[25]) * fb[11] +
(ob[ 9] + ob[23]) * fb[12] +
(ob[11] + ob[21]) * fb[13] +
(ob[13] + ob[19]) * fb[14] +
(ob[15] + ob[17]) * fb[15];
/* store last 24 IQ values for next read */
memcpy(tb, &(ob[d->lp_len - 48]), 192);
/* next reads are direct */
for (i = 0, j = 6; j < d->lp_len >> 3; i+= 16, j+= 2) {
/* I */
ob[j] = (ob[i ] + ob[i + 62]) * fb[0] +
(ob[i + 2] + ob[i + 60]) * fb[1] +
(ob[i + 4] + ob[i + 58]) * fb[2] +
(ob[i + 6] + ob[i + 56]) * fb[3] +
(ob[i + 8] + ob[i + 54]) * fb[4] +
(ob[i + 10] + ob[i + 52]) * fb[5] +
(ob[i + 12] + ob[i + 50]) * fb[6] +
(ob[i + 14] + ob[i + 48]) * fb[7] +
(ob[i + 16] + ob[i + 46]) * fb[8] +
(ob[i + 18] + ob[i + 44]) * fb[9] +
(ob[i + 20] + ob[i + 42]) * fb[10] +
(ob[i + 22] + ob[i + 40]) * fb[11] +
(ob[i + 24] + ob[i + 38]) * fb[12] +
(ob[i + 26] + ob[i + 36]) * fb[13] +
(ob[i + 28] + ob[i + 34]) * fb[14] +
(ob[i + 30] + ob[i + 32]) * fb[15];
/* Q */
ob[j + 1] = (ob[i + 1] + ob[i + 63]) * fb[0] +
(ob[i + 3] + ob[i + 61]) * fb[1] +
(ob[i + 5] + ob[i + 59]) * fb[2] +
(ob[i + 7] + ob[i + 57]) * fb[3] +
(ob[i + 9] + ob[i + 55]) * fb[4] +
(ob[i + 11] + ob[i + 53]) * fb[5] +
(ob[i + 13] + ob[i + 51]) * fb[6] +
(ob[i + 15] + ob[i + 49]) * fb[7] +
(ob[i + 17] + ob[i + 47]) * fb[8] +
(ob[i + 19] + ob[i + 45]) * fb[9] +
(ob[i + 21] + ob[i + 43]) * fb[10] +
(ob[i + 23] + ob[i + 41]) * fb[11] +
(ob[i + 25] + ob[i + 39]) * fb[12] +
(ob[i + 27] + ob[i + 37]) * fb[13] +
(ob[i + 29] + ob[i + 35]) * fb[14] +
(ob[i + 31] + ob[i + 33]) * fb[15];
}
/* copy data back to output buffer after encoding */
memcpy(ob, xb, 24);
/* output has always fixed size */
d->lp_len >>= 3;
}
void init_lp_real_f32(struct demod_state *fm)
{
int i;
float fmh, fpl, fph, fsl, fsh, fv, fi, fh, wf;
fprintf(stderr, "Init FIR hamming, size: %d sample_rate: %d\n", fm->lpr.size, fm->rate_in);
fm->lpr.rsize = (fm->lpr.size >> 1);
wf = PI2_F * 19000.0f / (float) fm->rate_in;
fm->lpr.swf = sinf(wf);
fm->lpr.cwf = cosf(wf);
fm->lpr.pp = 0;
fmh = 16000.0f / (float) fm->rate_in;
fpl = 18000.0f / (float) fm->rate_in;
fph = 20000.0f / (float) fm->rate_in;
fsl = 21000.0f / (float) fm->rate_in;
fsh = 55000.0f / (float) fm->rate_in;
fm->lpr.br = calloc(fm->lpr.size, 4);
fm->lpr.bm = calloc(fm->lpr.size, 4);
fm->lpr.bs = calloc(fm->lpr.size, 4);
/* filters are symetrical, so only half size */
fm->lpr.fm = calloc(fm->lpr.size >> 1, 4);
fm->lpr.fp = calloc(fm->lpr.size >> 1, 4);
fm->lpr.fs = calloc(fm->lpr.size >> 1, 4);
fm->lpr.pos = 0;
for (i = 0; i < fm->lpr.rsize; i++)
{
fi = (float) i - (float) (fm->lpr.size - 1) / 2.0f;
/* hamming window */
fh = 0.54f - 0.46f * cosf(PI2_F * (float) i / (float) (fm->lpr.size - 1));
/* low pass */
fv = (fi == 0) ? 2.0f * fmh : sinf(PI2_F * fmh * fi) / (PI_F * fi);
fm->lpr.fm[i] = fv * fh;
/* pilot band pass */
fv = (fi == 0) ? 2.0f * (fph - fpl) : (sinf(PI2_F * fph * fi) - sinf(PI2_F * fpl * fi)) / (PI_F * fi);
fm->lpr.fp[i] = fv * fh;
/* stereo band pass */
fv = (fi == 0) ? 2.0f * (fsh - fsl) : (sinf(PI2_F * fsh * fi) - sinf(PI2_F * fsl * fi)) / (PI_F * fi);
fm->lpr.fs[i] = fv * fh;
}
}
void deinit_lp_real_f32(struct demod_state *fm)
{
fm->lpr.rsize = 0;
free(fm->lpr.br);
free(fm->lpr.bm);
free(fm->lpr.bs);
free(fm->lpr.fm);
free(fm->lpr.fp);
free(fm->lpr.fs);
fm->lpr.br = NULL;
fm->lpr.bm = NULL;
fm->lpr.bs = NULL;
fm->lpr.fm = NULL;
fm->lpr.fp = NULL;
fm->lpr.fs = NULL;
}
float sin2atan2_f32(float x, float y)
{
float z;
if (x == 0.f) return 0.f;
z = y / x;
return (z + z) / (1.f + (z * z));
}
void lp_real_f32(struct demod_state *fm)
{
int i, j, k, l, o = 0, fast = (int) fm->rate_out, slow = (int) fm->rate_out2;
float v, vm, vp, vs, *ib = (float*) fm->result;
switch (fm->lpr.mode)
{
case 0:
for (i = 0; i < fm->result_len; i++)
{
if ((fm->prev_lpr_index += slow) >= fast)
{
fm->prev_lpr_index -= fast;
ib[o++] = ib[i];
}
}
break;
case 1: // Mono
for (i = 0; i < fm->result_len; i++)
{
fm->lpr.br[fm->lpr.pos] = ib[i];
if (++fm->lpr.pos == fm->lpr.size) fm->lpr.pos = 0;
if ((fm->prev_lpr_index += slow) >= fast)
{
fm->prev_lpr_index -= fast;
for (j = fm->lpr.pos, k = 0, l = fm->lpr.pos, vm = 0; k < fm->lpr.rsize; k++)
{
/* next value before storing, easiest way to get complementary index */
if (l == 0)
{
l = fm->lpr.size - 1;
}
else
{
l--;
}
vm += (fm->lpr.br[j] + fm->lpr.br[l]) * fm->lpr.fm[k];
/* next value after storing */
if (++j == fm->lpr.size) j = 0;
}
ib[o++] = vm;
}
}
break;
case 2: // Stereo
for (i = 0; i < fm->result_len; i++)
{
fm->lpr.br[fm->lpr.pos] = ib[i];
for (j = fm->lpr.pos, k = 0, l = fm->lpr.pos, vm = 0, vp = 0, vs = 0; k < fm->lpr.rsize; k++)
{
/* next value after storing */
if (++j == fm->lpr.size) j = 0;
v = fm->lpr.br[j] + fm->lpr.br[l];
vm += v * fm->lpr.fm[k]; // L+R low pass (0 Hz ... 17 kHz)
vp += v * fm->lpr.fp[k]; // Pilot frequency band pass (18 kHz ... 20 kHz) --> filters out the 19 kHz
vs += v * fm->lpr.fs[k]; // L-R band pass (21 kHz ... 55 kHz)
/* next value before storing, easiest way to get complementary index */
if (l == 0)
{
l = fm->lpr.size - 1;
}
else
{
l--;
}
}
fm->lpr.bm[fm->lpr.pos] = vm;
// AM L-R demodulation
// sin2atan2f(...) doubles the pilot frequency 19 kHz --> 38 kHz
// vs * sin2atan2_f32(...) AM demodulation
fm->lpr.bs[fm->lpr.pos] = vs * sin2atan2_f32(vp * fm->lpr.swf, vp * fm->lpr.cwf - fm->lpr.pp);
fm->lpr.pp = vp;
if (++fm->lpr.pos == fm->lpr.size) fm->lpr.pos = 0;
if ((fm->prev_lpr_index += slow) >= fast)
{
fm->prev_lpr_index -= fast;
for (j = fm->lpr.pos, k = 0, l = fm->lpr.pos, vm = 0, vs = 0; k < fm->lpr.rsize; k++)
{
/* next value before storing, easiest way to get complementary index */
if (l == 0)
{
l = fm->lpr.size - 1;
}
else
{
l--;
}
vm += (fm->lpr.bm[j] + fm->lpr.bm[l]) * fm->lpr.fm[k]; // low pass (0 Hz ... 17 kHz)
vs += (fm->lpr.bs[j] + fm->lpr.bs[l]) * fm->lpr.fm[k]; // low pass (0 Hz ... 17 kHz), removes unwanted AM demodulation high frequencies
/* next value after storing */
if (++j == fm->lpr.size) j = 0;
}
/* we can overwrite input, but not for downsample input buffer 16384 */
// Calculate stereo signal
ib[o] = vm + vs;
ib[o + 1] = vm - vs;
o += 2;
}
}
break;
}
fm->result_len = o;
}
/* absolute error < 0.0015, computation error: 0.012%, mono: 0.010, stereo: 0.007% */
static float atan2_lagrange_f32(float y, float x)
{
float z;
if (x == 0.f)
{
if (y < 0.f) return -PI_2_F;
if (y > 0.f) return PI_2_F;
return 0.f;
}
if (y == 0.f) return (x < 0.f) ? PI_F : 0.f;
/* Q3 + Q2 */
if (x < 0.f)
{
/* Q3 + */
if (y < 0.f)
{
/* abs(x) >= abs(y) */
if (x <= y)
{
z = y / x;
return z * (PI_4_F - (z - 1.f) * (0.2447f + 0.0663f * z)) - PI_F;
}
/* abs(x) < abs(y) */
z = x / y;
return z * (-PI_4_F + (z - 1.f) * (0.2447f + 0.0663f * z)) - PI_2_F;
}
/* Q2 - */
if (-x >= y)
{
z = y / x;
return z * (PI_4_F + (z + 1.f) * (0.2447f - 0.0663f * z)) + PI_F;
}
z = x / y;
return PI_2_F - z * (PI_4_F + (z + 1.f) * (0.2447f - 0.0663f * z));
}
/* Q4 - */
if (y < 0.f)
{
if (x >= -y)
{
z = y / x;
return z * (PI_4_F + (z + 1.f) * (0.2447f - 0.0663f * z));
}
z = x / y;
return z * (-PI_4_F - (z + 1.f) * (0.2447f - 0.0663f * z)) - PI_2_F;
}
/* Q1 + */
if (x >= y)
{
z = y / x;
return z * (PI_4_F - (z - 1.f) * (0.2447f + 0.0663f * z));
}
z = x / y;
return PI_2_F - z * (PI_4_F - (z - 1.f) * (0.2447f + 0.0663f * z));
}
void fm_demod_f32(struct demod_state *fm)
{
int i;
float *ib = (float*) fm->lowpassed, *ob = (float*) fm->result, v;
fm->result_len = 0;
for (i = 0; i < fm->lp_len; i += 2)
{
/* atanf function needs more computer power, better is to use approximation */
v = atan2_lagrange_f32(fm->pre_r_f32 * ib[i + 1] - fm->pre_j_f32 * ib[i],
ib[i] * fm->pre_r_f32 + ib[i + 1] * fm->pre_j_f32);
fm->pre_r_f32 = ib[i];
fm->pre_j_f32 = ib[i + 1];
ob[fm->result_len++] = v;
}
}
void deemph_filter_f32(struct demod_state *fm)
{
int i;
float *ib = (float*) fm->result;
if (fm->lpr.mode == 2)
{
for (i = 0; i < fm->result_len; i += 2)
{
/* left */
fm->deemph_l_f32 = (ib[i] += fm->deemph_lambda * (fm->deemph_l_f32 - ib[i]));
/* right */
fm->deemph_r_f32 = (ib[i + 1] += fm->deemph_lambda * (fm->deemph_r_f32 - ib[i + 1]));
}
}
else
{
for (i = 0; i < fm->result_len; i++)
{
fm->deemph_l_f32 = (ib[i] += fm->deemph_lambda * (fm->deemph_l_f32 - ib[i]));
}
}
}
void convert_f32_s16(struct demod_state *fm)
{
int i;
float *ib = (float*) fm->result, coef;
int16_t *ob = (int16_t*) fm->result;
coef = fm->volume * 32768.0f;
for (i = 0; i < fm->result_len; i++)
{
ib[i] *= coef;
if (ib[i] > 32767.0f)
{
ob[i] = 32767;
}
else if (ib[i] < -32768.0f)
{
ob[i] = -32768;
}
else
{
ob[i] = (int16_t) lrintf(ib[i]);
}
}
}
void full_demod(struct demod_state *d)
{
int i, ds_p;
int sr = 0;
// Low pass to filter only to the tuned FM channel
lp_f32(d);
// Shadow buffer to calculate the RMS
memcpy(json_rpc.RMSShadowBuf, d->lowpassed, d->lp_len * sizeof(float));
json_rpc.RMSShadowBuf_len = d->lp_len;
// FM demodulation
fm_demod_f32(d); /* lowpassed -> result */
/* todo, fm noise squelch */
// use nicer filter here too?
if (d->post_downsample > 1)
{
/* For float not implemented */
}
if (d->rate_out2 > 0)
lp_real_f32(d);
if (d->deemph)
deemph_filter_f32(d);
convert_f32_s16(d);
}
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;
/* mute */
if (s->mute)
{
for (i = 0; i < s->mute; i++)
buf[i] = 127;
s->mute = 0;
}
pthread_rwlock_wrlock(&d->rw);
if (input_buffer_wpos + len <= input_buffer_size_max)
{
memcpy(input_buffer + input_buffer_wpos, buf, len);
input_buffer_wpos += len;
input_buffer_size += len;
/* begin new read with zero */
if (input_buffer_wpos == input_buffer_size_max) input_buffer_wpos = 0;
}
else
{
/* buffer_size_max must be multiple of len */
memcpy(input_buffer, buf, len);
input_buffer_wpos = len;
input_buffer_size += len;
}
/* already droped some data, so print info */
if (input_buffer_size > input_buffer_size_max)
{
fprintf(stderr, "dropping input buffer: %u B\n", input_buffer_size - input_buffer_size_max);
input_buffer_size = input_buffer_size_max;
}
pthread_rwlock_unlock(&d->rw);
//safe_cond_signal(&d->ready, &d->ready_m);
}
static void *
demod_thread_fn(void *arg)
{
struct demod_state *d = arg;
struct output_state *o = d->output_target;
uint32_t len;
while (!do_exit)
{
len = MAXIMUM_BUF_LENGTH;
while (input_buffer_size < len)
{
if ((d->exit_flag) || (do_exit)) return 0;
usleep(5000);
//safe_cond_wait(&d->ready, &d->ready_m);
}
pthread_rwlock_wrlock(&d->rw);