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rtl_ais.c #4

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79 changes: 72 additions & 7 deletions ais/rtl_ais.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,11 @@
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include <unistd.h>
#ifdef WIN32
#include <fcntl.h>
#endif


#include <pthread.h>
#include <libusb.h>
Expand Down Expand Up @@ -77,6 +80,10 @@ struct downsample_state
int16_t lp_i_hist[10][6];
int16_t lp_q_hist[10][6];
pthread_rwlock_t rw;
//droop compensation
int16_t droop_i_hist[9];
int16_t droop_q_hist[9];

};

struct demod_state
Expand All @@ -88,6 +95,7 @@ struct demod_state
int now_r, now_j;
int pre_r, pre_j;
int dc_avg; // really should get its own struct

};

struct upsample_stereo
Expand Down Expand Up @@ -122,7 +130,7 @@ void usage(void)
"\t[-r right_frequency (default: 162.025M)]\n"
"\t left freq < right freq\n"
"\t frequencies must be within 1.2MHz\n"
"\t[-s sample_rate (default: 12k)]\n"
"\t[-s sample_rate (default: 24k)]\n"
"\t minimum value, might be up to 2x specified\n"
"\t[-o output_rate (default: 48k)]\n"
"\t must be equal or greater than twice -s value\n"
Expand All @@ -146,6 +154,20 @@ static void sighandler(int signum)
do_exit = 1;
rtlsdr_cancel_async(dev);
}
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(int16_t *buf, int len)
/* 90 rotation is 1+0j, 0+1j, -1+0j, 0-1j
Expand Down Expand Up @@ -218,14 +240,43 @@ void fifth_order(int16_t *data, int length, int16_t *hist)
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;
}
}

void downsample(struct downsample_state *d)
{
int i, ds_p;
ds_p = d->downsample_passes;
for (i=0; i<ds_p; i++) {
for (i=0; i<ds_p; i++)
{
fifth_order(d->buf, (d->len_in >> i), d->lp_i_hist[i]);
fifth_order(d->buf+1, (d->len_in >> i)-1, d->lp_q_hist[i]);
}
// droop compensation
generic_fir(d->buf, d->len_in >> ds_p,cic_9_tables[ds_p], d->droop_i_hist);
generic_fir(d->buf+1, (d->len_in>> ds_p)-1,cic_9_tables[ds_p], d->droop_q_hist);
}

void multiply(int ar, int aj, int br, int bj, int *cr, int *cj)
Expand Down Expand Up @@ -280,6 +331,7 @@ void demodulate(struct demod_state *d)
int16_t *result = d->result;
pcm = polar_disc_fast(buf[0], buf[1],
d->pre_r, d->pre_j);

result[0] = (int16_t)pcm;
for (i = 2; i < (d->buf_len-1); i += 2) {
// add the other atan types?
Expand Down Expand Up @@ -370,6 +422,7 @@ static void *demod_thread_fn(void *arg)
dc_block_filter(&left_demod);}
//if (oversample) {
// downsample(&left);}
//fprintf(stderr,"\nUpsample result_len:%d stereo.bl_len:%d :%f\n",left_demod.result_len,stereo.bl_len,(float)stereo.bl_len/(float)left_demod.result_len);
arbitrary_upsample(left_demod.result, stereo.buf_left, left_demod.result_len, stereo.bl_len);
rotate_m90(right.buf, right.len_in);
downsample(&right);
Expand All @@ -392,6 +445,7 @@ void downsample_init(struct downsample_state *dss)
int i, j;
dss->buf = malloc(dss->len_in * sizeof(int16_t));
dss->rate_out = dss->rate_in / dss->downsample;

//dss->downsample_passes = (int)log2(dss->downsample);
dss->len_out = dss->len_in / dss->downsample;
for (i=0; i<10; i++) { for (j=0; j<6; j++) {
Expand All @@ -416,7 +470,9 @@ void stereo_init(struct upsample_stereo *us)

int main(int argc, char **argv)
{
#ifndef WIN32
struct sigaction sigact;
#endif
char *filename = NULL;
int r, opt;
int i, gain = AUTO_GAIN; /* tenths of a dB */
Expand All @@ -426,7 +482,7 @@ int main(int argc, char **argv)
int custom_ppm = 0;
int left_freq = 161975000;
int right_freq = 162025000;
int sample_rate = 12000;
int sample_rate = 24000;
int output_rate = 48000;
int dongle_freq, dongle_rate, delta;
int edge = 0;
Expand Down Expand Up @@ -550,7 +606,8 @@ int main(int argc, char **argv)
left_demod.result_len = left_demod.buf_len / 2;
right_demod.buf_len = left_demod.buf_len;
right_demod.result_len = left_demod.result_len;
stereo.bl_len = (int)((long)(DEFAULT_BUF_LENGTH/2) * (long)output_rate / (long)dongle_rate);
// stereo.bl_len = (int)((long)(DEFAULT_BUF_LENGTH/2) * (long)output_rate / (long)dongle_rate); -> Doesn't work on Linux
stereo.bl_len = (int)((double)(DEFAULT_BUF_LENGTH/2) * (double)output_rate / (double)dongle_rate);
stereo.br_len = stereo.bl_len;
stereo.result_len = stereo.br_len * 2;
stereo.rate = output_rate;
Expand All @@ -575,16 +632,23 @@ int main(int argc, char **argv)
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
signal(SIGINT, sighandler);
signal(SIGTERM, sighandler);
#endif
if (strcmp(filename, "-") == 0) { /* Write samples to stdout */
file = stdout;
#ifdef WIN32
setmode(fileno(stdout), O_BINARY); // Binary mode, avoid text mode
#endif
setvbuf(stdout, NULL, _IONBF, 0);
} else {
file = fopen(filename, "wb");
Expand All @@ -593,7 +657,6 @@ int main(int argc, char **argv)
exit(1);
}
}

/* Set the tuner gain */
if (gain == AUTO_GAIN) {
verbose_auto_gain(dev);
Expand All @@ -605,7 +668,9 @@ int main(int argc, char **argv)
if (!custom_ppm) {
verbose_ppm_eeprom(dev, &ppm_error);
}

verbose_ppm_set(dev, ppm_error);

//r = rtlsdr_set_agc_mode(dev, 1);

/* Set the tuner frequency */
Expand Down