#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <getopt.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>
#include <complex.h>
#include <math.h>
#include <stdbool.h>
#include <inttypes.h>
#include <sys/time.h>
#include <limits.h>
#include "rtl-sdr.h"
rtlsdr_dev_t *device;
FILE *record_file;
#define SAMPLE_RATE 250000
#define FREQUENCY 433920000
#define USE_RAW_DATA_FILE 0
typedef enum {
short_pulse,
short_gap,
sync_gap,
long_pulse,
long_gap
} ook_modulation;
const uint32_t short_width = 360;
const uint32_t long_width = 1070;
const uint32_t gap_limit = 1200;
int get_sample_file(uint8_t *buffer, int buffer_length) {
int len;
len = fread(buffer, sizeof(uint8_t), buffer_length, record_file);
return len == buffer_length;
}
int get_samples_rtl_sdr(uint8_t *buffer, int buffer_length) {
int length;
//length = fread(buffer, sizeof(uint8_t), buffer_length, record_file);
rtlsdr_read_sync(device, buffer, buffer_length, &length);
return length == buffer_length;
}
int32_t remove_dc_bias(int32_t sample, double weight, int32_t *previous_average) {
*previous_average = (int32_t) round(weight * sample + (1 - weight) * *previous_average);
return sample - *previous_average;
}
int32_t get_envelope(int32_t sample, double weight, int32_t previous_average) {
return (int32_t) round(weight * sample + (1 - weight) * previous_average);
}
int32_t is_pulse(uint32_t envelope, uint32_t threshold) {
if (envelope > threshold) {
return true;
}
return false;
}
int main() {
if (1) {
printf("Using file.\n");
record_file = fopen("good_sample_3", "r");
if (!record_file) {
return 3;
}
} else {
if (!rtlsdr_get_device_count()) {
return 1;
}
if (rtlsdr_open(&device, 0) != false) {
return 2;
}
// Disable automatic gain control on the RTL2832U chip
printf("Setting AGC mode.\n");
rtlsdr_set_agc_mode(device, 0);
// Auto gain
printf("Setting gain mode.\n");
rtlsdr_set_tuner_gain_mode(device, 0);
printf("Setting frequency and sample rate.\n");
rtlsdr_set_center_freq(device, FREQUENCY);
rtlsdr_set_sample_rate(device, SAMPLE_RATE);
printf("Flushing buffer.\n");
// Flush the device buffer
rtlsdr_reset_buffer(device);
}
size_t buffer_length = 2048;
uint8_t *buffer = malloc(2048);
// Signal is as follows:
// |¯|________|¯¯|__|¯|_|¯|_|¯¯|_|¯¯|_|¯¯|_|¯¯|_|¯¯|__|¯|_|¯|_|¯¯|__|¯|__|¯|__|¯|_|¯¯|_|¯¯|_|¯¯|_|¯¯|
ook_modulation protocol[] = {
short_pulse,
sync_gap,
long_pulse,
long_gap,
short_pulse,
long_gap,
short_pulse,
short_gap,
long_pulse,
short_gap,
long_pulse,
short_gap,
long_pulse,
short_gap,
long_pulse,
short_gap,
long_pulse,
long_gap,
short_pulse,
long_gap,
short_pulse,
short_gap,
long_pulse,
long_gap,
short_pulse,
long_gap,
short_pulse,
long_gap,
short_pulse,
short_gap,
long_pulse,
short_gap,
long_pulse,
short_gap,
long_pulse,
short_gap,
long_pulse
};
int protocol_index = 0;
int protocol_length = 37;
if (get_sample_file(buffer, buffer_length) == false) {
return 5;
}
int32_t dc_avg = buffer[0];
int32_t env_avg = buffer[0];
int start = 1;
// Keep track of the duration of the current protocol step; pulse or the absence of a pulse
uint32_t duration = 0;
// We will allow this amount of variance in the envelope signal when stepping through a pulse
uint32_t tolerance = 0;
// Threshold
uint32_t threshold = 50;
printf("Loop begin.\n");
FILE *test = fopen("test", "w+");
do {
if (protocol_index + 1 == protocol_length) {
fprintf(stdout, "OOK protocol match.\n");
protocol_index = 0;
tolerance = 0;
}
for (int i = start; i < buffer_length; i++) {
int32_t sample = buffer[i];
int32_t dc_sample = abs(remove_dc_bias(sample, 0.03, &dc_avg));
env_avg = abs(get_envelope(dc_sample, 0.10, env_avg));
uint8_t v = (uint8_t) env_avg;
ook_modulation part = protocol[protocol_index];
fwrite(&sample, sizeof(v), 1, test);
switch (part) {
case short_pulse: {
if (is_pulse(env_avg, threshold - tolerance)) {
tolerance = 10;
duration++;
} else {
if (duration > 130) {
protocol_index++;
} else {
protocol_index = 0;
}
tolerance = 0;
duration = 0;
}
break;
}
case short_gap: {
if (!is_pulse(env_avg, threshold - tolerance)) {
duration++;
} else {
if (duration > 130) {
protocol_index++;
} else {
protocol_index = 0;
}
tolerance = 0;
duration = 0;
}
break;
}
case long_pulse: {
if (is_pulse(env_avg, threshold - tolerance)) {
tolerance = 10;
duration++;
} else {
if (duration > 270) {
protocol_index++;
} else {
protocol_index = 0;
}
tolerance = 0;
duration = 0;
}
break;
}
case sync_gap: {
if (!is_pulse(env_avg, threshold - tolerance)) {
duration++;
} else {
if (duration > 2850) {
protocol_index++;
} else {
protocol_index = 0;
}
tolerance = 0;
duration = 0;
}
break;
}
case long_gap: {
if (!is_pulse(env_avg, threshold - tolerance)) {
duration++;
} else {
if (duration > 270) {
protocol_index++;
} else {
protocol_index = 0;
}
tolerance = 0;
duration = 0;
}
break;
}
default: {
printf("Finished reading file!\n");
exit(1);
}
}
}
start = 0;
} while (get_samples_rtl_sdr(buffer, buffer_length) == true);
return 0;
}
