//
//=========================================================================
//
void view1090Init(void) {
// Allocate the various buffers used by Modes
if ( NULL == (Modes.icao_cache = (uint32_t *) malloc(sizeof(uint32_t) * MODES_ICAO_CACHE_LEN * 2)))
{
fprintf(stderr, "Out of memory allocating data buffer.\n");
exit(1);
}
// Clear the buffers that have just been allocated, just in-case
memset(Modes.icao_cache, 0, sizeof(uint32_t) * MODES_ICAO_CACHE_LEN * 2);
// Validate the users Lat/Lon home location inputs
if ( (Modes.fUserLat > 90.0) // Latitude must be -90 to +90
|| (Modes.fUserLat < -90.0) // and
|| (Modes.fUserLon > 360.0) // Longitude must be -180 to +360
|| (Modes.fUserLon < -180.0) ) {
Modes.fUserLat = Modes.fUserLon = 0.0;
} else if (Modes.fUserLon > 180.0) { // If Longitude is +180 to +360, make it -180 to 0
Modes.fUserLon -= 360.0;
}
// If both Lat and Lon are 0.0 then the users location is either invalid/not-set, or (s)he's in the
// Atlantic ocean off the west coast of Africa. This is unlikely to be correct.
// Set the user LatLon valid flag only if either Lat or Lon are non zero. Note the Greenwich meridian
// is at 0.0 Lon,so we must check for either fLat or fLon being non zero not both.
// Testing the flag at runtime will be much quicker than ((fLon != 0.0) || (fLat != 0.0))
Modes.bUserFlags &= ~MODES_USER_LATLON_VALID;
if ((Modes.fUserLat != 0.0) || (Modes.fUserLon != 0.0)) {
Modes.bUserFlags |= MODES_USER_LATLON_VALID;
}
// Prepare error correction tables
modesInitErrorInfo();
}
//
//=========================================================================
//
void ppup1090Init(void) {
int iErr;
// Allocate the various buffers used by Modes
if ( NULL == (Modes.icao_cache = (uint32_t *) malloc(sizeof(uint32_t) * MODES_ICAO_CACHE_LEN * 2)))
{
fprintf(stderr, "Out of memory allocating data buffer.\n");
exit(1);
}
// Clear the buffers that have just been allocated, just in-case
memset(Modes.icao_cache, 0, sizeof(uint32_t) * MODES_ICAO_CACHE_LEN * 2);
// Validate the users Lat/Lon home location inputs
if ( (Modes.fUserLat > 90.0) // Latitude must be -90 to +90
|| (Modes.fUserLat < -90.0) // and
|| (Modes.fUserLon > 360.0) // Longitude must be -180 to +360
|| (Modes.fUserLon < -180.0) ) {
Modes.fUserLat = Modes.fUserLon = 0.0;
} else if (Modes.fUserLon > 180.0) { // If Longitude is +180 to +360, make it -180 to 0
Modes.fUserLon -= 360.0;
}
// If both Lat and Lon are 0.0 then the users location is either invalid/not-set, or (s)he's in the
// Atlantic ocean off the west coast of Africa. This is unlikely to be correct.
// Set the user LatLon valid flag only if either Lat or Lon are non zero. Note the Greenwich meridian
// is at 0.0 Lon,so we must check for either fLat or fLon being non zero not both.
// Testing the flag at runtime will be much quicker than ((fLon != 0.0) || (fLat != 0.0))
Modes.bUserFlags &= ~MODES_USER_LATLON_VALID;
if ((Modes.fUserLat != 0.0) || (Modes.fUserLon != 0.0)) {
Modes.bUserFlags |= MODES_USER_LATLON_VALID;
}
// Prepare error correction tables
modesInitErrorInfo();
// Setup the uploader - read the user paramaters from the coaa.h header file
coaa1090.fUserLat = MODES_USER_LATITUDE_DFLT;
coaa1090.fUserLon = MODES_USER_LONGITUDE_DFLT;
strcpy(coaa1090.strAuthCode,STR(USER_AUTHCODE));
strcpy(coaa1090.strRegNo, STR(USER_REGNO));
strcpy(coaa1090.strVersion, MODES_DUMP1090_VERSION);
if ((iErr = initCOAA (coaa1090)))
{
fprintf(stderr, "Error 0x%X initialising uploader\n", iErr);
exit(1);
}
}
//
//=========================================================================
//
void modesInit(void) {
int i, q;
pthread_mutex_init(&Modes.data_mutex,NULL);
pthread_cond_init(&Modes.data_cond,NULL);
// Allocate the various buffers used by Modes
if ( ((Modes.icao_cache = (uint32_t *) malloc(sizeof(uint32_t) * MODES_ICAO_CACHE_LEN * 2) ) == NULL) ||
((Modes.pFileData = (uint16_t *) malloc(MODES_ASYNC_BUF_SIZE) ) == NULL) ||
((Modes.magnitude = (uint16_t *) malloc(MODES_ASYNC_BUF_SIZE+MODES_PREAMBLE_SIZE+MODES_LONG_MSG_SIZE) ) == NULL) ||
((Modes.maglut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) ||
((Modes.beastOut = (char *) malloc(MODES_RAWOUT_BUF_SIZE) ) == NULL) ||
((Modes.rawOut = (char *) malloc(MODES_RAWOUT_BUF_SIZE) ) == NULL) )
{
fprintf(stderr, "Out of memory allocating data buffer.\n");
exit(1);
}
// Clear the buffers that have just been allocated, just in-case
memset(Modes.icao_cache, 0, sizeof(uint32_t) * MODES_ICAO_CACHE_LEN * 2);
memset(Modes.pFileData,127, MODES_ASYNC_BUF_SIZE);
memset(Modes.magnitude, 0, MODES_ASYNC_BUF_SIZE+MODES_PREAMBLE_SIZE+MODES_LONG_MSG_SIZE);
// Validate the users Lat/Lon home location inputs
if ( (Modes.fUserLat > 90.0) // Latitude must be -90 to +90
|| (Modes.fUserLat < -90.0) // and
|| (Modes.fUserLon > 360.0) // Longitude must be -180 to +360
|| (Modes.fUserLon < -180.0) ) {
Modes.fUserLat = Modes.fUserLon = 0.0;
} else if (Modes.fUserLon > 180.0) { // If Longitude is +180 to +360, make it -180 to 0
Modes.fUserLon -= 360.0;
}
// If both Lat and Lon are 0.0 then the users location is either invalid/not-set, or (s)he's in the
// Atlantic ocean off the west coast of Africa. This is unlikely to be correct.
// Set the user LatLon valid flag only if either Lat or Lon are non zero. Note the Greenwich meridian
// is at 0.0 Lon,so we must check for either fLat or fLon being non zero not both.
// Testing the flag at runtime will be much quicker than ((fLon != 0.0) || (fLat != 0.0))
Modes.bUserFlags &= ~MODES_USER_LATLON_VALID;
if ((Modes.fUserLat != 0.0) || (Modes.fUserLon != 0.0)) {
Modes.bUserFlags |= MODES_USER_LATLON_VALID;
}
// Limit the maximum requested raw output size to less than one Ethernet Block
if (Modes.net_output_raw_size > (MODES_RAWOUT_BUF_FLUSH))
{Modes.net_output_raw_size = MODES_RAWOUT_BUF_FLUSH;}
if (Modes.net_output_raw_rate > (MODES_RAWOUT_BUF_RATE))
{Modes.net_output_raw_rate = MODES_RAWOUT_BUF_RATE;}
// Initialise the Block Timers to something half sensible
ftime(&Modes.stSystemTimeBlk);
for (i = 0; i < MODES_ASYNC_BUF_NUMBER; i++)
{Modes.stSystemTimeRTL[i] = Modes.stSystemTimeBlk;}
// Each I and Q value varies from 0 to 255, which represents a range from -1 to +1. To get from the
// unsigned (0-255) range you therefore subtract 127 (or 128 or 127.5) from each I and Q, giving you
// a range from -127 to +128 (or -128 to +127, or -127.5 to +127.5)..
//
// To decode the AM signal, you need the magnitude of the waveform, which is given by sqrt((I^2)+(Q^2))
// The most this could be is if I&Q are both 128 (or 127 or 127.5), so you could end up with a magnitude
// of 181.019 (or 179.605, or 180.312)
//
// However, in reality the magnitude of the signal should never exceed the range -1 to +1, because the
// values are I = rCos(w) and Q = rSin(w). Therefore the integer computed magnitude should (can?) never
// exceed 128 (or 127, or 127.5 or whatever)
//
// If we scale up the results so that they range from 0 to 65535 (16 bits) then we need to multiply
// by 511.99, (or 516.02 or 514). antirez's original code multiplies by 360, presumably because he's
// assuming the maximim calculated amplitude is 181.019, and (181.019 * 360) = 65166.
//
// So lets see if we can improve things by subtracting 127.5, Well in integer arithmatic we can't
// subtract half, so, we'll double everything up and subtract one, and then compensate for the doubling
// in the multiplier at the end.
//
// If we do this we can never have I or Q equal to 0 - they can only be as small as +/- 1.
// This gives us a minimum magnitude of root 2 (0.707), so the dynamic range becomes (1.414-255). This
// also affects our scaling value, which is now 65535/(255 - 1.414), or 258.433254
//
// The sums then become mag = 258.433254 * (sqrt((I*2-255)^2 + (Q*2-255)^2) - 1.414)
// or mag = (258.433254 * sqrt((I*2-255)^2 + (Q*2-255)^2)) - 365.4798
//
// We also need to clip mag just incaes any rogue I/Q values somehow do have a magnitude greater than 255.
//
for (i = 0; i <= 255; i++) {
for (q = 0; q <= 255; q++) {
int mag, mag_i, mag_q;
mag_i = (i * 2) - 255;
mag_q = (q * 2) - 255;
mag = (int) round((sqrt((mag_i*mag_i)+(mag_q*mag_q)) * 258.433254) - 365.4798);
Modes.maglut[(i*256)+q] = (uint16_t) ((mag < 65535) ? mag : 65535);
}
}
// Prepare error correction tables
modesInitErrorInfo();
}
