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Fix Issue 88, Wrong Longitude in ADSB RX (#242)

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Tyler Roussos 2019-05-21 11:44:14 -04:00 • committed by Furrtek
parent aa77657092
commit 9f587e6085
3 changed files with 18 additions and 9 deletions
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23
firmware/common/adsb.cpp
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@ -211,7 +211,7 @@ void encode_frame_pos(ADSBFrame& frame, const uint32_t ICAO_address, const int32
adsb_pos decode_frame_pos(ADSBFrame& frame_even, ADSBFrame& frame_odd) {
uint8_t * raw_data;
uint32_t latcprE, latcprO, loncprE, loncprO;
float latE, latO, m, Dlon;
float latE, latO, m, Dlon, cpr_lon_odd, cpr_lon_even, cpr_lat_odd, cpr_lat_even;
int ni;
adsb_pos position { false, 0, 0, 0 };
@ -237,10 +237,17 @@ adsb_pos decode_frame_pos(ADSBFrame& frame_even, ADSBFrame& frame_odd) {
latcprO = ((frame_data_odd[6] & 3) << 15) | (frame_data_odd[7] << 7) | (frame_data_odd[8] >> 1);
loncprO = ((frame_data_odd[8] & 1) << 16) | (frame_data_odd[9] << 8) | frame_data_odd[10];
// Calculate the coefficients
cpr_lon_even = loncprE / CPR_MAX_VALUE;
cpr_lon_odd = loncprO / CPR_MAX_VALUE;
cpr_lat_odd = latcprO / CPR_MAX_VALUE;
cpr_lat_even = latcprE / CPR_MAX_VALUE;
// Compute latitude index
float j = floor((((59.0 * latcprE) - (60.0 * latcprO)) / 131072.0) + 0.5);
latE = (360.0 / 60.0) * (cpr_mod(j, 60) + (latcprE / 131072.0));
latO = (360.0 / 59.0) * (cpr_mod(j, 59) + (latcprO / 131072.0));
float j = floor(((59.0 * cpr_lat_even) - (60.0 * cpr_lat_odd)) + 0.5);
latE = (360.0 / 60.0) * (cpr_mod(j, 60) + cpr_lat_even);
latO = (360.0 / 59.0) * (cpr_mod(j, 59) + cpr_lat_odd);
if (latE >= 270) latE -= 360;
if (latO >= 270) latO -= 360;
@ -255,9 +262,9 @@ adsb_pos decode_frame_pos(ADSBFrame& frame_even, ADSBFrame& frame_odd) {
ni = cpr_N(latE, 0);
Dlon = 360.0 / ni;
m = floor((((loncprE * (cpr_NL(latE) - 1)) - (loncprO * cpr_NL(latE))) / 131072.0) + 0.5);
m = floor((cpr_lon_even * (cpr_NL(latE) - 1)) - (cpr_lon_odd * cpr_NL(latE)) + 0.5);
position.longitude = Dlon * (cpr_mod(m, ni) + loncprE / 131072.0);
position.longitude = Dlon * (cpr_mod(m, ni) + cpr_lon_even);
position.latitude = latE;
} else {
@ -265,9 +272,9 @@ adsb_pos decode_frame_pos(ADSBFrame& frame_even, ADSBFrame& frame_odd) {
ni = cpr_N(latO, 1);
Dlon = 360.0 / ni;
m = floor((((loncprE * (cpr_NL(latO) - 1)) - (loncprO * cpr_NL(latO))) / 131072.0) + 0.5);
m = floor((cpr_lon_even * (cpr_NL(latO) - 1)) - (cpr_lon_odd * cpr_NL(latO)) + 0.5);
position.longitude = Dlon * (cpr_mod(m, ni) + loncprO / 131072.0);
position.longitude = Dlon * (cpr_mod(m, ni) + cpr_lon_odd);
position.latitude = latO;
}