Seppel2000and3

Hi, sorry i ask again, but this seems to be a very hard nut for me ;-) Im standing on EDDF (have a HDG of 111). Now my question, is -214 a good value for the MagVar??? What is the MagVar? Sorry, im posting again my try: ___MAIN.CPP___ TCAS_DATA slots[20]; // i know i can realize that with a list, but for testing its ok short int siMagVar; __int64 liMyOwnLat, liMyOwnLon; double dMyOwnLat, dMyOwnLon; //... getting datas from FSUIPC, then convert to degrees dMyOwnLat = liMyOwnLat * (90.0/(10001750.0 * 65536.0 * 65536.0)); dMyOwnLon = liOwnLon * (360.0/(65536.0 * 65536.0 * 65536.0 * 65536.0)); Bearing(dMyOwnLat,dMyOwnLon,slots[0].lat,slots[0].lon,siMagVar); ___MyTCAS.CPP___ double Bearing(double dMyLat, double dMyLon, double dAiLat, double dAiLon, short int MagVar) { double dHdg; // result in degrees double rad_dMyLat = (dMyLat * PI) / 180.0; // User Latitude converts to RAD double rad_dMyLon = (dMyLon * PI) / 180.0; // User Longitude converts to RAD double rad_dAiLat = (dAiLat * PI) / 180.0; // AI Latitude converts to RAD double rad_dAiLon = (dAiLon * PI) / 180.0; // AI Longitude converts to RAD double rad_dDst = acos(sin(rad_dMyLat) * sin(rad_dAiLat) + cos(rad_dMyLat) * cos(rad_dAiLat) * cos(rad_dMyLon - rad_dAiLon)); dHdg = (dMyLat == dAiLat) ? 90.0 : (180.0 * atan(fabs(rad_dDst/(rad_dAiLat-rad_dMyLat))) / PI); if (dMyLat >= dAiLat) { if (dMyLon >= dAiLon) dHdg += 180.0; else dHdg = 180.0 - dHdg; } else if (dMyLon > dAiLon) dHdg = 360.0 - dHdg; // correct for magvar dHdg -= ((MagVar * 360.0) / 65536.0); if (dHdg < 0.0) dHdg += 360.0; if (dHdg > 360.0) dHdg -= 360.0; //dHdg = (dHdg * 180) / PI; //(rad to deg); return dHdg; } Im very confused about this RAD and DEG things, but i need this Bearingvalue realy, want to implement a nice radar. I know im on the first mile of a marathon, but i like to do this ;-) Thanks for your great help, Sebastian

Hi, hmmpf, im getting crazy ;-) Thank you for your answer, but one answer = lots of new questions ;-) 1.) i compute the distance with this: double dDst = acos(sin(dMyLat) * sin(dAiLat) + cos(dMyLat) * cos(dAiLat) * cos(dMyLon - dAiLon)); do i have first the Lat and Lon values turn into RAD??? with (dMyLat/180 * PI) or something else? 2.) the magvar im getting from FSUIPC (long int), i have to recalculate it with something before i give it to my function? like this: db_own_magvar = (double)li_own_magvar * (360/65536); 3.) before return dHdg; i have to convert it to another format (RAD/DEG/360/PI or something else) Here is a short table from values you have in TrafficLook and i have: yours|mine 181|136.175 103|98.7678 179|136.144 271|270.908 152|129.048 346|313.924 Thats not very near the values you have ;-) Thanks for your answers, Sebastian

Hi, i tried the whole night, to calculate the bearing from to points in given format (dd.mmmm) I tried several things but didnt received the same result as in TrafficLook. I'm programming in C++, and if somebody can give me a hint i would be more happy than now. I hope its ok, when i post my last try here: - Lat1&Lon1 are my aircraft position from the offset described in the SDK - Lat2&Lon2 are the AI Aircraft position from the TCAS Data described in the SDK - The value for distance is okay, so it must be a fault with the bearing algorithm double Bearing(double Lat1, double Lon1, double Lat2, double Lon2) { double B1 = Lat1/180 * PI; //DEG to RAD double B2 = Lat2/180 * PI; double L1 = Lon1/180 * PI; double L2 = Lon2/180 * PI; double t1,t2,t3,t4,t5; double rad_bearing; double rad_dist = acos(sin(B1) * sin(B2) + cos(B1) * cos(B2) * cos(L1 - L2)); if (sin (L2 - L1) < 0.0) { t1 = sin(B2) - sin(B1) * cos(rad_dist); t2 = cos(B1) * sin(rad_dist); t3 = t1 / t2; t4 = atan(-t3 / sqrt(-t3 * t3 + 1)) + 2 * atan(1); rad_bearing = t4; } else { t1 = sin(B2) - sin(B1) * cos(rad_dist); t2 = cos(B1) * sin(rad_dist); t3 = t1 / t2; t4 = -t3 * t3 + 1; t5 = 2 * 3.14 - (atan(-t3) / sqrt(-t3 * t3 + 1)) + 2 * atan(1); rad_bearing = t5; } double BG = rad_bearing * 57.2957795; return BG; } Two hours ago, i tried another source (from an website) this gave me some values that were somehow in relationship with the values in TrafficLook. But they were always too small?!? I can post that later, if somebody wants ;-) OK, last word: Sorry for my bad english... Hope for good answers, Sebastian