public static PlanePosition DecodeGlobalADSB(ADSBPositionMessage OldADSBMessage, ADSBPositionMessage NewADSBMessage)
{
if (!OldADSBMessage.ICAO.Equals(NewADSBMessage.ICAO))
{
throw new ArgumentException("Not the same ICAO! -> CPRCoder static PlanePosition");
}
if (OldADSBMessage.CprFormate == NewADSBMessage.CprFormate)
{
throw new ArgumentException("Same CPR - Error!");
}
TimeSpan OldMesTimespan = TimeSpan.FromTicks(OldADSBMessage.Timestamp.Ticks);
TimeSpan NewMesTimespan = TimeSpan.FromTicks(NewADSBMessage.Timestamp.Ticks);
if ((NewMesTimespan.TotalSeconds - OldMesTimespan.TotalSeconds) > 10)
{
throw new ArgumentException("Timestamp too old!");
}
int i = NewADSBMessage.CprFormate;
//Latitude
double CprLat0 = (i == 0) ? NewADSBMessage.CprLatitude : OldADSBMessage.CprLatitude;
double CprLat1 = (i == 1) ? NewADSBMessage.CprLatitude : OldADSBMessage.CprLatitude;
double j = Math.Floor(((59 * CprLat0 - 60 * CprLat1) / Nb17) + 0.5);
double RLat0 = Dlat0 * (mod(j, 60) + CprLat0 / Nb17);
double RLat1 = Dlat1 * (mod(j, 59) + CprLat1 / Nb17);
double latitude = (i == 0) ? RLat0 : RLat1;
int nl = 0;
if ((nl = NumberOfLongitudeZones.lookup(RLat0)) != NumberOfLongitudeZones.lookup(RLat1))
{
// if the longitude zones are not the same, we cannot calculate the longitude
// so we discard this position object
throw new ArgumentException("CprCoder.decodeGlobalAirborne(): Messages with matching number of longitude zones expected");
}
double CprLon0 = (i == 0) ? NewADSBMessage.CprLongitude : OldADSBMessage.CprLongitude;
double CprLon1 = (i == 1) ? NewADSBMessage.CprLongitude : OldADSBMessage.CprLongitude;
double m = Math.Floor((CprLon0 * (nl - 1) - CprLon1 * nl) / Nb17 + 0.5);
double lon = (i == 0) ? CprLon0 : CprLon1;
double dlon = 360.0 / Math.Max(nl - i, 1);
double longitude = dlon * (mod(m, nl - i) + lon / Nb17);
//System.err.println ( String.format("%-8s LAT LON %-3.8f %-3.8f global pos", newMsg.getIcao(), latitude, longitude) );
return(new PlanePosition(NewADSBMessage.Timestamp, (double)latitude, (double)longitude, (double)NewADSBMessage.Altitude));
}
public const double Nb17 = 131072.0; //Number of bits for Encoding
public static PlanePosition DecodeADSBToPosition(PlanePosition ReferencePosition, ADSBPositionMessage NewMessage)
{
double LatitudeReference = ReferencePosition.Latitude;
double LongitudeReference = ReferencePosition.Longitude;
int LatitudeCpr = NewMessage.CprLatitude;
int LongitudeCpr = NewMessage.CprLongitude;
int Cpr = NewMessage.CprFormate;
double DLat = (Cpr == 0) ? Dlat0 : Dlat1;
double j = Math.Floor(LatitudeReference / DLat) + Math.Floor(0.5 + mod(LatitudeReference, DLat) / DLat - LatitudeCpr / Nb17);
double RLat = (double)DLat * (j + LatitudeCpr / Nb17);
double Dlon = 360.0 / (NumberOfLongitudeZones.lookup(RLat) - Cpr);
double m = Math.Floor(LongitudeReference / Dlon) + Math.Floor(0.5 + mod(LongitudeReference, Dlon) / Dlon - LongitudeCpr / Nb17);
double RLon = (double)Dlon * (m + LongitudeCpr / Nb17);
return(new PlanePosition(NewMessage.Timestamp, (double)RLat, (double)RLon, (double)NewMessage.Altitude));
}
