private string DecodeVelocityOverGroundMsg(ModeSReply msg, DateTime timestamp)
{
VelocityOverGroundMsg velocity = (VelocityOverGroundMsg)msg;
if (msg.ICAO24 == null)
{
return("VelocityOverGroundMsg: No ICAO24 found.");
}
string icao24 = BitConverter.ToString(msg.ICAO24).Replace("-", String.Empty);
// check if ICAO is already stored in lookup table
ADSBInfo info = null;
if (!adsbinfos.TryGetValue(icao24, out info))
{
// no --> add new entry
info = new ADSBInfo();
info.ICAO24 = icao24;
adsbinfos.Add(icao24, info);
}
// add information
if (velocity.HasValidVelocity)
{
info.Speed = velocity.Velocity;
}
if (velocity.HasValidHeading)
{
info.Heading = velocity.Heading;
}
return("[" + info.ICAO24 + "] VelocityOverGroundMsg: Speed=" + info.Speed.ToString() + ", Heading= " + info.Heading.ToString());
}
public string DecodeMessage(string raw_msg, DateTime timestamp)
{
// decode an ADS-B message and add information to list
// cut off first and last character
raw_msg = raw_msg.Substring(1, raw_msg.Length - 2);
// do generic decoding first
ModeSReply msg = LibADSB.Decoder.GenericDecoder(raw_msg);
if (!msg.CheckParity)
{
return("Parity error, no decode.");
}
// parity is OK, let's start to sort the messages and calculate
// Console.WriteLine(msg.ToString());
// lock adsbinfolist
lock (adsbinfos)
{
try
{
if (msg.GetType() == typeof(IdentificationMsg))
{
// Identification message;
return(DecodeIdentificationMsg(msg, timestamp));
}
else if (msg.GetType() == typeof(AirbornePositionMsg))
{
// Airborne position message
return(DecodeAirbornePositionMsg(msg, timestamp));
}
else if (msg.GetType() == typeof(VelocityOverGroundMsg))
{
// Velocity over ground message
return(DecodeVelocityOverGroundMsg(msg, timestamp));
}
else if (msg.GetType() == typeof(AirspeedHeadingMsg))
{
// Airspeed heading message
return(DecodeAirspeedHeadingMsg(msg, timestamp));
}
}
catch (Exception ex)
{
string s = msg.GetType().ToString();
return("Error while decoding " + s + ": " + ex.Message);
}
}
return("Unknown message.");
}
private string DecodeIdentificationMsg(ModeSReply msg, DateTime timestamp)
{
IdentificationMsg ident = (IdentificationMsg)msg;
if (msg.ICAO24 == null)
{
return("IdentifyMsg: No ICAO24 found.");
}
string icao24 = BitConverter.ToString(msg.ICAO24).Replace("-", String.Empty);
// check if ICAO is already stored in lookup table
ADSBInfo info = null;
if (!adsbinfos.TryGetValue(icao24, out info))
{
// no --> add new entry
info = new ADSBInfo();
info.ICAO24 = icao24;
adsbinfos.Add(icao24, info);
}
// add call sign
info.Call = ident.getIdentity();
return("[" + info.ICAO24 + "] IdentificationMsg: Call=" + info.Call);
}
private string DecodeAirbornePositionMsg(ModeSReply msg, DateTime timestamp)
{
// Airborne position message --> we need subsequent messages to decode
AirbornePositionMsg pos = (AirbornePositionMsg)msg;
if (msg.ICAO24 == null)
{
return("AirbornePositionMsg: No ICAO24 found.");
}
string icao24 = BitConverter.ToString(msg.ICAO24).Replace("-", String.Empty);
// check if ICAO is already stored in lookup table
ADSBInfo info = null;
if (!adsbinfos.TryGetValue(icao24, out info))
{
// no --> add new entry
info = new ADSBInfo();
info.ICAO24 = icao24;
adsbinfos.Add(icao24, info);
}
// adsbinfo found --> update information and calculate position
// contains valid position?
if (!pos.HasValidPosition)
{
// no --> return error meesage
return("[" + info.ICAO24 + "] AirbornePositionMsg: No valid position found.");
}
info.ICAO24 = icao24;
info.NICSupplementA = pos.NICSupplementA;
// position calculated before
if (!double.IsNaN(info.Lat) & !double.IsNaN(info.Lon))
{
try
{
// use local CPR
double[] localpos = pos.getLocalPosition(info.Lat, info.Lon);
// we have a pos --> store in info and update timestamp
info.Lat = localpos[0];
info.Lon = localpos[1];
if (pos.HasValidAltitude)
{
info.Alt = pos.Altitude;
}
info.Timestamp = timestamp;
return("[" + info.ICAO24 + "] AirbornePositionMsg: Lat= " + info.Lat.ToString("F8") + ", Lon=" + info.Lon.ToString("F8") + ", Alt= " + info.Alt.ToString() + ", Time= " + info.Timestamp.ToString("HH:mm:ss.fff"));
}
catch (Exception ex)
{
}
}
// no position calculated before
if (pos.IsOddFormat)
{
try
{
// odd message
info.LastOddAirborne = pos;
info.LastOddTimestamp = DateTime.UtcNow;
// check if even message was received before and not older than 10secs--> calculate global CPR
if ((info.LastEvenAirborne != null) && ((info.LastOddTimestamp - info.LastOddTimestamp).TotalSeconds <= 10))
{
try
{
double[] globalpos = pos.getGlobalPosition(info.LastEvenAirborne);
// we have a position --> store in info and update timestamp
info.Lat = globalpos[0];
info.Lon = globalpos[1];
if (pos.HasValidAltitude)
{
info.Alt = pos.Altitude;
}
// info.Timestamp = timestamp;
return("[" + info.ICAO24 + "] AirbornePositionMsg: Lat= " + info.Lat.ToString("F8") + ", Lon=" + info.Lon.ToString("F8") + ", Alt= " + info.Alt.ToString() + ", Time= " + info.Timestamp.ToString("HH:mm:ss.fff"));
}
catch
{
return("[" + info.ICAO24 + "] AirbornePositionMsg: Error while decoding position");
}
}
return("[" + info.ICAO24 + "] AirbornePositionMsg: No decoding possible yet");
}
catch (Exception ex)
{
}
}
// even message
info.LastEvenAirborne = pos;
info.LastEvenTimestamp = DateTime.UtcNow;
// check if odd message was received before and not older than 10secs --> calculate global CPR
if ((info.LastOddAirborne != null) && ((info.LastEvenTimestamp - info.LastOddTimestamp).TotalSeconds <= 10))
{
try
{
double[] globalpos = pos.getGlobalPosition(info.LastOddAirborne);
// we have a position --> store in info and update timestamp
info.Lat = globalpos[0];
info.Lon = globalpos[1];
if (pos.HasValidAltitude)
{
info.Alt = pos.Altitude;
}
// info.Timestamp = timestamp;
return("[" + info.ICAO24 + "] AirbornePositionMsg: Lat= " + info.Lat.ToString("F8") + ", Lon=" + info.Lon.ToString("F8") + ", Alt= " + info.Alt.ToString() + ", Time= " + info.Timestamp.ToString("HH:mm:ss.fff"));
}
catch
{
return("[" + info.ICAO24 + "] AirbornePositionMsg: Error while decoding position");
}
}
else
{
return("[" + info.ICAO24 + "] AirbornePositionMsg:No decoding possible yet");
}
}
/**
* A top-down ADS-B decoder. Use instanceof to check for the message type.
* @param raw_message The Mode S message in hex representation
*/
public static ModeSReply GenericDecoder(String raw_message)
{
ModeSReply modes = new ModeSReply(raw_message);
// check parity; Note: some receivers set parity to 0
if (modes.IsZeroParity() || modes.CheckParity)
{
// check if it is an ADS-B message
if (modes.DownlinkFormat == 17 || modes.DownlinkFormat == 18)
{
ExtendedSquitter es1090 = new ExtendedSquitter(raw_message);
// what kind of extended squitter?
byte ftc = es1090.FormatTypeCode;
if (ftc >= 1 && ftc <= 4) // identification message
{
return(new IdentificationMsg(raw_message));
}
if (ftc >= 5 && ftc <= 8) // surface position message
{
return(new SurfacePositionMsg(raw_message));
}
if ((ftc >= 9 && ftc <= 18) || (ftc >= 20 && ftc <= 22)) // airborne position message
{
return(new AirbornePositionMsg(raw_message));
}
if (ftc == 19) // possible velocity message, check subtype
{
int subtype = es1090.Message[0] & 0x7;
if (subtype == 1 || subtype == 2) // velocity over ground
{
return(new VelocityOverGroundMsg(raw_message));
}
else if (subtype == 3 || subtype == 4) // airspeed & heading
{
return(new AirspeedHeadingMsg(raw_message));
}
}
/*
* if (ftc == 28) { // aircraft status message, check subtype
* int subtype = es1090.getMessage()[0]&0x7;
*
* if (subtype == 1) // emergency/priority status
* return new EmergencyOrPriorityStatusMsg(raw_message);
* if (subtype == 2) // TCAS resolution advisory report
* return new TCASResolutionAdvisoryMsg(raw_message);
* }
*
* if (ftc == 31) { // operational status message
* int subtype = es1090.getMessage()[0]&0x7;
*
* if (subtype == 0 || subtype == 1) // airborne or surface?
* return new OperationalStatusMsg(raw_message);
* }
*/
return(es1090); // unknown extended squitter
}
}
return(modes); // unknown mode s reply
}
