XML Message Description

[FarnboroughUser]

Firstly, Great Product!

I'm using the XML datafeed provided by the system. The user manual describes the XML formatting to one level of detail but doesn't give some important information.

1. The units of the value. For instance, the example altitude is 120300. I'm guessing it's in feet, but that must have been Concorde. Am I right? Similarly, the groundspeed, vrate and airspeed values have no units. I surmise that latitude and longitude to be in degrees displayed as a real number, rather than minutes and seconds.

2. There is no information as to which XML fields will be present. The example telnet output shows that groundspeed, vrate and airspeed to be optional, i.e. they don't appear in all the displayed records. Are all fields optional other than datetime, modes and the latitude/longitude pair?

Thanks for your help.

[Allocator]

Hi there and welcome to the forum!

I presume that you have read this FAQ:

http://www.airnavsystems.com/forum/index.php?topic=9.0

The formats are as follows:

<MODESMESSAGE>

   <DATETIME>20070622141943</DATETIME> -  YYYYMMDDHHMMSS

   <MODES>400F2B</MODES> - 6 figure Hex code

   <CALLSIGN>BAW134</CALLSIGN> - Alpha numeric (7 chrs maximum)

   <ALTITUDE>120300</ALTITUDE> - Altitude in feet amsl (not a good example, must be a typing error or an incorrectly reading Mode S box!)

   <GROUNDSPEED>451</GROUNDSPEED> - In Nautical MPH

   <TRACK>234</TRACK> - Degrees magnetic relative to magnetic north

   <VRATE>0</VRATE> - > Rate of climb or descent in feet per minute with climb being “+” and descent “-“

   <AIRSPEED></AIRSPEED> - In Nautical MPH

   <LATITUDE>-14.1102</LATITUDE> - Decimal degrees of Latitude, with East being “+” and West “-“

   <LONGITUDE>-31.5789</LONGITUDE> - Decimal degrees of Longitude, with North being “+” and South “-“

</MODESMESSAGE>

And yes, the data is "optional" as some or all of it might be sent by the aircraft.  All units are standard aviation units.

Hope this helps.

Allocator

[FarnboroughUser]

Hey, thanks for the information and quick response.

I got the sample data out of the manual (page 75). Coming from the ATC world, altitude is usually Flight Level (100's of feet) but I realised that 120300 was unlikely to be one of those.

Regarding the optional data, reading the previous posts on the data feeds it seems that the unit doesn't broadcast those messages that don't contain a position. Therefore was I right in saying that the datetime, modes and position fields will always be present as the message is useless without the time it is valid, the aircraft it is for and isn't output unless it has a position?

Thanks once again.

[Allocator]

The display of Flight Levels, be it on a radar screen or on the RadarBox map, is purely a result of data processing.  The Mode S box sends its data in feet.

You must be right regarding time having to be present, as the XML data is time stamped and I presume that this comes from the PC clock?

I think I remember the "non-positional" reports being discussed in another thread.  I think that the answer was that these don't appear in the port 7879 XML output.

Of course, there is the Port 30003 data to play with too.  This comes out as comma delimited and the format is roughly similar to that output by the SBS-1.  It imports well into MS Excel, and if you are clever enough with vba (I'm not), you could have a live display of data as used in Dr Allan's Overflight Logger which mostly works OK with the RadarBox output.

Either way, I think that there are a number of people here who would be interested in an XML data processing utility.

[jmhayes]

Of course, there is the Port 30003 data to play with too.  This comes out as comma delimited and the format is roughly similar to that output by the SBS-1.

Maybe I'm being dense, but I don't see any hex codes in the 30003 output.  Is there a description of this data and maybe a clarification of what you mean by "roughly similar" ...?  Thanks!