A distributed listener for the AJAX tracker

$$<CALL SIGN>,<COUNTER D>,<TIME HH:MM:SS>,<LATITUDE DD.DDDDDD>,<LONGITUDE DD.DDDDDD>,<ALTITUDE METERS MMMMM>,<O SPEED KM/H DDDD.DD>,<O BEARING DDD.DD>,<O TEMPERATURE INTERNAL C D.DD>,<O TEMPERATURE EXTERNAL C D.DD>,<O TEMPERATURE CAMERA C D.DD>,<O BAROMETRIC PRESSURE hPa(millibars)>,<O CUSTOM DATA>*<Checksum>

All fields starting with O are optional

The checksum is also optional

example

$$icarus,12342,12:34:17,52.345645,-1.02342,10232,21.35,192.3,15.4,-22.34,-18.27,1232,Blah;Blah;Blah*00

Useful code to calculate checksum

sprintf (checksum, "*%02X\n",gps_checksum(string));

unsigned int gps_checksum (char * string)
{
		
	unsigned int i;
	unsigned int XOR;
	unsigned int c;

	// Calculate checksum ignoring any $'s in the string
	for (XOR = 0, i = 0; i < strlen(string); i++)
	{
		c = (unsigned char)string[i];
		if (c != '$') XOR ^= c;
	}

	return XOR;
	
}

• Adapted version of fldigi with uploading built in, no need to run a seperate python client, will upload status and also receieved telemetry to the server.
• Binaries and Source can be found on Google Code.

• Updated client can be found on the Atlantic Halo Wiki

• Data - http://www.robertharrison.org/listen/view.php
• Map - http://www.robertharrison.org/tracker/

• Most recent position http://www.robertharrison.org/listen/lastpos.php

The callsign ID can also be passed to distinguish between multiple payloads / chase cars etc …

http://www.robertharrison.org/listen/lastpos.php?callsign=horus

Data can now be polled from the listening server using the following script

http://www.robertharrison.org/listen/poll.php?callsign=atlas&lastid=0&format=HTML

There are various options that can be passed

callsign=payload or vehicle name your interested in

format=

• DATA used for parsing by machine <newlines> for each row of CSV data. NB This is the default setting if format is omitted.
• HTML laid out for browser viewing,
• KML used for pumping into Google Earth or Google Maps just past URL into Google maps

lastid=ID of your last data string and only subsequent data will be sent to you. Leave this out and all payload data will be sent.

missionid=ID of historical mission. Leave this out data will be from current mission only. There is no list of historical missions at the moment