Automatic Packet Reporting System (APRS) is an amateur radio-based system for real time tactical digital communications of information of immediate value in the local area. APRS is digital communications information channel for ham radio. As a single national channel, it gives the mobile ham a place to monitor for 10 to 30 minutes in any area, at any time to capture what is happening in ham radio in the surrounding area. Announcements, Bulletins, Messages, Alerts, Weather, and of course a map of all this activity including objects, frequencies, satellites, nets, meetings, hamfests, etc. The APRS network has grown to most countries with strong Amateur Radio populations.
Tips
Dash Number after the Call Sign
Packet requires (as does the FCC) your call sign. This is the FROM part of the AX.25 protocol and is your own call sign. For a fixed station, this is enough. The dash number is an OPTIONAL Secondary Station ID (SSID) and it allows you to have and then distinguish between your multiple APRS stations. It can provide a little additional information about your station. It is not a requirement.
The dash number after your call sign is the symbol you display on the map software or internet.
Update: I don't know the relationship between this field and the field that truly conveys your station type. The table below is from a source. This number after the dash communicates "something" however is not what tells APRS trackers your station icon type.
- -0 Home Station, Home Station running IGate.
- -1 walking ?
- -5 IGate
- -7 HT
- -8 is for boats, sailboats and ships
- -9 is for Mobiles (aprs in your car)
- -14 is for Truckers
APRS Symbol aka Icon Field
Some programming software will label this "Symbol" or "Icon 1". It will be populated with two ASCII characters. The first character selects the table (primary or secondary) and the second character selects the symbol from that table. Some programming software will present you with images representing the symbols (like a picture of a running man, a picture of a car, a boat, and airplane) as an image icon while other software simply displays the ASCII characters. If the programming software does not use image icons then as an example the running man icon is represented as /[ (forward slash, forward square bracket); the car is /> (forward slash, greater-than).
Path
In sparse areas where IGates are few, start with the above, however, you may change to WIDE1-1,WIDE2- 2. The –1 and –2 add to indicate 3 hops.