What APRS is
The Automatic Packet Reporting System (APRS), developed by Bob Bruninga WB4APR, is a shared data channel on 2m used for position reports, weather data, short messages and bulletins. Every station transmits on the same frequency, and digipeaters on high sites relay packets further. Internet gateways, called iGates, pass what they hear to the worldwide APRS-IS network, which is how sites like aprs.fi show stations on a map.
Setting the path
The path tells digipeaters whether to relay your packet. The usual recommendation is WIDE1-1,WIDE2-1 for mobiles and handhelds, which lets a nearby fill-in digi and then one wide-area digi repeat you. Fixed stations on a good site can use WIDE2-1 or no path at all. Longer paths fill the channel with copies of the same packet, so avoid them.
Sending a good beacon
- Use SmartBeaconing in a car, which sends more often when you turn or speed up and less when parked.
- Don't beacon too often from home: every 10 to 30 minutes is plenty for a fixed station.
- Pick a sensible symbol and a short status message, such as the frequency you're listening on.
APRS positions use latitude and longitude, and many stations also send their Maidenhead locator. For the ISS digipeater, the satellite pass predictor shows when it's in range.
Questions
What is the APRS frequency in the UK?
144.800 MHz, the same as the rest of Europe.
What is the APRS frequency in the USA?
144.390 MHz.
What SSID should I use in my car?
-9 for your main mobile. Use -7 for a handheld and no SSID, or -0, for your home station.
Is an APRS passcode secret?
No. It's a simple check derived from your callsign, used only to stop casual misuse of the APRS internet system by unlicensed people.