Finally, I’ve gotten my APRS stations coordinated. I have a weather station transmitting via TCP/IP APRS, my iPhone portable station transmitting via TCP/IP APRS, and my mobile station transmitting via RF (using a TinyTrak4 by Byonics).
APRS works by sending a digital packet of information, via RF, to a receiving station (anyone can have a receiving station at their house with a receiver, computer, and Internet service), and then that station (referred to as an iGate) sends the information to the APRS servers via the Internet. The default 2-meter frequency used is 144.3900MHz, and so as you’re out driving (for example), you set your transceiver to 144.390, turn on your APRS TNC (in my case, a TinyTrak4), and it does the rest.
There are also “digipeaters” that listen for your packets and repeat them again, so they may be passed to an iGate, to be uploaded to the Internet APRS servers. I have my TinyTrak4 set up as a digipeater to repeat any path requests with “TEMP” or “SAR” in them. That means if my station hears another station with “TEMP” or “SAR” programmed in, it will repeat it for them. I do this because “TEMP” is used for temporary situations, such as Field Day or perhaps emergency or other situations, and “SAR” is used for search and rescue operations. If I participate in such events, I’m already set up to be of assistance by helping to get their packets out to an iGate, which can upload them to the Internet APRS servers.
There’s lots of reading out there on APRS; just go to Google and type in APRS Amateur Radio!