Many people and vehicles use APRS to broadcast their location. Their radios act as beacons, and they can be seen online here: http://aprs.fi. (Give it a minute to load – you may have a lot of data to show in your area.) This map provides up-to-date, accurate location information showing people, vehicles, boats, etc., as they continuously transmit packets GPS of data to other APRS-compatible radios. Take a look and see for yourself.
You can see a recent snapshot of APRS activity across the U.S. here, from late 2010: http://www.aprs.org/maps/USA-Turkey-10.png. As you can see, most of the APRS traffic takes place in urban areas or near highways, but plenty of people in rural areas use APRS too.
APRS gives your radio some fascinating flexibility! But what is it? ‘APRS’ stands for Automatic Packet Reporting System, a system developed by Bob Bruniga, whose call sign is WB4APR. (In case you’re wondering why the call sign matters, ham guys like you to know what their call sign is, in case you come across it on the airwaves sometime.)
It’s an interesting, flexible, and useful system, which allows users to transmit text messages, alerts, bulletins, etc., in addition to their GPS coordinates. It’s a form of digital communication that you can use with handheld, mobile, and base station amateur radios.
You might be able to imagine how handy this system would be for people on search and rescue missions or during other emergencies, aside from during everyday communications. A rescuer can transmit his or her location while searching for a victim. A support vehicle on scene or a vehicle on the way to help could be located in an instant on a map, at any time. A standard status report could be given with a few button clicks. That’s cool!
Here are a couple places to learn more about APRS: http://www.aprs.org and http://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System.