APRS Overview

APRS is a system developed by Bob Bruninga, WB4APR, in the early 1990's. APRS was designed for tracking and digital communications with mobile GPS equipped stations utilizing amateur radio.

The APRS system was designed to support rapid, reliable exchange of information for local, tactical, real-time events or nets. The concept is that each station with new information transmits his new data to everyone in the net and every station captures that information for consistent and standard display to all participants. THE GOAL IS COMMUNICATION, NOT JUST VEHICLE TRACKING. It is ideal for use in Public Service Events, Emergency Operations and Weather Station Reporting/SKYWARN activities.

APRS uses a simplex 2 meter frequency (144.39 across the US). It operates at 1200 baud. There are a variety of APRS station types, just like voice ham stations: Home, Mobile, Portable, Weather, Repeater (digital repeater or digipeater for short), and IGate. Each station consists of a transceiver a TNC and generally a display and (when mobile) a GPS unit.

Any 1200 baud packet TNC will generally work. A soundcard interface on a PC is also very functional and the cost is minimal.

Mobile tracking installations utilize a GPS connection to the radio through the TNC interface, although the "APRS Ready" Kenwood TM-D700 has their own built-in TNC.

A portable tracker is usually low powered-like an HT with a GPS and a TinyTrak3 (www.byonics.com) or a Kenwood TH-D7 with a GPS. These units work well with bike-a-thons, parades and other community events, along with search and rescue operations.

Weather station setups with APRS are similar to normal setups, but the GPS is usually replaced by outside weather monitoring equipment.

IGates are stations that feed data to and from the internet. www.Findu.com is a database archiving weather, position, telemetry and message data.

Home stations usually involve a laptop with a graphical display. The most popular Windows APRS software is UI-View32. You must register the software, but there is no registration fee - it is asked that you make a donation to your local or national cancer research organization. UI-View32 is available at www.ui-view.org

APRS is growing in popularity in East Tennessee; In 2006, I was involved in 4 events where APRS was really used.

In the Knoxville Marathon, APRS was used to track the lead runner and then the last runner. It was accomplished with a Kenwood TH-D7 on a motorcycle following the runners and one APRS station at the Start/Finish line using a Kenwood TM-D700 connected to a laptop running APRS+SA and Delorme Street Atlas USA. We had plans for a couple of portable trackers to help keep track of some shuttle buses, but we had issues that made those inoperable. This event drew a lot of attention to what we could do with APRS from the served agencies.

The next event was a bicycle ride called the Tour de Blount. It was a 25, 50 and 62 mile ride in Blount County. Here we had several more stations - everyone mobile (5 SAG vehicles) had APRS abilities and we had a station setup at Net Control using UI-View with a KPC 3+.

Then there was the Cherohala Challenge - a 115 mile ride with a climb up to 5477 feet. All of the SAG vehicles and a couple of stations at rest stops and another at Net Control had APRS capabilities. It was a route that required 3 repeaters to cover the event, so we were concerned about APRS coverage. We did a lot of pre-event route analysis/testing and used that information to determine the location for our temporary digi's. All-in-all, the APRS coverage turned out to be at least as good as the voice coverage if not better.

And most recently, the Mill House Run. We had 4 total stations involved; one in lead, one in tail, one temporary digi and one display station at the Start/Finish line.

In all 3 events, using APRS provided great benefits to those of us mobile as well as to the event coordinators. As they say, a picture is worth a thousand words.

So APRS is growing, fun and useful. If you would like to learn more about APRS, join the EastTNAPRS Yahoo! group (http://groups.yahoo.com/group/EastTNAPRS) or join us in our weekly APRS net Sunday nights at 8:00 PM on the WB4GBI repeater (146.94) in the Knoxville area.

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