Summer 2006 Issue
Building an APRS Tracker
By Carlton Doe, W3DOE
In an effort to build radio skills as a new ham in 2004, I volunteered for several road races and marathon events. I was told by the communication directors that while they appreciated my efforts, I could be more valuable to them if I had an APRS (Automatic Position Reporting System) tracker. This resulted in my first ham-oriented research and construction project: What was APRS and how would I build what everyone called an “APRS tracker”?
This article will briefly introduce APRS and
tell how you can build a simple, low-cost portable tracker. Part 2 will
cover construction of a more advanced and powerful tracker. I should
explain that as a “bear of very little brain,” I built the harder tracker
first before building the one featured in part 1. I did learn a lot in the
process, though, resulting in what I think is the simple and elegant
“nimble” tracker covered here.
The Automatic Position Reporting System was
developed by Bob Bruninga, WB4APR, as an enhancement to regular
packet-mode transmission oriented specifically for publishing
location-based information via RF. There are two parts to an APRS system:
One part transmits where the tracking object is (the job of a tracker);
the second part is the display software which receives APRS transmissions
and plots the position information on maps. There are a number of software
packages, such as UI-View (www.ui-view.org), that can be used to display
APRS data. Some of the packages will only work if connected to a radio
through either a software or hardware interface. Other packages are
internet-aware and can display APRS information gated by digipeaters to
APRS internet-based servers. Digipeaters function like the voice repeaters
most of you are familiar with, although they handle packet-mode traffic.
As a result, you can have a lower power radio yet still achieve broad
distribution of your APRS information.1 Many APRS digipeaters are linked
to internet-based servers which provide a rolling and filterable archive
of position reports the software uses to plot on its maps. APRS software
will not be covered in either part of this article.
Photo 1. The Garmin eTrex GPS receiver and its cabling.
© Copyright 2006, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted.