Introduction Introductions to APRS Procedure Database Design First Attempts APRS Parser Gazetteer Nearest Road Search Polygon Searching Traffic Maps Conclusions Acknowledgements
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Thousands of amateur radio operators drive around the United States each day transmitting their latitude and longitude to anyone listening. Tens of thousands of companies use Automatic Vehicle Locating technology to dispatch and track their fleets. Police, fire, and emergency medical service groups use Global Position System (GPS) tracking equipment for their day-to-day operations. A wealth of geospatial data is generated each day from these activities and many more. The purpose of my project is two-fold: to develop techniques and a system for effectively collecting this data, and to analyze the data to provide useful output products.

The first system, used by amateur radio operators, is called Automatic Packet Reporting System or APRS. APRS was developed in 1992 by Bob Bruniga as a means of tracking Naval Academy boats during summer cruises. Since then it has evolved to become a complex mesh of protocols for transmitting position, weather, messages, and status information by way of digital packet radio. In most cases APRS uses GPS for determining the user's precise latitude, longitude, and elevation anywhere on earth. The position is digitally encoded into a packet radio signal then transmitted by VHF radio. Other information can be included with each transmission such as course of movement, speed, messages, and text-based status information.

From 1992 until 1996 APRS was a collection of radio-based networks spread out across the country. For people to communicate with each other they had to both be within range of the same radio network. In 1996 Steve Dimse developed a means of combining all of the different networks into a common APRS network on the Internet. In each area with a radio-based network there would be an IGATE computer running special software to receive the messages from the radio and transfer them to Dimse's Internet server. Once the data was combined at the Internet server, anybody could connect to it and receive an aggregate stream of all of the information from all of the networks. When Dimse's system first came online he was aggregating data from San Francisco, Los Angeles, Nashville, Atlanta, Miami, and New Jersey. The data represented, at most, a few hundred users, accounting for a few thousand packets each day. Since 1996 APRS has grown in leaps and bounds. Amateur radio operators all around the world are building APRS networks. Today the APRS Internet stream aggregates over 600,000 packets per day from thousands of networks and users around the world.