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Live APRS Map for Louisville, Kentucky

Automatic Packet Reporting System (Wikipedia:APRS) is an amateur radio-based system for real time tactical digital communications of information of immediate value in the local area. In addition, all such data is ingested into the APRS Internet system (APRS-IS) and distributed globally for immediate access. Along with messages, alerts, announcements and bulletins, the most visible aspect of APRS is its map display. Anyone may place any object or information on his or her map, and it is distributed to all maps of all users in the local RF network or monitoring the area via the Internet. Any station, radio or object that has an attached GPS is automatically tracked. Other prominent map features are weather stations, alerts and objects and other map-related amateur radio volunteer activities including Search and Rescue and signal direction finding.

APRS has been developed since the late 1980s by Bob Bruninga, callsign WB4APR, currently a senior research engineer at the United States Naval Academy. He still maintains the main APRS website. The acronym “APRS” was derived from his callsign.

In its simplest implementation, APRS is used to transmit real-time data, information and reports of the exact location of a person or object via a data signal sent over amateur radio frequencies. In addition to real-time position reporting capabilities using attached Global Positioning System receivers, APRS is also capable of transmitting a wide variety of data, including weather reports, short text messages, radio direction finding bearings, telemetry data, short e-mail messages (send only) and storm forecasts. Once transmitted, these reports can be combined with a computer and mapping software to show the transmitted data superimposed with great precision upon a map display. 

APRS is also supported by several of the AMSAT amateur radio satellites that orbit the earth, and these satellites can recieve tactical APRS data from amateur radio stations on the ground to the satellite in space, and then relay the APRS information back down to earth covering a great distance between sites. There is even an APRS system on board the International Space Station that many amateur radio operators communicate with on a regular basis as it passes overhead.

A common use of APRS is to provide real time tactical mapping in such situations as search and rescue operations, parades, as well as events such as running and bike races.

Many amateur radio operators maintain high quality weather stations at their home and transmit the data via APRS to participate in the CWOP (Citizen Weather Observer Program). This data is then collected from the APRS system and used by weather services and homeland security.  If you see the little blue WX on the map, that is a APRS station that reports weather data.  You can view graphs of the weather data by clicking on that station to view more information.

While the map plotting is the most visible feature of APRS, the text messaging capabilities and local information distribution capabilities combined with the robust network should not be overlooked; the New Jersey Office of Emergency Management has an extensive network of APRS stations to allow text messaging between all of the county Emergency Operating Centers over radio in the event of the failure of conventional communications.

All APRS messages are delivered live in real-time to on-line recipients. Messages are not stored and forwarded, but retried until timed out. The delivery of these messages is global, since the APRS-IS distributes all packets to all other igates in the world and those that are messages will actually go back to RF via any IGate that is near the intended recipient.

A special case message can be sent to EMAIL and these messages are pulled off the real-time APRS-IS by the WU2Z Email engine and wrapped into a standard Internet Email protocol and forwarded into regular internet email addresses.

Some APRS Websites:

Some popular APRS Programs:
  • http://www.ui-view.org/ - UI-View is no longer being updated since the death of the author but it remains the most popular APRS program on Windows (Free).
  • http://www.agwtracker.com AGWTracker is not a popular as UI-View on Windows yet but its in active development and is starting to look very good.(commercial)
  • http://www.aprspoint.com/ - APRS Point is another non-free APRS program on Windows that has most of the basic useful features(commercial).
  • http://www.xastir.org - XASTIR is a free open-source program that runs on Linux, Mac, and Windows.  It is the most popular APRS program to run on Linux and Mac, and probably second in total users behind UI-View.  It is particularly popular with those that run APRS weather stations.
  • There are also several APRS programs that run on the iPhone which can take advantage of the built in GPS to the iphone and be used to send APRS Tatical position data.  Most of them simultaneously provide real-time APRS maps to the user as well. Here are a couple of the better ones.
    • iBCNU is an APRS GPS position reporting and text-messaging application for the Apple iPhone($1.99).
    • iAPRS is a free APRS GPS position reporting program with a map display. (free)
    • OpenAPRS is an APRS GPS position reporting, map display, messaging and has some extra features such as bearing and distance calculations to other stations.  ($3.99)