Automatic Packet Reporting System (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.
(A common mistake is what APRS stands for. A lot of websites refer to it as "Automatic Positioning Reporting System", it actually stands for "Automatic Packet Reporting System".)
APRS has been developed since the late 1980s by Bob Bruninga, call-sign 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 call-sign. In the 1990s as GPS excitement dominated many new applications, the "P" was often referred to as "Position" instead of the original "Packet". This skewed the perception of APRS as only a vehicle tracking system. Recently, the community has emphasized the term "packet" in the name, as the system's use and capabilities are far more robust.
The Automatic Packet Reporting System was designed to support rapid, reliable exchange of information for local, tactical real-time information, events or nets. The concept, which dates back to the mid 1980's, is that all relevant information is transmitted immediately to everyone in the net and every station captures that information for consistent and standard display to all participants. Information was refreshed redundantly but at a decaying rate so that old information was updated less frequently than new info. Since the primary objective is consistent exchange of information between everyone, APRS established standard formats not only for the transmission of POSITION, STATUS, MESSAGES, and QUERIES, it also establishes guidelines for display so that users of different systems will still see the same consistent information displayed in a consistent manner (independent of the particular display or mapping system in use).
APRS GLOBAL INTERNET SYSTEM: Although APRS is a local, tactical real-time two-way communications system, the enormous free bandwidth of the Internet was added in the mid 1990's to allow global monitoring of all real-time data from all local communities around the world. Everything on any APRS frequency is being monitored locally and fed globally into the APRS internet system by hundreds of Igates See live list (complete) or a Map of I-G symbols. Not only does this allow for global monitoring of any local activity, it also allows two-way point-to-point messaging between any two APRS users anywhere on the planet (that has an APRS infrastructure). Think of it as everything goes in so it is available to everyone, but the only thing that comes from the internet back to local RF are messages and selected position data requested locally.
Frequency for APRS on 2 Meters is 144.390. (My radio has to be in Digital Mode, "D". I use the IC 746 Pro with SignaLink USB device at home with my laptop.