Glossary

A

• Announcement - An APRS message that is repeated a few times an hour, perhaps for several days.
• APRS - Automated Packet Reporting System
• APRS Data - The data that follows the APRS Data Type Identifier in the AX.25 Information field and precedes the APRS Data Extension.
• APRS Data Extension - A 7-byte extension to APRS Data. The Data Extension includes one of Course/Speed, Wind Direction/Wind Speed, Station Power/Antenna Effective Height/Gain/Directivity, Pre-Calculated Radio Range, DF Signal Strength/Effective Antenna Height/Gain, Area Object Descriptor.
• APRS Digipeater Path - A digipeater path via repeaters with RELAY, WIDE and related aliases. Used in Mic-E compressed location format.
• APRS Data Type Identifier - The single-byte identifier that specifies what kind of APRS information is contained in the AX.25 Information field.
• APRS-IS - APRS-Internet System
• Area Object - A user-defined graphic object (circle, ellipse, triangle, box and line).

D

• digi - short for "digipeater"
• digipeater - a "digital repeater," a radio transceiver (often mounted on a hill or mountain) which re-broadcasts the packets it receives over a wide area

F

• findu - a web site at http://www.findu.com which collects APRS data from APRS-IS and can answer queries on the database. Also, generically, the Internet aspect of APRS, though there are many other useful APRS sites

G

• gate - short for IGate
• GPS - Global Positioning System. A //GPS receiver// uses signals from satellites to determine its position. For APRS use, the GPS receiver will then send the location information to a TNC for transmission by radio

H

• ham - a person who uses amateur radio. The origin of the nickname is obscure
• hop - when a digipeater repeats a packet, it's considered a "hop." If a second digi receives the packet from the first digi and retransmits it, that counts as a second hop

I

• IGate - Internet Gateway, a radio and computer setup for receiving packet data via radio and sending those packets to the Internet (via APRS-IS)

P

• packet - a bundle of data (like an APRS user's call sign and location, or a weather station's report on conditions) plus a path and other information, represented as a set of bytes in a computer or transmitted via radio as a series of rapidly-changing tones
• path - a specification of the path a packet should take through the digipeater system. Can be explicit (using the callsigns of the intended repeaters and the ultimate destination) or symbolic, like "WIDE2-2" which digipeaters will interpret to mean "repeat twice."

T

• TNC - Terminal Node Controller. A device which can control a radio and transmit computer data (like a user's call sign and GPS position information) using a series of rapidly-changing tones

V

• Voice Alert - is a way of setting up an APRS station to notify you if other active stations come into simplex voice range