The APRS Network

1. The APRS Network Presented by Wes Johnston, KD4RDB kd4rdb@usa.net

2. Overview of this slide show Introduction Software and features Protocol and implementation Hardware Network

3. Introduction APRS is an open system that uses unconnected packet radio to transmit and collect data. This data is usually overlaid on a map You can find APRS: 2m, 6m, 20m, 30m, CB, GRMS, TCP/IP National Hurricane Center, Miami Florida MIR, ICOM Funmobile

4. Versions Versions of APRS are available for: • DOS, Win3.1, Win95/98/NT • MacOS • APRS Plus • JAVA • Interactive Web Browser

10. Maps • GIS • Tiger • Commercial Street • DEM • Contour

16. Station Status • Latitude and Longitude. • 200 Icons: • Power Height and Gain

17. Messages • Messages are the only APRS packet type that is acknowledged. • Announcements are not acknowledged; they are repeated at various intervals for either 4 hours or 4 days. • Can be sent over RF or Internet or combination of both.

18. Telemetry • NMEA data from GPS receivers • Mic-Encoder packets • Weather data from Peet Brothers weather station • Voltages, Water levels, Temperatures

19. Objects • Can be created by any station • Can be moved or updated by any station • Can contain additional information such as course and speed, wind speed

20. Hardware Ordinary hardware: • TNC, Radio, GPS, Weather Station Exotic Hardware: • Mic-E, Trackers, DFjr, Kenwood TH-d7

21. TNC The TNC is the connection between computer and radio. • Many features: • GPS compatible • Low power consumption • Advanced routing • Multiple serial ports • Telemetry

22. Radios • Cost between $79 and $150 • Data radios require DCD “true carrier detection” type TNCs

23. GPS • Inexpensive - $85 to $300 • 12 Channel Receivers common • DGPS signal available from the Coast Guard on 200khz

24. Weather Station • Support for many models • Peet, Davis, Radio Shack, Heath • Peet can hook directly to TNC • Data can be graphically trended by APRS

25. MIM and MIC-Encoder • Transmit only TNC • GPS and analog values • Works over voice repeater or on digital channel • Voice Repeaters can mute ‘packet racket’

26. Trackers • Built into waterproof containers • Usually mag mount on roof • Remotely administered • Run for 8 to 12 hours

27. DF jr • Plots lines right on maps • 4 antenna array • Resolution of 2° • Interfaces with TNC and GPS

29. Kenwood HT • Built in 1200 and 9k6 TNCs • 2 serial ports for GPS and Laptop • Transmit and receive APRS formatted messages • Shows icon, distance and bearing to 40 stations and can plot stations on GPS as waypoints

30. Network Infrastructure The network uses identically named digipeaters. All APRS digipeaters are nationally coordinated on 144.39Mhz. Types: • RELAY - every station is a relay • WIDE - digipeater higher than 100 feet • WIDEn and TRACEn - special software

31. APRSDIGI • 286 PC becomes an APRS “super digi” • On the fly compression • WIDEn, TRACEn and call substitution • Remotely trend channel usage

32. Traknet • Mobiles in isolated areas can hit satellites with 10 watts and a 5/8 wave on 144.90 • $3 XOR chip can convert TNC to PSK at the flip of a switch • Ground stations receive data and post to ARPSERV

33. Internet The internet is used to interconnect cities that are too far apart to have reliable connections via radio. Precautions have been taken to insure non-hams cannot get on the air. • JAVA Web browser: http://www.aprs.net • Telnet: WWW.APRS.NET:10151

34. Time of Emergency • An APRS field station can be assembled in minutes with any computer from a 286 to a Pentium. Old monochrome laptops are ideal. • ZIP LAN - many PC’s, 1 TNC • Works with any voice grade radio • Any station on the air becomes digipeaters if primary digipeater is damaged

35. National Weather Service Local NWS office can publish storm warnings on a county by county basis. Affected counties will appear in silhouette

36. For additional information • TAPR APRSSIG news group • http://www.tapr.org/tapr/html/sigs.html • World Wide Web • http://www.qsl.net/kd4rdb • Email • kd4rdb@usa.net