APRS Automatic Position Reporting System

1
APRS - Automatic Position Reporting System

• Dennis Kidder
• WA6NIA
• 1 June 2001

2
What is APRS?

• What started out in 1990 as a digital-equivalent
  of voice networks has evolved into the
  RF-equivalent of the Internet. Imagine being
  able to send a short message to anyone, anywhere,
  anytime.

• Automatic Position Reporting System
• Developed (and trademarked) by Bob Bruninga
  WB4APR
• Based on AX.25
• Unnumbered Information packets (UI)
• UI s are unacknowledged
• VHF and HF mobile and fixed operation
• Uses GPS (mobile) or fixed coordinates
• Other terms
• Mic-E -- Mic Encoder, TNC-less encoding of
  location, course and speed
• MIM - Micro Interface Module -- Telemetry TNC on
  a chip

3
More about APRS

• Can be used to send simple text messages
• May be directed to a specific address or
  broadcast
• Text messages are acknowledged
• Beacon can contain other information
• Weather station
• Station status text, e.g., email address, QTH,
  etc.
• Protocol contains encoding for displayed icon
• Can filter on groups
• use special, designated messages
• limits what is displayed
• Applications
• Locating stations in disaster, public service
  events, etc.
• Tracking moving stations
• Simple messaging

4
What is needed for APRS?

• Simple just a computer with Internet connection
• More complex
• Hardware
• VHF -or- HF transceiver
• antenna with vertical polarization
• APRS-ready TNC -or-
• Any APRS software-compatible TNC
• Computer if using APRS software
• Optional NMEA-compatible GPS receiver
• Software
• Depending on radio/TNC, possibly none
• -or-
• WinAPRS -or- MacAPRS
• APRS
• PocketAPRS for Palmtop computers

5
Typical Hardware
Garmin GPS units
StreetPilot
MFJ Data Radio and Kantronics KPC-3
eMap
Kenwood
GPSmap 162

• TH-D7G

TM-D700A
6
GPS requirements

• What is NMEA?
• National Maritime Electronics Association
• Defines standardized protocol used by GPS
  receivers to send coordinates and receive
  waypoints
• TNC or computer receives coordinates from GPS
  receiver
• GPS map displays received stations
• Received from TNC or computer as waypoints
• Displays callsign of APRS station

7
WinAPRS Screen Shots
8
APRSSA Screen Shots
DeLorme Street Atlas Display
Station List
9
How is APRS distributed?

• For small groups, just point-to-point
• For larger areas, uses digital repeaters and
  routing protocols
• Digital repeaters (digipeaters or digis) are
  wildcard named RELAY and WIDE
• RELAY can talk to WIDE or to any local
• WIDE talks to WIDE
• Anyone can run RELAY
• WIDEs tend to be fixed and well known.
• VHF-HF gateways
• Internet gateways
• When configuring an APRS station for packet
  path
• Use RELAY,WIDE,WIDE or,
• Specific callsign of RELAY or WIDE station, if
  known

10
How is APRS distributed?

• Listing of raw packets from WA6NIA-14
• Shows position info, repetitive message (email)
• Shows two specific WIDE digis ...K7GIL-1 and
  W6KRW-2
• Also shows the generic wildcard routes RELAY and
  WIDE

• WA6NIA-14APD214,RELAY,WIDE,WIDE3346.12N/11806.
  37Wk191/000/Mic-E/M0/Off duty.. "42dennis
  wa6nia_at_arrl.net
• WA6NIA-14APK101,RELAY,K7GIL-1,W6KRW-2_at_100347z33
  46.11N/11806.36Wk191/000/Mic-E/M0/Off duty
• WA6NIA-14APD214,RELAY,WIDE,WIDE3346.12N/11806.
  37Wk191/000/Mic-E/M0/Off duty.. "4,
• WA6NIA-14APK101,RELAY,K7GIL-1,W6KRW-2_at_100352z33
  46.11N/11806.36Wk191/000/Mic-E/M0/Off duty
• WA6NIA-14APD214,RELAY,WIDE,WIDE3346.12N/11806.
  37Wk191/000/Mic-E/M0/Off duty.. "4.dennis
  wa6nia_at_arrl.net
• WA6NIA-14APD214,RELAY,WIDE,WIDE3346.11N/11806.
  38Wk191/000/Mic-E/M0/Off duty.. "4(

11
Where do I find APRS on the air?

• HF
• Typical operation is on 30 meters - 10.151 MHz
  (this is actually inside the band limit uses
  AFSK on LSB)
• VHF
• National APRS freq - 144.390 MHz
• This is a very active frequency in Southern
  California
• Something new! ARISS - International Space
  Station
• Uplink 145.990
• Downlink 145.800
• Route info NOCALL

12
Internet Resources

• Information
• http//web.usna.navy.mil/bruninga/aprs.html
• http//www.aprs.net
• http//aprs.rutgers.edu
• http//aprs.org
• APRS servers on the net
• www.aprs.net and mirrors
• connects with Telnet from WinAPRS or APRS
• Provides real-time, world-wide display
• www.findu.com
• Can be accessed by anyone
• example http//map.findu.com/wa6nia-14
• Software sources
• TAPR http//www.tapr.org
• WinAPRS
• APRS
• PocketAPRS http//www.pocketaprs.com

13
Demo Configuration

• In the conference room
• Kenwood TH-D-7G (WA6NIA-1)
• Dual-band (VHF/UHF) data radio with built-in
  APRS-capable TNC
• Garmin eMap GPS receiver with interconnecting
  cable
• Notebook with WinAPRS
• Palm III with PocketAPRS
• In the parking lot
• Kenwood TM-D700A (WA6NIA-14)
• Garmin Street Pilot GPS with interconnecting
  cable
• (No waypoint display NMEA out only)

14
Demo

• WA6NIA-14
• beacons on five minute intervals
• parked in FU parking lot
• WA6NIA-1
• should display WA6NIA-14 and possibly others
• stations displayed depends on nearby RELAY or
  WIDE digi