APRS in Wisconsin

1
APRS in Wisconsin

• The Automated Packet
• Reporting System
• by Michael Martens, KB9VBR and
• Mark Rasmussen, N9MEA

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Overview

• Introduction
• Protocol and Implementation
• Software
• Hardware
• Network

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APRS is

• A one-to-many, unconnected packet protocol.
• A tactical protocol designed for local RF use.
• A protocol with many reporting capabilities.
• A protocol with SMS capabilities.
• A protocol also adapted to the Internet.
• A protocol with extensive flexibility built-in.
• A protocol still under development.

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Introduction

• APRS, the Automated Packet Reporting System, is
  an open system that uses unconnected AX.25 radio
  packets to transmit and collect data. This data
  is usually overlaid on a map

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Uses of APRS

• Using GPS data to track vehicle location
• Sending short, tactical bulletins and messages
  between stations
• Transmitting data collected by a weather station

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The APRS Network

• Home stations
• Mobile and Portable GPS enabled stations
  (trackers)
• Digipeaters (Wide-area and Fill-in)
• Internet I-Gates
• Automatic Weather Stations

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What is needed to begin

• Computer with APRS software installed
• Terminal Node Controller (TNC)
• VHF transceiver and antenna
• GPS required for mobile stations only

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APRS Data Flow
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APRS Frequencies

• VHF 144.39 MHz
• HF 10.151 MHz LSB
• Experimental work is being done on other
  frequencies.

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APRS Raw Packet
Originator
Path
Application
KB9DEDgtAPW251,W9SM-10,WIDE4-4,qAo, N9SDL4457.01
N/08938.76W- WinAPRS 2.5.1 -WIMARWAUSAU -251-
Location
Status
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APRS Paths

• WIDEn-N (ex, WIDE3-3)
• WIn-N (ex WI2-2, keeps packets within the state
  of Wisconsin)
• Named Path (KC9NW-10, KB9VBR)
• Relay and Trace (Obsolete, Do Not Use)

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WIDE and WIDEn-N

• Digipeaters acknowledge WIDE paths
• Home stations should not set myalias to Wide
• WIDEn-N is not the same as WIDE (WIDE3-3 is not
  the same as WIDE,WIDE,WIDE)

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Named Paths

• Most efficient form of message propagation
• Only the station with the matching Alias will
  digipeat the message
• AB9PJ-4, N9QIP-10, K9ABC-1

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WIn-N

• Keeps APRS Packets within a geographic location,
  in this case Wisconsin
• Reduces APRS overload as packets wont propagate
  beyond their geographic confines
• Great for public service event stations (eg
  walks, parades, races, etc)

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Best Path to Use

• In the Wausau area W9SM-1, WIDE2-2
• If you are mobile WIDE1-1, WIDE2-2
• If you dont want your packets to leave the state
  WI2-2

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How APRS Packets Propagate
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APRS Real Time Propagation
http//www.mountainlake.k12.mn.us/ham/aprs
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SSID

• Special Station Identifier (SSID) allows multiple
  stations with the same callsign to coexist on the
  network.
• Home stations have no SSID
• Digipeaters may use the ID -1 (W9SM-1)
• Mobile Stations may use the ID -9 (KB9VBR-9)
• Kenwood APRS radios may use -7 (WA9NBC-7)

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SSID Suggestions

• No SSID - Home Station, Home Station running
  I-Gate.-1 Digipeater, Home Station running a
  Wide1-1 Digi, WX Digipeater-2 Digipeater 2 or
  on 70CM-3 Digipeater 3-4 HF to VHF
  Gateway-5 I-Gate (Not home station) -6 is for
  Operations via Satellite-7 Kenwood D7 HH-8 is
  for boats, sailboats and ships (maybe 802.11 in
  the future)-9 is for Mobiles-10 is for
  operation via the internet only-11 is for APRS
  touch-tone users  (and the occasional
  Balloons)-12 Portable Units such as Laptops,
  Camp Sites etc.-14 is for Truckers-15 is for
  HF

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APRS Software

• WinAPRS/MacAPRS
• UI-View
• APRSDOS
• APRSpoint
• Other platforms include Palm, Linux, Java

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WinAPRS/MacAPRS

• www.winaprs.org
• Very easy to use
• Uses USGS Tiger maps and integrates with
  Precision Maps from Undertow Software
• Also uses old style APRSDOS vector maps.

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UI-View

• www.uiview.org
• Lots of features, more complex interface
• Handles plug-ins. Vibrant developer network
• Uses raster maps. Integrates with Precision maps.
  Plug-ins for Street Atlas, Mapblast, and Tiger
  Maps

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APRSDos

• web.usna.navy.mil/bruninga/aprs.html
• The original APRS application. Development going
  back to 1992
• Very rudimentary maps
• Has satellite tracking features, network
  utilization analysis, and direction finding
  support

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APRSpoint

• www.aprspoint.com
• Easy to use, familiar Microsoft style interface
• Integrates with Microsoft Streets and Trips
  exclusively

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APRS Software
All APRS software applications are shareware and
require a registration fee for continued use.
Registration fees range in cost from charity
donation to around 100. Some applications may
also require you to purchase a map package.
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APRS Hardware

• VHF Transceiver
• Terminal Node Controller (TNC)
• GPS for mobile operation

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VHF Transceiver

• Any 2 meter radio will work as long as it will
  work on 144.390 csq. You will need to make a
  cable to connect mic audio, RX audio, and PTT to
  the TNC.

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APRS Enabled Radios

• Some radios have built in TNCs for direct
  connection to a computer or APRS interaction
  right on the display.

Alinco DR-135
Kenwood D-700A
Kenwood TH-D7A
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TNC

• The TNC, also known as a radio modem converts the
  digital information from the computer and/or GPS
  into audio tones.
• The APRS network runs at 1200 baud
• The TNC communicates with the computer via the
  serial port.

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TNC

• The most common TNC is the Kantronics KPC-3
• TNCs can be purchased used on EBay for about
  40-50. Kantronics TNCs will be higher in price.
• Older TNCs work great for home stations, ex AEA
  PK-12, MFJ 1270 series, KPC-3
• Tiny Trak 3 and 4 - Open Tracker 1 and 2

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Kantronics KPC-3

• About 230 retail
• Has a dual port that allows simultaneous computer
  and GPS connection
• Great TNC choice for running an APRS computer in
  a vehicle

Kantronics KPC-3
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Tiny Trak 4 and Open Tracker 2

• About 65-100 retail
• Has a dual port that allows simultaneous computer
  and GPS connection
• Cheaper than a regular TNC but has limitations

Tiny Trak 4
Open Tracker 2
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Tiny Trak 3 and Open Tracker 1

• About 32 or 33 (kit) - 42 or 46 (built)
  retail
• Has a single port that only allows connection to
  a GPS
• Cheaper than a regular TNC but it only transmits
  data

Tiny Trak 3
Open Tracker 1
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Global Positioning System (GPS)

• A GPS unit is required for real time mobile
  tracking
• GPSs come in many different forms
• Any GPS with NMEA output will work with APRS

Garmin Etrex Legend
Garmin Streetpilot
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Home Station Equipment

• Watching on RF
• Radio
• TNC
• Computer
• Watching on the Internet
• Computer

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Tracker Station Equipment

• There are two ways to send out your position when
  mobile.
• Dedicated APRS system
• Mic-E system

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Dedicated Tracker Station Equipment

• With computer
• Radio
• TNC (High end unit)
• Computer
• GPS
• Without computer
• Radio
• TNC (simple unit)
• GPS

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Dedicated Equipment Pros and Cons

• Pros
• Can watch other units on map and send messages
• Position is sent out at predetermined intervals
• Separate radio system in the car in case your 2M
  voice radio dies
• Separate radio infrastructure in case your
  repeater goes down
• Could also be used as Winlink or Packet station
• Cons
• Another radio in the car
• More 2M RF to interfere with your local repeater
  traffic
• Higher cost because of more equipment

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Mic-E Station Equipment

• GPS
• Cheaper Encode only TNC
• Uses your normal voice radio, no extra radio

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Mic-E Pros and Cons

• Pros
• Dont have to install another radio in the car
• Cheaper than the dedicated equipment way
• Can use the cheaper encode only TNC
• Cons
• Can not track other units on a map
• Can not send messages to other units
• Position only goes out when you talk on the radio
• Position on map could be very old because you
  didnt talk on the radio
• More expensive for the repeater owners
• Wont work on all repeater systems
• No back-up radio if your voice radio fails
• If the repeater fails, no one sees your position

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Putting it all together

• Mobile tracking unit with integrated computer.

GPS
Computer running WinAPRS
Transceiver tuned to 144.390 csq
KPC-3 TNC
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Putting it all together

• Portable tracker box

Tracker
GPS
Antenna
Radio
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Putting it all together
Who could this be?

• Bike Mobile APRS

GPS
Antenna
Radio/Tracker
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Putting it all together

• APRS Home Station- notice no GPS

Radio
TNC
Computer
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Digipeaters

• Digipeaters extend the coverage of the portable
  and mobile units much like a repeater but
  operating on a simplex frequency. They are
  usually located at a high location on a tower but
  can also be located at someones home to help
  fill in a certain area.

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Digipeaters in the NE District

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Estimated APRS Coverage to a Mobile

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APRS Network

• I-Gates are internet gateways that expand the
  reach of APRS worldwide.
• An I-Gate listens to the local RF channel and
  relays the information into an APRS Internet data
  stream.
• I-Gates also relay information from the Internet
  data stream to a local RF station

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Benefits of I-Gates

• Reduces RF network congestion
• Increases the trackability of mobile stations
• Allows RF access of weather service bulletins and
  alerts
• Can set up an APRS station without a radio and
  TNC
• Any APRS station can be queried at www.findu.com
  (map.findu.com/kb9vbr)

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Weather Service Messages

• The National Weather EMWIN data stream is
  injected into the APRS data stream.
• Alerts and messages can be color coded on the
  APRS maps.

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APRS and the Internet

• UI-View radar plug-in superimposes NWS radar data
  onto the APRS screen.
• WinAPRS has a similar feature.

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Weather Stations

• You can also send out your local weather
  information if you have the right equipment.
• 2M radio on 144.390
• TNC
• Weather Station
• Possibly a computer

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Weather Information

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APRS Satellites

• PCSAT2 is the second generation APRS satellite
• PCSAT1, launched in 2001, is no longer fully
  operational
• PCSAT2 launched August of 2005 has returned to
  earth with STS-115 in 2006

• The ISS is capable of digipeating APRS when the
  radio is not used for other activities.

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APRS Books

• APRS, Moving hams on Radio and the Internet
• A good basic introduction to the mode
• OUT OF PRINT
• ISBN 0-87259-916-7

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APRS Books

• VHF Digital Handbook
• Covers APRS, Packet, D-STAR, and more
• 2008 printing, 19.95
• ISBN 0-87259-122-0

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For Additional Information

• Wisconsin APRS discussion group
  groups.yahoo.com/group/wisconsinaprs
• web site http//wisconsinaprs.net
• KB9VBR APRS page www.kb9vbr.net
• Michael Martens kb9vbr_at_wvraclub.org
• Mark Rasmussen n9mea_at_wisconsinaprs.net