• BARC– http://www.barconline.org

• CC ARES– www.barconline.org/about/ares

APRS & YOU

Northern Utah APRS Network

Why We Are Here

• APRS is a powerful tool for emergency management

• Readiness requires skilled reserve of Hams

What is APRS

• Automatic Packet Reporting System

• Packet communication protocol for sharing live data on a network in real time

• Real time tactical communications and display system for emergencies and public service applications (APRS Spec)

APRS Features

• Maps• Messaging• Objects• Bulletins and announcements• Weather station reporting• DX Cluster reporting• Internet access• Telemetry• Voice Alert

History

• Invented by Bob Bruninga, WB4APR in 1992

• The Automatic Packet Reporting Sys-tem was designed to support rapid, reliable exchange of information for local, tactical real-time information, events or nets.

History

• APRS for DOS was the first program

• MacAPRS & WinAPRS 1994 by Sproule brothers

• UI-View—best & most popular

• Many other APRS apps since – runs on Windows 3.x, NT and XP, Mac, Linux, iPhone, Android and DOS

• GPS adjunct came afterwards

Uses• Passive Fun

– Watch the display of many stations– Watch the ISS or PCsat fly by– Watch emergencies in action

• Tracking– Find your buddies– Track your teenager, wife– Balloons, rockets and public service events– Meet hams spontaneously on the road

Uses

• Telemetry– Balloons and rockets

• Post bulletins, event notices and venues

• Send short messages

• Send email

More Uses

• Events– Track the parade Grand Marshal– Track the last marathoner or bike

racer

• Emergencies– Search and rescue– Disaster information– EOC messaging (Single Line)– Track the fire chief

Still More Uses

• Weather monitoring– See wind speeds and temperatures in

the area– Report wind damage– Track tornados

Weather monitoring

• Users can create and move objects such as hurricanes and funnel clouds.

• The objects can be transmitted through the APRS network to the NWS

• Objects could be used to transmit attributes not quantifiable as a number

• Collection of data• Trending Weather Data• Weather Alerts from NWS• Superimposed RADAR

Theory

• Assumptions

• Packet radio

• Digipeaters

• APRS Protocol

• Frequencies

• GPS

Assumptions

• Radios

• Antennas

• PC Skills

How does APRS Work?

• Some details…

Packet Radio

• History– AX.25 protocol was approved by

ARRL in 1984– Came from X.25 protocol (the A is for

Amateur)– Primary difference from X.25 is

allowance for call signs and for unconnected packets

Packet Radio

• Packets – Strings of data bytes called frames– 3 kinds of frames in ordinary packet

• Information (I frame)• Supervisory (S frame)• Unnumbered (U frame)

– 6 kinds of U frames, one is Unnumbered Information frame

– UI frames are used for transmitting data in an unconnected mode

Packet Radio

• In packet radio, qso’s are always between ‘connected’ stations

• Several qso’s can take place simultaneously on the same frequency

• Packet qso’s may be digipeated but by specific stations

How is APRS different from Packet Radio?• Communication is ‘one to many’

• Uses generic digipeating with well-known aliases

• Supports intelligent digipeating to reduce network flooding

• Uses UI frames for messaging, bulletins and announcements

• Provides maps and other features

How APRS uses Packets

• Uses the same AX.25 protocol but only a part of it

• Uses Unnumbered Information (UI) frames exclusively

• Always runs in connectionless mode

How APRS uses Packets

• Frames are transmitted without expecting any response

• Reception is not guaranteed

• Messages work same way but use an ‘ack’ technique

The UI Packet

Destination Address

• From the APRS spec…

Destination Address

• The adr ‘SPCL’ is to be used for special events. APRS s/w should provide for only showing stations with this adr (but it doesn’t).

• Usually just shows the software version. WinAPRS v2.6.1 sets this to APW261

Destination Address

Destination Address

Destination Address

Destination Address

Destination Address

• May also contain– MIC-E encoded data– Other unique encoded data

• No reason to change this since s/w can’t cope

Source Address

• My station call sign

An Intervening Word about Digipeaters• Why do we need them?

– Increase coverage

• Digipeater versus repeater– Voice repeaters operate in duplex

mode– Digipeaters operate in simplex mode– Digipeaters use store and forward

technique

Digipeaters

• Wide area digipeaters– In this area are usually on a tower – Have good antennas and high power– Operate automatically– Operate all the time– Have Battery Backup

Digipeaters

• Fill-In digipeater– Usually somebody’s home station– Should be able to communicate with a

WIDE station– Purpose is to help low powered

stations get to the WIDE

Digipeaters

• WIDE– Examples: KF7VJO-3

• …or not– Examples: W7BOZ

Digipeaters

FIX #1: Phase out RELAY and WIDE Paths (also eliminate TRACE, TRACEn-N):

• The single biggest improvement in the USA was simply getting users to stop using the obsolete RELAY and WIDE paths. The obsolete RELAY and WIDE paths generated multiple dupes in the KPC-3 and PacComm and some other implementations because there is no dupe elimination for dupes heard from other digis. . These obsolete paths generated 3 to 5 times more load on the system than the comparable WIDEn-N path which has perfect dupe elimination algorithms. The fix was easy. Use WIDE1-1 in place of RELAY and WIDEn-N in place of WIDE.

FIX #2: Make WIDEn-N Traceable:

• The original WIDEn-N system was not traceable, making it impossible to do any network assessment or management. . The New-N Paradigm made WIDEn-N traceable!. . (By eliminating TRACEn-N, Sysops can now move WIDEn-N support from the UIFLOOD parameter to the UITRACE parameter.)

FIX #3: Use WIDEn-N everywhere. The New n-N Paradigm Solution:

• WIDEn-N is the most efficient APRS path, but it is vulnerable to out-of area QRM from user settings of large values of N. . Fortunately, under the New n-N Paradigm, existing digis now trap large-N abuse and greatly simplify user recommendations to simply one WIDEn-N path. . The New n-N Paradigm simplifies the APRS network to a few distinct digipeater types:

• WIDEn-N ..- The basis of the New n-N Paradigm. They also support SSn-N for state nets (S overlay).

• WIDE1-1 ...- Fill-In digis (where required only). Set these fill-in digis MYALIAS to WIDE1-1.

• One-Hop .. - These digis force big-N packets to 1 hop in extreme density areas. (LA or Dayton for example)

• PacComm . - These old "T" digi ROMS can still be used locally for up to WIDE2-2 support (with P overlay)

Fix #6, Proportional Pathing for DIGI beacons!

• One of the biggest loads on the network prior to this New-N Paradigm was simply the flooding in all directions at all distances of the individual DIGI beacons. Many digis were sending out their beacon to 4 and 5 hops in all directions every 10 to 30 minutes. There is no need for this spam. . So part of the New-N paradigm was to come up with the Proportional Pathing algorithm that kept the information update rate at 10 minutes in the immediate direct range of the digi so that passing travelers would be informed, but then the rate was much less for more hops to cut overall load on the network and out-of-area spam.

Back to the UI Packet -- Digipeater Addresses• Also known as the ‘unproto path’

• Up to 9 addresses

• Specific or generic aliases• Specified in s/w configuration or in the

UNPROTO command: APRS V WIDE1-1, WIDE2-1

• Represents the route you want your packet to follow

Digipeater Addresses

• Rules of thumb – Don’t use RELAY

– If you can hit a wide, then include it as the first digi in the string

– For maximum range, add WIDE2-2 or WIDE3-3 after a specific DIGI

• Examples:

• APRS V KF7VJO-3, WIDE2-2

• APRS v WIDE1-1, WIDE2-2

• APRS V WIDE3-3

• Anything MORE than 3 should be avoided!

Digipeater Addresses

– You can be really specific about the path• Example:• APRS V KF7VJO-3, REDSPR, BLKMTN would

route you up to Star Valley, nowhere else

Types of Data

• There are ten main types of APRS Data:– Position– Direction Finding– Objects and Items– Weather– Telemetry– Messages, Bulletins and Announcements– Queries– Responses– Status– Other

Data Example

• Position data

Data Extension Example

• PHG extension refers to power, height and gain (also directivity)– Height is above ‘average local terrain’

• Form is ‘PHGphgd’

Frequencies

• VHF 144.39– 1200 baud

• HF 10.15151 LSB– 300 baud

• Satellite– ISS Downlink 145.800, uplink 145.990– PCsat simplex 145.828– 1200 baud

Getting on the Air with APRS – What to Buy/Scrounge

• Details…

Hardware

• Home station requirements– 2 meter radio and antenna– Desktop computer– TNC or soundcard/interface

• Mobile station requirements– 2 meter radio and antenna– Variables

Hardware

• Mobile variables – Track & View– GPS– Laptop– TNC

Hardware

• Mobile variables – Mobile Tracking– GPS– Tiny Track, or Tracking TNC

Hardware

• Mobile variables – Portable tracking– GPS– No computer– Tracker interface device– Power source for portability

Hardware

• Kantronics KPC-3+– Supports single PC Serial Port Tracker– Supports UI Flood Protocol– Current Version is 9.0 – Simple Mobile Operation– Cost $189

Hardware• Kantronics KPC-3

– Good for Home use

– Version 8.2 Supports UI Flood Protocol

– Average cost used: $80

Hardware• KPC-2, KAM, MFJ, others

– Good for Home use

– Low cost

– Check http://swap.qth.com/ for deals

Hardware

• Kenwood Mobiles – TM-D700, TM-D710, TM-D710G

• AV Map

Hardware

• Yaesu Mobiles

• AV Map

FTM-350AR No longer in production

Hardware

– A self-contained tracking/telemetry module• Tiny Trak 4 Kit ($65) Already built ($75)• Tiny Trak 3Plus kit ($33) Already built ($42)

– See http://www.byonics.com/tinytrak/

Hardware

• Computers– Running with a TNC doesn’t require a

fast computer or recent O/S• A slow machine means your maps will

refresh very slo-o-o-oly

– As with all apps, more memory is better

Hardware

• TNCs– Any TNC will do when a computer is

attached.– Old style TNCs may not be GPS

aware, but they work for base stations

Hardware

• Cables– Sources

• Packet Radio.com http://packetradio.com• MFJ http://www.mfjenterprises.com

Hardware

– TNC cables• Computer serial port to TNC

– Unique to your TNC

• TNC to radio mike connector– Unique to your TNC and radio

Hardware

• Consideration for GPS with TNC– 2 serial ports are needed (Unless KPC3+)

– If only 1 serial port is available, can use a “Port sharing” device

Hardware

• GPS Receivers– Must have PC interface port– Must output NMEA messages on the

PC port– Good to have an external antenna for

the GPS– RS-232 or TTL

Software

• WinAPRS– Pros

• Everybody knows about it• Free maps• Can use high quality Precision Maps• Unregistered version has full functionality

Software

– Cons• Help function is bad• Not totally stable• Not everything works• Maps aren’t so good• Expensive to register• Somewhat limited in scope

Software

• APRS+SA– Pros

• Comprehensive functionality• High quality Street Atlas maps

Software

– Cons• No (I said no) help• Hard to manipulate maps• Confusing• Only works with Street Atlas• Have to register to use AGWPE• Expensive to register

Software

• UIView– Pros

• 16 bit version is free, 32 bit version is free too but they request a donation.

• Quality coding• Extensive help files• Any GIF or bitmap file can be a map• Works with Street Atlas and others• Detailed Street level Mapping with Precision

Maps

Software

– Cons• Limited Individual Replay options• Author has passed away and sotware no

longer supported

Software

• Xastir– Pros

• Works on Linux• Good map capability

– Cons• Not a Windows program

Software

• MacAPRS– Shares same code with WinAPRS

Software

• APRSICE/32– Pros

• Follows WB4APR’s APRS spec very well• Maps are available • Connects to the internet

– Cons• Has to be connected to the internet to get

maps• Hard to configure. Especially to use on RF

Software

• My recommendation– Use UI-View with Precision Maps 8

Satellites

• ISS– Excellent signal

• PCsat– Built by Bruninga’s students at

Annapolis

• Find the satellite’s position– http://liftoff.msfc.nasa.gov/realtime/

JTrack/Spacecraft.html

Another way to view APRS

• Internet

• APRS.FI– http://aprs.fi– Great online tracking source. – Does dead reckoning

• FINDU– http://map.findu.com

• Struggling to find a free mapsource

Voice Alert

• Have you ever driven on an all day trip and never found anyone to talk to?

• Have you passed someone with antennas all over the roof of his car, yet, can't raise him at all?

• Have you tried to look through the Repeater Guide to help you find a local QSO repeater, but find the listing of 10,000 mostly silent repeaters daunting, especially while moving?

• Remember, statistically, one out of every 500 cars you pass is another ham! On some interstates, that is one every 10 minutes.

Voice Alert

• Now, imagine a HAM radio radar that automatically alerts you to other mobiles in simplex range, or a dual band radio with a permanent 3rd full-time nationwide Voice Alert CALL channel that is always on. Driving the interstates with such a radio would guarantee you a new LOCAL contact on average about every 10 minutes or so! Amazingly, such a radio does exist, in fact, two of them. Thousands of HAMs have them and most use them every day. But unfortunately, many of these owners, do not fully use the radio to its full potential on the open road and most of the rest of us are unaware of their amazing functionality. The radios, of course, are the Kenwood TH-D7A(g) Handheld the TM-D700/710 and the Yaesu FTM-350R APRS mobile radios. (And any other APRS radio with the TNC connected directly to the discriminator).

Voice Alert

• But in the year 2001 or so, we realized that EVERY single APRS mobile operator out there was driving around with a radio guaranteed to be ALWAYS listening on the same North American Continent wide channel, 144.39. The only problem was they all had the volume turned completely off (who wants to listen to a wall-to-wall packet channel while mobile?).

• Well, it only takes about a second's thought to realize that if we simply turned up the volume to normal level, and set CTCSS-100, then the speaker would still be ALWAYS QUIET, but if someone in simplex range did want to call us, then he could do so with PL-100 and we would always hear the call! Think of it as a 3rd radio in the car. Always on, Always listening for simplex calls, and yet completely silent at all other times. We called this great concept "Voice Alert".

Important Links• NEKSUN APRS http://www.k0ham.com/aprs• Tucson Amateur Packet Radio (TAPR) – http://www.tapr.org• NWAPRS – http://www.nwaprs.org• Bob Bruninga WB4APR’s site - http://www.aprs.org• Tiny Trak - http://www.byonics.com/• Web Tracking - http://aprs.fi• Another Web Tracking - http://www.findu.com• Yet another Web Tracking - http://www.aprs.net• Open APRS Website - http://www.openaprs.net• ARPRICE/32 - http://aprsice.wikidot.com• UI-View Web site - http://www.ui-view.org• Balloon/Rocket tracker - http://www.bigredbee.com• Argent Data Tracker -

http://www.argentdata.com/products/aprs.html• WA8LMF Website - http://www.wa8lmf.net/ham/index.htm• K9DCI APRS Beginner Guide -

http://k9dci.home.comcast.net/APRS%20Beginner%20Guide%20-%20K9DCI%20Ver%205-1.pdf

Questions

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