• 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
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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 System 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
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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 wellknown 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:
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WIDEn-N is the most efficient APRS path, but it is vulnerable to outof 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
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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
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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:
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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, TMD710G
•
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
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Everybody knows about it
Free maps
Can use high quality Precision Maps
Unregistered version has full functionality
Software
– Cons
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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
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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/JT
rack/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
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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
• ??