Post on 25-Dec-2015
transcript
What is APRS?
Automation of what we doRelay radio messages to their destination
Simplified AX.25 implementation for ease of use
Ad-hoc data infrastructure Cheap GPS location tracking Check weather station data
What is APRS NOT?
NOT a way to pass encrypted data from one place to another
NOT for streaming video or pictures NOT the internet
OK, this is a bit of a lie due to IGates like TF3RPG
I have a smartphone with GPS, why do I care?
Your cellphone has a maximum power of 100mW at ~1-3Ghz
Without Siminn/Vodaphone, you have an expensive brick
APRS can use higher power, higher gain, different frequencies
You get greater control over your data and who sees it.
What do I need to use APRS? You need three parts
Something to generate or process data○ GPS module, weather station, microcontroller
Something that understands AX.25 signalling○ Microcontroller, custom ASIC○ Terminal Node Controller
Something that can transmit/receive radio signals○ You know what this is...
A valid wireless license of course!
Generate or Process Data
http://arduino.cc/en/uploads/Main/arduino_uno_test.jpg
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AX.25 ModemsPortable TNC
TinyTrak4 OpenTracker USB
http://www.byonics.com/tinytrak4/http://www.argentdata.com
AX.25 ModemStandard TNC
http://www.universal-radio.com/used/UW61lrg.jpg
http://wb0wao.net/images/tnc-x.jpg
APRS-ready Transceivers
Kenwood TH-D72A Yaesu VX-8GR
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<yourcallsign>-<SSID>
APRS Callsigns
-0 Primary -1..4 Generic -5 Other net -6 Special -7 Human -8 Boats/RV -9 Primary -10 Internet -11 Balloons -12 Trackers -13 Weather
-14 Truckers -15 Generic
Digipeater“Digital Repeater” Two kinds
WIDE1 (fill-in)WIDE2 (wide area)
Frequency: 144.800 MHz (Europe) You can use other frequencies too!
Digipeater Aliases
All respond to WIDE1 Only WIDE2 responde to WIDE2 If WIDE(n) where n>2,
WIDE2 respond, and relay WIDE(n-1)To prevent packets bouncing forever
Paths
APRS is simplified AX.25AX.25 allows long-range many hopsAPRS intended for local use
SuggestedMobiles: WIDE1-1,WIDE2-1Stations: <relay>,WIDE2-1Airborne: WIDE2-1 or WIDE2-2
○ Low altitude: WIDE1-1
Beaconing
Transmit “something” to every ARPS Station in earshot (usually location)
Set transmit rate according to speed>2 min for driving>20 min for stationary
Position comment“Emergency” will cause people to notice!
ObjectsHamfest, accident, meeting
Sending Messages
You can broadcast or sendSpecific callsignGroupsALL in range
This message can have a position, so people can go there
Internet Gates (IGates)
If you can get to one, you can:Send emailReport position to webpage https://aprs.fiWHO-IS: Lookup info on a callsignCQ Server for APRS QSO
Questions?
Much of this material is from “APRS Beginner Guide 2011 by K9DCI”
There is interest at RU for APRS development
Joe Foley foley@ru.is N1ZRN/TF is an instructor of mechatronics and mechanical design at Reykjavik University