joe foley n1zrn/tf ira meeting 29/3/2012. what is aprs? automation of what we do relay radio...
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
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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 [email protected] N1ZRN/TF is an instructor of mechatronics and mechanical design at Reykjavik University