Joe Foley N1ZRN/TF IRA Meeting 29/3/2012

What is APRS?  Automation of what we do Relay 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

AX.25 Modems Portable TNC TinyTrak4OpenTracker USB

AX.25 Modem Standard TNC

AX.25 Modem Arduino Argent Radio ShieldTrackuino Shield: Arduino is the TNC!

APRS-ready Transceivers Kenwood TH-D72AYaesu VX-8GR o/Portables/TH-D72A

- APRS Callsigns  -0 Primary  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: 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.25 AX.25 allows long-range many hops APRS intended for local use  Suggested Mobiles: WIDE1-1,WIDE2-1 Stations:,WIDE2-1 Airborne: 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!  Objects Hamfest, accident, meeting

Sending Messages  You can broadcast or send Specific callsign Groups ALL 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 Report position to webpage WHO-IS: Lookup info on a callsign CQ 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 N1ZRN/TF is an instructor of mechatronics and mechanical design at Reykjavik