1. Ken Adkisson, WB4FAY www.wb4fay.com wb4fay@wb4fay.com
Introduction to APRS
Ken Adkisson, WB4FAY
Intro myself

2. Topics to be covered What is APRS? Why do I want APRS?
How do I view APRS?
OK, now how do I go mobile?
Current software
The internet piece of the puzzle
Upcoming goodies

3. What is APRS Automatic Position Reporting System
By Bob Bruninga, WB4APR
Brief history
tell about how Bob originally used it to track boat races.

4. History of APRS
Initial use as we know it in 1990 to track boats during summer cruises. The following flavors followed.
MacAPRS
WinAPRS
APRS+
pocketAPRS
PerlAPRS
XAPRS

5. Why do I want APRS? For Starters….
Ok, Joe Ham tells me he has a bike rider down but has no clue were he is.
Or, Joe Ham has hail coming down and still has no clue were he is.
Joe Ham is part of a disaster evaluation team.
elaborate on uses, Skywarn, bike rides, Red Cross assistance, general public service, balloons, DF, messaging

6. How do I view APRS?

7. Software There are many flavors to APRS DOS APRS WinAPRS and APRS+SA
XAPRS for Linux
pocket APRS (Palm Pilot)
APRSdigi and Uidigi (digi software)
PerlAPRS

8. OK, now how do I go mobile? TNC route Mic-E route Soundcard as TNC
GPS receiver
Do I have/want to use a laptop ?
Use Sound Card for TNC ?
address laptop config
HSP, PCM serial port card or a tnc with software serial port.

9. Mobile Equipment tell about each item
starting with mic-e and gong clockwise
mic-e
gps engine for mic-e
tnc
pic-e
talk about laptop and serial port issues.

10. TNC Verses Mic-E TNC route requires a separate radio
Mic-E can go in-between radio and microphone
Either route can be run on separate radio
Either route is referred to as a “TRACKER”

11. Definitions A tracker is a mobile station Posits are position reports
UI Frames are frames that do not employ error correction techniques, entirely that is.
Digipeaters are stations that act as a simplex repeater except in a digital format
IGATES are stations that feed data to and from the internet

12. Definitions
GATES are stations that take the HF APRS data and retransmits them on VHF and possible the internet.
IGATES are stations that take the APRS data and retransmits it between an RF channel and the internet.
APRServers are stations that IGATES send data to and redistribute them to the IGATEs

13. How does it work, basically?
A tracker or fixed stations sends out a UI frame that has lat/long and possibly other data (e.g. altitude, course, speed, wx info, etc.)
If the packet burst passes the checksum, the info is then displayed on the screen.
If the checksum fails, the packet is lost. This is not a big deal since the posit will be transmitted again soon.
Check sum failure: if the checksum does fail, the fact that the packet will be retransmitted in a relatively short time frame will improve chances of the packet being received.

16. The Next Level IGATES, why would I want to do this?
IGATES provide a feed to the net so everyone can see what is going on and allows for messaging on a world level
Balloons, mobile stations, weather events you want to track, using automated watch/warning data to transmit in your area.

17. What else can I do with APRS
Connect your weather station
DF abilities
track vehicles (balloons, trucks, space vehicles, hurricanes)
messages

18. Guy Story:
W8XF balloon launch on The X indicates max altitude achieved.

20. Digipeater does and don’ts
Don’t use wide, wide wide or relay, wide, wide. This can lead to channel saturation due to unneeded duplicate packets.
Use no more than 2 wides or a wide then a relay in a unproto path
Use discrete calls when possible.
Alias’ can be used but with restraint.
Base stations need to use discrete calls in unprotopaths after a path has been determined.
The digis located on this page are all at high altitudes. Unless you are the only station in the area, homes or stations that are at lower altitudes should not use WIDE in the alias list. Relay is prefered. All other stations on this page are home stations or at city facilities.

21. Other station tips What is my tnc deviation?
The target is 3 kHz deviation
Greatly improves channel throughput.
Go to for more data.
Open squelch??????
Hidden and deaf transmitters
Deviation is probably one of the most important aspects of packet. If the deviation is not set right then the tones may not get decoded correctly if at all. The end result is increased activity on the channel for the wrong reasons. The retry rate goes up dramatically.
Can you run open squelch? Many tnc’s can be modified to do so. This will increase your ability to rx weak signal stations. This helps reduce collisions and reduce the turn around to ptt time. Reduces hidden transmitters.
A hidden transmitter is a station that few people can hear. This is why hts are not ideal.
Deaf transmitters/trackers. Please avoid if you can. While it is not discouraged to use deaf transmiters it hurts channel througput. A deaf transmitter does not have the abiltiy to hear if the channel is active or not. This will cause a collision.

22. Captured screen shot showing the storms of Sunday evening, November 10, 2002.

23. Captured screen shot showing the storms of Sunday evening, November 10, 2002.

25. Findu.com screen shot from Sunday, November 10, 2002

26. Findu.com screen shot from Sunday, November 20, 2002.