1. Demonstration • WinAPRS Running with TNC

2. Welcome • FWARC APRS Clinic

3. Why We Are Here • APRS is a powerful tool for emergency management • Readiness requires skilled cadre of Hams • Federal Way is not an APRS hotspot

4. Our Sponsor • Weyerhaeuser Foundation • Making WAVEs • Weyerhaeuser Active Volunteer Employees • Grant to FWARC for this activity

5. CD • WinAPRS, UI View and APRS+SA programs • AGWPE program • WinAPRS map files • Setup information • APRS Spec • Satellite tracker programs

6. Other Sources of Information • Tucson Amateur Packet Radio (TAPR) – http://www.tapr.org • NWAPRS – http://www.nwaprs.org • http://aprs.rutgers.edu • Use Google to search • Books – check what’s available from ARRL

7. What is APRS • Automatic Position Reporting System • Packet communication protocol for sharing live data on a network in real time • Realtime tactical communications and display system for emergencies and public service applications (APRS Spec)

8. APRS Features • Maps • Messaging • Objects • Bulletins and announcements • Weather station reporting • DX Cluster reporting • Internet access • Telemetry

9. History • Invented by Bob Bruninga, WB4APR in 1992 • Devised to facilitate short haul, short duration data transfer – conventional packet was not suitable

10. History • APRS for DOS was the first program • MacAPRS 1994 by Sproule brothers • WinAPRS is recompiled from MacAPRS • Many other APRS apps since – runs on Windows 3.x, 9x, NT and XP, Mac, Linux, Palm, CE and DOS • GPS adjunct came afterwards

11. 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 • Balloons and rockets

12. Uses • Telemetry • Balloons and rockets • Post bulletins, event notices and venues • Send email

13. More Uses • Events • Track the parade Grand Marshal • Track the last marathoner or bike racer • Emergencies • Search and rescue • Disaster information • EOC messaging • Track the fire chief

14. Still More Uses • Weather monitoring • See wind speeds and temperatures in the area • Report wind damage • Track tornados

15. Theory • Assumptions • Packet radio • Digipeaters • APRS Protocol • Frequencies • GPS

16. Assumptions • Radios • Antennas • PC Skills

17. How does APRS Work? • Some details…

18. 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

19. 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

20. 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

21. How is APRS different from Packet Radio? • Communication is ‘one to many’ • Uses generic digipeating with well-known aliases • Supports intelligent digipeating to reduce network flooding • Uses UI frames for messaging, bulletins and announcements • Provides maps and other features

22. 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

23. How APRS uses Packets • Frames are transmitted without expecting any response • Reception is not guaranteed • Messages work same way but use an ‘ack’ technique

24. The UI Packet

25. Destination Address • From the APRS spec…

26. 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

27. Destination Address • May also contain • MIC-E encoded data • Other unique encoded data • No reason to change this since s/w can’t cope

28. Source Address • My station call sign

29. 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

30. Digipeaters • Wide area digipeaters • In this area are usually on a mountaintop • Have good antennas and more power • Operate automatically • Operate all the time

31. Digipeaters • Relay 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

32. Digipeaters • Wide area digipeaters may be known by an alias • Examples: SOMTN, KOPEAK, SEATAC • …or not • Examples: N7OEP-10, K7NWS-10

33. Digipeaters • Digipeaters respond to certain generic aliases • Relay, used by any station to relay mobiles to a wide • Echo, HF only, same function as Relay • Wide, all high digipeaters • Trace, use call sign substitution to indicate path the packet took • WideN-N, wide digipeating limited to N hops • Gate, HF to VHF connection

34. Digipeaters • Digipeaters only repeat if their call sign, their unique alias, or a generic alias is in the digi path

35. Back to the UI Packet -- Digipeater Addresses • Also known as the ‘unproto path’ • Up to 9 addresses • Specific or generic aliases • Specified in s/w configuration • Represents the route you want your packet to follow

36. Digipeater Addresses • Rules of thumb (see WinAPRS help file) • Don’t use RELAY unless you are a mobile • If you can hit a wide, then include it as the first digi in the string • If you want wide coverage then use WIDE2-2 or WIDE3-3 after a specific WIDE • Example: SOMTN,WIDE2-2

37. Digipeater Addresses • You can be really specific about the path • Example: SOMTN,KOPEAK,MEGLER would route you down to Seaside, OR area and nowhere else

38. Data Field

39. Data Type ID

40. Types of Data • There are ten main types of APRS Data: • Position • Direction Finding • Objects and Items • Weather • Telemetry

41. Types of Data • Messages, Bulletins and Announcements • Queries • Responses • Status • Other

42. Data Example • Position data

43. Data Extension Example • PHG extension refers to power, height and gain (also directivity) • Height is above ‘average local terrain’ • Form is ‘PHGphgd’

44. 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

45. Getting on the Air with APRS – What to Buy/Scrounge • Details…

46. Hardware • Home station requirements • 2 meter radio and antenna • Desktop computer • TNC or soundcard/interface • Mobile station requirements • 2 meter radio and antenna • Variables

47. Hardware • Mobile variables – the Full Meal Deal • GPS • Laptop • TNC or soundcard/interface or Baycom modem

48. Hardware • Mobile variables – minimal functionality • No GPS • Laptop • TNC or soundcard/interface

49. Hardware • Mobile variables – tracking • GPS • No computer • Tracker interface device • Power source for portability

50. Hardware • What is a sound card interface? • Connects the computer’s sound card i/o to the radio mike and speaker terminals • Provides isolation and attenuation • May provide a VOX capability