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BARC barconline CC ARES barconline/about/ares

BARC http://www.barconline.org CC ARES www.barconline.org/about/ares. APRS & YOU. Northern Utah APRS Network. Why We Are Here. APRS is a powerful tool for emergency management Readiness requires skilled reserve of Hams. What is APRS. Automatic Packet Reporting System

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BARC barconline CC ARES barconline/about/ares

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  1. BARC • http://www.barconline.org • CC ARES • www.barconline.org/about/ares

  2. APRS & YOU

  3. Northern Utah APRS Network

  4. Why We Are Here • APRS is a powerful tool for emergency management • Readiness requires skilled reserve of Hams

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

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

  7. History • Invented by Bob Bruninga, WB4APR in 1992 • The Automatic Packet Reporting Sys-tem was designed to support rapid, reliable exchange of information for local, tactical real-time information, events or nets.

  8. History • APRS for DOS was the first program • MacAPRS & WinAPRS 1994 by Sproule brothers • UI-View—best & most popular • Many other APRS apps since – runs on Windows 3.x, NT and XP, Mac, Linux, iPhone, Android and DOS • GPS adjunct came afterwards

  9. 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, wife • Balloons, rockets and public service events • Meet hams spontaneously on the road

  10. Uses • Telemetry • Balloons and rockets • Post bulletins, event notices and venues • Send short messages • Send email

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

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

  13. Weather monitoring • Users can create and move objects such as hurricanes and funnel clouds. • The objects can be transmitted through the APRS network to the NWS • Objects could be used to transmit attributes not quantifiable as a number • Collection of data • Trending Weather Data • Weather Alerts from NWS • Superimposed RADAR

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

  15. Assumptions • Radios • Antennas • PC Skills

  16. How does APRS Work? • Some details…

  17. 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

  18. 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

  19. 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

  20. 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

  21. 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

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

  23. The UI Packet

  24. Destination Address • From the APRS spec…

  25. 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

  26. Destination Address

  27. Destination Address

  28. Destination Address

  29. Destination Address

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

  31. Source Address • My station call sign

  32. 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

  33. Digipeaters • Wide area digipeaters • In this area are usually on a tower • Have good antennas and high power • Operate automatically • Operate all the time • Have Battery Backup

  34. Digipeaters • Fill-In 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

  35. Digipeaters • WIDE • Examples: KF7VJO-3 • …or not • Examples: W7BOZ

  36. Digipeaters

  37. FIX #1: Phase out RELAY and WIDE Paths (also eliminate TRACE, TRACEn-N): • The single biggest improvement in the USA was simply getting users to stop using the obsolete RELAY and WIDE paths. The obsolete RELAY and WIDE paths generated multiple dupes in the KPC-3 and PacComm and some other implementations because there is no dupe elimination for dupes heard from other digis. . These obsolete paths generated 3 to 5 times more load on the system than the comparable WIDEn-N path which has perfect dupe elimination algorithms. The fix was easy. Use WIDE1-1 in place of RELAY and WIDEn-N in place of WIDE.

  38. FIX #2: Make WIDEn-N Traceable: • The original WIDEn-N system was not traceable, making it impossible to do any network assessment or management. . The New-N Paradigm made WIDEn-N traceable!. . (By eliminating TRACEn-N, Sysops can now move WIDEn-N support from the UIFLOOD parameter to the UITRACE parameter.)

  39. FIX #3: Use WIDEn-N everywhere. The New n-N Paradigm Solution: • WIDEn-N is the most efficient APRS path, but it is vulnerable to out-of area QRM from user settings of large values of N. . Fortunately, under the New n-N Paradigm, existing digis now trap large-N abuse and greatly simplify user recommendations to simply one WIDEn-N path. . The New n-N Paradigm simplifies the APRS network to a few distinct digipeater types: • WIDEn-N ..- The basis of the New n-N Paradigm. They also support SSn-N for state nets (S overlay). • WIDE1-1 ...- Fill-In digis (where required only). Set these fill-in digis MYALIAS to WIDE1-1. • One-Hop .. - These digis force big-N packets to 1 hop in extreme density areas. (LA or Dayton for example) • PacComm . - These old "T" digi ROMS can still be used locally for up to WIDE2-2 support (with P overlay)

  40. Fix #6, Proportional Pathing for DIGI beacons! • One of the biggest loads on the network prior to this New-N Paradigm was simply the flooding in all directions at all distances of the individual DIGI beacons. Many digis were sending out their beacon to 4 and 5 hops in all directions every 10 to 30 minutes. There is no need for this spam. . So part of the New-N paradigm was to come up with the Proportional Pathing algorithm that kept the information update rate at 10 minutes in the immediate direct range of the digi so that passing travelers would be informed, but then the rate was much less for more hops to cut overall load on the network and out-of-area spam.

  41. 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 or in the UNPROTO command: APRS V WIDE1-1, WIDE2-1 • Represents the route you want your packet to follow

  42. Digipeater Addresses • Rules of thumb • Don’t use RELAY • If you can hit a wide, then include it as the first digi in the string • For maximum range, add WIDE2-2 or WIDE3-3 after a specific DIGI • Examples: • APRS V KF7VJO-3, WIDE2-2 • APRS v WIDE1-1, WIDE2-2 • APRS V WIDE3-3 • Anything MORE than 3 should be avoided!

  43. Digipeater Addresses • You can be really specific about the path • Example: • APRS V KF7VJO-3, REDSPR, BLKMTN would route you up to Star Valley, nowhere else

  44. Types of Data • There are ten main types of APRS Data: • Position • Direction Finding • Objects and Items • Weather • Telemetry • Messages, Bulletins and Announcements • Queries • Responses • Status • Other

  45. Data Example • Position data

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

  47. 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

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

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

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