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[aprssig] Appalachian Trail Golden Packet!

Robert Bruninga bruninga at usna.edu
Fri Mar 20 22:09:43 UTC 2009


Been making great progress on picking Peaks along the
Appalachian Trail for the APRS Golden Packet event this July 18
or 19.  Need lots of APRS portable stations along the 2000 mile
route.

Anyway, I just discovered that you can do excellent RF ray
tracing on Google Earth and then just FLY over the landscape and
see the path from one end to the other!  You can even see cars
on the highways!

See the 110 mile RF path from AppleOrchard Mtn to Hoggback and
how Google Earth cleary shows it intersects two other
mountains...  Its just like being there!  See the image at the
bottom of the event web page: www.aprs.org/at-golden-packet.html

Maybe I am just a clueless newbee, and you guys do this every
day, but using google earth for RF paths is fantastic! And its
free!

TO do this, just select PATH between the two points, set the
altitude of the path to be the altitude of the mountains then
click the box that says extend path to ground and you get a wall
from one peak to the other and can see all along the height of
the LOS path above local ground (real earth)...

I bet when you are done, you can make a route and animate a
FLYBY view of the entire route!  But hey, I am only a user for
about 2  hours and I have lots yet to learn..

But this Golden APRS packet event should really get some
shack-potato's out of their caves and playing real radio!

Bob, Wb4APR


> -----Original Message-----
> From: aprssig-bounces at tapr.org 
> [mailto:aprssig-bounces at tapr.org] On Behalf Of Robert Bruninga
> Sent: Monday, March 16, 2009 5:45 PM
> To: 'TAPR APRS Mailing List'
> Subject: Re: [aprssig] Appalachian Trial Golden Packet!
> 
> We now have a target date for the Appalachian Trail Golden
> Packet Event:
> 
> To coincide with the AT annual conference this year on the
> 18th/19th weekend in July.  Can anyone thinnk of any
conflicts?
> Also, some sites can use Field Day the month before to check
out
> paths.  We also now have a web page:
> 
> http://www.aprs.org/at-golden-packet.html
>  
> Bob, Wb4APR
> 
> > -----Original Message-----
> > 
> > Did some more thinking for the Appalachian Trail Golden 
> > Packet.  Here are some possible refinements for the
operations
> plan:
> > 
> > STATION ABREVIATIONS:  We need very condensed station 
> > tactical nomenclature. Ideally we could use a single byte 
> > using A-Z and 0-9 for 36 hops.  But this would be impossible

> > to coordinate, since any change would affect ALL
participants 
> > over the entire 2000 miles.  So I propose two bytes.  We 
> > break the trail into 6 regions where each region should be 
> > able to make the links with 5 or 6 peaks each.  Then we can 
> > refer to the region by first letter and a digit to represent

> > the peak in that region. 
> > 
> >   M# for Maine
> >   E# for New England
> >   N# for Ny/Nj
> >   P# for PA
> >   V# for Virginia
> >   S# for the southern states
> > 
> > STATION CALLS:  We could use ATX-# where X is the byte above

> > and # is the SSID.  (Most APRS software expects at least 3 
> > letter callsigns).
> > 
> > STATION TEXT:  Each station begins with simply his FCC call 
> > as his only position text.  But as he begins to see other 
> > stations, he can "qsl" them by inculding their X# in his 
> > text.  Example:  WB4APR,V1,P6 which means WB4APR can see 
> > other stations as far south as V1 and as far north as P6 and

> > all stations in between.
> > 
> > FREQUENCY:  This will be hard, but we have got to find an 
> > underused packet frequency that is pretty clear along the 
> > entire east coast.  But we can all easily monitor from our 
> > shacks in preparation to find any hot spots.
> > 
> > UIFLOOD PATHS:  We only need to trace the message paths, not

> > the station postions paths.  This will drastically reduce
the 
> > length of each packet.  So we set all portable digipeaters 
> > with UIFLOOD set to HOP and NOID.  This will support HOP7-7 
> > paths for position reports.  As we watch APRS we can see the

> > trail stations appear + and - 7 hops in both directions from

> > each site.
> > 
> > UITRACE PATHS:  The special messages (Golden Packets) will 
> > use the Traceable TEMP7-7 paths for accountability.
> > 
> > MESSAGES:  We will use ONLY BULLETINS (BLNx) say NORTHbound 
> > and only ANNOUNCEMENTS (BLN#) southbound.  This eliminates 
> > ACKS and QRM.  
> > 
> > RE-TRANSMISSION:  This is the key to concise operations, and

> > I am not sure I have a final suggestion here.  But once a 
> > packet has gone 5 or 6 hops or so through a region, the very

> > long traceable path has to be stripped off and re-launched 
> > with a new TEMP7-7 path. My thinking is that this 
> > re-initiation would occur at each of the "region"
boundaries. 
> >  This makes it easy to abbreviate passage along the 5 or 6 
> > hops in that region by simply inserting the LETTER for that
> region.
> > 
> > So a north bound Golden Bulletin would begin at Springer 
> > Mountain as a BLNA, but once it gets through all the
Southern 
> > region peaks to VA, the bulletin would be started over as a 
> > BLNAS (showing it passed through all the "S" southern peaks 
> > successfully).  When it gets to PA, then it would be 
> > regenerated as BLNASV and so forth.  On arrival at Mount 
> > Katadin in Maine it would arrive as BLNASVPNE and would also

> > have the last 7 actual HOPS in its header.
> > 
> > Since the originators call will be lost at a retransmission 
> > station, then the first 3 bytes of the re-transmitted 
> > bulletin will be the originators abbreviation (and a colon).
> > Eample: "BLNASVP ... S1:What hath APRS wrought?"  would be a

> > message originated at station S1 that has made it through
all 
> > the SOUTH, VA and PA peaks...
> > 
> > So to pull this off, we only need to have 7 full function 
> > APRS packet stations at these key regional boundaries for 
> > easy re-entry and typing of the message and all the rest of 
> > the stations can simply be a D700 mobile (or portable KPC-3 
> > TNC digi) parked at the right place!
> > 
> > Oh, we also of course need a UHF voice coordination channel.
> > 
> > SWITCHING PATHS:  To be able to switch between the HOP7-7
and 
> > TEMP7-7 paths for our positions and for our messages, I
> suggest:
> > 
> > 1) use the high power portable digi itself to send the 
> > MESSAGES via TEMP7-7.  And disable its own position packets.
> > 
> > 2) Use an HT or other APRS station to send the local station

> > position via HOP7-7.  It will get picked up by the
co-located 
> > higher power digi and propogated efficiently (without the 
> > cumbersome traceable TEMP7-7 overhead).
> > 
> > Bob, WB4APR
> > 
> 
> 
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