Annual Golden Packet Event

LEAVE-NO-TRACE: To respect the environment and other outdoorsmen, this will be a low-impact event in a public place. We want to not impact other visitors, yet have a good time and introduce amateur radio to anyone nearby. Same goes for any hikers. We must stay well below the threshold that would trigger concern by any National, State, or local park authority and require copious red-tape. They have event application fees as much as $100 each, so it must be very clear to even the casual observer that this is NOT a park event though we have traditionally used the term event in amateur radio to describe a convergence of activity on-the-air. That is why we have a designated leader at each site to organize any participation without triggering park concern. For 2009 on the AT we luckally got the OK of the ATC Ranger but had to do a lot of explaining to insure the low impact of our plans. One team made the mistake of trying to get an event approval and nearly got denied access to the park. See our attempted letter to try to recover. There is no law or rule against opeating an Amateur Radio mobile in a park, just follow all existing rules and remain no-impact

VOLUNTEERS: We need volunteers for the planned peaks, plus any hikers that want to participate. Due to the criticality of each site to the whole event, it is a requirement to have backup people, and hardware. Also, an extra person to answer any questions of any bystanders. Details for each site are in the links below. Another opportunity would be setting up an amateur radio table at the AT Festival to recruit some hikers into amateur radio. Showing them what we can do with our HT's should have some interest to a few of them. Most day hikers are really into GPS, so why not APRS too? . To sign up as a volunteer, please contact wb4apr at amsat dot org or better, contact the individuals and team leaders for each team on each of the station web pages below. Due to the height of these stations, probably half of all east cost hams can monitor the test in the shaded yellow area shown at right.

APRS BACKGROUND: Although the APRS network provides full coverage along the Appalachians on the USA APRS channel of 144.39 MHz, this national channel is a very heavily shared asset concentrating on local coverage and support. Long haul communications is not possible nor encouraged due to congestion. . This test will use a special uncongested frequency (144.34) just for this one day. Using amateur radio from mountian peaks is part of the peak2peak and SOTA projects, but to reduce the risk of RF congestion, this test is planned to avoid any VHF contest weekend.

SIGNIFICANT APRS CHARACTERISTICS FOR THIS TEST:

The reason for the radio specific requirement is due to the elimination of ALL potential set-up, configuration, and interfacing issues. See below.

STATION AND ROUTE PLANNING: For maximum range between hops, the best path for all trails from Georgia to Maine or San Diego to Seattle, ZIG/ZAGs as shown on the above maps rather than trying to shoot straight along the ridge. The height-above-average-terrain between the peaks along the trail ridge is significanly less than across valleys and drastically limits line of sight distances. . But zig/zagging from the peaks to adjacent mountain ranges and back across valleys, takes advantage of thousands of feet difference in heights above average terrain and allows us to make much greater distances in fewer hops.

GOOGLE EARTH DOES RAY TRACING! (sort of)... See the views created in The free Google Earth to see the RF paths and ground clearance. (anyone can do this). You can also get these views with APRS stations actually plotted on them on both The OpenAPRS and APRS.fi sites. . If you zoom into any of the links below, you can see these 3D views including the heights of The rays.

SOUTHERN HALF OF THE APPALACHIANS ON GOOGLE EARTH. SEE BELOW:

Using this Google Earth Technique, we nailed down Apple Orchard Mountain along the Blue Ridge Parkway with excellent views both north and south as a solid location due to its popularity with VHF Contesters. Also it has three FM repeaters on 146.685, 442.65, 443.3 MHz with PL 100 making path testing easy. From there we explored all options north and south. the view below shows all the possible routes from Springer Mountain in Georgia to Apple Orchard Mountain through the southern Appalachians.

WESTERN I-81 Valley Route: The western route is shown in red via 4 hops. You can see each link in The 4 links below:

We had looked at trying to make a 2 hop path from Clingman's to Apple Orchard via Rogers Mountain, (see path) but it was very marginal and Mount Rogers is all tree covered with no drive-up access. The adjacent Whitetop Mountain has good access and is popular with VHF contesters but is blocked to AO by Mount Rogers.

EASTERN PATH ALTERNATE: We found another 4 hop path around to the east starting with a 68 mile path from Springer Mountain to Whiteside Mountain in North Carolina, then on to Sugarloaf, and to Pilot Mountain and on to AO as shown below. But we never got any volunteers along this route.

Whiteside Mountain to Sugarloaf Mountain . . . 54 miles
Sugarloaf Mountain to Pilot Mountain. . . . . . . 120 miles
Pilot Mountain to Apple Orchard Mtn. . . . . . . . 98 miles

But again, we do not know if those peaks are accessible? But we could activate both paths, and simply include a DWAIT on the eastern path. This would slightly delay those packets and avoid any collisions with the other I-81 path. And it could double our reliability!

NORTHWARD FROM APPLE ORCHARD MOUNTAIN: The best path zig's across the I-81 valley to White Rock Cliff on Little Sluce Mountain on the Virginia and West Virginia line and then on to the Maryland mountains. These links all the way to Mount Katahdin are listed below.

STATION CALLSIGNS-SSID's: Since there are 15 stations, we used the 15 SSID's in sequence for the convenience of knowing the relationships between sites along the way. Specific callsigns have been assigned so that messaging can occur in the blind. Please see the callsign list. The sequence is South to North which is the usual direction of through-hikers who begin the treck in the spring in Georgia and hope to end by the Fall in Maine.

STATION TEXT: Initially, each station sets his position text to include his FCC call and his estimated event-end-time. Something like WB4APR till 1600EDT (meaning 1400 Eastern Daylight Time). But as he begins to see other stations, he can show what he is seeing by including their X# in his text. Example: WB4APR till 1600 QSL:12345689ABC which means WB4APR can see other stations as far south as 1 and as far north as 12 ("C" in Hex) and all stations in between.

FREQUENCY - Packet and UHF coordination: Finding a clear frequency for the 4 hour event is a severe problem. Since the duration of this event is about the same as the duration of a Balloon flight, and just as exciting, we asked the ATV Balloonests if we could operate on 144.34. For simplex voice coordination, the national APRS FM simplex channel of 445.925 is used. In addition, parallel operation of a second APRS station on the national 144.39 can also be used for end-to-end coordination. The below diagrams show how a TM-D7 dual band APRS radio can serve all functions of Digipeater, Text Messagingand Voice coordination. While a D7 HT can be used for the 144.39 normal APRS opertaion.

ECHOLINK COORDINATION: Since this is a communications exercise, we also like to test our ability to establish voice communications with all the sites while we are up there. Each site can call into a conference server set up for this event via a UHF Echolink node near their mountain. To find the nearest EchoLink node please see the Echolink node finder. Its a good idea to get permission to use the local node. We can use this for end-to-end overall coordination from 11 AM to noon. Think of it! End-to-end Voice, end-to-end APRS messaging (on 144.39 via IGates) and hopefully end-to-end APRS on RF alone for the test.

For the 2009 conference node, WB3GXW has offered his *WASHDC* node, number 6154 for this test. Just connect in at 11 AM and join in (AT Stations only).

POSITION PACKET RATES: To maximize the potential for getting messages through, EVERYONE should limit his TX period to no less than 10 minutes to give reasonalbe info latency while keeping background channel loading low. Each digi will hear two other digis direct, but will hear up to 14 other station position reports (using 7-7, 7-7 hops). . So for these 15 position packets, the channel will be blocked for 3 seconds each or 45 seconds total in 10 minutes or about 8%. . This is close to half of the channel ALOHA capacity and leaves plenty of room for the messages. Hopefully Mic-E format will be used for efficiency.

MESSAGE PACKET RATES: The other half of ALOHA channel capacity is for message packets. Using the above logic, once The Phase-I golden end-to-end packets have been successful, Phase-II communications between other stations should be limited to only one message every 10 minutes outgoing too. . During set-up and throughout the test, end-to-end APRS coordination is easy on 144.39 either normal operation or via the CQSRVR with messages to CQ AT CQ AT. (see CQSRVR).

DIGIPEATER HARDWARE: The Mountain top Digipeaters consist of a D700/D710, a mast as required to clear the trees, and a power source. The mimimum test is 3 hours long, but the optional phases can last up to a total of 5 hours, so ample AMP-Hr capacity should be considered. The D700 draws about .6 amps on receive and the D710 about .7 amps, and about say 4.5 amps on TX (medium power 10W). Under normal operation, the duty cycle of an APRS digipeater is typically 20% so the average power demand of the AT digipeater will be about .2 * 4.5A +.6A or about 1.5 Amps per hour. You can either carry a 7.5 Amp Hour battery to the mountain top, or if the day is sunny, a 1 Amp-Hr battery and a 1.5 amp solar panel as shown.

We are requesting that only D700 or D710 radios be used as the digipeater, since there can be so many different ways for a TNC/radio combo to be tuned or set up wrong. Listening to packets on the air, MOST have poor audio, tone, levels, tone inbalance unknown pre-and-de emphasis and deviation settings adding up to 20 dB or more in performance loss. We can eliminate these variables by just using D700's that at least were all set for optimum at the factory, and provide reliable packet operation down to a very good 0.3 uV (-117 dBm).

DIGI SETTINGS: Each digi along The trail will be set to support traceable TEMPn-N packets and the shorter non-traceable HOPn-N path. The two settings are: "UITRACE TEMP" and "UIFLOOD HOP,ID" or similar depending on exact TNC used. Once these settings are in the D700/710, they can actually remain there forever since we want all D700/710's always to be able to at least support the come-as-you-are TEMPn-N backup system. All D700/710's are supposed to be configured with the TEMPn-N support by default for emergency backup communications at any time. TEMPn-N is great for omni-directional temporary communications for special events like Field Day. Here we cannot afford the bulk, however, of the long trace packets using TEMPn-N, so we are using HOP7-7 which should only ID the last digi in each packet.

MESSAGE PATHS: All packets will use the HOP7-7,HOP7-7 path so that packets will go the length of the trail. Using this non-traceable path keeps the packets short. But to resolve any anomolies, the Traceable TEMPn-N paths are also possible for short tests, but these packets grow by 7 bytes at each hop and should be avoided most of the time. No one knows what will happen beyond that.

POSITION PATHS: Using non-traceable HOP7-7,HOP7-7 paths for all position reports, will drastically reduce the length of each packet. As we watch APRS we can see the trail stations appear north and south from each site.

MESSAGE FORMATS: For the official long haul Golden Packets that you want everyone to see, use only BULLETINS (BLN#xxxxx). This eliminates ACKS and QRM, yet lets everyone read the mail. To indicate a specific recepient, squeeze their identifier into the available optional 5 bytes xxxxx, but otherwise the xxxxx is not needed. Stations with D700's must read and delete incoming messages to make sure to keep room for more incoming messages. D710's can hold as many as 100 unread messages. Keep a paper log if you are not using a PC APRS as well.

GOLDEN PACKET TRACING: We only use HOPn-N paths instead of TEMPn-N paths. You can see how these packets would get very long, if TEMP7-7 Tracing was used. The packet can only go 7 hops and would arrive as SGRLOF-14,MTWASH-13,N1CNA-12,GRYLCK-11,SAMSPT-10,CMLBCK-9,GDHILL-8,TEMP7*

But using HOP7-7,HOP7-7 it can go 14 hops and arrive simply as: MDMTN-7,HOP7,MAINE-14,HOP7*. This shows that it took 7 hops to get to Maryland Mountains and then 7 more hops to the MAINE RELAY site.

DUAL SYSTEMS: Each participating digipeater site station should operate with two APRS stations.

2-WAY IGATES PROHIBITED! It would be a disaster if someone brought up a 2-way IGate on the test frequency. But, on the other hand, having a SINGLE monitor-only Igate at each end and in the middle might let the world watch-in. But again, this is playing with fire, and a missconfigured IGate could spoil the entire event.

HARPERS FERRY and TRAIL CONFERENCE DEMO: Another possible volunteer need would be to set up a Ham Radio demo table near the Appalachian Trail Conservancy Headquarters in Harpers Ferry on the test day to monitor the messages and another possible table the week before on 18/19 July at the Biennial Appalachian Trail Festival to promote Amateur Radio to the assembled thousands of hikers attending the festrival in Rutland VT. Other low-key demonstration stations at public areas along the AT would also be welcome.

Is it LIVE or is it Google?: The next two images are the Google View and an actual photo provided by W4WWQ. The ray traced is towards Mt Rogers.

the ray shown is to Rogers Mountain

See slightly more to The SW.. and Hogback to Quirauk

OTHER REFERENCES MAYBE: