Saturday, July 31, 2010

History and Working of Wide1-1,WideN-1

Under the current "New Paradigm" standards, WIDE1-1 IS treated differently from higher orders of N-N

The whole WIDE1-1, WIDE2-1 construct was invented (it was my proposal years ago) to work around the "brain-dead" firmware limitations in Kantronics KPC3 TNCs. These TNCs are by far the most widely-used piece of hardware for stand-alone digis without a computer in the US. [It's hard to beat the simplicity and low power consumption (15mA at 12 VDC) of a KPC3+radio digi at a remote site.] The problem is that KPCs do dupe suppression on WIDEn-N paths but NOT on plain RELAY or plain WIDE.

On the other hand, many home users operating first-tier low-level digipeaters (that in the past responded to "RELAY") use old TNCs (such as PK-232s, TAPR TNC-2s, MFJ 1270s, etc) that do not have APRS-aware firmware in them. These older devices CAN NOT do n-N decremented SSIDs.

With rapid APRS growth in the early '2000s, the volume of unnecessary APRS traffic due to RELAY and plain WIDE not supporting dupe checking just exploded. A lot of discussion followed on how one could migrate to an exclusively WIDEn-N network (with effective dupe control) while still allowing non-N-N-aware home fill-in digis to remain part of the APRS infrastructure. At the same time, one wanted to prevent home digis from acting on anything but the very first hop of a path.

The solution was the two-part WIDE1-1,WIDE2-n path I proposed.

All home low-level digis set WIDE1-1 as a simple alias to be treated as an ordinary callsign of WIDE1 with an SSID of -1. When a "dumb" home digi hears WIDE1-1 as the first hop in a path, it digipeats it just like any other fixed callsign, marks it as used, and passes the second WIDE2-1 or WIDE2-2 part onward to the next tier of "real" N-N digis. (The home digis completely ignore WIDE2-anything or higher since only WIDE1-1 is set as an alias to digipeat on.)

True high-level WIDEn-N will respond to any value of WIDEn. If a high-level digi (that DOES have proper WIDEn-N support) happens to hear the initial transmission, it will process WIDE1-1 as a decremented n-N, mark it used up and hand the second half WIDE2-n to the next (high-level) digipeater(s).

The difference when monitored off the air after the first hop is that a home fill-in digipeat of the first hop would yield

WA8LMF to APRS via WIDE1-1*,WIDE2-1

while a first hop captured by a "real" decrementing WIDEn-N digi, would produce

WA8LMF to APRS via WIDE1-0*,WIDE2-1

or possibly

WA8LMF to APRS via *WIDE1*,WIDE2-1

if the monitoring TNC's firmware treats an SSID of "zero" as effectively no SSID at all for display purposes.

The low-level WIDE1-1 home digis far outnumber the WIDE2-n "true wides". Beaconing WIDE1-1 as the first hop from aircraft (that have a range of hundreds of miles/km line-of-site) can potentially trigger hundreds of home WIDE1-1 digis simultaneously, when then ALL retransmit to the nearest true WIDEn-N systems. If the first hop from an airborne station is a WIDE2-n only (which the home digis just ignore) a few "true wides" rather than hundreds of home stations will be triggered.

Yes, the whole scheme is a kludge to work around the limitations of 20-year-old "clunker" TNC hardware, but it does kinda' sorta' work.........


Stephen H. Smith wa8lmf (at)
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"APRS 101" Explanation of APRS Path Selection & Digipeating

Friday, July 30, 2010

Airborne APRS Suggestions

> Above altitude of 3000 feet one should use at most WIDE1-1, preferrably no via paths at all.

>> Bob should really write some new guidance on path definitions for flyers.

The recommendation has never changed in the last decade.

NEVER-EVER USED WIDE1-1 !!!! There is no DUPE suppression in APRS for WIDE1-1!.

For BALLOONS, the recommendation is to use a payload with variable paths and rates at altitude and on the ground * OR * if a less-smart payload is used, use WIDE2-2 and no more often than 1 minute. This is not as bad as it sounds. Every digi will ONLY DIGIPEAT IT ONCE (not twice or more) because the New-N paradigm eliminates dupes. And having a new "vehicle" appear in every digi area for a 3 hour mission special event, is no worse than another driver driving though the area.

If a DIGI is causing dupes, FIX THE DIGI! Update to the 2004 New-N Paradigm!!! See

For Aircraft, the PATH is WIDE2-1. There is no reason to need 2 hops on the ground. The plane should not be lost...

NEVER USE WIDE1-1 on any airborne mobile.

Bob, Wb4APR

Wednesday, July 14, 2010

2010 APRS Golden Packet Attempt

On 25 July please consider participating in this year's APRS Golden Packet Attempt along the Appalachian Trail (and Pacific Coast Trail). Please see and also page 99 in July's QST. There is also an effort being made this year on the West Coast see

All it takes is a mobile with a D700 or FTM-350 to drive up to the top of the mountain and park for 4 hours.

Many teams have formed, but the New England area has many gaps from New York to Maine:

  • Sam's pt NY (not manned in 2009)
  • Mt Greylock
  • New Hempshire (innop in 2009)
  • Mt Washington (2009 team all moved to texas)
  • Middle Maine (not manned in 2009)
  • Mt Katahdin (not manned in 2009)

We still have not formed solid teams from these southern sites:

  • Huntsville AL
  • Lookout Mountain TN
  • Roan Mountain NC (maybe)
  • Comer's rock VA (not operational in 2009)(near Wythville)
  • Apple Orchard Mtn (near Roanake

It's a 4 or 5 hour event on Sunday Afternoon and a great way to escape the heat down below by getting up there on the mountain top. If you cannot participate, spread the word, and find an out-doors type that can. Most sites are DRIVE-UP sites, so just about anyone with a car and a D700 or FTM-350 can participate as a temporary digi site after proper set-up.

Think of it as APRS Field Day.

Bob, Wb4APR