[aprssig] Digipeater Symbol Overlays

Kenneth Finnegan kennethfinnegan2007 at gmail.com
Tue Oct 18 15:27:52 CDT 2016

On Tue, Oct 18, 2016 at 10:36 AM, Robert Bruninga <bruninga at usna.edu> wrote:

> If a digi performs differently than others, then we should identify that
> difference.

A digi can respond to WIDEn-N, WIDE1-1, or neither.
A digi can respond to SSn-N, or it can not.
A digi can trap long paths, or it can not.
A digi can have backup power, or it can not.
A digi can be an I-gate, or it can not.
A digi can have an alt-freq input, or it can not.
A digi can be a viscous digi, or it can not.

That is 192 different possible types of digipeaters, which is more than
your 36 codes. Is it more important that my digipeater advertise that it's
a fill-in digipeater, an I-gate, or viscous?There is no way we're going to
be successful encoding all of the operational behavior in just the
digipeater overlay, so I think we should be considering a different
mechanism for advertising those details; my vote is to focus on developing
the station capabilities packet and keep the overlays simple.

On Tue, Oct 18, 2016 at 12:51 PM, Lynn W. Deffenbaugh (Mr) <
ldeffenb at homeside.to> wrote:

> If I'm sitting right next to a (non-differentiated) WIDE1 digipeater that
> is actually Viscous, I could wonder a long time why it isn't digipeating my
> WIDE1-1 packets when in fact, I was also in range of a WIDE2 digi that was
> copying me direct.  Until and unless I hide from the WIDE2 digi while still
> in range of the Viscous WIDE1 digi, I would never see it digipeat.

If you're sitting next to a WIDE1 digi and a WIDE2 digi and you
consistently hear your echo from the WIDE2 digi, shouldn't your first
thought be that Bob's APRS fratricide idea is working? Fill-in digipeaters
are meant to assist low-power trackers get their packets to the local WIDE2
digis, so why would any user care that the local fill-in viscous digi
doesn't seem to be needlessly digipeating them?

Alternatively, if your tracker has longer range than the WIDE2 digi so you
aren't hearing your echo from the WIDE2, then that's all the more reason
why you don't need to be using fill-in digipeaters.

If you're concerned that viscous digipeating is that much of a source of
confusion, then encourage viscous digi operators to use the eXperimental
overlay. Random users in the field stand a much better chance knowing what
the X overlay means than what the V overlay means; I'd bet that even if you
had the comment field be "WARNING! VISCOUS DIGI!" most users wouldn't have
a clue what it meant.

Saying it in comments or capabilities is nice, but that's even more of a
> free-for-all land than the symbols.

Then update the documentation for the capabilities format. If we define a
dozen mutually exclusive symbols, they're going to become just as much of a
Kenneth Finnegan
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