[aprssig] Broken digis (Ohio to Oklahoma and everywhere inbetween)
bruninga at usna.edu
Mon Jul 30 09:11:35 CDT 2007
> OK, maybe I'm one... that needs educating.
> I thought that the 'new paradigm' was just
> [replacing RELAY,WIDE with WIDE2-2]...
> No big deal. It saves a few bytes of bandwidth.
Actually, it cuts QRM from unneeded dupes by a factor of 2 to 5!
That is the main advantage. It changes the worst networks from
wall-to-wall packet where reliability for being tracked is
miserable due to QRM, to one packet only every several seconds
and much higer reliability for local users.
> I never understood... something like WIDE2-1.
> Since that only allows one more hop, why not
> save three bytes and just say WIDE? [or WIDE1-1]
Because we encourage the use of "fill-in digis" and home digis
to support the alias of WIDE1-1 as the replacement for RELAY.
So we encourage mobiles to use the path of WIDE1-1,WIDEn-N so
that the first hop can take advantage of those fill-in digis.
But if the intent is only a total of two hops in an area, then
the path would be WIDE1-1,WIDE1-1. But in this case, the first
hop would be picked up by HIGH digi sometimes, and then it would
cause ALL of those home digis and fill-in digis to respond,
fully flooding the area with hoplessly duplicated packets. To
avoid that problem, the reecommended two hop path is
WIDE1-1,WIDE2-1 which does not cause this triggering of all the
home digis on that second hop.
Hope that helps.
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