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[aprssig] PATH clarification when travelling

Stephen H. Smith wa8lmf2 at aol.com
Fri Jul 29 17:54:48 UTC 2005

smithb at bpsmicro.com wrote:

> [Apologies if this gets posted twice...]
> Okay, I *think* I'm pretty clear on the new paradigm, but there's one 
> lingering question to toss out. It involves a mobile taking a trip 
> that'll involve travelling through areas that have upgraded to the new 
> paradigm, and some that haven't.
> If one were to set the path to, say "RELAY,WIDE1-1,WIDE2-1", would 
> that be the best compromise? I'm well aware that stopping to change 
> the path as you entered each area would be ideal, but without adequate 
> info (eg. a centralized database) of what PATH works best in what 
> areas, that's a tad difficult (not to mention inconvenient in some cases).
> Specifically, if I'm in an area where RELAY has been discontinued, and 
> a local digi hears the above packet, will it just ignore the RELAY and 
> deal with the WIDE1-1? Or will the fact RELAY is in the packet cause 
> the whole thing to be tossed out?
> Brad.

Packet paths are processed SEQUENTIALLY, not in parallel.   The first 
hop in the string MUST BE USED FIRST before any subsequent hops are 
acted on.    If RELAY doesn't get processed first, and marked as "used" 
in the example above, you are not going to go anywhere!    A full 
discussion of this issue is on my website at:

In the case of the D700, or a TinyTrack, alternate paths can be stored 
in the device (5 in the case of the Kenwoods, 2 in the case of the 
TinyTrack) and then selected as needed enroute.     You might store a 
path of  "RELAY, WIDE, WIDE2-2" in one mode,  and "WIDE2-2" or "WIDE1-1, 
WIDE2-2" in the other. 

Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
Home Page:          http://wa8lmf.com

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