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[aprssig] Hop Counting (Local Determination)

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Mon Dec 28 21:27:45 UTC 2009


To the powers that be (and the experience of the group),

I'm working on new APRS software and am trying to avoid any hard-coding 
of "knowledge".  However, I'm running into an issue when counting used 
hops to determine if a station is "local" enough for gating message from 
-IS to -RF.  For instance, the following packet was received via RF: 
(yes, the * represents the "used" bit in the AX.25 header)

N8ENJ>R7UV2X,NI4CE-12*,WIDE1*,WC4PEM-14*,WX4MLB-3*,WIDE2*:'n-Fl#&v/]"4$}

Now, "I" know that that packet probably had only THREE hops (NI4CE-12, 
WC4PEM-14, and WX4MLB-3), but without coding the "knowledge" of WIDE 
being a "special" station (and having to hard-code all of the SSn-N 
and/or TEMPn-N and/or anything else that comes up in the future), is 
there any way of convincing a program to not come up with FIVE hops for 
that packet?

Does anyone know the exact algorithm used by UI-View and/or javAPRSsrvr 
to determine "local"?

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32






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