[aprssig] Help explaining packets

David L. Martin dlmarti at kc2lcf.net
Wed May 11 12:29:41 EDT 2005

> > No we cannot hear each other.
> Actually, you _are_ hearing him via digipeaters and that was my
> question.  My question to Ken was to verify whether he is hearing your
> packets on RF (which is probably the case) via any path.

No I am _not_ hearing him via digi or direct, at least not consistently.
> This is a valid concern and why I believe IGates should not gate to RF
> packets from stations which they have recently heard on RF.

Personnally, I don't understand the need for IGATES to gate to RF at
all.  But I'm willing to concede that this could be important to some

> > I'm working on an APRS diagnostic plan now, I'll send it out 
> > once complete.
> If you look at the packets without considering their origin, your
> diagnostic plan will be incomplete.  You have digipeater anomalies
> (duplicate digipeating when there shouldn't be), client anomalies (some
> send multiple acks, some don't, some multiple acks get killed with digi
> dupe checking), and IGate anomalies (different IGates use different
> algorithms for gating to RF).  This simply emphasizes the problems which
> can occur when attempting multihop messaging in the current APRS
> environment.

Basically my plan entails have a series of listening stations throughout
the state, monitor and time stamp all packets for a 24 hour period.  By
melding the data from the different stations together we could determine
who can hear whom, and what they will repeat.  Using this data I could
write a simulator that would allow us to simulate changing the rules to
determine what is the best solution.

David L. Martin
w0snj at arrl.net

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