[aprssig] Airborne Digis

[Gregory A. Carter]

Hi Stephen,

When I pictured that scenario what I really was getting at is, assuming the
WIDE1-1 got fill in repeated first and we're now up to the digi level where
it would see WIDE2-1.  In fact, my question would be more appropriate here:

Tracker TXs: Packet A (WIDE2-1,SAR1-1,WIDE2-1)
Airborne Digi Sees SAR1-1, retransmits using up WIDE2-1*,SAR1-1* leaving
WIDE2-1: Packet B
Mountain Digi Sees original (packet A), digis on first WIDE2-1
Mountain Digi Sees last unused WIDE2-1 from Airborne digi (packet B) and
Digis a second time.

Greg

On Mon, Sep 14, 2009 at 1:40 PM, Stephen H. Smith <wa8lmf2 at aol.com> wrote:

> Gregory A. Carter wrote:
>
>> Hi Keith,
>>
>> I hadn't thought of using: WIDE1-1,WIDE2-1,SAR1-1,WIDE2-1
>>
>> The only down side to that I can think of would be this scenario:
>>
>> Tracker TXs: Packet A
>> Airborne Digi Sees SAR1-1, retransmits using up WIDE1-1*,WIDE2-1*,SAR1-1*
>> leaving WIDE2-1: Packet B
>> Mountain Digi Sees original (packet A), digis on first WIDE2-1
>> Mountain Digi Sees last unused WIDE2-1 from Airborne digi (packet B) and
>> Digis a second time.
>>
>> I am assuming that dup checking on the mountain digi should catch that
>> last one right?
>>
>>
> NO.
> Before "Mtn digi sees original (packet A)", either home fill-ins or other
> Mtn digis have to process WIDE1-1 first.
> No matter what the SARn-N digi does, "normal" digis will process the first
> two hops independently and simultaneously.  All digis including home
> fill-ins will respond to the "WIDE1-1" part and then the big guns only will
> respond to the "WIDE2-1" part.
> Remember, the home digis are primarily using "dumb" non-APRS-aware classic
> clunker hand-me-down TNCs (like PK-232s and TNC2 clones like MFJ-127x) that
> blindly respond to the fixed alias WIDE1-1 and *DON'T DO *dupe checking.
>  (Dupe checking is an APRS-specific feature only present in KPC3s and the
> new-generation APRS-centric TNCs like Tracker2s, TT4s, TNC-X, etc. or in
> TNCs under  control of KISS-mode APRS software like UIview.)
>
>
> ------------------------------------------------------------------------
>
> --
>
> Stephen H. Smith    wa8lmf (at) aol.com
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