[aprssig] Msg reply path

Robert Bruninga bruninga at usna.edu
Sun Oct 6 17:38:50 CDT 2013


It is interesting to note.

In Maryland a MD3-3 from the center would get to every digi in the
state.  But it would take a good MD5-5 to go from one end to the
other.  But neither of these has any different result than a MD7-7.
All three of these paths accomplish the same thing:  Hit every
Maryland Digi.  And none of them reduce any QRM compared to the MD7-7.

So for participating in net traffic trying to hit everyone in the ARRL
section I hve no qualms at all about using MD7-7 even though MD3-3
might work from my location.  The 7-7 buys just a little bit more
assurence that one digi tht heard collisions at the 3-1 level might
get a second chance by the time it gets to 7-3 or lower.

Again, no additional QRM at all.  Every digi will only do it once and
once only.  SO no difference between 7-7 or 3-3.

But a HUGE difference from WIDE7-7 which would QRM over 13 states with
over 300 generated dupes in unwanted areas.  Whereas a MD7-7 hits only
the 9 digipeaters in the state, and no dupes.

Bob, Wb4APR



On Sun, Oct 6, 2013 at 4:22 PM, Andrew P. <andrewemt at hotmail.com> wrote:
> I understand what a SS7-3 would do, but why not use a SS3-3 to begin with? That's why I was asking whether a digi repeating SS7 should also repeat SS6, SS5, etc.
>
> Andrew KA2DDO
> ------Original Message------
> From: Stephen H. Smith
> To: aprssig at tapr.org
> Sent: Oct 6, 2013 12:37 PM
> Subject: Re: [aprssig] Msg reply path
>
>
> On 10/6/2013 11:44 AM, Andrew P. wrote:
>> On a tangent from this, is there ever a reason to_initiate_  a message with either a WIDEn-N or SSn-N alias where N < n? I've seen cases like WiDE1-1,WIDE2-1, but are there any other cases that make sense (except possible smart reverse-pathing where it is obvious that the whole n wasn't needed)? Should digis that support SSn-N also support SSm-M where 1 <= m < n?
>>
>> Just a thought to stir the pot.
>>
>> Andrew Pavlin, KA2DDO
>
>
> You don't need any explicit support at the digi for constructs like WIDE2-1
> (or hypothetically for something like SS7-3, etc).
>
> The receiving digi simply sees this as a partially-used N-n path (i.e the digi
> "thinks" the packet passed through several digis already) and just decrements
> the -N by one count.   If it arrived as WIDE2-1, then it decrements to -0
> meaning NO more digipeats.   If something like SS7-3 arrived, it would go out
> as SS7-2 and be good potentially for two more digi hops.
>
> I could see a potential use for "pre-decremented" SSn-N.  If someone wanted to
> broadcast a bulletin all over a major metro area, but not the remoter more
> rural parts of a state, something like SS7-4 would ensure it blankets the metro
> area including the outer-ring 'burbs, without blanketing the entire state.
> Could be of use for things like urban freeway tisups and closures due to major
> accidents, bridge failures, etc.
>
> Or the recent flooding in Colorado to blanket the Denver-Boulder-Ft
> Collins-Greeley area WITHOUT also blanketing outlying areas like Colorado
> Springs, Pueblo, Glenwood Springs, Grand Junction, Durango, etc that a full
> CO7-7 would do.
>
>
>
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