[OZAPRS] VK3 Draft Guide for APRS Parameters

Robert Bruninga bruninga at usna.edu
Fri Nov 10 11:40:28 EST 2006


> In responce to Chris's email below this is what we propose for
VK3.
> 2) Home stations set path to APRS v 'Closest Digi',WIDE2-1

My only comment is that this probably does not need to be
mandated.  It was a good idea back when we were using WIDE,WIDE
to cut down on dupes, but since WIDEn-N system inherently has
full dupe suppression, then I think it is better to just let
home stations use WIDE2-2 from the get-go.  This way they are
not dependent on the reliability of that single digi to get out.

And if 3 digis here them, then that is fine, since they all will
still only digipeat that packet once (under WIDEn-N).  And even
if  there is a collision at one, the others may still hear it.

I'd also put the word "routine" beside the suggestions for
mobiles, because it is "routine" operation that is the problem.
When someone is doing something special, then they would expect
to operate at maybe the 1 minute rate.

This shows the power of the Proportional Pathing Algorithm we
began pushing last year.  Instead of trying to cut mobiles back
in rate and hops (one setting does *not* suit all situations)it
is better to set a single PROPORTIONAL PATHING rate and then it
works not only for routine at  low rates, and minimum QRM, but
it also provides higher rates closer in.
Here is how it works.

The basic rate might be 1 minute.... (DIRECT!)
Every other minute it goes via WIDE1-1
Every 4th minute it goes via WIDE1-1,WIDE2-1
Every 8th minute it goes via WIDE1-1,WIDE2-2

So if you are within a few miles of the mobile, you get 1 minute
updates.  If you are within the first digi of the mobile, you
get a 2 minute update rate, if you are 2 hops away, you get a 4
minuite  update and if you are 3 hops away, you will get only an
8 minute update.  The beauty of this system is that it never has
to be changed between routine operation and 
Local events of higher priority.  See the plan:

http://www.ew.usna.edu/~bruninga/aprs/ProportionalPathing.txt

This is part of the APRS1.2 addendum shown on:
http://www.ew.usna.edu/~bruninga/aprs/aprs12.html

De WB4APR, Bob

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