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[aprssig] Proportional Pathing and Aprstracker v0.11?

Robert Bruninga bruninga at usna.edu
Wed Nov 29 00:49:56 UTC 2006


Arno,

> Aprstracker is an open source firmware for PIC based trackers 
> like the  TinyTrak, KF161-Tracker, or KF163-Tracker.
> ...including... SmartBeaconing...

Smart beaconing was a great improvement over fixed rates.  APRS
was never intended for fixed rates anyway, but was supposed to
use algorithms such as "decaying" to limit duplicates and old
data and provide priority to new and fresh data.  I am glad you
have this in your code.

But there are many user settings for smart-beaconing that need
to be changed depending on the situation and this can sometimes
make things worse instead of better if these settings are set
improperly.

Would you consider adding PROPORTIONAL PATHING to your system?
It is also much simpler to implement and could be offered as a
user option and easily modified in the field with an A/B
switch...

PROPORTIONAL PATHING simply recognizes that frequent updates are
only needed close to the sender and less frequently farther and
farther away.  You can give the user only a single external 2/3
HOP switch for setting his PATH (no PC required)...

HOP SWITCH SET TO 2:

Every 1 minute a DIRECT packet
Every 2nd minute a WIDE1-1 packet
Every 4th minute a WIDE1-1,WIDE2-1 packet

HOP SWITCH SET TO 3:  (in remote areas)

Same as above except adds via WIDE1-1,WIDE2-2 every 8th minute.

RATE SWITCH SET TO 3:  In the above examples the RATE switch is
set to "/2" because at each additional hop, the RATE is divided
by 2.  But if the RATE SWITCH is set to "/3" then the user's
packets are further reduced at a distance by a factor of 3 as in
this example:

Every 1 minute a DIRECT packet
Every 3rd minute a WIDE1-1 packet
Every 9th minute a WIDE1-1,WIDE2-1 packet
Every 27th minute a WIDE1-1,WIDE2-2 packet

This will work in almost any typical application and will
greatly reduce QRM from high rate trackers that are far away
while giving good updates close in...  It is nice to see
everyone at a 1 minute rate when you are close to them, but you
do not need such frequent updates when they are much farther
away...

Please see the Proportional Pathing Recommendation in the APRS
1.2 Addendum.

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

De WB4APR, Bob





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