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[aprssig] Fundamental APRS capacity

Rick Green rtg at aapsc.com
Mon Oct 4 18:54:39 UTC 2004


On Mon, 4 Oct 2004, Robert Bruninga wrote:

> Thanks for considering the display of the ALOHA circle
> on all maps.  Using the example before, it will be revealing
> then as everyone converges on a HAMfest with their
> 1 minute mobiles how the usable range of APRS shrinks
> to the size of the parking lot!
  So if I'm hearing you correctly, you're advocating that the mobiles then
respond by removing all digipeater paths from their trackers, right?  So
how is a TT3 or Pocketracker user supposed to do that, short of running
home and plugging it into the computer for reprogramming?
  What is the expected response of the home stations in the vicinity?
Just how closely are we to watch the channel activity and how often are we
to reset our beacon frequency and/or UNPROTO path?
  In an earlier message, a ham reported that findu reports some stations
within his closest 40 to be on the other side of a mountain, with no RF
path or linking digi available.  I understand your algorithm only pertains
to RF-heard packets, so I imagine that considering terrain and
use/population densities, the ALOHA range will be anything but a circle.
In the case cited, the ALOHA group for that station will extend a much
greater distance away from the mountain.
Possibly the map implementors would draw a polygon around the the most
distant stations within the ALOHA group, rather than assuming it's a
circle at the radius of the farthest station heard.

  I still think the place for this algorithm is in the smart digipeater,
which simply drops any packets that originate outside the defined ALOHA
region.

-- 
Rick Green

"They that can give up essential liberty to obtain a little
 temporary safety, deserve neither liberty nor safety."
                                  -Benjamin Franklin





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