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[aprssig] ALOHA Circle on findU and/or APRSWorld

Christensen, Eric CHRISTENSENE at MAIL.ECU.EDU
Mon Nov 1 19:22:30 UTC 2004


Makes sense, Steve.  Thanks for the info.


73s,
Eric KF4OTN
kf4otn at amsat.org
http://www.ericsatcom.net

Project OSCAR Member
AMSAT-NA Member: 35360
AMSAT Eastern North Carolina Area Coordinator

-----Original Message-----
From: aprssig-bounces at lists.tapr.org
[mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Steve Dimse
Sent: Sunday, October 31, 2004 22:04
To: TAPR APRS Mailing List
Subject: Re: [aprssig] ALOHA Circle on findU and/or APRSWorld


On 10/31/04 at 8:52 PM Christensen, Eric <CHRISTENSENE at MAIL.ECU.EDU>
sent:

>Is it possible to view the 40 closest stations that are on RF (i.e. no 
>Winlink, CW, or just IS stations) listed?  That way people could tell 
>what kind of path to use if they weren't using APRSdos?  I like the way

>findU shows the closest stations but it shows both IS and RF stations. 
>Maybe it could be done using the Q-construct or the presence of an 
>I-Gate in the path?  Not sure if it can be done with the current code.

Not with findU's current code, and furthermore this is much harder to do
than it appears at first glance. Positions arrive at findU by many
different routes, there is no single test you could perform on a packet
to tell which originated on RF, so the code would be complex, and in a
few cases it may not be possible at all. Worse is the problem of IGates
and others on both RF and INet...in most cases client programs transmit
on both RF and INet at the same time, so the INet packet is the one that
makes it onto the APRS-IS and therefore findU. These would be eliminated
from the list, even though they appear on RF. 

I don't believe it is possible to generate the info you ask for reliably
with findU. The reason is the same one I always give whenever a
propagation question is posed for findU and the APRS-IS. These systems
were designed to transport the data; the dup-checking and other
characteristics of the system preclude their being used for any
propagation studies.

Steve K4HG

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