Re: symbol filtering
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Lynn Deffenbaugh
¿ªÔÆÌåÓýUnfortunately, the APRS system has no
definitive way to determine if any given station is truly message
capable.?? There's some distinction in the Mic-E type codes, but
that would only apply to stations using established type codes and
doesn't apply to any station not using Mic-E encoded location
packets.
As for "moving" vs "fixed", there is also
no filter on whether or not a station has changed coordinates (the
true meaning of "moving", but then a drifting fixed GPS moves as
well).? There is a piece of one of Bob's original symbol
definition pages that define "JUST-MOBILE-SYMBOLS", and presuming
that folks actually set symbols relfecting what they are, you
could construct a suitable s/ filter based on this information.
says:
JUST-MOBILE-SYMBOLS: The following two lists of symbols were defined as "mobile" symbols for the purposess of filtering etc. This list has been published in APRS1.1 for over a decade. As of Nov08, this list was reviewd and updated: WAS: Pri: '<=>()*0COPRSUXY[^abefgjkpsuv Alt: /0>AKOS[^knsuv IS NOW: Pri: !'<=>()*0123456789CFOPRSUXY[\^abefgjkpsuv <== [added !F\ ] Alt: >KOSY[^ksuv\ <==[removed /0An] I'll leave the actual "mobile" symbol
filter as an exercise for the reader.?? But keep in mind that
APRS-IS filter terms are OR'd together.?? If you put a symbol
filter like the following in your APRS-IS server filter, you'll
get ALL stations matching that filter from the ENTIRE PLANET!?? A
hyphen will give you an "AND NOT" term, but there is no strictly
"AND" qualifier (except in APRSIS32's internal filter
implementation which uses a plus sign to be "AND ALSO").
s/!'<=>()*0123456789CFOPRSUXY[\^abefgjkpsuv/>KOSY[^ksuv\
I believe Direwolf's internal filter
processing is much more expressive and may be able to do more than
the APRS-IS server-side filters.
Lynn (D) - KJ4ERJ - Author of APRSISCE
for Windows Mobile and Win32
PS.?? Read, study, and experiment with ? Just be warned that it is unbelievably easy to put in a filter that gives you the planetary feed when you weren't expecting it. PPS.?? If you are above an average
computer user, you can actually use telnet to test APRS-IS filter
terms.? Simply telnet to your favorite APRS-IS server on port
14580 (if I have to tell you how to do that, or where to get the
Windows telnet client, then this isn't for you).? As the first
line, enter "user {makesomethingup} pass -1" and hit Enter.? To
set a filter, enter "#filter {filtertermhere}" and hit enter.??
That filter will immediately apply and you should start seeing
packets.?? Entering a new "#filter {differentterm}" will REPLACE
your active filter with the new one.?? And note that this
interface was designed for programs to use, so back-space/delete
doesn't work.?? It's best to compose the filter (especially
multi-term filters) in Notepad or something, copy to the
clipboard, and paste it into the telnet session.? Also, if you
find your session gets disconnected, it's because you weren't very
creaive or unique in your {makesomethingup}.? Any single APRS-IS
server will only allow a single connection from any specific
{makesomethingup}, so using something simple like "TEST" might
cause conflicts and get you disconnected.
PPPS.? Teaching a few more people how
to fish!
On 8/2/2023 11:29 AM, Russell, KV4S
wrote:
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