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ZL3AI > APRDIG 14.05.04 21:08l 249 Lines 9279 Bytes #999 (0) @ WW
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To : APRDIG@WW
TAPR APRS Special Interest Group Digest for Tuesday, April 27, 2004.
1. arrl ax.25 ver 2.0 spec
2. timeslotting
3. RE: arrl ax.25 ver 2.0 spec
4. Re: arrl ax.25 ver 2.0 spec
5. RE: timeslotting
6. RE: timeslotting
7. Re: Objects and D7 are easy.
8. RE: timeslotting
9. Re: timeslotting on 30m
10. digipeater naming conventions
11. Call For Papers: DCC 2004
12. AX.25 Spec question
13. Re: AX.25 Spec question
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Subject: arrl ax.25 ver 2.0 spec
From: "rich painter" <painter@ieee.org>
Date: Mon, 26 Apr 2004 23:22:56
X-Message-Number: 1
i have been trying to locate a copy of the arrl ax.25 version 2.0 spec.
can someone provide a link where i can find this spec?
thanks,
rich
ab0vo
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Subject: timeslotting
From: "K. Mark Caviezel" <kmcaviezel@yahoo.com>
Date: Mon, 26 Apr 2004 21:38:34 -0700 (PDT)
X-Message-Number: 2
Curt:
thanks for the explanation about the difference between the time in the
data out and the time showed on the screen.... I had no idea.
Scott:
I've seen timeslotting used once and it was very slick. We had two
separate APRS payloads, both with TinyTraks, on two different balloons at
last year's Great Plains super launch. One payload was set for once a
minute at :10 after the top of the minute, and the other at :45. I
watched the time on my GPS and -wham!- those position reports came in
exactly as planned. Now, two birdies braodcasting one packet a minute on
an otherwise dead freq is no big deal, but from the performance I witnessed
that day, I can imagine 30 stations sharing a frequency and all beaconing
once a minute and working fine. Possibly even 60 stations if they didn't
have big packets. (I am of course talking about not on 144.39 and not
digipeated). You're good at coming up with algorithms. If you cooked
up something that allowed an event operator to select the second and
possibly 'on even minutes' or 'on odd minutes' then it could be possible to
share 120 OpenTrackers all on one frequency with rapid updates. That is
of course, if all the tracker units had a good time source and the timing
issue was properly addressed. But like I said, the TT2/3 do it very well
already.
- KMC ac0ak
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Subject: RE: arrl ax.25 ver 2.0 spec
From: "Scott Miller" <scott@3xf.com>
Date: Mon, 26 Apr 2004 21:40:03 -0700
X-Message-Number: 3
http://www.tapr.org/tapr/html/Fax25.html
The HTML version is 2.0, dated October 1984. PDF version is 2.2, dated
November 1997.
If anyone knows who to contact about a PID table listing, let me know. I
gave up awhile back and just picked one myself.
Scott
N1VG
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Subject: Re: arrl ax.25 ver 2.0 spec
From: Robbie - WA9INF <mwrobertson@comcast.net>
Date: Mon, 26 Apr 2004 23:42:08 -0500
X-Message-Number: 4
Hi Rich,
Did you try here? http://www.tapr.org/tapr/html/pktf.html
Seems this page has all kinds of goodies, :-)
Robbie
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Subject: RE: timeslotting
From: "Scott Miller" <scott@3xf.com>
Date: Mon, 26 Apr 2004 21:50:38 -0700
X-Message-Number: 5
That's a good idea, hadn't given much thought yet to what timslotting
options to support. It'd require keeping track of minutes as well... unless
maybe it's limited to a 4-minute cycle, or 240 seconds. That'd fit in a one
byte counter. Hmm, then two config bytes, one XOR'ed and one AND'ed with
the counter... that'd allow for a lot of flexibility. And it'd also let you
screw it up so that it'd transmit every second except for once every 4
minutes.
I guess I'd better give that some thought. But it shouldn't be too hard to
code. Maybe a bit harder to present in a user-friendly fashion in the
config screen.
Scott
N1VG
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Subject: RE: timeslotting
From: "K. Mark Caviezel" <kmcaviezel@yahoo.com>
Date: Mon, 26 Apr 2004 22:13:36 -0700 (PDT)
X-Message-Number: 6
Scott:
If you come up with a way for 100+ stations to share a freq for *frequent*
position reports, eventually someone will find a use for it. For an event
with prior co-ordination and planning, time slotting can overcome the
limitation of packet collisions from deaf trackers.
Something I want to get into is APRS on 30m HF. Now that is an application
that could hugely benefit from timeslotting I think. One of these days
I'll get HF APRS tracking set up in my car. Then we can all have a heated
discussion here about the merits and demerits of however I implement it. ;)
- KMC ac0ak
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Subject: Re: Objects and D7 are easy.
From: "Robert Bruninga" <bruninga@usna.edu>
Date: Tue, 27 Apr 2004 08:14:22 -0400
X-Message-Number: 7
The reason for being able to move a station is if his GPS/APRS system stops
working and yet he is still participating in the event and may be moving
from place to place. Then someone needs to be able to update his position
manually for all to see. (identically to an object).
Of course if his station returns to the air, it will move itself again. In
fact, since APRSdos does everything based on the decaying algorithm, if you
move a station (which normaly only reports once every 30 mintutes) that is
NEW info, so his station will then reset its decay algorithm and its next
posit will be 1 minute later (instead of 30). THus, he should take it back
in under a minute.
>>>Robbie - WA9INF <mwrobertson@comcast.net> 4/26/04 6:52:06 PM >>>
Group,
I don't think UI-View32 whould have had these capabilities incorporated if
it wasn't true Curt.. I have had occasion to play with the objects, and
would be very surprised if I could take ownership of someone's home station
and then move it?? That would be plain terrible.. I was going to make this
comment after reading Bob's post and forgot, :-)
So, what's this all about? I will see if I can take over a few stations and
move them...
Robbie
Curt, WE7U wrote:
>On Mon, 26 Apr 2004, Robert Bruninga wrote:
>
>>So, it was never the intent of APRS to have any distinction
>>between stations and objects, they are the same thing.
>>Its just that one uses a different format to be able to carry
>>the name if it is different from the TNC. On receipt and
>>after identificaiton of the sender, they should be treated
>>identically...
>>
>>I think many implementations of APRS mistake this
>>fundamental lack of distinction...
>
>
>Per the spec, Objects/Items are allowed to be "taken over" by
>another station.
>
>I don't believe there's a provision for that in terms of stations.
>It's been a while since I read the entire thing though.
>
>--
>Curt, WE7U archer at eskimo dot com
>Arlington, WA, USA http://www.eskimo.com/~archer
>"Lotto: A tax on people who are bad at math." -- unknown
>"Windows: Microsoft's tax on computer illiterates." -- WE7U
>"The world DOES revolve around me: I picked the coordinate system!"
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Subject: RE: timeslotting
From: WB4GQK@aol.com
Date: Tue, 27 Apr 2004 08:16:33 EDT
X-Message-Number: 8
Mark has some interesting posts in his 4/27/04 message
>Something I want to get into is APRS on 30m HF. Now
>that is an application that could hugely benefit from
>timeslotting I think. One of these days I'll get HF
>APRS tracking set up in my car. Then we can all have
>a heated discussion here about the merits and demerits
>of however I implement it. ;)
However,
I don't believe you can timeslot 30M APRS stations, for the simple reason I
know there are several stations in the Carribean as well as a couple in
central America that apparently cannot be heard by APRS stations in the mid
west and northern USA. The reason I say this is I can turn the audio up on
my SGC 2000 and hear weak stations transmitting. I can watch the LED
display on my KAM 98 I can see the LEDs indicating there is a signal
present on the band but inevitably a strong station will transmit while the
weak station is still transmitting and as a consequence I don't decode
either transmission.
Sometimes when the propagation is really long I copy a number of European
stations. I strongly suspect a large number of the weak transmissions I
hear/see are from EU stations. They are generally too weak to decode. It is
truly amazing to see how much activity is on the frequency but very
unfortunately I would say I decode less than 10% of the transmissions I
see/hear.
Collisions are a major problem on 30M from what I see. But if a station
cannot hear other stations transmitting I don't see how you could timeslot
HF stations.
I clear out and save my station list once a week. I average decoding 125 HF
stations over that time period. What you may find interesting is I
generally record 1,500 WX station transmissions from both stations in Turks
and Cacios and about 1000 from the WX station in PR.
73 de Jim
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