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ZL3AI > APRDIG 29.10.06 22:00l 174 Lines 6452 Bytes #999 (0) @ WW
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Subj: [APRSSIG] Vol 28 #21, 1/1
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From: ZL3AI@ZL2BAU.#87.NZL.OC
To : APRDIG@WW
Today's Topics:
1. RE: Too many digi's ? (Robert Bruninga)
2. RE: Too many digi's ? (Robert Bruninga)
3. Re: KPC3+ lost settings (Andrzej AB9FX)
4. Re: KPC3+ lost settings (VE7GDH)
5. RE: Too many digi's ? (Keith - VE7GDH)
6. Re: Too many digi's ? (Patrick Green)
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Message: 1
Date: Fri, 20 Oct 2006 15:05:33 -0400
From: "Robert Bruninga" <bruninga_at_usna.edu>
Subject: RE: [aprssig] Too many digi's ?
>If the digis are all configured with dwait=0 and other
>appropriate settings so that they all digi, immediately
>and in unison, more digis, in general, are a
>good thing.
Yes, DWAIT must be set to 0. But I wonder about the phrase "more digis are
a good thing. Of course it depends. If a mobile can be heard in an area,
then more digis is a bad thing. And remember there will always be some
collisions, so just because a single track had an outage area, does not
mean it is always blocked.
One way to improve coverage in a bad area is to *** reduce all the QRM
coming in from out of the area from all other directions to the existing
digis ***. Most digis are high enough so that even if they could hear a
mobile in the black-hole, they might normally be able to hear other QRM
from elsewhere just as strongly or strong enough so that it collides with
the mobile in the area under consideration.
SO my suggestion is to -not- start adding many digis to fill in black holes
until the wider area has first fully adopted the New-N paradigm to cut down
on the QRM that the existing digis are hearing from all over. Once they
are hearing a clearer channel, then they should be able to hear better down
into some of the previous black holes.
De WB4APR
------------------------------
Message: 2
Date: Fri, 20 Oct 2006 15:13:59 -0400
From: "Robert Bruninga" <bruninga_at_usna.edu>
Subject: RE: [aprssig] Too many digi's ?
>I've been speculating to myself that maybe we don't have enough
>digis. If we got the existing digis down to a reasonable HAAT,
>thereby reducing the cell size, and added more digis we might get
>both better coverage and better control of the traffic. 3000' HAAT
>may be great for a voice repeater, but I suspect it isn't all that
>great for a digital network node.
One thing to consider with the multiple lower digis, is to keep the big
digi up there but put its output on another frequency so that it does not
QRM everything else from its high location. If you want to hear the big
picture, tune in to its output. And having one permanent Igate over there
will make sure what it hears gets into the APRS-IS, but does not add QRM
everywhere. Think of this as instantly doubling channel capactiy because
now every packet heard by that big digi does not get digipeated back onto
the same channel.
But then not having the output on 144.39 kinda defeats the purpose of APRS.
So here is the recommended way to do it. Shift the HIGH site digi to input
on 144.99 and the output remain on 144.39. This way low power and local
stations or HT's can get into the high-site digi using +600 on transmit but
without any contention or collisions with other traffic on 144.39. These
local users get priority over all out-of-area packets on 144.39.
Throughput for all local users to that digi goes up TREMENDOUSLY because
they now have no competition with any other traffic but themselves. Out of
area packets are not hear by this digi with it's 144.99 input.
>Maybe the high-site digis should be set so that they don't
>repeat a packet unless it isn't repeated by someone else
>in a reasonable time, thereby leaving the high-site digis
>to do fill-in and backup work.
That is another way to do it, but the alt-input digi takes only the setting
of the -600 offset at the digi and it's done.
De Wb4APR, Bob
------------------------------
Message: 3
Date: Fri, 20 Oct 2006 14:40:18 -0500
From: "Andrzej AB9FX" <ab9fx_at_aprs.pl>
Subject: Re: [aprssig] KPC3+ lost settings
Another question.
Is there possible remote operation, at least remote tnc reset, if there was
nothing for RTEXT and MYREMOTE in KPC3+?
73!
Andy
------------------------------
Message: 4
Date: Fri, 20 Oct 2006 14:39:43 -0700
From: "VE7GDH" <ve7gdh_at_rac.ca>
Subject: Re: [aprssig] KPC3+ lost settings
Andrzej AB9FX wrote...
>Is there possible remote operation, at least remote tnc reset, if there
>was nothing for RTEXT and MYREMOTE in KPC3+?
No. If RTEXT is empty, you won't be able to log in remotely.
73 es cul - Keith VE7GDH
--
"I may be lost, but I know exactly where I am!"
------------------------------
Message: 5
Date: Fri, 20 Oct 2006 19:13:15 -0700
From: "Keith - VE7GDH" <ve7gdh_at_rac.ca>
Subject: RE: [aprssig] Too many digi's ?
Bob WB4APR wrote...
>That is another way to do it, but the alt-input digi takes only
>the setting of the -600 offset at the digi and it's done.
But if this is a single transceiver listening on 144.990 and transmitting
on 144.390, it would be transmitting blind without listening on 144.390.
It's a nice idea, but wouldn't it really take two TNCs & two radios to do
it properly... or at least one TNC & a transceiver on 144.990 / 144.390
plus a receiver on listening on 144.390 to at least listen to see if the
frequency was clear? Of course, in busy areas, it may never be clear.
Perhaps it would be no worse than mobiles transmitting from an RF black
hole and not knowing that someone the next valley over was already
beaconing.
73 es cul - Keith VE7GDH
--
"I may be lost, but I know exactly where I am!"
------------------------------
Message: 6
Date: Fri, 20 Oct 2006 21:28:07 -0500
From: "Patrick Green" <pagreen_at_gmail.com>
Subject: Re: [aprssig] Too many digi's ?
Outside of most metro areas, APRS is RF horizon challenged but as traffic
gets more dense, stations ends transmitting on top of each other. Think
about a scenario if every car had APRS in it. Aloha circles would be in
blocks instead of miles. Dual receive sounds like a better step but it
raises the complexity. Sometimes you can't do this at the mountain digi
because of logistics.
Perhaps the thing to concentrate on after the new paradigm is establishing
power recommendations for stations?
73 de Pat --- KA9SCF.
------------------------------
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