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ZL3AI > APRDIG 19.09.06 21:51l 243 Lines 8907 Bytes #999 (0) @ WW
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From: ZL3AI@ZL2BAU.#87.NZL.OC
To : APRDIG@WW
Message: 11
Date: Sun, 10 Sep 2006 21:51:40 -0600
From: Joel Maslak <jmaslak-aprs_at_antelope.net>
Subject: Re: [aprssig] Packet Node on 144.390 ?
On Sep 10, 2006, at 9:30 PM, Daron J. Wilson wrote:
>>In an area with one or two or three active users total - it wouldn't
>>be cost effective to build two separate systems when one would
>>work just fine. Any more users and activity would make sense
>>to build a separate system to carry the additional load.
>
>In that small of area, they could just run on the voice repeaters, it's just
>sharing bandwidth right?
I'll add that the repeater may be the more efficient option for emergency
communication if all the stations can hear it effectively, more then two
stations are communicating, it has a reasonable TX Delay, and at least one
station on channel can't hear at least one other station.
Repeaters solve many of the hidden transmitter issues. The only major
issues using them are to ensure the repeater is "flat" (doesn't emphasize
certain tones) and that the users use software carrier detect. The problem
with software carrier detect is if a voice user does try to use the
repeater the packets won't detect that as an active station, and also the
repeater's ID will clobber a few packets.
Hidden transmitter issues are ignored far more often than they should be.
Channel utilizations of 60% or higher are perfectly reasonable even with a
reasonably large number of active stations - IF everyone can hear everyone.
If someone can't hear someone else (but maybe some node or central station
can), you might be lucky to get a tenth of that. That's because neither
stations realizes it's clobbering another's transmissions. (with APRS,
this is even more likely since most stations are bad packet stations - they
are low power, often mobile, with sometimes less than ideal geographies,
and large area digis that can hear other large area digis that their users
cannot hear; Adding connected mode packet to the mix will make things
miserable for both APRS and connected-mode communities, as neither will
work right)
It's also a lot less important to have good emergency packet stations in
this configuration.
Surely there is a nearly unused voice repeater in nearly every area of the
US (and possibly elsewhere in the world).
But of course no one likes to hear packet on their voice repeater, but it's
fine to jam APRS! ;) So it probably won't even be considered a reasonable
option. But neither should using 144.39.
Besides, if you have a digi site for 144.39 that doesn't have any 70cm
equipment already, all you'll really need to add a second digi is a radio
(cheap for 1200, more for 9600) and TNC (cheap for 1200, more money to do
9600). And you can go 9600 instead of 1200 - so that you can increase the
number of users and amount of information transmitted. Heck, you can even
build real packet nodes fairly easily rather than just relying on "dumb"
digipeaters.
If the organization isn't interested in using voice repeaters or building
new permanent digis, why not build a temporary digi? One that fits in,
say, an ammo can and can be carried by hand to a tall building or left in a
car parked on a mountain top, in an area sufficient to provide the coverage
needed during the disaster? (I know where I live there are plenty of areas
without good coverage by digis on 144.39, anyhow, and Murphy says that
those are the most likely areas to need communication) Build 2 or 3 of
these portable boxes as true nodes and you could have a mobile network that
you can use not only in your local area, but also in another area if
another Katrina or something happens. Heck, it might be a fun project!
------------------------------
Message: 12
Date: Sun, 10 Sep 2006 22:08:51 -0600
From: Joel Maslak <jmaslak-aprs_at_antelope.net>
Subject: [aprssig] Recommended IGate Connection
I'm running an IGate for a relatively small geographic area (transmit path
of WIDE2-1, considering shortening even more to one specific named WIDE).
Right now, I use aprsd (2.2.5 I think). I'm using the following to connect
to the internet stream in the aprsd.conf:
Server rotate.aprs.net 23 hub-sr
I'm not sure I'm using the prefered port (or other options for that
matter).
What's the current recommendations for systems like mine? I want to
support message traffic to my local RF users, but less bandwidth for the
upstream server would be a good thing if it doesn't impact my local users.
------------------------------
Message: 13
Date: Sun, 10 Sep 2006 21:12:30 -0700
From: "Eric Goforth" <eric_at_goforthtech.com>
Subject: [aprssig] APRSDepot.com
Hi all;
A new project was launched recently to record every position posted to the
APRS IP stream forever. The hopes is to get a long term picture of APRS
network coverage and effectiveness. Once a sufficient number of positions
are recorded the project will be building map files that show the effective
coverage. Should be an interesting project.
Details of the project can be found at www.aprsdepot.com.
Every station and digi or igate can pull down KML files that show their
effective contribution to the project. Details of the process are also on
the site.
73's all!
Eric Goforth, N6GOF
------------------------------
Message: 14
Date: Sun, 10 Sep 2006 21:12:53 -0700
From: "Eric Goforth" <eric_at_goforthtech.com>
Subject: RE: [aprssig] Recommended IGate Connection
Hi Joel;
If all you want to do is message traffic, i would connect to the Message
only port of the server. If you are also wanting to do position reports
then you have to consider how much traffic your network connection (or how
much you willing to give up) can handle. Port 23 is the entire network,
world-wide. That's a lot. If you think your users would apprecieate
getting msg traffic from Africa (for example), then you kind of have to do
that. However, I have my iGate only connecting to North America traffic
only and it serves my community very well.
Just my opinion and I'm sure your going to get a lot of them here.. ;-)
73's
Eric J. Goforth, N6GOF
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Message: 15
Date: Mon, 11 Sep 2006 12:08:48 +0200
From: Asier Garaialde <agara_at_kantauri.com>
Subject: Re: [aprssig] GPS Display of D700 stations
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Message: 16
Date: Mon, 11 Sep 2006 06:14:50 -0500
From: Jason Winningham <jdw_at_eng.uah.edu>
Subject: Re: [aprssig] Yaesu Memorizer FT-227R manual?
On Sep 10, 2006, at 9:17 PM, Derek Koonce wrote:
>I just did a Google search for "Yeasu FT-227R manual" and it pulled
>up several sites.
I googled for it before I posted to the list. The hits that actually were
related to an FT227R manual were site that wanted to sell a copy of the
manual at prices ranging from $8 for an electronic copy all the way to $30
for a paper copy.
Thanks for the replies. I found one at mods.dk.
-Jason
kg4wsv
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Message: 17
Date: Mon, 11 Sep 2006 06:19:06 -0500
From: Jason Winningham <jdw_at_eng.uah.edu>
Subject: Re: [aprssig] Recommended IGate Connection
On Sep 10, 2006, at 11:08 PM, Joel Maslak wrote:
>I'm running an IGate for a relatively small geographic area
>(transmit path of WIDE2-1, considering shortening even more to one
>specific named WIDE).
WIDE2-1 is a one hop path; the only way to get it shorter is to transmit
with an empty path, direct only.
WIDE is a one hop path element, obsolete in most areas. WIDE2-1 (or
WIDE1-1) is the "newN-N paradigm" equivalent.
-Jason
kg4wsv
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Message: 18
Date: Mon, 11 Sep 2006 06:35:23 -0500
From: "john b. leonard, jr." <w9jbl_at_comcast.net>
Subject: RE: [aprssig] APRSDepot.com
Outstanding work! Thanks. I put W9JBL-9 in there, and immediately I could
see where the digis didn't hear my sig. I was using a 5 watt ht.
bl
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Message: 19
Date: Mon, 11 Sep 2006 13:10:46 +0100
From: "Dave Baxter" <dave_at_emv.co.uk>
Subject: RE: [aprssig] Path loss question
But as the frequency goes up, the wavelength goes down, so you can have
more gain in the antenna department, omni (co-linear) or beam, for the same
sort of size, negating much of the effects of increasing frequency.
So, in practice, for the same physical sizes and powers, there is not a
great deal of difference between 144 and 432 for a direct line of sight
path, especialy at a distance (well into the "far field" region)
What realy kill's things, is cable losses as the frequency goes up, unless
you push the boat out big time in the cost of cables, or other types of
feeder...
Have Fun!
Dave G0WBX.
>-----Original Message-----
>From: Bob Bruninga [mailto:bruninga_at_usna.edu]
>
>Yes,
>Path loss increases with the SQUARE of frequency.
>
>Thus from 2m to 70cm is about -9 dB
>
>de Wb4APR, Bob
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