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ZL3AI > APRDIG 20.02.04 14:48l 257 Lines 9142 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Feb 18, 4/6
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: RE: Coordinate question
From: "Christensen, Eric" <CHRISTENSENE@MAIL.ECU.EDU>
Date: Wed, 18 Feb 2004 17:26:44 -0500
X-Message-Number: 20
Ken,
What software will you be using with APRS or is this a stand-alone tracker
in which case what is your hardware?
Eric
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Subject: RE: Excessive paths on balloons
From: Gonzales Andy <agonzales@arc.nasa.gov>
Date: Wed, 18 Feb 2004 14:35:22 -0800
X-Message-Number: 21
The radius of your viewing circle, is:
V = 1.22 h ^ 0.5
V in miles
h in feet
--
Andy Gonzales
KG6RWO
NASA / Ames Research Center
Moffett Field, CA 94035-1000
Bldg. N-244, Rm. 240
MS 244-19
agonzales@arc.nasa.gov
650-604-0309
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Subject: Re: Excessive paths on balloons was RE: High Altitude Balloon Flights
From: "Joe Della Barba" <joe@dellabarba.com>
Date: Wed, 18 Feb 2004 17:36:37 -0500
X-Message-Number: 22
I have always used a apth of WIDE while airmobile with good results.
73
Joe N3HGB
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Subject: Excessive paths on balloons was RE: High Altitude Balloon Flights
From: "Robert Bruninga" <bruninga@usna.edu>
Date: Wed, 18 Feb 2004 17:37:25 -0500
X-Message-Number: 23
ONE MORE CONSEQUENCE OF RELAY:
There are many more problems not mentioned about that RELAY,WIDE,WIDE path
at altitude.
But first,the RIGHT way is just WIDE. The result of that is just 1 second
of airtime everywhere. Absolutely fine, whether 1 or 100 digipeaters hear
it. It is still just one second everywhere (and at the same instant).
Thats what APRS is designed for...
But here is the consequence of RELAY at the start of RELAY,WIDE,WIDE. It
can tie up more than 50% of the channel over thousands of square miles for
10,20 30 seconds at each packet!
1) Lets sayt 100 digis hear the packet
2) Assume that each digi hears 3 others.
3) Assume that each digi hears 10 stations (RELAYs)
4) EVERY RELAY (and every digi) digipeats the paceket.
Every packet from a home station does not do callsign substitution, thus
EVERY COPY of the packet is different and is NOT ignored as a dupe. Thus
the digi digipeats it, then lets say just 3 of the 10 home stations for
EACH digi get heard by the digi due to CSMA. EACH digi will also digipeat
those 3 copies because they are each a unique (different packet).
Now we have 100 digipeaters digipeating every Balloon packet 4 times. And
there are still 2 hops to go. And EACH COPY, because it originates at a
different RELAY home station that does not do callsign subsititution then
is a UNIQUE packet and ALL Of them must be digipeated until the chain
reaction dies.
Its like nuclear meltdown. The QRM that results is unbelievable and can go
on and on for 10,20 or even 30 seconds after each such RELAY,WIDE,WIDE
packet from a balloon.
Never ever start a packet with RELAY from altitude.
Bob, WB4APR
*--------------------------------------------------------------------------
As I posted in my email about what RELAY does to almost every single
station, It keys them all up! Not only does this cause QRM on the APRS
channels, but at EVERYONE's HOME, CAR, or wherever there is an APRS
station, it QRMS and BLOCKS all use of the 2 meter band on ALL frequiencies
for the duration of that packet. That is just wrong, bad, inconsiderate,
and not desired, not appreciated and not to be done when there is no valid
reason for it.
Again, never-ever use RELAY as a path at altitude. The consequenceis are
far more than most people realize and we should not have to learn this
lesson over and over.
Again, Great project, and we LOVE balloons. And no real harm done. I was
just preaching to the masses in the above post, because many people just do
not understand the consequencies of some subtle things in APRS. So keep
up the good work.
Keep 'em coming...
de WB4APR, Bob
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Subject: RE: Coordinate question
From: "Christensen, Eric" <CHRISTENSENE@MAIL.ECU.EDU>
Date: Wed, 18 Feb 2004 17:40:35 -0500
X-Message-Number: 24
Okay... I'm going to go out on a limb and say that you won't have any
problems with that. If memory serves me correct the KPC3+ reads GPRMC
sentences without a problem. I just looked in the KPC3+ manual but didn't
see what I was looking for.
Does anyone have anything to add???
Eric KF4OTN
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Subject: RE: Excessive paths on balloons
From: "Christensen, Eric" <CHRISTENSENE@MAIL.ECU.EDU>
Date: Wed, 18 Feb 2004 17:43:16 -0500
X-Message-Number: 25
Thanks Andy! I'm assuming this is HAAT... (should be right?)
So at 10,000ft my handy dandy calculator says 122 miles LOS. Hmmm...
What was the max height on the last balloon??? Just for fun I wanted to see
what its' LOS area was!
Eric KF4OTN
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Subject: Re: Excessive paths on balloons was RE: High Altitude Bal loon
FlightsFrom: "Scott Miller" <scott@opentrac.org>
Date: Wed, 18 Feb 2004 14:49:38 -0800
X-Message-Number: 26
>As I explained before, anything starting with RELAY is just down right
>irritating to EVERYONE within 500 miles. Dont do it.
>Beyond that, an abusive path of making it multiple hops is just
>adumb mistake, that doesnt hurt that much. But it doesnt
>INTERFERE with communications in progress like RELAY does.
It seems to me that it'd still be useful for recovery though. Since the
OpenTracker now has the capability to drop the path above a specified
altitude, what would you suggest for a standard setting? I think it
defaults to 4999 meters right now.
Scott
N1VG
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Subject: Amperage rating of cigarette ligher plug
From: Adi Linden <adil@adis.on.ca>
Date: Wed, 18 Feb 2004 17:26:09 -0600 (CST)
X-Message-Number: 27
I am installing a Mitrek converted for APRS in my 2002 Chevy Venture. I
thought of sticking the radio into the very back of the van and run RG-58
to a mag mount on the roof. I am having problems getting power to the
mounting location of the radio, though.
Any ideas what the current rating of the auxillary cigarette lighter
socket by the back door of the van would be? The Mitrek draws some 13.5A
on transmit. I am just wondering if plugging it into that power outlet is
a suitable solution.
Thanks,
Adi
--
Adi Linden | va3adi | va3adi@adis.ca | http://adis.ca
+-----------------------------------------------------------------+
IRLP Node 2590 in Sioux Lookout, Ontario
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Subject: Re: Amperage rating of cigarette ligher plug
From: Derek Koonce <redderek@jps.net>
Date: Wed, 18 Feb 2004 15:43:00 -0800 (GMT-08:00)
X-Message-Number: 28
Adi,
Check your car manual, it should show what is on the fuse line of the
lighter. I would suspect a typical fuse on a lighter is around 10A. Then
you have interior lights and other stuff so that you could be safe to
assume about 5 to 7A capability. However, if you are running the power line
to the back of the van with a small wire, then you will not only have a
current limitation, but also a voltage drop.
My suggestion is to run a separate 10AWG wire from the battery to the back
of the van. Then be sure to fuse it with a 15A fuse to handle long duration
transmissions.
Other thought, if the transmission is brief, then you can probably do an LC
filter at the radio end with a large capacitance to handle the brief
transmission. You would have to calculate how much energy you will draw and
the allowed voltage drop on the power line to determine the minimum
capacitor value.
Derek
KE6JTP
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Subject: Re: High Altitude Balloon Flights
From: "Spider" <spider@rivcom.net>
Date: Wed, 18 Feb 2004 16:54:08 -0700
X-Message-Number: 29
..From: "Bill Martin" <wa6rtx@bellsouth.net>
>As an abnormal APRS User (Pun) I would like to follow the flight of the
>Balloons without having to rely on FindU or other servers. I wish that the
>people flying the balloons would Gate the position reports to the Internet
>especially if on a frequency other than 144.39.
>
>Too much traffic for some people? There is an on and off switch on most
>equipment.
>
>Bill - WA6RTX
Bill,
I set up a special use Igate for just such things. It normally rests on the
PCSAT freqs and is frequency agile for special events, such as chasing
balloons (although who would know when that is going to happen in my area!).
But that is what is needed....people who are willing to take that extra
step! This station does not take away from the standard 144.390
mhz stuff. However, I've heard no technical reason as to why 144.390 Mhz
should not be used. It's a special event....144.390 is perfect for
that....if it covers 3 states...SO WHAT!
Jim, WA6OFT
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