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ZL3AI > APRDIG 24.04.03 10:13l 268 Lines 10660 Bytes #999 (0) @ WW
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: KPC 3+ and Motorola Maxtrac Quesion
From: Bob Bruninga <bruninga@usna.edu>
Date: Mon, 21 Apr 2003 10:33:06 -0400 (EDT)
X-Message-Number: 9
>>The only thing wrong with obtaining rx audio from the discriminator is
>>there is no de-emphasis circuit. This will result in the TNC having
>>problems decoding because the transmitted packet would be pre-emphasized.
Of course, when I say connect to the discriminator, I mean to do the job
right. That means to add a de-emphasis capacitor or, move the jumper in
the TNC to the de-emphaiss position...
Yes, there is a difference and hopefully packet people know the difference
and do the right thing...
Bob
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Subject: Re: [ "Daron J. Wilson" ] RE: a few basic questions....
From: "Gregg G. Wonderly" <gregg@skymaster.cytetech.com>
Date: Mon, 21 Apr 2003 09:37:42 -0500
X-Message-Number: 10
>Seems like having a packet station at home would better serve as a
>message handling center than doing that on APRS?
One interesting thing here is that there are in fact technologies, and past
experiences that make people shout out answers like this one. However, as
we gain these experiences and move forward, we need to try and figure out
how we can integrate these ideas and experiences into a single solution.
The devices that we use for Amateur Radio need to become network terminals,
more than transceivers, TNCs and computers. They need to be able to
utilize a wide range of transmission media and modes. Cell phones are a
great example of network terminals.
Connected mode packet is to TCP what APRS is to multicast UDP. We need to
create infrastructure, with our digis, and software, that allows both to
coexist, and for more explicit routing to occur so that we can provide
services that work effectively in the networks we create.
The AX.25 protocol provides a form of 'port' addressing through the use of
the PID. It would possible to build a very sophisticated routing mechanism
by exploiting the PID to create a layered network that would direct APRS
traffic onto highspeed networks.
The primary issue with RF is that we can't create a lot of traffic on a low
bandwidth segment such as 144.390mhz and direct it onto a highspeed network,
and then put it back on low bandwidth 144.390mhz and save any capacity.
There are some interesting problems to be solved here. There could be some
subscription by callsign possible that would allow a mobile to receive data
from high bandwidth stations via direct traffic. The mobiles subscription to
weather data, could follow it along the roadway, with handoffs occuring along
the way to other stations...
Technically, all kinds of cool things could be done. But, until we design a
network that scales, and throw out some of the old 'must-do-this' and
'have-to-have-that' ideas, it will be difficult to do new things.
I, for one, am banking on OpenTRAC as the way to start doing new and fun
things. I'd even suggest that throwing out AX.25 would be a great thing, so
that we don't have to keep falling into the backwards compatible pit that is
full of all the old sludge that keeps sucking the life out of new ideas and
motivated individuals...
-----
gregg@cytetech.com (Cyte Technologies Inc)
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Subject: Re: a few basic questions....
From: Bob Bruninga <bruninga@usna.edu>
Date: Mon, 21 Apr 2003 10:51:57 -0400 (EDT)
X-Message-Number: 11
On Sun, 20 Apr 2003, Daron J. Wilson wrote:
>... I am somewhat confused about what APRS is supposed to do.
>
>1. Automatic Position Reporting System as I understand it, so why do so
>many home stations (who obviously are in the same place all the time)
>beacon endlessly with their position? What is the benefit of this?
APRS is a real-time tactical distributed digital communications network
for come-as-you-are communications. In such a network you need to know
who is on the air and you need that updated as often as the overall design
latency in the network. In HAM radio, stations come and go. In APRS, we
defined the net-cycle time for real-time local events to be 10 minutes.
Thus in 10 minutes you want to hear from everyone to know that they are
still on line...
For larger areas, we relaxed that requirement to 30 minutes. But APRS is
not supposed to be designed nor optimized for 24/7 long term benign use.
But that is what "every one sees" most of the time. But that is NOT what
APRS is designed to do.
>2. The weather data is very interesting, and I have a home weather
>station putting data on the internet already. But then I got to
>thinking, if we are concerned with channel crowding, what roll in
>Automatic Position Reporting do fixed weather stations provide?
See #1. APRS is tactiacl real-time, come-as you are. When you arrive at
the scene and turn on your APRS station, a WX report WITHOUT a position is
USELESS!
Bob
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Subject: MFJ 1270C On HF
From: "Matthew Stennett" <wa4tkg@iwon.com>
Date: Mon, 21 Apr 2003 11:14:45 -0400 (EDT)
X-Message-Number: 12
I like to TRY to leave SOME HF set up running, whether the computer is on
or not.
I PREFER to NOT have the computer on, and my 1270C obviously burns LESS
power, then leaving my PK-900 on, so I like to do that.
HOWEVER:
The 1270C suffers from needing too much DRIVE?/Audio signal, hence, I do
NOT get full power outta' the radio (a 706MKIIG).
Anyone have any suggestions about this?
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Subject: Re: a few basic questions....
From: Alex <kr1st@amsat.org>
Date: Mon, 21 Apr 2003 11:19:51 -0400
X-Message-Number: 13
Bob Bruninga wrote:
>When you arrive at
>the scene and turn on your APRS station, a WX report WITHOUT a position is
>USELESS!
Heck, the whole concept of a WX report in this sense is USELESS (caps
added for extra effect). When I arrive at the scene I think I pretty
much know if it rains or not, or what the wind conditions are like. No
need to turn on my APRS station and wait for an APRS WX report. :)
73,
--Alex KR1ST
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Subject: Re: a few basic questions....
From: David VanHorn <dvanhorn@cedar.net>
Date: Mon, 21 Apr 2003 10:27:16 -0500
X-Message-Number: 15
At 11:19 AM 4/21/2003 -0400, Alex wrote:
>Bob Bruninga wrote:
>
>>When you arrive at
>>the scene and turn on your APRS station, a WX report WITHOUT a position is
>>USELESS!
I've always wondered why we have positionless, timestampless weather reports.
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Subject: Re: a few basic questions....
From: "Dan" <ke4slc@midusa.net>
Date: Mon, 21 Apr 2003 11:39:06 -0400
X-Message-Number: 16
Alex:
I disagree. Here in Tornado Alley, things can change RAPIDLY. Just because
it's sunny here, doesn't mean that the west side of the county isn't getting
rain with 50 mph winds. Nor can I tell that the temp just dropped 40 degrees
in the last 10 minutes. WX stations are VERY useful. In my opinion, there
aren't enough of them.
73 de Dan
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Subject: Re: a few basic questions....
From: Alex <kr1st@amsat.org>
Date: Mon, 21 Apr 2003 12:10:14 -0400
X-Message-Number: 17
Dan wrote:
>
>Alex:
>I disagree. Here in Tornado Alley, things can change RAPIDLY.
I HOPE you SPOT the TORNADOS in YOUR Tornado ALLEY better THAN that SMILEY
face I added. I thought it was rather obvious that I was kidding. I didn't
even make generic statements about the usefulness of WX stations. Not
everything is an argument.
73,
--Alex KR1ST
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Subject: RE: a few basic questions....
From: Bob Bruninga <bruninga@usna.edu>
Date: Mon, 21 Apr 2003 12:16:06 -0400 (EDT)
X-Message-Number: 18
On Sun, 20 Apr 2003, Daron J. Wilson wrote about fixed station position
reports:
>>It allows others to know that they are there?
>>The arguement about if a stations moves or not is moot.
>
>I disagree. The whole point to having a dynamic positioning system is
>that the data transmitted indicates change.
Ah, but define "change". To the person that arrives on the scene of his
EOC or the on-scene command that just turns on his radio. EVERYTHING is
CHANGE. You are assuming a fixed network of known fixed stations that are
on the air 24/7 on emergency power and guaranteed to always be there.
Any AMATUER RADIO system who's design is based on that fallacy is doomed.
APRS is a tactical-real-time digital distributed communications system for
real time. THink about it.
Why does EVERY emergency or specialy net take "CHECK INS" it is because
otherwise you have no idea who is out there. Further, every half hour,
any prudent NET CONTROL goees down his list and CONFIRMS that everyone
that has checekd in and has NOT checked out is still on the air. That is
what APRS does too. That is why every station on the air repeats his
status (included in his position report) at least once every
"net-cycle-time"..
>>Although it may look like a home station, they could be acting as an
>>I-Gate or a relay station and just choose the House Symbol.
>
>Certainly it could. I have successfully transmitted from my mobile
>tracker my position many times without any knowledge of who was an
>I-Gate or relay station, so I'm unclear why they must beacon regularly.
Try being a traveler in a new city... If you operate in the blind without
verifying your connectivity, then you will not be much use to anyone...
>>I think you will notice hardly anything
>>is truely represented in your own grid square. I use the grid square
>>approach to show that APRS and the data that is there now is nothing
>>compared to what it could be. The ability is there!
Yes, APRS can report anything and everythign at tht location. Position
is just one of them.
>The technology is there....the attitudes and the rules Hams have to live
>by do nothing but hurt the ability of APRS.
That seems like a non sequitur, but what ever your point, I agree that
most hams only use 5% or less of the capabilities of APRS and then they
only use those critical items less than 1% of the time. But APRS can do
it if people do something with radio instead of just watch stagnant pretty
maps..
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