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ZL3AI > APRDIG 12.05.04 09:58l 252 Lines 10980 Bytes #999 (0) @ WW
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: Additional thoughts on the great debate....
From: "J. Lance Cotton" <joe@lightningflash.net>
Date: Thu, 22 Apr 2004 10:56:47 -0500
X-Message-Number: 13
Curt, WE7U wrote:
>Precision: I'm still hopeful that this thread will actually lead to
>something. Bob has changed his mind with respect to promoting
>Base-91 Compressed posits (which are in the ratified spec), so that
>only leaves us NMEA posits with more digits after the decimal point
>to support higher precision, like the TinyTrak-3 and perhaps the
>OpenTracker can do.
And I would say that Bob's original proposal of the !XYZ! does a very good
job of being backward compatible with ALL existing clients, including
Kenwoods. Those client authors that are able and willing can upgrade their
client to recognize this field in the comment and act accordingly.
Of course that spurred part of this whole "what a kludge, why can't we move
on to some better way" thing, but really it is a very nice way to add
precision to position reports without breaking ANYTHING.
-Lance KJ5o
--
J. Lance Cotton, KJ5O
http://map.findu.com/kj5o-14
joe@lightningflash.net
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Subject: Re: APRS greater precision
From: "Curt, WE7U" <archer@eskimo.com>
Date: Thu, 22 Apr 2004 09:08:25 -0700 (PDT)
X-Message-Number: 14
On Wed, 21 Apr 2004, Keith Allen wrote:
>Sir, I don't know about others, but I am not a very financially forward
>person. It's the antiquated equipment you speak of at very low prices
>that has allowed me to experiment further into APRS by using DOS
>programs. I for one do not wish to see formats upgrades that will not
>allow backwards compatibility. A lot of new amateur Operators today are
>from the "working" class of folk who sometimes don't make much above 6
>bucks an hour. a 50-60 buck HT along with a used TNC and a 5 dollar 486
>laptop from a HAMFEST (how much I paid for mine) allows these new
>operators a taste of some tactical to practical type Amateur fun. Just
>food for thought.
Which is why I run Xastir ($0) on Linux ($0) with all the maps I could ever
need/want ($0) on throwaway boxes myself... ;-)
Xastir is one of the more "progressive" applications, as we change things
usually on a daily basis, adding features, fixing bugs. It still runs on
old hardware.
--
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: APRS greater precision
From: "Curt, WE7U" <archer@eskimo.com>
Date: Thu, 22 Apr 2004 09:24:29 -0700 (PDT)
X-Message-Number: 15
On Wed, 21 Apr 2004, Keith Allen wrote:
>I think APRS is a fun and useful thing as is. But realize that GPS
>accuracy has it's limits also.
Also realize that there are ways of using positioning with APRS.
Specifically objects/items and placing them relative to each other. The
current APRS positioning will only allow them to be placed within
approximately 60 feet of each other unless Base-91 Compressed posits are
used.
For SAR we need both GPS positioning of our mobile assets and
high-resolution placement of objects/items.
Everyone seems to be stuck in this "APRS is only GPS" rut. I'm not saying
that you are Keith, but overall that seems to be the gist of things in
these threads.
--
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: APRS greater precision
From: "Curt, WE7U" <archer@eskimo.com>
Date: Thu, 22 Apr 2004 09:30:03 -0700 (PDT)
X-Message-Number: 16
On Thu, 22 Apr 2004, Curt, WE7U wrote:
>On Wed, 21 Apr 2004, Keith Allen wrote:
>
>>I think APRS is a fun and useful thing as is. But realize that GPS
>>accuracy has it's limits also.
>
>Also realize that there are ways of using positioning with APRS.
^other^
>Specifically objects/items and placing them relative to each other.
>The current APRS positioning will only allow them to be placed
>within approximately 60 feet of each other unless Base-91 Compressed
>posits are used.
>
>For SAR we need both GPS positioning of our mobile assets and
>high-resolution placement of objects/items.
>
>Everyone seems to be stuck in this "APRS is only GPS" rut. I'm not
>saying that you are Keith, but overall that seems to be the gist of
>things in these threads.
--
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!"
----------------------------------------------------------------------
Subject: Re: Additional thoughts on the great debate....
<LYR36507-195826-2004.04.22-12.06.35--mikejp#videotron.ca@lists.tapr.org>
From: "Michael J. Pawlowsky" <mikep@mikeathome.net>
Date: Thu, 22 Apr 2004 12:42:52 -0400
X-Message-Number: 17
I somewhat have to agree with what a kludge.
Personally whenever I read all these specs it looks like this kind of stuff
was done and seems like a quick fix to a problem. A bit like altitude.
I don't have the APRS spec fresh in my head at all at the moment.
But why not simply have another format type.
That way applications/people that want to use it can.
Other's that do not will not.
If you are part of a select group of individuals that use all the same
equipment etc. you can all decide to use the new format.
If you are like most of us and don't care about being that precise, or
prefer that you have as many people see you as possible you stay with the
old format.
So instead of starting with ! or / start it with another byte for the
"Extended Precision" format or whatever you will call it.
New software coming out should be able to recognize which format is used
and handle either one of them.
Cheers,
Mike
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Subject: compatibility question
From: wes@johnston.net
Date: Thu, 22 Apr 2004 12:52:15 -0400 (EDT)
X-Message-Number: 18
All this talk of moving forward with new additions to the spec brought to
mind a question... Does the original version of APRS written on a
commodore 64 still work today? Does it decode our packets? Can we see
its? Will the commodore 64 version decode a mic-e formatted packet? Why
not?
Just wondering....
I really don't know the answer to this... I'm asking rhetorically. There
is some point when older hardware will not be supported one day - and when
that hardware is not supported any more the software won't be maintained
either. We will have to draw a line in the sand someplace. Not that I'm
looking forward to the day when my kenwood d700 is obsolete, but I know it
will happen. Progress has happened in the past and even older methods ended
up being incompatible with newer methods. I would love to use my old
acoustic coupled 300 baud modem, but I can't make my cordless phone fit in
the cups. The switch over from AM to SSB did not produce a tower of
babble, nor did the sky fall in on us that day. DOS has not been sold by
microsoft for coming up on 10 years now. We have not reached a plateu
where we are not going to develop aprs any more because you can't find a PC
with a floppy drive or which will run DOS. Heck even DOS APRS is to the
point that if anything new is to be added, something must be taken away
(Bob answered Bill Gates question "who will use all of 64k anyway?"). What
we have is a tangled mess of protocol held together with duct tape and
bailing wire. The APRS concept will contine to be developed and refined or
some other telemetry / messaging set of protocols will emirge and continue
on into the future. Steve Dimse put it quite well... those who want to
develop something new will and those who don't won't.... and if the new
system works better, then ham radio as a whole is better off.
I know alot of you out there on the sig are glazing over at all of this in
the past few days. I'm not saying that open trac is *the* end all, do all
fix, but it is a darned good stab at it. APRS started out putting all of
the smarts in the client software, and the sending stations (GPS and
weather stations) were relatively dumb. It was simple and life was great.
But have you noticed that we have GPS data on the air with nautical MPH...
weather stations putting out knots or statute miles per hour? Is that
temperature reading you see in F or C? Is the rain gauge indicating
accumulated rain fall over the past week or year to date? We *do* have a
tower of babble now. We have a confusing set of protocols which have a mix
match of standards, and just try to write software to decode all of them.
Now there is talk of adding !XYZ! on the end of a packet. The data is
loaded up with context clues. If your client software misses a clue, it
cannot complete decoding the packet. The problem is that APRS in it's
current form is like that car in Johnny Cash's song "one piece at a time".
The one with two headlights on one side and one on the other. But never
fear all three come on when we pull out the switch.
Open trac addresses this tower of babble by making all sending stations
send their data in the same units. Each packet has a clearly defined
structure which even allows our client software to gracefully skip data
that it does not know how to decode. Open trac puts the smarts and burden
of uniformity in the sending station.
Bob has done a heck of a job through the years maintaining APRS as a whole.
He's really a great thinker! Anyone read all the ideas he's listed in the
aprs documentation? I still read thru them sometimes and spot something
new. Heck I don't know if I could have stuck with this as long as he has.
Bob has managed to wring 10 gallons of water from a 6 inch square hand
towel. His inventiveness has gotten things from our TNCs we never
imagined. Back to the example of cars though.... the problem is that our
car has 16 layers of duct tape on it.
Scott Miller has also done a great job and put alot of thought into open
trac. If it hadn't been for the lessons learned from aprs, open trac likely
wouldn't be what it is today...
Perhaps more radio manufacturers have not jumped on the APRS band wagon
because it is so tangled. They all seem interested in using that "must
use" word APRS in their advertisements.
Wes
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