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ZL3AI > APRDIG 10.05.04 08:56l 281 Lines 11413 Bytes #999 (0) @ WW
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To : APRDIG@WW
Subject: Re: APRS greater precision
From: "Robert Bruninga" <bruninga@usna.edu>
Date: Tue, 20 Apr 2004 11:32:54 -0400
X-Message-Number: 10
I'm not talking about hacking inside the radio.
>>>Wes Johnston <wes@johnston.net>>>>
>there is no more room in the th7a(g) for more code
>due to the complexity of the mic-e packets.
>
>Now how are we going to (legally) hack into copyrighted
>software? These radios are not flash programmable...
No, what I suggest is writing a PIC processor on a fiddle
board hanging off the serial port. The uP interrogates
data from the radio on the serial port, and then uses the
radio-control protocol of the *same serial port* to write
back into the radio, what the uP wants to display on
the front panel.
No hack to the radio. Just a simple external processor...
I hope...
>our only hope (for these radios) is to make a new spec,
>make it as u-processor friendly as possible, and let
>kenwood play catch-up later since they already know
>how to program it. As for _hams_ programming a
>relatively easy to make display, look at the hamhud.
>My wish is for the kenwood radio to send a copy of
>received packets out the serial port when in APRS
>mode so that we *can* use an external processor to
>supplement the kenwood display or remotely program
>and control it.
Yes, that is exactly what I am talking about. Though,
as you say, it isnt easy, because the data doesnt
drible out. The Pic will have to interrogate the radio
to see what it has, and then re-store anything that
it might be able to re-format... I hope that would work...
>I brain stormed this before and came
>up with all sorts of cool applications like:
>1)Auto jammer finder network: commanding every 'on'
>and unused d700 to QSY to some frequency,
>take a s-meter reading and send a message to the
>requester with a few seconds.
>2)Smart Beaconing
>3)auto local repeater memory programming
>
>These are just a few end user features...
>haven't even though about protocol level stuff.....
Yep,
>Right now, there is no way to do it without switching OUT
>of APRS mode - and then you forfeit the lovely built in text
>display. It is a very nice,
But while it is in APRS mode, can't you interrogate its STATION
and LIST and MSG memories to read the data that way?
That is the basis of my hopes....
Bob
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Subject: APRS Kenwood Radios
From: "Robert Bruninga" <bruninga@usna.edu>
Date: Tue, 20 Apr 2004 11:56:13 -0400
X-Message-Number: 11
>>>Jeff King <jeff@aerodata.net> 4/19/04 11:11:50 PM >>>
>Are you talking about Kenwood? And are you saying they have
>washed their hands of APRS and will not upgrade their
>radios any further?
Not at all. The D7 and D700 is one of their best sellers!
They love the radio and the sales and the APRS.
>10,000 is a big number, and 10,000 angry hams calling
>customer support might motivate them not to abandon
>their customers.
Yep, which is *exactly* why they have resisted the temptation to diddle
with any upgrades. If they came out with a new radio every year that did
*anything* different that the old radio could not do, then BINGO, angry
hams...
>It really does seem ashame ham radio has dropped so far
>that a vendor is holding back progress.
Duh, wrong planet you're on. Kenwood is holding nothing back. It is just
a radio and a display. And it can display almost ALL of the APRS
protocol. What is lacking is the creativity and initiative of HAMS to
make use of it in imaginiative ways...
Are you sayunig lack of precision to 1 foot is holding us back? Nope. What
good is that precision to a mobile radio?
Do you want to see 500 stations on the front panel of your radio instead of
the nearest 40? Duh, it would be impossible to make any sense out of the
500 nearest APRS users spread over half the continent. If you do want to
see that many, then plug in a laptop. They conveniently provide you a
serial port for that purpose..
Name me ONE thing that you think the Kenwood Mobile Radio APRS capability
is "holding back" for the mobile or hand-held user? And I bet I can think
of a way to do it with a little ingenuity instead of a lot bitching...
>Maybe we should organize a protest at their
>booth in Dayton this year?
A typical angry HAM approach for those who have no imagination or
incecntive to make use of what they have. Creative HAMS are notorious for
doing amazing things with what they find. I say that the potential to
provide "tiny-web-pages" of real-time-pertinant information to the mobile
operator on the front panel of his radio is significantly untapped...
And it seems that the most vociferous detractors and complainers don't even
own one... or have a clue how they work and what they can do...
Bob, WB4APR
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Subject: Re: [ui-view] Ambiguity?
From: "Curt, WE7U" <archer@eskimo.com>
Date: Tue, 20 Apr 2004 09:10:55 -0700 (PDT)
X-Message-Number: 12
On Sun, 18 Apr 2004, Robert Bruninga wrote:
>>Its very simple. Each of these latitudes has more and more
>>accuracy:
>> 38__.__ is good to the nearest 60 miles
>> 385_.__ is good do the nearest 10 miles
>> 3859.__ is good to the nearest mile
>> 3859.1_ is good to the nearest tenth of a mile
>> 3859.13 is good to the nearest 60 feet or so
>> YYYY is a compressed position good to the nearest foot or so.
>>
>>How do you use this in APRSDos? I am trying to think
>>why I would need this.
>
>Because as everyone learned in Middle School, any number
>that is used to represent a measureable quantity MUST also
>convey the precision to which that number is known.
The above should be drawn as rectangles BTW, because that's what it draws
if you allow the unknown numbers to vary across all possible values. We
draw the above posits using rectangles to represent the unknown area for
that reason in Xastir.
Some of the other APRS clients draw them as circles, which is just plain
wrong. Work the numbers yourself.
--
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 Kenwood Radios
<LYR36507-194979-2004.04.20-12.06.38--mikejp#videotron.ca@lists.tapr.org>
From: "Michael J. Pawlowsky" <mikejp@videotron.ca>
Date: Tue, 20 Apr 2004 12:17:26 -0400
X-Message-Number: 13
All I know is I love my D700. Especially that it can display APRS positions
as waypoints on my plain old GPS. Beats trying to secure a laptop to my car
dash! ;-)
---------
Different subject.... If I would like to propose an addition to the AX.25
protocol, where would I submit it?
Thanks,
Mike
*********** REPLY SEPARATOR ***********
On 4/20/2004 at 11:56 AM Robert Bruninga wrote:
>And it seems that the most vociferous detractors
>and complainers don't even own one... or have
>a clue how they work and what they can do...
>
>Bob, WB4APR
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Subject: Precision, False Precision, Resolution, and Granularity
From: "KC2MMi" <kc2mmi@verizon.net>
Date: Tue, 20 Apr 2004 12:17:36 -0400
X-Message-Number: 14
Scott-
< The point is, that's RESOLOUTION, not PRECISION.>
I was recently made aware of a term I'd never heard before in any context of
navigation. Granularity. If your instrument has four, five, ten, digits on
the display, that's the GRANULARITY of the instrument. Literally, how many
grains (digits) it has to show us.
Granularity is often mistaken for precision, which it isn't. Precision is
how well the instrument matches the actual position, or whatever it is
supposed to be reading. Precision is mainly instrument error, and needs to
be accounted for, ignored, calibrated, noted, or whatever for that one
instrument and that instrument only.
It seems that there is a lot of misuse of "precision" to mean "position
error" when in fact the two are not at all the same. To a newbie they might
be, but they aren't. With all of our varied backgrounds...I guess not many
of them make the difference clear.
I'm not sure of "resolution"...to me that is similar to granularity, but for
a non-digital system. If I need to read and interpret a vernier scale on a
sextant, or try to make optical alignments, there may be some issue of
resolution in the very plain sense of "how clear is this". If my ruler is
marked in millimeters and I can still interpolate "well, this is about 2.5
mm, it is halfway between two and three" to me that's resolution. Given a
larger ruler, with the same markings on it, I can interpolate 2.4 or 2.6
instead of 2.5, and that's resolution. I think of that as strictly an analog
issue.
I have no idea if these terms are better defined or specified elsewhere.
My GPS has a clear granularity, that is DDD.MM.mmm and I can count the
grains <G> on the display. It also has a PRECISION, and that is shown by the
Estimate Position Error (EPE) display on the screen, which as I understand
it is calculated from the three position error strings in the NMEA $GPGSA
sentence:
PDOP, Position dilution of precision
HDOP, Horizontal dilution of precision
VDOP, Vertical dilution of precision
APRS, unlike my GPS, apparently has no way of indicating EPE. It lacks any
way of passing on the instrument error, the uncertainty, any comment on
precision or the lack thereof. In this area, APRS meets the normal standard
of cartography and navigation, which generally does not convey this
information but relies on the USER to do some work.
APRS cannot supply false precision when it passes along data that has too
many digits (too much resolution or granularity) because error is error and
APRS is simply passing data along regardless of good or bad. This is not a
matter of "false" anything, it IS the best data so far as the party
reporting it is concerned. Logically, ALL position data is imprecise false
data--that's the nature of navigation, we are taught quickly that we never
know where we are, we only know where we think we might be--and that's
always got a circle of error associated with it.
By truncating positions, APRS does damage. My own home position cannot be
properly shown without DDD.MM.mmm format, because that last digit matters,
and the instrument error and all still usually places me closer WITH the
extra digit than it will without. So I'd submit that APRS, as it is now,
DOES HARM. That is not a good thing. The only relevant question is how to
fix APRS so it does not do harm. I'd suggest that adding digts (DDD.MM.mmmm
format) and adding an EPE or precision code, so that an optional "How good
do you think your position is?" data was included, would fix the problem in
APRS.
As to the other problem, of users misusing data and failing to account for
the inherent lies in position data, that's something else again. Some of the
software already takes this into account very nicely, using the GPS EPE data
to change the size of the dot on the map, from a dot to a blob. APRS doesn't
allow this--now. That could be improved.
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