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ZL3AI > APRDIG 23.11.06 04:38l 248 Lines 9958 Bytes #999 (0) @ WW
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Subj: [APRSSIG] Vol 29 #19, 2/3
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From: ZL3AI@ZL2BAU.#79.NZL.OC
To : APRDIG@WW
Message: 6
Date: Tue, 21 Nov 2006 15:42:44 -0500
From: "Robert Bruninga" <bruninga_at_usna.edu>
Subject: RE: [aprssig] APRS DF reporting
The Agrelo format mentioned below is a standard interface for APRS, But it
is never transmitted on the air. It is the interface between the Doppler
DF unit and the PC that is running APRS (with DF code in it). The APRS
software then parses out the DF info and the interleaved GPS info and then
when appropriate, sends the combined single packet containing the DF
unit's:
LAT/LONG/CSE and SPEED
DF bearing
Signal quality
Range of the bearing line
All of these are "smartened-up" by the APRS software so that it is not just
regurgitating raw data, but is applying some kind of smarts (even a human
"send now" button) that decides if the DF report seems valid and worth
putting out on the air. This should be very easy to do in the PIC
especially if you use the "send-now" button.
For automatic unattended fixed sites, then some kind of weighting function
should be applied to make sure the report seems reasonable compared to
pervious values... Etc.
Bob, WB4APR
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Message: 7
Date: Tue, 21 Nov 2006 14:43:25 -0800
From: <scott_at_opentrac.org>
Subject: RE: [aprssig] APRS DF reporting
>(with DF code in it). The APRS software then parses out the DF
>info and the interleaved GPS info and then when appropriate,
>sends the combined single packet containing the DF unit's:
>LAT/LONG/CSE and SPEED
>DF bearing
>Signal quality
>Range of the bearing line
My only question here is what the range is supposed to mean. How can you
know the range, if you don't know the transmitter power?
Scott
N1VG
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Message: 8
Date: Tue, 21 Nov 2006 17:01:11 -0800
From: "Herb Gerhardt" <hgerhardt_at_wavecable.com>
Subject: [aprssig] RE: [Kenwood_TH-D7] TH-D7 Power up problem
SAR_APRS_at_yahoogroups.com
Our county recently tried to use their TH-D7 SAR tracker I set up for them
several years ago and they could not make it work. I did my darnedest to
try to talk them through all the possible problems. I did not succeed.
So, I now have the entire tracker here at my house for troubleshooting.
Here is what I discovered so far:
1. Even with a good fully charged battery attached, it will not power
up. I bent the radio contacts out some more but that did not help.
2. With 12+ V attached to the external plug, I can read voltage (11.6 V,
which is normal since a diode is involved) on the normal battery connection
terminals.
3. The external battery pack cable that I made for them years ago,
causes intermittent connection to the radio. It does the same when
connected to my radio. I built a new cable using the power connectors I
bought from Mouser and those are also too loose and work intermittently.
This looseness/intermittent connection was experienced on both the county's
SAR TH-D7 and my personal TH-D7 radio.
4. I supplied external power to the normal radio battery terminals on
the SAR TH-D7 and it will NOT power up. Applying the same power to the
battery terminals on my radio makes mine work just fine.
So, it appears that there is a problem between the normal battery terminals
on the back of the DEM radio to the circuit board inside the radio. Joy,
joy...... I have never seen or heard of such a problem. Is there anyone
that has seen this problem before? If so, what did you do to fix it?
My late elk hunting season starts tomorrow, so this radio problem will have
to wait till after my hunting season. Any inputs in the mean time would be
appreciated.
The unfortunate part of this problem is that this is the first time that
they really tried to use this TH-D7 tracker during an actual search. Sure
would have been nice if it had worked. I have been trying for years to get
them to use this tracker during an actual search and now when they finally
tried it, it would not work. It worked just fine about a year ago when I
checked it out. As far as I know, no one has used it since then.
Herb, KB7UVC
Mason County ARES/RACES ex-President & APRS Coordinator
Mason County ComVan: http://map.findu.com/KB7UVC-1
Mason County Relay Truck: http://map.findu.com/KB7UVC-2
Mason County EOC: http://map.findu.com/KB7UVC-3
Mason County Foot Tracker: http://map.findu.com/KB7UVC-6
------------------------------
Message: 9
Date: Tue, 21 Nov 2006 20:05:14 -0500
From: "carl szentes" <n9ibd.szentes_at_worldnet.att.net>
Subject: Re: [aprssig] Opinions for a small ultra compact notebook PC?
If any of the aprs users do find a Toshiba Libretto, make sure it includes
the docking adaptor model CAB0346A. There is no serial port on the basic
unit. My note book is the Libretto 70CT and am pleased with it as a
portable unit. Like many lap tops, the screen is washed out in bright
light, and in my eyesight, need magnifying glasses to read the print. You
are viewing a display intended for a 14 inch display on a Toshiba 3.75 in
by 4.875 in ( 6.0 in diag )
73 Carl, N9IBD
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Message: 10
Date: Tue, 21 Nov 2006 21:01:14 -0500
From: "Robert Bruninga" <bruninga_at_usna.edu>
Subject: RE: [aprssig] APRS DF reporting
>>(with DF code in it). The APRS software then parses out the DF
>>info and the interleaved GPS info and then when appropriate,
>>sends the combined single packet containing the DF unit's:
>>LAT/LONG/CSE and SPEED
>>DF bearing
>>Signal quality
>>Range of the bearing line
>
>My only question here is what the range is supposed to mean.
>How can you know the range, if you don't know the transmitter power?
The human who is Dfing knows it or has the best guess on it. In APRSdos,
it is automatically assigned based on the range-scale of the map he is
currently viewing. If he is driving around and looking at a 16 mile range
scale map, then he probably is not expecting the FOX to be beyond that
range. When he is zoomed into the 1 miel range scale and is clearly
zooming in on the fox, then the bearing lines are transmitted as only 1
mile long lines.
This is very important because distant viewers may be looking at any number
of range scales. We don't want him looking at a 128 mile long DF bearing
line on his map implying the fox is in West Virginia because he is looking
at a state map of virginia, while the mobile is only 5 blocks east of the
FOX and has a west heading.
Back in 1993 when we added Dfing to APRS, the very first use of it made it
obvious that SCALE must be included in the transmitted information or on
receipt the informaiton is useless.
EXAMPLE: I was on a fox hunt with APRSdos and my Doppler DF. I started
about 8 miles from the fox. As I got closer and closer, and due to limited
exits on interstates and limited turns on highways, My final several miles
were all right turns as I spiraled in on the FOX. Now if you are zoomed
into the few mile scale, my DF bearing lines looked perfect as they always
pointed inward to the fox as I spiraled in. BUT TO SOMEONE ON any map
scale larger than about the 8 mile range scale, my infinately long bearing
lines looked like random OUTWARD bound bearing lines in all directions of
the compass!
People in other parts of the state assumed it was garbage (because it was
to them since they were not zoomed in....). So since 1993, APRS has always
included the DF operators estimate of the LENGTH of his bearing line based
on his best estimate. If it is a fox hunt in your conuty, then the rules of
the hunt will place a limit on the rnage. Start there. But as one gets
closer, he needs to indicate that he is getting closer and that his lines
should be shorter on everyone's maps.
Of course it is an estimate, but again, we don't want someone that is 3
miles from a fox to be sending out a bearing line that appears on
everyone's display that is infinately long no matter what scale map they
are on...
Bad data is worse than no data... Etc...
Bob, Wb4APR
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Message: 11
Date: Tue, 21 Nov 2006 21:12:00 -0600
From: Jason Winningham <jdw_at_eng.uah.edu>
Subject: Re: [aprssig] APRS DF reporting
On Nov 21, 2006, at 8:01 PM, Robert Bruninga wrote:
>BUT TO SOMEONE ON any map
>scale larger than about the 8 mile range scale, my infinately
>long bearing lines looked like random OUTWARD bound bearing
>lines in all directions of the compass!
This seems like a non-issue to me. If there's more than one report, anyone
with any sense at all will look at the intersection and not the ends of the
lines.
-Jason
kg4wsv
------------------------------
Message: 12
Date: Tue, 21 Nov 2006 23:27:08 -0500 (EST)
From: "Bob Bruninga " <bruninga_at_usna.edu>
Subject: Re: [aprssig] APRS DF reporting
>>BUT TO SOMEONE ON any map scale larger than about
>>the 8 mile range scale, my infinately long bearing
>>lines looked like random OUTWARD bound bearing
>>lines in all directions of the compass!
>
>This seems like a non-issue to me. If there's
>more than one report, anyone with any sense at
>all will look at the intersection and not
>the ends of the lines.
Then I dont think you have seen what I am talking about. There is no
intersection at large maps scales. All the bearing lines appear to be
radiating outward. As you say, "anyone with any sense" may see that as
"typical garbage" from yet another person playing with their new doppler DF
box and so will ignore the junk when maybe it is something he should look
at.
We dont want someone on a fox hunt in California with bearing lines
crossing the USA into New York just because someone is looking at a map of
the USA.
I disagree, it is a very improtant issue. Bearing lines have an estimated
length relative to the knowledge of the person doing the bearing line.
That information must be included in the DF report. Else it is just more
well intentioned, but useless missinformation regurgitated onto APRS...
de Wb4APR
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