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ZL3AI > APRDIG 05.10.03 10:33l 300 Lines 12588 Bytes #999 (0) @ WW
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: [ Henk de Groot ] Re: [ Bob Bruninga ] Re: Digipeater Duplicate
Checking is broke
From: Henk de Groot <henk.de.groot@hetnet.nl>
Date: Thu, 02 Oct 2003 14:35:21 +0200
X-Message-Number: 10
At 01:17 2-10-03 -0500, Gregg G. Wonderly wrote:
>>At 22:42 30-9-03 -0500, Gregg G. Wonderly wrote:
>>>Last time we talked about fratricide, I volunteered a diagram. The
>important
>>>detail is that if both Digis are DWAIT=0, then the area that has zero
>fade is
>>>the place that is the RF middle between the digis. If they are equal power
>>>and gain and haat, then it is smack in the middle. If I am closer to B
>than
>
>Henk, I was trying to say that the RF middle is the location of the worse
>reception, not the best. So, whereever the RF middle is, is the place where
Oh, then I misunderstood "zero fade". I took it to mean that that was the
only place with a stable signal in the overlapping area (given equal field
strength of both digis). Sorry for the confusion...
Kind regards,
Henk.
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Subject: Is there more to this group than path discussions ?
From: "Andrew Rich" <vk4tec@hotmail.com>
Date: Thu, 02 Oct 2003 23:45:33 +1000
X-Message-Number: 11
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Subject: RE: DigiNed, was: Re: Take Control of your DIGI part 4
From: Jeffrey Nast <jpnast@lca.duluth.mn.us>
Date: Thu, 02 Oct 2003 09:14:57 -0500
X-Message-Number: 12
I am currently toying with putting DigiNed on a Neoware thin client. A
co-worker has successfully reloaded one of our thin clients with a Linux
kernel and booted from it. This model (NeoWare EON4000s) comes with a
24MB DiskOnChip (DOC, larger sizes available, http://www.m-sys.com), 2
serial ports, 2 USB, 10/100 Ethernet, keyboard/video/mouse, 1 printer
port, sound and 1 empty ISA/PCI slot (more serial ports?). Runs direct
on 100-240VAC (no external power supply), 15 watts, no fans and no disk
(in short, the only moving parts are the cover screws and the power
switch!). Perfect platform for remote sites... if I can get it to work.
Other TC manufacturers also use the DiskOnChip, WYSE comes to mind...
Just started last week, so I don't have much more than this... and I
don't have a whole lot of spare time.
-Jeff
KC0MKS
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Subject: Re: [ Henk de Groot ] Re: [ Henk de Groot ] Re: [ Bob Bruninga ] Re:
Digipeater Duplicate Checking is broke
From: "Gregg G. Wonderly" <gregg@skymaster.cytetech.com>
Date: Thu, 02 Oct 2003 10:14:31 -0500
X-Message-Number: 13
>At 01:17 2-10-03 -0500, Gregg G. Wonderly wrote:
>>Henk, I was trying to say that the RF middle is the location of the worse
>>reception, not the best. So, whereever the RF middle is, is the place where
>
>Oh, then I misunderstood "zero fade". I took it to mean that that was the
>only place with a stable signal in the overlapping area (given equal field
>strength of both digis). Sorry for the confusion...
I should have said equal power I suppose. I meant that there is a zero
fade margin between the two and thus they have equal power visible to a
receiver in that area, and thus FM capture is problematic.
-----
gregg@cytetech.com (Cyte Technologies Inc)
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Subject: Re: Even cheaper GPS receivers
From: Floyd Rodgers <kc5qbc@swbell.net>
Date: Sun, 28 Sep 2003 21:41:55 -0500
X-Message-Number: 14
Anyone have the PC flavor software and like to trade for the PDA version?
Floyd Rodgers KC5QBC
Multi ended candle burning artist in training
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Subject: RE: DigiNed, was: Re: Take Control of your DIGI part 4
From: "Scott Miller" <scott@opentrac.org>
Date: Thu, 2 Oct 2003 09:08:08 -0700
X-Message-Number: 15
Sweet - any idea if this works on the older HDS units? I've got at least a
dozen of 'em in my garage, I think. I had tons more, but sold most of
them.
Scott
N1VG
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[commercial content deleted]
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Subject: Re: APRS Linux digi, was: Re: DigiNed, was: Re: Take Control of your
DIGI part 4
From: "Curt Mills, WE7U" <hacker@tc.fluke.com>
Date: Thu, 2 Oct 2003 09:26:23 -0700 (PDT)
X-Message-Number: 18
On Thu, 2 Oct 2003, Henk de Groot wrote:
>Just thinking about it, Linux also runs from CF cards on Psion orgranizers.
>These are also very small and have a low power consumption and I think they
>have a standard serial port. I have no idea if they can be had cheap
>second-hand. If it runs a kernel with AX.25 support then I don't think
>getting DIGI_NED to run should give any problem (I tried hard to make
>DIGI_NED portable so there should not be any big-endian/little-endian
>problems, I guess Psion uses a ARM processor inside). If it doesn't have
>AX.25 support a small piece of software has to be added to make DIGI_NED
>talk KISS directly to the serial port, shouldn't be too hard to do.
Another possibility might be the Sharp Zaurus PDA's. They run Linux
already with Qt. Used ones in the 200MHz class are under $200.
Besides, they're cute.
As far as flash, make sure you minimize writes to the filesystem and/or use
a flash filesystem underneath so that you "walk" the writes across the
flash system. If you don't do that you'll end up replacing your flash too
often 'cuz it'll wear out.
I've used Slackware before when I had to do minimum systems. It's fairly
easy to only install what you need and skip the rest. There are other
_very_ tiny distributions out there that might do better for this project
though.
--
Curt Mills, WE7U hacker_NO_SPAM_@tc.fluke.com
Senior Methods Engineer/SysAdmin
"Lotto: A tax on people who are bad at math!"
"Windows: Microsoft's tax on computer illiterates!" -- WE7U
"The world DOES revolve around me: I picked the coordinate system!"
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Subject: APRS link margins and RELIABILITY
From: Bob Bruninga <bruninga@usna.edu>
Date: Thu, 2 Oct 2003 12:28:56 -0400 (EDT)
X-Message-Number: 19
On Thu, 2 Oct 2003, Gregg G. Wonderly wrote:
>I should have said equal power I suppose. I meant that there is a zero fade
>margin between the two and thus they have equal power visible to a receiver in
>that area, and thus FM capture is problematic.
Except that no signal is constant or perfect. With the 6 to 20+ dB of
multipath signal varation no matter where you stand or put your antennna
within every 18" or so (every 1/4 wavelength, the multipath will be quite
different). Thus the -difference- between the two signals can varry from
Plus AND minus by 20 + 6 dB or over 26 dB.
Now since the FM capture effect has been shown to require only a 10 dB
signal difference for one or the other to capture the FM receiver, this
means that this EXACT center location where the two signals can collide
with neither being detected can vary by as much as 16 dB (26dB - 10dB)
and still have ONE or the OTHER signal be decoded without a collision.
Now a 16 dB margin in "location" means a difference in 8 dB of range
(power is proportional to the square of range). And 8 db is a factor of
9. Thus you can still get a collision, or you can still get one signal
above the other and still be NINE times closer or farther from either
digi.
With these VAST degrees of variability in the APRS mobile environment is
why APRS must have redundancy in PACKET delivery. That is why APRS was
designed with the recognition that there needs to be a few dupes to help
assure reliability.
And that is ALSO why, these people that are on crusades to eliminate ALL
dupes and make sure that only one and only one copy of a packet are seen
anywhere will make APRS FAR more unreliable. If there is not some
probability of some dupes, then there is an equally high probability that
you wont get ANY. And combine that with the loss of the dupes and you
will be building a network that will NOT be reliable.
APRS is working in a VERY dynamic RF environement of +/- 6 to 26 dB of
mobile fluuter added on top of probably another 60 dB of variabiitly
depending on WHERE you are in relation to the digi, means propogating one
and only one copy of somethign can be GUARANTEED not to get to everyone.
There was a WHOLE lot of fundamentals that went into the APRS network
design that has been TRASHED because few take the time to understand all
these nuances and just start hacking away...
de WB4APR, Bob
(Going off email for the next 4 days to go to my High School reunion)
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Subject: Re: Super Deal for APRS / Data Radio
From: WA8LMF2@aol.com
Date: Thu, 2 Oct 2003 13:12:56 EDT
X-Message-Number: 20
In a message dated 10/2/2003 9:25:22 AM Pacific Daylight Time,
dvanhorn@cedar.net writes:
>same pinout as the tm-v7a, incidentally.
Not a coincidence. This is a standard adopted by all the Japanese ham mfrs.
===== Yet another repost of my commentary on this issue ========
The 6-Pin MiniDIN "DATA" or "PACKET" connector is an industry standard
adopted by all the Japanese ham mfrs. The contacts on this connector
provide access to:
TWO kinds of receive audio:
Raw non-deemphasized discriminator output sometimes labeled "9600 Baud
Receive".
De-emphasized squelched audio similar to what come out the speaker, but
at a fixed level unaffected by the volume control. It is sometimes labled
"1200 Baud Receive".
On multi-mode radios (Yaesu FT-817, FT-100, etc), only the 1200 baud output
will be live on AM, SSB or CW since the 9600 baud output is associated only
with the discriminator of FM receivers.
Receiver Squelch status line (normally no sig-squelch-closed = 0V, signal
active-squelch open = 5V). Sometimes labled "COR", "COS", "RX" or
"Activity".
TX audio input (sometimes misleadingly labeled "TX Data Input") In many
radios, this input can go either into the same channel as the mic input
(but at a higher audio level) for 1200 baud packet, SSTV, EchoLink, etc, or
DC-coupled directly into the TX modulator (for 9600 baud packet) depending
on the setting of an item in the radio's configuration menu.
TX PTT (confusingly labeled "Standby" by Kenwood) -- normal
ground-to-transmit line just like most mic inputs.
Common/Ground.
Note that despite the misleading labels referring to data input and output,
the jack only carries AUDIO, AUDIO, AUDIO! THERE IS NO ACTUAL DATA in
the sense of RS-232 or TTL-level streams of 1s and 0s anywhere on this
connector!!!
This connector is the perfect point to connect packet TNCs, soundcard
interfaces, phone patches, IRLP/EchoLink controllers, paging encoders, or
any other device that needs access to the transmit and receive audio of a
radio.
These audio inputs and outputs are high-level 100-300mV, similar to home
stereo "LINE" input level seen at RCA jacks on tuners, amps, tape decks,
etc, rather the the 5-10mV level seen at most mic input jacks.
On most radios with this port, grounding the DIN-6 PTT line mutes the front
panel mic input to prevent extraneous shack noises from getting mixed with
whatever you feed into the transmit audio input.
You can connect a TinyTrak here very effectively if you:
1) Change R5 (220K resistor) on the TT to about 27-33K to boost the TX audio
level from mic level to line level.
2) Connect the direct DC-coupled "CARRIER DET" line of the TT to the
MiniDIN "SQUELCH" or "COR" line.
An annotated pinout diagram of this connector is on my website at:
http://members.aol.com/wa8lmf/miscinfo
Click through the link on this page which will take you to a directory of
assorted downloadable files, not a web page. Look for the file
MiniDIN6-Packet.pdf
Note that this connector is exactly the same one used on PS/2 keyboard and
mouse cables. A dead mouse, or a PS/2 keyboard extension cable, is an
excellent source of a plug and cable assembly to mate with the jack on the
radio.
Stephen H. Smith wa8lmf (at) aol.com
Home Page: http://wa8lmf.com
Ham Radio/Mobile SSTV page: http://members.aol.com/wa8lmf/ham
APRS Stuff
http://members.aol.com/wa8lmf/aprs
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