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ZL3AI > APRDIG 24.04.03 10:14l 243 Lines 9664 Bytes #999 (0) @ WW
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: Multiple Sound Cards
From: Miller Scott Contr 30SCS/FTI <Scott.Miller@vandenberg.af.mil>
Date: Mon, 21 Apr 2003 19:36:21 -0000
X-Message-Number: 37
Well, *I* have a lab coat anyway. A stylish anti-static blue one, in fact.
I may even have a pocket protector around someplace. =] Is there a TAPR
projects SIG where we can follow what's going on and what project ideas are
being discussed?
Scott
N1VG
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Subject: Re: Recommended Standalone TNC for APRS
From: David VanHorn <dvanhorn@cedar.net>
Date: Mon, 21 Apr 2003 14:27:48 -0500
X-Message-Number: 38
>So now my question is this: Can anyone recommend a good PC-based
>oscilloscope, or would I be better off watching eBay for a used HP or Tek
>'scope?
I use a Tek TDS-420A. I wouldn't mess with a PC based scope, unless it had
some serious recommendations. I could scope it for you, and email
waveforms...
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Subject: Re: Recommended Standalone TNC for APRS
From: Miller Scott Contr 30SCS/FTI <Scott.Miller@vandenberg.af.mil>
Date: Mon, 21 Apr 2003 19:46:58 -0000
X-Message-Number: 39
The PC based ones seemed to have some nice user interface features for
measurement and data capture. Looking at eBay, though, it looks like I
could pick up a good used stand-alone scope for the same price as a low-end
PC unit.
I'm sure I'll get this figured out (already found an incorrect resistor and
a possible software glitch), it's just annoying not having the right tools
on hand.
A good logic analyzer would be nice, too. I hacked together a low-speed
tool using my 56-bit DAQ board that does a passable job at least.
Scott
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Subject: Re: Recommended Standalone TNC for APRS
From: John Kraus <flyfisher452@cox.net>
Date: Mon, 21 Apr 2003 15:55:14 -0400
X-Message-Number: 40
Sigh
But of course we are Americans and we must reinvent the wheel at every
opportunity. It would be much to simple for TAPR to try and find a way to
market these in the U.S.
http://www.baycom.org
The BayCom USB modem was designed by HB9JNX. It allows AFSK operation at
1200bd/s AND FSK operation between 9k6 and 300kbit/s (G3RUH compatible).
Standard speed is 76k8, but other baudrates can be achieved by changing six
capacitors.
The new EPPFLEX high speed modem. The EPPFLEX modem allows 76k8 - 600kbit/s
FSK operation (G3RUH compatible) on the EPP and ECP port of the PC. An FPGA
based design, it integrates all digital and analog functions on a single
100 * 100mm PCB - and also allows decoding of 1200Bd AFSK by just loading
another driver!
Not just for APRS but all of packet could benefit as well.
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[duplicate]
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Subject: Digi bulk retransmits again
From: Miller Scott Contr 30SCS/FTI <Scott.Miller@vandenberg.af.mil>
Date: Mon, 21 Apr 2003 20:01:24 -0000
X-Message-Number: 42
This is something I'm following up on the opentrac list, but I still think
it'd be of use to APRS.
The issue is that we've got houses and other fixed sites beaconing on a
regular basis. Even here in California with the earthquakes and mudslides,
houses don't move that often. My idea is to add a 'persist' flag to these
beacons.
A digi would retransmit a persistent packet immediately, just like every
other packet. But a memory-equipped digi would also retransmit all stored
packets (assuming they hadn't been superceded) every net cycle. The end
result is that you still get to see your callsign show up on everyone's
screen, but you don't have to tie up the channel advertising it every ten
minutes and adding to the collision load.
Adjacent digis would have non-overlapping time slots assigned, and with an
appropriate path your packet would migrate to other digis during the block
retransmits, subject to limits configured in the digis.
This would also give you a good reason to start encouraging 9600 baud
capability. A backbone-connected digi might provide retransmits from a much
wider area at 9600, giving the average user a real benefit from the higher
speed.
TNCs often have a lot of RAM that's going to waste in digi operation. Why
not put it to good use?
Opentrac's pursuing the ability to specify differing persistence for
individual message elements - done properly, it'd let you set up a weather
station to transmit its position and comments maybe once every few hours,
while updating WX data every few minutes. The block retransmits would
include the aggregated report so new stations wouldn't need any a priori
knowledge of the local stations.
I think the key is really that you have to make sure the fixed stations
DON'T keep transmitting every 10 minutes so long as they can hear their own
persistent reports. By having the fixed station reports come from the digi,
you save a ton of TX overhead and hidden station collisions.
Scott
N1VG
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Subject: Re: Multiple Sound Cards
From: "John R. Ackermann N8UR" <jra@febo.com>
Date: Mon, 21 Apr 2003 16:00:37 -0400
X-Message-Number: 43
--On Monday, April 21, 2003 7:36 PM +0000 "Miller Scott Contr 30SCS/FTI"
<Scott.Miller@vandenberg.af.mil> wrote:
>Well, *I* have a lab coat anyway. A stylish anti-static blue one, in
>fact. I may even have a pocket protector around someplace. =] Is there
>aTAPR projects SIG where we can follow what's going on and what project
>ideas are being discussed?
>
>Scott
>N1VG
Good question. We open up separate mailing lists for most projects.
Whether they are open to anyone, or limited to a smaller group, is up to
the folks spearheading the effort. We don't have a single general project
list because there's so much diversity that any single list would have, in
the perception of some significant number of the people involved, a
horrible SNR.
If you want to get involved in a project but don't already have something
particular in mind, the best thing to do is touch base with one of the TAPR
BoD (or the office) and let them know what areas you're interested in. We
can then scout around to see if there's something going on that we can
attach you to. It's informal, but this process works pretty well.
73,
John
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[commercial content deleted]
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Subject: Re: Digi bulk retransmits again
From: Bob Bruninga <bruninga@usna.edu>
Date: Mon, 21 Apr 2003 16:20:17 -0400 (EDT)
X-Message-Number: 45
On Mon, 21 Apr 2003, Miller Scott Contr 30SCS/FTI wrote:
>The issue is that we've got houses and other fixed sites beaconing on a
>regular basis....
>
>... But a memory-equipped digi would also retransmit all stored (not
>changed) packets... every net cycle. The end result is that you still
>get to see your callsign show up on everyone's screen, but you don't
>have to tie up the channel advertising it every ten minutes and adding
>to the collision load.
Good idea in principle, but it violates the fundamental principles of KISS
and dependency on network knowledge, configuraiton, and a whole layer of
complexity which is not needed and only adds to unreliability (in a
come-as-you-are ham radio system)...
You can use a printer and make a copy of what you see on your APRS screen
and mail it to someone also. But every step away from "real-time" is a
step away from APRS.
If you are trying to re-design APRS, think only in terms of arriving on a
scene, opening up your briefcase of toys, turning it on, and then how
quickly can you join the network in progress and collect the full tactical
picture WITHOUT adding to QRM.
If that is not your objective, then your objective is not the tactical
real-time come-as-you are non-apriori objective of APRS and should be
clearly identified as something different. Define what those
objectives are and make it clear where you are going with it and Then
there are lots of other ways to do lots of other things...
But make sure you know where you are headed...
APRS was suppsoed to work for anyone, at any time, with only a radio and a
TNC and PC (or tracker or Kenwood radio) and no apriori knowledge of
anything except the frequency. 144.39. It was not designed nor intended
for looking at 24/7 maps of benign activity, though that is essential for
being ready to use it when you do need it...
Bob, WB4APR
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Subject: Re: Digi bulk retransmits again
From: Miller Scott Contr 30SCS/FTI <Scott.Miller@vandenberg.af.mil>
Date: Mon, 21 Apr 2003 20:32:17 -0000
X-Message-Number: 46
I don't really see how it requires any network knowledge. You turn on your
rig, and not more than ten minutes later you get a burst containing all of
the more-or-less static stations/objects/facilities that would otherwise be
cluttering up the channel at random intervals. A smart tracker might even
transmit the 'persist' flag when it sees it's not moving. As soon as it
starts moving and transmits a non-persist packet, the digi would dump the
persist packet.
Again, the key is that stations refrain from transmitting if they've heard
their current status retransmitted in the last n minutes. If the digi goes
down, a network cycle or two later the stations start transmitting again.
Scott
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