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ZL3AI > APRDIG 21.04.03 09:34l 253 Lines 9712 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Apr 18, 2/3
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Recommended Standalone TNC for APRS
From: "k7ftp" <k7ftp@commtechreview.net>
Date: Fri, 18 Apr 2003 14:18:20 -0600
X-Message-Number: 6
Howdy all,
I just wanted to see what this group recommends for a really basic setup. I
have been told that the MIC-E is no longer available. If someone happens to
have a spare 2m mobile radio and a GPS, what's the best standalone TNC to
use without a laptop in the vehicle?
Thanks in advance!
Jim K7FTP
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Subject: Re: Recommended Standalone TNC for APRS
From: "Curt Mills, WE7U" <hacker@tc.fluke.com>
Date: Fri, 18 Apr 2003 13:34:40 -0700 (PDT)
X-Message-Number: 7
On Fri, 18 Apr 2003, k7ftp wrote:
>I just wanted to see what this group recommends for a really basic
>setup. I have been told that the MIC-E is no longer available.
>If someone happens to have a spare 2m mobile radio and a GPS,
>what's the best standalone TNC to use without a laptop in the
>vehicle?
Transmit-only? Tinytrak-3 @ www.byonics.com. Cheap too!
Transmit/Receive capability for laptop/PDA connections in the
future? Kantronics KPC-3+ (the '+' is important).
--
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: Re: Recommended Standalone TNC for APRS
From: Miller Scott Contr 30SCS/FTI <Scott.Miller@vandenberg.af.mil>
Date: Fri, 18 Apr 2003 20:49:05 -0000
X-Message-Number: 8
I was just looking at the TT3 homepage. I see it's got a carrier detect -
is it just an energy detect that requires squelch on the radio, or is it a
tone decoder?
On a related subject, has anyone built a packet demodulator using an NJM2211
decoder?
Scott
N1VG
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Subject: Re: Recommended Standalone TNC for APRS
From: Miller Scott Contr 30SCS/FTI <Scott.Miller@vandenberg.af.mil>
Date: Fri, 18 Apr 2003 21:01:01 -0000
X-Message-Number: 9
Never mind, just found it in the docs. Looks like it requires squelch.
Ok, next question. I see the TT3 uses four resistors to form a D/A
converter. I was considering the same scheme. How clean is the output
signal from the TT3? Any trouble with harmonics?
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Subject: Re: Recommended Standalone TNC for APRS
From: Kirk Mefford <kc2elo@softhome.net>
Date: Fri, 18 Apr 2003 16:58:49 -0400
X-Message-Number: 10
It is just an energy detect CD so yeah you gotta have squelched audio
feeding it.
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Subject: Re: Recommended Standalone TNC for APRS
From: Dave VanHorn <dvanhorn@cedar.net>
Date: Fri, 18 Apr 2003 16:09:41 -0500
X-Message-Number: 11
At 09:01 PM 4/18/2003 +0000, Miller Scott Contr 30SCS/FTI wrote:
>Never mind, just found it in the docs. Looks like it requires squelch.
>
>Ok, next question. I see the TT3 uses four resistors to form a D/A
>converter. I was considering the same scheme. How clean is the output
>signal from the TT3? Any trouble with harmonics?
If you pick the resistors right, it will be pretty clean up to the 16th, by
then it won't matter much.
It's a common technique for DTMF generation, even in places that require
pretty high spectral purity.
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Subject: Re: Recommended Standalone TNC for APRS
From: Miller Scott Contr 30SCS/FTI <Scott.Miller@vandenberg.af.mil>
Date: Fri, 18 Apr 2003 21:12:32 -0000
X-Message-Number: 12
Good to know. How about with three resistors? That'd cut it down to 8
voltage levels. I've seen it used for model rocket telemetry, but I don't
have the equipment to test it properly for spectral purity.
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Subject: Re: HSMM hamming (was can 'o worms)
From: Jeff King <jeff@aerodata.net>
Date: Fri, 18 Apr 2003 17:15:10 -0400
X-Message-Number: 13
On Fri, 18 Apr 2003 13:01:48 -0700, Bill Vodall wrote:
>
>>Further, amateurs are NOT forbidden from using "other digital codes" as long
>>as they are published.
>
>Right. Which can have the same effect as encryption.
If the intent is to encrypt, then it is illegal. If someone doesn't know the
code (for example ax.25), and they can't decode it or get into the network,
that doesn't make it illegal. The kicker is it has to be publicly available
and done for a legitimate reason other then encryption.
>So why shouldn't we
>just get things changed so we don't have to "fudge" and can do it for real.
We agree on this. I know what I am trying to do to get it changed, do you
have any suggestions?
>>Any hacker can break any network.... your "secure" part 15
>>networks you are touting could be cracked by any script kiddie in a short
>>period of time. See:
>>
>>http://airsnort.shmoo.com/
>
>Really? I didn't think it was that easy to break SSH, IPSEC and VPN's.
I said secure Part 15 network, in which I meant WEP. The others can be used
atop other networks.
>Everybody should know that the built in WEP security and MAC restrictions on
>Wi-Fi gear function like a lock on a car door. It keeps out the honest
>folks but not the script kiddie with a brick.
Right, and I was referring to your comment about the "neighbors" watching the
name. While it is not hard to be a script kiddie, your average Part 15 user
can barely configure their AP let alone even know what airsnort is. Hence, in
a adhoc, emergency situation, it would be reasonably secure.
>>Further, my real point was that hams have to obey FCC rules
>
>I never said anything different.
By association, I inferred this. Sorry if I was mistaken. Reason I did, was
by saying that it could be done under part 15, in apparently all cases. But
it can't be done unless you have a RF path, which part 97 gives you far more
latitude to engineer. So I say yes, by all means, do it under part 15 if it
is a legal setup, but if you can't get a link, do it under the greater
latitude of part 97.
>So why shouldn't be able to use technologies that are available to
>unlicensed folks.
We should be able to. I think hams should be allowed to use encryption.... it
is nuts that we cannot when any joe blow with part 15 can...I mean, we passed
the license test, they didn't.
>>Sure, if you
>>can do the link with Part 15 in a legal configuration, then do it. But if you
>>have to modify it to get the link, then technically you are in violation of
>>Part 15 rules and should be doing it under Part 97.
>
>Some experimentation is allowed under Part 15 rules..
15.23, best read it. For the applications being discussed, routine health and
welfare traffic, it likely does not apply. And in no case can external
amplifiers be sold legally without certification. The emergency folks are
going to want "kits" they can deploy at a moments notice and will not be
interested in "experimenting" when people are dieing. Yes, Part 15 gear could
be used, but it would have to be certified as a system. Not cheap.
But again, in a real emergency, I' d not worry too much either way. Just get
something that works and sort the part 97 from part 15 later. But in testing
and drills, that is another matter. If it was me, I'd test under part 97 and
make the decision to encrypt (or "say" I was under part 15) when the actual
emergency came about. And not talk about it afterwords ;-)
>That's exactly what I've been saying all along. Use Part 15 with encryption
>for the local stuff and go to amateur rules for the longer hops.
Can't see where we disagree.
>What I'm suggesting here is that it would be a good thing if we could use
>the encryption technology on Amateur links. It would make it "more useful"
>and wouldn't hurt anything.
We deserve it as amateurs. We passed a federal test and submitted to
administrative law yet unlicensed users have more liberty then we do. The
whole Part 15 community network folks, in most cases, should all be hams and
be able to do the stuff they are doing now under amateur radio. It would be a
tremendous boost to the hobby.
>Anybody who hasn't yet jumped on the Wi-Fi wave - do it. Get an Orinoco
Silver PC card.
>Get a WAP-11 or similar AP. Play. Experiment. Do it. Do it today!
And also I'll add, run a 802.11b link to your field day site. You'll get 100
extra bonus points for a demonstration mode. Did a mini demo at my local club
and they want to deploy it at Field Day now. The field day site is is at the
local fairgrounds and we generally get a story in the newspaper.
73
Jeff wb8wka
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Subject: Re: Recommended Standalone TNC for APRS
From: Dave VanHorn <dvanhorn@cedar.net>
Date: Fri, 18 Apr 2003 16:25:54 -0500
X-Message-Number: 14
At 09:12 PM 4/18/2003 +0000, Miller Scott Contr 30SCS/FTI wrote:
>Good to know. How about with three resistors? That'd cut it down to 8
>voltage levels. I've seen it used for model rocket telemetry, but I don't
>have the equipment to test it properly for spectral purity.
I wouldn't reccomend it. Half the steps, twice the distortion.
Resistors are cheap.
What's the state of the art in hpr telemetry these days.
I've been out of it for a while.
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