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ZL3AI > APRDIG 05.03.03 09:13l 308 Lines 12053 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Mar 02, 1/2
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
TAPR APRS Special Interest Group Digest for Sunday, March 02, 2003.
1. WTB Tripmates
2. RE: TXD (Final answer?)
3. TH-D7 Magellan GPS and other stuff
4. thd7 and pcsat
5. RE: TXD (Final answer?)
6. Re: TNC Power Drains, GUESS WHAT!
7. TAPR Monthly Update
8. DeLorme once again a source for GPS receivers!?!
9. Re: WTB Tripmates
10. FW: Announce UI-Traffic V2.2.5 Beta
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[commercial content deleted]
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Subject: RE: TXD (Final answer?)
From: Henk de Groot <henk.de.groot@hetnet.nl>
Date: Sun, 02 Mar 2003 17:21:50 +0100
X-Message-Number: 2
Hello Jeff,
At 11:46 1-3-03 -0500, Jeff King wrote:
>Point being, APRS is based on CSMA. The fact that the network is
Sure, but with mobile stations it suffers more from the "hidden
transmitter" problem than conventional AX.25 with fixed stations; which
means that CSMA does not contribute as much as for other AX.25
applications. This is no surprise, X.25, and therefore AX.25, was not
designed with mobile use in mind.
In a lot of cases CSMA only works between an APRS station and its
digipeater; almost all APRS stations can hear their digipeater and will not
jam the QRG when the digipeater is transmitting. The digipeater will not
start transmission when it still recieves a signal from an APRS station. So
between these two CSMA works okay but it does not work if the mobile
station has to use a RELAY to reach the digipeater.
Note also that every transmitted packet will (in principle) load the QRG
twice, once from the APRS station and once the repetition from the
digipeater (and assuming that the digis following after that are far enough
away not to load the local QRG). Its very hard to make an accurate model
for this. Therefore we can keep it simple, when it fits in an ALOHA type
network then it will also fit in APRS with semi-working CSMA.
>over-extended is no excuse to ignore this. CSMA does have some value on APRS
>and users should not be encouraged to ignore it.
Off course not! The observation was just that when calculating the link
budget under ALOHA conditions, one should not use the total time for TXD
but only the portion that it is actually transmitting. But trancievers with
a low RX<->TX (and TX<->RX) changeover time will outperform those with a
longer time when the network is not pure ALOHA but also partly CSMA.
The only reason I can think of why Kenwood choose to have 500ms as TXD is
because that's the TAPR TNC2 default and nobody thought one second about
this. This and the fact that the T2 and T3 timers do not even work leads me
to the conclusion that they didn't understand what they where building. So
I guess that must be the reason why Kenwood did this, ignorance and lack of
competence.
Kind regards,
Henk.
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Subject: TH-D7 Magellan GPS and other stuff
From: "Joe Della Barba" <joe@dellabarba.com>
Date: Sun, 2 Mar 2003 16:17:36 -0500
X-Message-Number: 3
I tried 200 msec TXD with poor results and 300 msec TXD with good results.
Second, I found a "Magellan 6 digit" setting to get the TH-D7 to send
waypoints to my Magellan 315. I thought this only worked with Garmin, so
this is a treat.
Other than this list, is there a SIG for this radio? I am fining it very
complicated to operate.
73
Joe
N3HGB (-5,-1,-7,-14)
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Subject: thd7 and pcsat
From: Kevin Deckert <kdeckert@mercuryspeed.com>
Date: Sun, 02 Mar 2003 06:00:47 -0800
X-Message-Number: 4
Living here as I do in the middle of radio no-where! It is somewhat
exciting to be able to stand in my yard with the my new kenwood thd7 and
press one button and reach pcsat! and hear KB9IBW 2921 kms away! (with
the stock rubber duck)
Thanks Bob et all for adding so much to the hobby!!!
ve7whk
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Subject: RE: TXD (Final answer?)
From: Jeff King <jeff@aerodata.net>
Date: Sun, 2 Mar 2003 18:07:49 -0500
X-Message-Number: 5
On Sun, 02 Mar 2003 17:21:50 +0100, Henk de Groot wrote:
>At 11:46 1-3-03 -0500, Jeff King wrote:
>>Point being, APRS is based on CSMA. The fact that the network is
<snip>
>>over-extended is no excuse to ignore this. CSMA does have some value on APRS
>>and users should not be encouraged to ignore it.
>
>Off course not!
Then lets not give people a reason to ignore it, that is all I am saying. I
already admitted I am aware of the reality of the network, but just because
it is already broken is no reason to make it even worse.
>The only reason I can think of why Kenwood choose to have 500ms as TXD is
>because that's the TAPR TNC2 default
TNC2 default was 300ms, TNC1 default was 140ms. So, it seems as radios have
gotten better, for some odd reason TNC makers think they have gotten worse.
Go figure?
>and nobody thought one second about
>this. This and the fact that the T2 and T3 timers do not even work leads me
>to the conclusion that they didn't understand what they where building. So
>I guess that must be the reason why Kenwood did this, ignorance and lack of
>competence.
I'm not sure if I agree with this. More then likely they are very capable
technically (at least for 1200 baud AFSK), it is just their marketing people
have a low opinion of amateur radio operators and they (Kenwood marketing)
are lazy. They aspire to the lowest common denominator and as one of their
"marketing types" once told me, their goal is to reduce their customer
support load... hence, they market products that can be used by the most
ignorant right out of the box without having to learn the local network or
read a manual.
Still, in the end it is the same, but the Kenwood walkie talkie is capable of
a <70ms TXD. That is darn good for a PLL rig let alone a HT.
Regards,
Jeff
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Subject: Re: TNC Power Drains, GUESS WHAT!
From: RWendel@aol.com
Date: Sun, 2 Mar 2003 18:12:14 EST
X-Message-Number: 6
AEA PK232 MBX 970mA
AEA PK88 560mA
MFJ 1270B 325mA
Kantronics Original KAM with enhancement board 250mA
Kantronics KPC3+ 12mA ( ! )
Stephen:
Thanks! I added (above) my PK88.
You motivated me to measure my PK88 because I've been thinking about running
packet while camping.
Also...
I'm glad I decided to check the current draw. It's been at least a few years
since I've even used my PK88, and since I decided to put it on the bench for
the current-draw measurement, I opened it up...AND...(guess what) realized
that my 2-AA batteries were leaking quite moderately (stuck onto the inside
of the top cover) and were dripping onto the main board/components. Time to
get out the old toothbrush and clean off some white crystally-flaky stuff!
When's the last time *anyone* here opened up their TNC and checked for backup
battery leakage! I better open up my PK232...I did it a few years ago. Best
I do it and just replace them and be done. HINT: Put a sticker somewhere on
the TNC when you last replaced batteries!!!
Randy KM=D8D
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Subject: TAPR Monthly Update
From: John Ackermann N8UR <jra@febo.com>
Date: Sun, 02 Mar 2003 18:40:34 -0500
X-Message-Number: 7
(Sent on behalf of Darryl, VK2TDS, TAPR Membership Director -- mailto:
vk2tds@tapr.org)
People
TAPR Membership
[commercial content deleted]
Digital Communications Conference
This years DCC will take place at the Hartford/Windsor Marriott Airport
Hotel in Windsor, Connecticut, on the weekend of September 19-21, 2003.
The hotel is 6 miles south of Bradley International Airport (BDL) and 13
miles north of ARRL Headquarters in Newington. Information will soon be
available on http://www.tapr.org/tapr/html/conff.html. Until then you
can find more information in the PSR at
ftp://ftp.tapr.org/psr/Winter_86_2003.pdf
We will soon be issueing a call for papers for this event. Have a think
about what you want to write about and start planning your paper now. If
you are unable to come up with a subject, it is often possible to find
friends with something to write about, but who don't have the time. You
can help your friend and the Ham community by writing the paper on their
behalf. There will be two popular discussion points at the conference -
Software Defined Radios and 802.11 networks.
DCC Conference Proceedings
We have also reduced the price of each of the proceedings of the DCC up
until 1997 to only US$x each. This makes the a real bargain. We are also
making available sets of volume 1-10 and 11-16 available for $US$xx each
- but please bear in mind that we no longer have copies of a number of
the proceedings so we cannot guarenttee that the sets will be complete.
Electronic Distribution of Packet Status Register (PSR) Magazine
Listening to members we have found that many people are concerned about
missing out on the PSR now that it has gone electronic. We recognise
this as an issue, and we have come up with a solution to make things a
bit easier in this digital age. We have created two mailing lists to
assist you with keeping up to date with the quarterly magazine. They are
PSR-Announce
PSR-PDF
PSR-Announce is designed to advise the availability of the PDF file for
download. We recognise that many people are on slow internet connections
at home, or in fact have to pay for their bandwidth. So we have created
a mailing list just to tell you when the magazine comes out, and to let
you know how to get it. You can subscribe by visiting
http://www.tapr.org/cgi-bin/lyris.pl?enter=psr-announce&text_mode=0
PSR-PDF is designed for people who have a faster internet connection, or
who know that they will never get to read it unless it is sent directly
to them. Since PSR often contains graphics, the file can be over one
mByte. You can subscribe by clicking
http://www.tapr.org/cgi-bin/lyris.pl?enter=psr-pdf&text_mode=0
802.11 Mailing List
Whilst we are on the subject of mailing list, TAPR have started a
mailing list for 802.11 'Wireless Internet' operations. It seems that
every community has a mailing list dedicated to 802.11. So how is the
TAPR one different? It is dedicated to 802.11 use in ham radio. The list
contains active members of the entire range of technical ability - from
the most basic understanding of how radio works, to the deep internals
of this equipment. Such a broad range that everyone is sure to fit in.
You can join by visting
http://www.tapr.org/cgi-bin/lyris.pl?enter=ham-80211&text_mode=0
GNUradio receives HDTV
Matt Etus and the other people at the GNUradio project have announced
that they have managed to decode the HDTV data stream on their PC's and
have published the source code online. This is an amazing feat by Matt
and the team. They are not quite to the stage of real time HDTV decoding
on a PC, but are close.
Write for PSR!!!
PSR needs articles, and we would love to publish lots more in the PSR
magazine. PSR is a great place to publish articles on everything from
local operating practices to deep technical papers. And since the last
issue TAPR is now rewarding those people who are helping others by
writing articles for the magazine. Following the last issue, six people
had their memberships extended by three months. This is just a small
thank you from us at TAPR to those people who help us out. More details
on PSR can be found on www.tapr.org
Conclusion
I hope you have found this document informative and useful. TAPR is
always looking for new things to do and how to improve what it is
already doing. If you have any ideas or concerns, please email me on
darryl@radio-active.net.au
Darryl
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