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ZL3AI > APRDIG 13.07.04 22:07l 285 Lines 12618 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Jul 11, 1/1
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
TAPR APRS Special Interest Group Digest for Sunday, July 11, 2004.
1. Re: More Anti-BPL Ammo
2. Re: help with Street Atlas
3. Pinout For GPS Module
4. Re: APRS 144.39 dual channel upgrade
5. Re: APRS 144.39 dual channel upgrade
6. 9612+
7. Re: APRS 144.39 dual channel upgrade
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Subject: Re: More Anti-BPL Ammo
From: Rick Green <rtg@aapsc.com>
Date: Sun, 11 Jul 2004 00:00:48 -0400 (EDT)
X-Message-Number: 1
On Sat, 10 Jul 2004, Dale Blanchard wrote:
>But the story on how Nextel got the frequencies the are using now in
>interesting.
>May some one remembers.
The way I heard it went something like this:
In the good old days, Motorola obtained many licenses for FM two-way
dispatch systems around the country. They then leased these licenses to
their dealers, who then set up the network of myriad little mom-and-pop
Motorola shops around the country.
Eventually, these operations grew from VHF repeaters to UHF trunking
systems, servicing all the small businesses that service our appliances
and homes.
FInally, along comes Digital, and rather than allow their franchisees to
convert to this new technology, Motorola instead sold all the licenses to
Nextel, who in turn agreed to use Motorola as a sole equipment supplier.
Basically, Nextel is a spun-off subsidiary of Motorola.
Because they were creating a unified nationwide system, it was necessary
to expedite the conversion of all the local licenses, so they gave some
real sweetheart deals to the existing customers, offering them generous
tradins and/or free new radios, along with the warning that their local
trunking system wouldn't work with their old radios anymore.
They got into the cellular business by the back door. One of the
sweeteners in this deal was the inclusion at each node of a 'phone patch',
which would allow restricted users (just the foreman or business owner,
usually) to make phone calls from his walkie-talkie.
For years, Nextel operated in this mode, servicing the small business
market that it knew well. Eventually, the cellular phone business
overtook the trunking walkie-talkie business, and now it's the
walkie-talkie PTT button that's advertised as the 'added feature'!
So in esssence, Nextel is running a cellular system on a hodge-podge of
frequencies cobbled together by aggregating all the old Motorola trunking
UHF FM licenses. INterspersed are the frequencies used by the various
public service trunking systems. Both are growing, and in the current
political climate there is percieved a need to consolidate the disparate
public service systems inso a unified interoperable one (Did you see the
booth at Hamvention this year?). SO it comes down to the old question:
WHo's going to move?
Nextel is well-funded, centrally managed, and easily led by sweetening
the deal with a wider allocation. Local Public service organizations are
generally under-funded, and their diverse nature and political management
is not conducive to an expedited coordinated implementation. Looks like
an obvious choice to me.
I'm a Nextel customer. I don't run a business, I have a single handset
which I use for its cellular capabilities alone. My handset is the
original one I bought in 1997. For the past year or so, Nextel has been
sending me more and more frequent 'invitations' to 'upgrade' to one of
their newer phones. But each 'upgrade' offer has several drawbacks: One,
they're asking me to pay money for a phone I don't need. Two, their new
phones are lighter and have very fragile connectors. Three, they are not
offering any trade-in or deal on my collection of accessories for my
existing phone. and Four, they are asking for a multi-year service
agreement if I accept their invitation. I've satisfied my service
agreement terms years ago, I'm not about to go back under one again now.
When I heard about this allocation swap, it all began to make sense. My
phone is probably too old to be frequency-agile enough to migrate, so they
want to get me to buy one of the newer ones before it proceeds to the
point where they have to give me one in order to keep my business.
--
Rick Green
"They that can give up essential liberty to obtain a little
temporary safety, deserve neither liberty nor safety."
-Benjamin Franklin
P.S. Another case of old technology being sold as a 'new feature': The
'party line' that my family had to share in the fifties with another
family down the block, and we were glad to give up for the more
prestigious private line, is now sold to single families as 'distinctive
ring service'.
----------------------------------------------------------------------
Subject: Re: help with Street Atlas
From: "WA8LMF@aol.com" <WA8LMF2@aol.com>
Date: Sat, 10 Jul 2004 22:02:45 -0700
X-Message-Number: 2
JBCrafts wrote on 7/10/2004, 3:43 PM:
>HOW do I get EXTRACTOR installed??
>
>I am putting SA7 on one of my laptops and want to add maps.
During the install, you have to opt for "Custom Install" instead of the
default install.
Stephen H. Smith wa8lmf (at) aol.com
Home Page: http://wa8lmf.com
----------------------------------------------------------------------
Subject: Pinout For GPS Module
From: "M. Schneider" <msokla@brightok.net>
Date: Sun, 11 Jul 2004 06:38:08 -0500
X-Message-Number: 3
Several years ago I purchased a GPS module from somebody on this sig that
was selling them on ebay. I've finally unearthed it and decided to do
something with it, but I can't find the pinouts for the header strip. It's
a double row of pins, 10 per row. The board has AXIOM printed on it and
ASSY VLRO1D, REV C. It has a GSP1/LX chip. It also says on the board
"POWERED BY SiRF". Can anybody help me with the wiring for this board,
along with any other specs or information that might be useful? I'm
planning on putting this in a case with a TinyTrak, wiring then directly
together.
Thanks & 73,
Mark Schneider - K5MAR
----------------------------------------------------------------------
Subject: Re: APRS 144.39 dual channel upgrade
From: "Robert Bruninga" <bruninga@usna.edu>
Date: Sun, 11 Jul 2004 09:21:13 -0400
X-Message-Number: 4
Well, wes, you said you disagree, but then went on to describe exactly the
design for my proposal. Maybe you are only disagree ing about the
conversion of WX. In that case your concerns are no issue, because the
unconverted original packets are on the NON-144.39 frequency and the
converted ones only on 144.39. There is no problem. But again, that is a
minor issue, not worth condeming the whole concept... de WB4APR
>>>Wes Johnston <wes@johnston.net> 07/10/04 2:48 PM >>>
Bob, I gotta respectfully disagree. Several years ago, I thought it
would be advantageous to compress packets on the fly via the
digipeater.... ie if a digipeater heard a packet which was uncompressed,
it would compress it before digi'ing it. Of course this created two
problems.... 1)there were now two copies of each packet floating around
on the air... one compressed and one uncompressed foiling the WIDEn-n
checksum meant to prevent dupes, and 2)winaprs at one time, did a
conversion on air (still does on TCP) which caused stations to "jump" to
the nearest integer 60 foot mark.
Based on these two things I came to the conclusion that we should never
modify the contents of a packet on the fly. Header/Path yes,
information no. That would also include altering WX packets. As cheap
as pic processor tncs are (and with so many of them now open sourced),
why not just insist that WX station operators add a little extra
processing?
In so far as the alt frequency 'bundling tnc' goes... Wire a 2nd kpc3
at the digipeater site so that it talks to the same radio as the
existing TNC on 144.39. This 2nd TNC will have it's XCD pin wired to a
555 timer which will drop the XCD pin every 15 to 30 seconds. This TNC
will collect packets on the alt digipeater input frequency of say 144.99
(144.39+600). Every 15 seconds it will TX any packets collected... In
addition to the 555 timer, if we wired the MUTE pin from the 144.39 TNC
to the XCD to the alt input TNC, we could prevent it from transmitting
if the 144.39 tnc was receiving a packet (we're trying to do this with
no cavities on the same band). Those of you who have made it this far
in this paragraph may say "what happens if the 555 timer drops the XCD
for 1 second, and during that one second, the other TNC asserted it's
mute pin?" The answer is that the alt input TNC would not TX at all...
it would wait until the next time the 555 dropped the XCD pin again.
The correct fix for this is to use a J/K flip flop tied to the 555 timer
and the alt input's PTT line. That way the 555 could drop and enable
the TNC to TX. That "enable" would stay available until the TNC TX'ed,
then reset. This "enable" wire would then be diode OR'ed with MUTE from
the other TNC.
On the main 144.39 digi, you'd need to wire it's XCD pin to the alt
input digi's MUTE output so that 144.39 would not TX and desense any
packets being rx'ed on the alt input frequency.
KPC3's will honor BOTH software dcd and XCD... Older kpc3's w/o the MUTE
function can wire the CD led thru a diode/cap/transistor to provide this
carrier indication function to the other TNC.
Wes
Robert Bruninga wrote:
>SOFTWARE IMPROVEMENT #1.
>
>Then the next level of improvemnt would be for there
>to be a processor that collects all the non-standard
>APRS WX reports and weatherless position and positionless
>weather, and converts them all to the standard
>COMPLETE WX format before dumping them in a bundle.
>Being smart, it can always wait till it has
>5 in a bundle making for a nice neat channel burst.
----------------------------------------------------------------------
Subject: Re: APRS 144.39 dual channel upgrade
From: wes@johnston.net
Date: Sun, 11 Jul 2004 15:45:17 -0400 (EDT)
X-Message-Number: 5
Yes, I was only disagreeing with the WX conversion... the rest sounded fine
to me. That's why it sounded like I agreed with most of what you said... I
did! I must've missed the part about unconverted WX only on the alternate
frequency (it makes perfect sense now that I have "read between the lines"
and figured out that WX station = Home station = Alternate digi input
frequency). In _that_ case, this sounds great. Since only one digi will
be listening on the alt input frequency, then there would be no possibility
of doubling up on converted / non converted packets. Full steam ahead. My
kpc4 just became more valueable. Of course the kpc9612's with the extra
1200 baud modem header get real interesting really quickly too.
The slick part about this alt frequency is that 144.39 + 600khz'ish gets us
right into the largely unused 144.90 - 145.09 packet sub band. The simple
(and likely prized alt input frequency will be 144.99 because all the home
stations have to do is to transmit 144.39 with the standard plus offset. I
guess the gentleman's rule will need to be that no digipeater will tx on
144.99. And the home stations can specify their local digi's callsign in
their outbound path. This just gets more and more interesting.
Wes
ham callsign: kd4rdb
find me: http://wesvan.zapto.org
----------------------------------------------------------------------
Subject: 9612+
From: wes@johnston.net
Date: Sun, 11 Jul 2004 15:56:35 -0400 (EDT)
X-Message-Number: 6
Was it my imagination or did I read somewhere that the kpc9612plus
supported an optional extra 1200 baud modem? I can't find a reference to
it on their web pages anywhere...
Wes
----------------------------------------------------------------------
Subject: Re: APRS 144.39 dual channel upgrade
From: "Richard Amirault" <ramirault@erols.com>
Date: Sun, 11 Jul 2004 21:24:53 -0400
X-Message-Number: 7
----- Original Message -----
From: "Robert Bruninga"
Subject: [aprssig] APRS 144.39 dual channel upgrade
>144.39 Dual Channel Upgrade:
>
>As wes suggests, one thing we can do to vastly
>improve APRS reliability would be to have an
>alternate (local) input frequency for WX and
>home stations. Packets heard on this channel
>can be bundled and then transmitted in occasional
>5 second bursts on 144.39. Advantages:
(snip)
Disadvantages:
Reduced access to digis for mobiles ... (or am I missing something here?)
Richard Amirault N1JDU Boston,
MA, USA
www.erols.com/ramirault "Go Fly A Kite"
---
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