[ao16aprs] More Path Statement

["Bob Hart" <rahart@hctc.com>]

Thanks to all who responded to my request for suggestions regarding the path
statement to work AO-16.

The responses to my query and certain comments about the new Kenwood radio
shown at the DCC tell me there are many in our APRS group who are not really
knowledgeable about the digital satellites. This is not meant to be
critical. Just because it is ham radio doesn't mean that every Ham knows
every thing. However, since there is obviously an interest in using the 1200
baud Pacsats for APRS, a short primer on their operation is probably in
order.

The primary mission of AO-16, LO-19, and IO-26 has been to serve as orbiting
store and forward BBS's. A Ham on one side of the world could post a message
on the BBS and it could be read later by another Ham virtually anyplace else
in the world. They use a very special Pacsat protocol to do so and they have
done a great job for 10 years. Things are beginning to fail. I believe the
BBS on LO-19 is now out of service. There was never any real intent to use
them for real time communications as we are planning to do. However, since
they do have digipeaters that can be turned on for our use we can be
grateful that the managers have agreed to do so. If we screw up, they can
also be turned off.

As Bob, WB4APR, has pointed out, a simple $2 modification is all that is
required to adapt any TAPR TNC 2 or clone to transmit Manchester encoded FM
on 2 meters which is what the satellites expect to hear. I found everything
in my junk box. I would class it as a one evening job. Hearing the
satellites is another matter. The 437 Mhz downlink is phase shift keyed
(PSK) on single side band. It requires a special modem, tracking software
and antennas, and a 3/4 meter ssb receiver that can tuned for Doppler shift.
Unless you are "into" satellites you are not likely to have all of this. The
good news is, you don't have to hear the satellites. If there are properly
equipped ground stations physically located to be in the footprint of the
satellite at the same time you are, they will hear your posits and can then
post them to the APRSServ network. From the looks of things, I would say
that two or three ground stations or PACGATES are all that would be needed.

Now, this brings us back to the original question. What path statement
should be used. I define path statement as all that stuff that follows the
"via" in your unproto broadcast. The first thing has to be the call sign or
the alias of the satellite. At the present time, this will have to be the
call sign. PACSAT-1, LUSAT-1, ITMSAT-1, respectively. Bob is working on a
common alias which will allow us to have a single path statement. The next
thing will have to be the alias of the PACGATE. The alias GATE has been
around for a long time, so why not use it? This decision has probably
already been made, and is really what my original question was all about.
I envision the path statement as   VIA PACSAT-1, GATE     That should be
the whole path statement. PACGATES sending out a plethora of
WIDE's, even if they could doesn't make any sense to me.

The only PACGATE I am currently aware of is KB2WQM-1 in New Jersey. Really
great if you live in Annapolis. Is there anyone on the West Coast or the
Central Sates?

Please, if you respond to this "big one", don't quote the whole thing. I
have used up enough band space already.

Bob Hart
Hoodsport, WA 98548
Amateur Radio WA7HRA



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