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Re: A Newcomer question(dumb)



On Sun, 21 Feb 1999, Norm Kluever wrote:

> Hi! Being a newcomer to the satellite hobby, I have a question.
> Is satellite communication(HAM) viable from  handheld low power
> equipment(maybe digital) from the Philippines to the US? 

Yes, it can be done easily, and routinely from an HT!  But there are
restrictions.  Here is how...

1)  SOmewhere within the same satellite footprint of the mobile or remote
traveler, someone needs to be running the APRS software and be linked into
the worldwide 199.227.86.221 port 23 APRServe backbone.  This station will
automatically and transparently relay all packets that it hears digipeated
by the satelite to all other APRS networks worldwide.

2)  The traveler can carry the new Kenwood HT with built in TNC and APRS
messaging capabilty in his pocket (NO laptop needed).  When ever an AX.25
capable satellite passes overhead, he can digipeat his one-line
position/status and any outgoing one-line message.  His HT will similarly
receive and capture any message to him.

3)  Now the catch.  The only 1200 baud AX.25 digipeater in space now is
the Space Station MIR.  Stations are asked not to use the MIR as a
digipeater when someone is logged on to the packet PMS.  Thus, it is not
good amateur practice to use this digipeater under routine conditions.
But in cases of urgent or emergency amateur communications, or for use in
remote areas where there is little PMS activity, it is probably OK.

4)  Thus, via the SPACE digiepater and the one APRS station acting as a
gateway in your area of the world, you will have worldwide APRS keyboard
to keyboard two-way comms to anyone else within a similar APRS network.

There used to be a full time internet linked APRS MIR downlink station in
Taiwan which would probably link you to the USA.  In fact, there were 3
permanent MIR downlink stations all feeding 199.227.86.221 port 10001.
TELNET to that site and you should see raw MIR packets whenever MIR is
over Tainwan, Madrid, or the east coast of the USA.   Monitor for at least
15 minutes or so, since even if MIR is not in range, each of the
monitoring stations injects an ID packet every now and then.

Finally, it is also easy to do this via AO-16, IO-26 and LO-19 using any
TAPR compatible TNC with a $3 mod to transmit manchester.  The only
problem is that we still do not have the needed full time 1200 baud PACSAT
ground stations monitoring the links and feeding the APRServe system..
It is a chicken-egg problem.  Donwlink sites wont go to the trouble if
there are no uplinks.  and no one will uplink if there are no downlinks.

Three underutilized birds on orbit, a perfect worldwide application, and
just no way to get a critical mass of people all interestd at the same
time!

bob


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