[K3pzn-board] FW: [amsat-bb] APRS on satellites

[Douglas Kearney]

This is a great article on the general purposes of APRS. I also would like
to draw the attention of the group to the procedure for satellite QSO's

Please take a few minutes to read this post.


Regards,
Doug N5LBJ 

-----Original Message-----
From: owner-AMSAT-BB at AMSAT.Org [mailto:owner-AMSAT-BB at AMSAT.Org] On Behalf
Of Robert Bruninga
Sent: Tuesday, July 13, 2004 14:17
To: amsat-bb at AMSAT.Org; billbruno at earthlink.net
Subject: Re: [amsat-bb] APRS on satellites

>>> "Bill Bruno"  7/13/04 1:40:48 PM >>>
>I have an APRS... station running... so i understand the APRS basics. 
>What i dont know is how to work APRS on the satellites. I assume i send 
>a message or position or weather packet as i would normally do...

Not really.  The joy of APRS and of APRS via satellites is in human to human
exchange of information in a net
of like users.   There is a grave missconception that
APRS is for 24/7 operation of unattended stations.
This is simply *not* what it was designed for.

APRS was designed to be the digital equivalent of the way we hams like to
operate a VOICE net on a repeater for example.  Where everyone is listening
to what is going on and periodically each person gets to add in his two
cents...
And everyone gets it.  Think of an APRS satellite pass as a group event with
everyone playing together instead of in competition with each other...

When APRS was invented it was to get away from all the problems and
innefficienceis of CONNECTED packet which is very inefficient via a
satelltie because of the ACK problems and can only be used point-to point.
APRS lets everyone talk to everyone and see everyone without any
addressing...

Thus, during a satellite pass you usually address your message to ALL so
that eveyone gets it.  And sometime during the pass you send your POSITION
Packet so that people can see on their maps where you are and how this fits
into the pass geometry unfolding before you.

Once your position and message have been digipeated by the satellite then
just watch everyone else and if you see someone or something you want to
comment on, go ahead.  Even when sending to another specific station, it is
common practice via the satellties to still address the message to ALL so
that everyone reading the mail gets a copy and feels like they are
participating too.

As to weather, I dont see any advnatage to sending a WX packet unless your
weather is  unusual and worthy of immediate note over the whole country...

> but im not sure of how to "path" it to or thru the sat . I could use 
>some advice.

That's easy.  Just send the packet via the callsign of the satellite.  We
have been trying to get all satellites to use the same generic aliases as
APRS
does on the ground so that it doesnt matter.   And
fortunately ISS does use the aliases of RELAY, WIDE and ARISS, and APRSAT.
We have also recoemmended these for the APRS mode on ECHO, but so far the
DIGIpeater on ECHO has not been enabled yet for users...

And PCsat is basically dead.  So right now, that leaves you with only ISS
using the path of ARISS or SAPPHIRE
(NO-45) using the path of KE6QMD...

Bob, WB4APR
----
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