Re: [amsat-bb] APRS portable without PC ?

[Bob Bruninga <bruninga@xxxxxxxx>]

> I am looking for some easy solution to send messages via satellites....
> All [APRS] programs need PCs to let the system work....
> The only thing APRS does do is recieve GPS data and send it...
> Sometimes I really don't understand why such simple modes have to work
> with so fast computers and complex computer programs.

Ah, but APRS was designed from the very beginning to always work with
just a keyboard and a TNC without any special software.  That is why I
have always insisted that all APRS formats are human readable.

The only thing you need to unnderstand about APRS is the following:

1) There are 3 main types of packets that are captured by everyone.
This means that if your callsign is on the air, then everyone will
receive and save in a special memory for every callsign these items:
   a) Your Position (if you transmit it)
   b) Your status   (if you transmit it)
   c) Any and all APRS messages that you send.

2) The simplest Position packet to send is a UI packet that contains a
grid square:    [GG##gg]... comments......

3) A STATUS packet is ANY packet that begins with a ">".  Thus, typing
this:

    >William visiting in London, listening on 146.52

Will be captured by everyone on APRS and they will see what you are doing.

4) There are two kinds of messages in APRS.  Bulletins to everyone and
messages to individuals.  Usually if you are just keyboarding to CQ or QSO
anyone, it is best to use a bulletin or message to ALL.  These formats
are:

    :BLN1.....:this is a bulletin to everyone
    :BLN2.....:this is the second line of a bulletin to everyone
    :ALL......:this is a message to everyone which expects no acks...
    :WB4APR-15:This is the first line of a message only to WB4APR-15 }1
    :WB4APR-15:and you will see the line number on the end of each }2
    :WB4APR-15:line.  If the line number is there, then the other }3
    :WB4APR-15:will send back an ACK# to confirm receipt. }4

Notice that all messages begin with a COLON (:) and then have a 9
character callsign field that must be 9 characters.  Then another COLON
and then any message line up to 64 characters.  If you want an ACK, then
put the }# line number on the end.  But via Satellite pleasse do not ask
for an ACK.  It wastes channel capacity.  If you see your packet repeated
by the satellite, then assume he got it.

That is all there is to it.
You do not need any software do type these packets.

If your packets make it throught the satelilte, then your packets will be
visible on:

http://www.ariss.net for ISS or
http://pcsat.aprs.org for PCsat.

I hope that helps.  Just remmeber that APRS is not just for GPS at all.
It is a PACKET communications system for any kind of information.  The
only reason that GPS is useful is if you want to report your position
while you are moving and don't want to look up your grid square.

Just remember, APRS is only 3 kinds of packets.  Each person can have ONE
position, and ONE status, but he can send as many messages as he wants.
And APRS was designed to encourage simple keyboard entry with just a TNC.

Oh yes, one other thing, the AX.25 TOCALL for your packets should be one
for the generic APRS TOCALLS:  CQ, BEACON, QST, ALL, or APxxxx so that
other receive software knows it is an APRS packet...

de WB4APR, Bob

Of course the fun of APRS is in the receiving software which then
organizes all of the positions onto the map and collects all of the status
into the STATUS list and separates the messages from the bulletins,
etc...  But on a satellite channel, with only a few users, this is not
needed...


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