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[aprssig] Ham radio, Advertise!

Robert Bruninga bruninga at usna.edu
Mon Oct 29 19:33:16 UTC 2007


During the 5 hour drive back from the AMSAT conference in
Western PA I was bored and scanning to find something to do on
my mobile rig.  After a long time, finally found a very weak QSO
on 145.62 just east of New Stanton.

As signals got stronger, it sounded more like pirates... Like a
work crew working on some maintenance prject.  This was fun.  A
bunch of pirates on ham radio in an unused portion of the band.
I was running APRS and GPS and was getting excited about turning
this into a short DF mission (using signal strength alone).. I
was getting a clearly increasing signal..

Then I thought.  Hummh... I've heard that sound before...
Sounds like scuba divers.  You can hear them breathing..

Duh.  Was space station crew out on an EVA!  I was hearing a
re-broadcast of the ISS audio, complements of a local club in
the wilderness of western PA.

Which gets me to the topic of this post.

It pays to advertise!  If something is going on in HAM radio,
put out a LIVE APRS beacon on-air.  Let people see it.  (APRS is
supposed to be the single clearing house of where to look for
this information live in real time)...

A simple once-every-10-minute local-direct APRS beacon will
inform everyone live in the vicinity of that transmission that
it is on the air now... Live...  This is needed whether they are
strangers passing through, or locals on their way to get bread
who forgot that today was EVA day.

Live advertising of real-time happenings on APRS is a service to
all of ham radio.  APRS was never intended as an end in itself.
It was supposed to be the catch-all information resource for the
local area.  A mobile seeing one of these beacons can now be
alterted and participate in the event...  In the new Kenwood
D710, he can even QSY with the press of one button if the beacon
also contains the frequency.

APRS is TWO-WAY. Everything in ham radio should be advertised
LIVE local direct on APRS for the benefit of local mobiles.
Here is how I would advertise Space Station Audio on APRS.

1) Give it the object NAME of "ISSrtx-xx"
2) Give it an approximate position
3) Include the local RE-TX frequency in the comment

This APRS object will flash on the front panel of the mobile D7,
D700 or HAMHUD as ISSrtx... and not just some other callsign.
The position information causes the radio to display the
direction, and distance to the transmitter for the benefit of
the mobile.  The frequency info shows him where to tune.  And if
the freq is in the right format, then the new Kenwood can
auto-tune to it.  You can put this object in ANY local TNC as a
BEACON TEXT.  Here is how:

BT ;ISSrtx-xx*111111zDDMM.hhN/DDDMM.hhWE 145.620MHz Space
Station audio.

UNPROTO APRS       (direct)
BEACON 10 minutes

Notice I added "xx" (I'd use "wP" in this case for Western PA)
to fill out the 9 byte object name field so that when this is
picked up by the global APRS system, then this object will be
unique from any other similar site.  To see if your particular
choice is already in use, just check FINDU.COM:

http://map.findu.com/ISSrtx*

And you will see everyone else's object choices, so you can
choose two unique "xx" characters for your system too.

Hook this TNC and spare 144.39 Transmitter to the same PTT of
the system controlling the ISS audio.  This way, it is all
automatic.  If this system is re-transmitting space station
audio, then the APRS advertising beacon will be on the air too!

Since this stuff is quite rare, I might even suggest that this
automatied beacon go out once every 5 minutes, so that locals
out for a short trip won't miss it.  Remember, it is a local
simplex direct packet from a high location that can hear all
local users, so therefore it will avoid any collisions and not
impact local channel load.

Many of us can only find time to play HAM radio while mobile.
So, please advertise.  Let us know what is happening live in
your area.  There certainly are enough old TNC's out there doing
nothing else that could be put into such use.....

Oh, and if you need a BEACON in a pinch, you can use your D7 or
D700 to generate the object.  Here's how:

http://www.ew.usna.edu/~bruninga/d700-objects.txt

Please do NOT beacon any such object farther than it can be
used.  This is important, because out of area,

1) It is QRM to anyone beyond its range 
2) If it was digipeated, it has double the collision potential
3) The Txing station if digipeated cannnot hear a clear channel

Thanks

Bob, WB4APR






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