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[aprssig] Ham radio, Advertise!

Robert Bruninga bruninga at usna.edu
Mon Oct 29 20:19:23 UTC 2007


> Ya...Andy, WA3PBD rebroadcasts the shuttle audio 
> in the Pittsburgh Area.  Great idea for a new APRS 
> object!  I'm already putting out a repeater object 
> - is it possible to do two?

Don't want the ISSrtx object transmitted except when there is
mission audio...  This should be possible by setting a spare TNC
for say 5 minute beacons (local only) and then connecting the
external-carrier-detect to the voice re-transmitter.  

Whenever the ISS audio transmitter keys, then it removes the
external carrier detect, and the TNC sends out the ISSrtx beacon
every 5 minutes while it remains active.  Then shuts down all
the rest of the time.

This makes it real-time, just like APRS is supposed to be.  Not
a bunch of stale beacons about non-changing things...  Neat.  I
think there are a lot of places that sometimes retransmit the
audio, though most of us don't know where or when.

This kind of capability should be easy to implement with a spare
TNC and low power transmitter.  A really slick trick could set
the ISS-AUDIO-RETX transceiver for SPLIT mode with TX on the ISS
re-trans frequency and RX on 144.39.  Then by just closing the
"REV" button contacts, this same transmitter could TX the packet
on 144.39 and then drop the REV button and then transmit the ISS
audio on its TX freq.  A little circuit should be able to do
that...

Bob, WB4APR

> On 10/29/07, Robert Bruninga <bruninga at usna.edu> wrote:
> 
> 	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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> 	
> 
> 
> 
> 
> -- 
> ===================================== 
> Charles L. Mills
> Email: w3yni1 at gmail.com 
> 





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