[aprssig] Re: flying digipeater (with ladderline feed)

[Floyd.Gene at mail.dc.state.fl.us]

> >big problems here.  The loss in the long coax will be far
> >worse than any height gained.  This is a common error
> >for dreamers with high towers.  We have access to a 600'
> >tower.  But in 10 years still have nothing on it:

Take a look at http://www.tfn.net/~gfloyd7/antenna/

Now imagine that antenna being hung from a balloon...ladderline is much
lighter and more efficient than any kind of coax that might be used in a
project like this, and with it out in open space like this, nearby objects
won't be an issue either. You could even put a small amp/preamp at the top
of it and use DC on the feedline to charge a small set of batteries in
between transmissions.


> >>For SAR, from time to time there are operations where a 
> >>plane just keeps circling a mountainous area with a 
> >>repeater onboard for voice communication. ...could...
> >> have an APRS digipeater onboard as well...

> >Yes, that recommendation, to put APRS digipeaters on all
> >SAR aircraft is an excellent plan.  The digis should be
> >set to listen on 144.99 and TX on 144.39.  This way they
> >can hear any SAR member with a small pocket tracker
> >because they do not compete with the tons of  other QRM
> >that is on 144.39.  Also the plane's digipeaters dont
> >respond to other terrestrial packets either, thus operating
> >transparently to the normal use of the frequency..

Airborne repeaters are awesome....I monitored groundteam operations in South
Florida from Daytona in the aftermath of Charley (we had already completed
our ground RECON mission from Punta Gorda up and were resting up for the
next assignment). Putting digipeaters on our birds on CAP freqs is one of my
interests, at least at the squadron level. I would love to see groundteams
with APRS units in their vehicles (or a tinytrack when on foot) operating on
the CAP data freq, with a digi in the search aircraft and a receive unit
back at mission base. No more sounding out, repeating, and then repeating
the confirmation of coordinates for position reports; just look at the map
and see where everyone is at a glance. Want to tell a unit to proceed to a
certain location? Place a marker or re-enter the mission base's coordinates
in the desired location.


Gene
KD4OUN /AE