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[aprssig] [amsat-bb] USNA Party Balloon Success!

Bob Bruninga bruninga at usna.edu
Mon Apr 30 13:52:49 UTC 2012


>> When we got in about 4 miles range we began to see the wireless 
>> camera again and could see chicken coops below.  At 2000' we 

> How'd the 4' dish with tracking work?  I still can't imagine 
> this thing being able to track the balloon while in motion.
> it's the opposing forces of a 1 RPM Az / El motor system vs 
> a bouncing, turning, wind buffetted minivan. 

The beamwidth of the 4'dish is 7 degrees and most roads are quite straight.
The only time it should loose the signal is at a 90 degree corner turn.
Then it would take take about 15 seconds to make the change in azimuth, but
with the 7 deg beamwidth and several seconds to actually make the turn, only
about 10 seconds probably.  But on the entire chase, we only made one 90 deg
turn.. Everything else was just following the highway, and those sweeping
turns the dish can follow easily.

But we did not do auto tracking.  We were 2 hours past our launch time and
found out we were still one cable short (between the van GPS and the
controller) it had to be custom made and there was just not time.  SO we
manually steered the beam.

Sometime today we will go back thorugh the 90 minute recording and see what
we got.  Though, only the last 10 minutes is what we remember.  And even
then we were more concentrated on finding a way to the balloon than watching
the video.

Bob, Wb4aPR




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