🚀 go-pugleaf

henry@zoo.toronto.edu (Henry Spencer) writes:

> The on-board computers don't have the horsepower to do serious compression
> at 100-odd kbps.

Perhaps the DSN improvements currently in the pipeline would increase
the HGA raw data rate, so that the processors would just have to send
the data faster.

Speaking of which, as I understand it, the claim is that the link
capacity can be increased 10-fold.  For HGA, that would give some
1+ Mb/s (assuming the better code could be run at that rate).  That is
remarkable.  Where does it come from?  The Gaspra briefing notes say
that the system noise temperature will drop to 12K, 4K better than
current; that's a couple dB.  This means that maybe 8 dB has to come
from more aperture, better coding, or out of the link margin: is there
that much reserve in the DSN?  Such a state-of-the-art system would be
hard to improve more than incrementally, I would have thought.

How will the arraying be done?  Is it real-time or recorded,
combined offline?  What coding is used?  Leech's notes mention
a "50% higher data rate", plus "several magnitudes better" error
rate; this might be another 2 dB.  That's a large jump, and the
natural question is why the new code wasn't used in the first
place.

A previous poster suggested chirping the motor:  does the spare
HGA on the ground show any such useful mechanical resonances?

I think many of us here in non-JPL-land are watching all of this
with intense interest and excitement.  Best of luck.

Peter Monta   monta@image.mit.edu
MIT Advanced Television Research Program