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Re: RUDAK MA 128-160

w9ae@earthlink.net (Wayne Estes W9AE) writes:

> 1. Is there a "RUDAK for Dummies" somewhere on the web?

Not that I know of, offhand.  While the hardware offers up a number of
interesting possibilities, the software we have today implements the same
sort of store and forward operation possible with the other existing digital
satellites that have 9k6 data links.  Plus, of course, some special programs
for interacting with the various experimental payloads.

> 2. What is being done with RUDAK now?  (I think it's being used to download
> data from one or more experimental payloads onboard AO40)

RUDAK is primarily collecting data from the onboard GPS receivers right now.
All of the use of RUDAK to date has either been testing RUDAK itself, or 
controlling the experimental payloads and returning data from them.

> 3. Will RUDAK ever be used for user communications of some kind?  If so,
> would it be real-time communication or some kind of store-and-forward file
> server?  Or something completely different?

It is not clear exactly what the future holds for RUDAK on AO-40.  

> I'm basically an analog guy.  About the only thing I know about RUDAK is
> that it's a digital thing that consumes so much power that the transponder
> has to be shut off.  I would like to know more about its present and future
> uses.

RUDAK does use some power, but that's not why the transponder has to be shut
off when access to RUDAK is enabled.  

During testing after launch, we discovered that the RUDAK downlink signal 
badly distorts signals in the analog passband including the IHU beacon.  We 
also discovered that the IHU beacon distorts the RUDAK downlink such that
data recovery was difficult.  We don't know for sure why this happens, but 
the effect is such that it does not make any sense to try and run a RUDAK 
downlink and analog operations at the same time with the same downlink 
transmitter.  That limits our choices pretty significantly, given what does
and does not work on AO-40 today!

We have also discovered that even when RUDAK has the spacecraft to itself, it
takes *substantially* more uplink power for RUDAK to hear us than it should,
on all of the relevant receivers.  This means that even if RUDAK operations 
were "opened" to general access, only a very few stations would be able to 
access it directly.

The experimental payloads on AO-40 are important to AMSAT for a number of 
reasons.  We're immensely pleased that enough of AO-40 works (including RUDAK!)
for interaction with these experiments to be possible at all... and we're even
more pleased to have delivered data that is leading to new insights from both
the GPS receivers and CEDEX... and to have taken a couple of really neat
pictures with SCOPE.

I hope that helps.

73 - Bdale, KB0G

ps:  I attended the International Space Development Conference recently.  
     During a talk about how to incubate space projects in the style of Open 
     Source projects, the (non-ham) presenter put up one of the pictures AO-40
     took of Earth using SCOPE, as a shining example of what amateurs doing 
     things in space could achieve!  I thought that was pretty neat...

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