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Re: Flight Computers



On Wed, May 01, 2002 at 08:44:03AM -0400, Rick Hambly (W2GPS) wrote:
> All,
> 
> On April 29th I sent the message (below) with a copy to amsat-bb. I am
> working on the design of the new AMSAT OSCAR-E satellite and there are a
> number of open issues that will need to be addressed, this being only
> one. I have sent out a call for volunteers and received a number of
> responses but none with expertise in this area.
> 
> The results have been phenomenal! In just a few days there has been a
> lively discussion covering a wide range of options.  I have spent hours
> on the phone and in private e-mails with people who have particular
> interests in this area. I have learned a great deal.
> 
> Thank you!  I want you to know that AMSAT is listening to your inputs
> (or at least I am). There are so many messages that I can't possibly
> respond to them all.
> 
> The conclusions, so far:
> 
> 1) RTLinux will not run on the V53 flight computer and an open source
> version of RTLinux is not currently available for the ARM-based payload
> processor, either.
> 
> 2) RTEMS is a strong candidate if we can get someone to volunteer to
> work on a trial port.
> 
> 3) Otherwise, SCOS is the only way to go for the flight computer.

Rick,

Obviously this discussion started before all the information was
deseminated, but is it a given that the V53 will be used for the
IHU?

If so, it seems that 3 is the best choice, based on the rational if
you are chosing known reliable hardware, you might as well have known
reliable software too.

But along that vein, for such a small satellite, I'm not certain that
the V53 isn't overkill and could not be replaced by a far simpler IHU
or even dedicated state logic. That would make available a lot more
power for a general purpose communications processor running whatever
OS the most talent is available for.  Based on some later information
that I received, the AO-40 IHU-2 sounds similar to this, but it was
unclear if enough logic was present to continue controlling the
satellite if the ARM cpu crashed.  While looking at TI's site for
some other parts, the TI OMAP processors (ARM + DSP) look very
interesting.

Mike W4LNA

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