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Re: Flight Computers



On Wed, May 01, 2002 at 10:51:45AM -0400, Rick Hambly (W2GPS) wrote:
> 
> You could be right, but there are good reasons for investigating
> alternatives, especially open source alternatives.  On what basis did
> you skip 2 (RTEMS)?  It is also being used on spacecraft.

The biggest reason is time. Using any untried OS will take a substantial
amount of time to port and validate the OS. More time to rewrite the pieces
that already exist in SCOS. Time that could be spent for writing application 
code. Checked the RTEMS web page and the only BSPes listed for non-MMU
processors are 68k and Coldfire.

> The V53 is not overkill.  AO-E is a much more complex satellite than you
> seem to think. Look for my article in the next AMSAT Journal for an
> introduction. We are hoping to also fly a payload processor that will be
> an ARM based CPU, similar to AO-40's IHU-2.  That decision doesn't
> require that we eliminate the V53.

I'm currently working with 200K FPGAs gates that are smaller than a quarter. 
There are a tremendous amount of housekeeping functions that could be implemented
in dedicated logic. Logic that can be designed to detect and correct for SEUs.
Direct implementation of hardware modems for command and control with encryption.
Small and low power consumption so that more than one could be carried onboard.
If the V53 dies, will it not be a single point failure?

Mike W4LNA

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