Re: [amsat-bb] Flight Computers

[ka1lm@xxxxxxxxx]

On Fri, 26 Apr 2002, Timothy J. Salo wrote:

> The SpaceQuest FCV-53 flight computer
> (http://www.spacequest.com/fcv53.asp) appears to dominate the
> microsat market. And, no, I'm not going to pay $15,000 for
> an 80186 clone, even for an externally funded research project.
> However, it seems like I could find another system that is
> software compatible with the FCV-53 for a lot less money.

Some background - I think SpaceQuest is using or has otherwise licensed
the technology used previously by Interferometrics to build the Eyesat-1
(we know and love it as AO-27) satellite.  My comments are based on this
assumption and my recollections from my involvement with the Eyesat and
AO-27 efforts.

The FCV-53 is likely built around the NEC V53 CPU, which is a more capable
extension of the older NEC CPU-based system (V30 or V40 - don't recall)  
flown on the original AMSAT Microsats.  It is FLIGHT PROVEN hardware - the
Microsats have been operating for over 10 years, AO-27 for 8 1/2 years.  I 
believe the hardware has flown on other spacecraft as well.

Reliability is far more important in space than having a fast CPU.  The
processing demands for flight control are much different than for playing
MP3 files and watching DVDs, or playing the latest shoot-em-up game.

The CPUs flying on AO-40 were also selected for their pedigree as much as 
for anything else.  Sometimes there are EXCELLENT reasons for flying what 
would otherwise appear to be "obsolete" hardware.

> o	What have people used for development systems when developing
> 	software for the FCV-53?  The IBM Real-time Interface
> 	Co-Processor card (whatever that is)?  (Is it still
> 	available?) Something else?

No idea.  At the time the Microsat CPU was selected, one of the reasons 
was the availability of the processor board for use in PC hardware, 
providing a relatively inexpensive development platform.  I expect that 
the SpaceQuest system builds on this pedigree.  I further expect that 
SpaceQuest has access to developers with experience with this platform.  
This should make for a better satellite and lower development costs, which 
are mostly labor.

> The BekTek Spacecraft Operating System (SCOS) seems to be
> the dominant operating system for use with the FCV-53.

It was used originally for the Microsats (maybe some of the UoSATs?) and
is FLIGHT PROVEN.  As is the application software running on top of it.  
I **LIKE** proven when you need a 800 km screwdriver and network cable and
have less than 15 minutes at a time to try to fix things after launch.

Keep in mind that at the time it was developed, inexpensive alternatives, 
such as a RT/embedded Linux OS, simply did not exist.  I'm not qualified 
to make any declaration on the tradeoffs between a platform with a track 
record versus more recent alternatives.  

73 Steve KA1LM

-------------------------------------------------------------------------
Stephan A. Greene                            sgreene@patriot.net
HAM: KA1LM@amsat.org  QRP-L #232 Grid FM18hx 38 59'83.33"N 77 23'6.15"W
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