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Re: AO-40 info from AMSAT-UK



on 12/17/00 10:37 PM, sco@sco-inc.com at sco@sco-inc.com wrote:

>> Please note that this is a *software* watchdog. There is no hardware
>> watchdog. If the IHU has crashed, than a RESET command can be issued from
>> ground. This would be the last resort. It is a very fail-safe system, which
>> has been used before on AO-10 and AO-13. However, it was decided to check
>> and analyze all other possibilities before issuing such a drastic command.
>> There is no need to hurry and we don't want to miss any option...
> 
> I may not be an engineer but know that NASA usually has two different
> backup systems to the primary. Am I to assume that we did not even have one
> backup to the software watchdog system, in case of computer failure? If so
> I think we should fix that in any future sats.
> 
> Still hoping for good news.

No, I don't think that's correct.  Peter says it is a "fail-safe" system.
Fail-safe by definition means there is redundancy built in.  Additionally,
if you read on you'll see that there is also the master reset command that
they can issue from the ground.

73,

Jon
NA9D

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Member:  ARRL, AMSAT, DXCC, NRA

http://www.qsl.net/ke9na

My President is George W. Bush -> The legal winner in Florida

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