Hello Said
What is the title / details of the book that you refer too ?
Thanks
Roy
----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Wednesday, November 18, 2009 11:01 PM
Subject: Re: [time-nuts] MTBF (was Rubidium standard)
Hi Alan,
I am reading a book about the Apollo computer, they bet their life on it
not failing (everything related to spacecraft maneuvering went through the
computer, there were no mechanical or other backups whatsoever). They only
had a single computer per spacecraft!
The book states that based on the entire Apollo program, they later
estimated the units MTBF to be in excess of 50,000 hours (which is
actually not a
lot compared to what typical GPSDO's can achieve today).
A single transistor, ROM bit, solder-joint, or resistor failure could have
killed them.
Scary considering they went for 2 week+ missions..
bye,
Said
In a message dated 11/18/2009 14:38:57 Pacific Standard Time,
[email protected] writes:
Sorry Mike , unless, as someone else said, the figures are derived from
field failures over at least a good porton of the expected like the MTBF
tells you absolutely nothing!! The statistics used on the usual 1000hour
test will only tell you the probability of failure in the first 1000hours
of
use!! It cannot tell you anything mathematically about the extrapolated
life....this has become another urban myth. If it works it is more by
luck
that by mathematical probability.
Alan G3NYK
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