I read in !emc-pstc that King, Richard <richard.k...@uk.thalesgroup.com>
wrote (in <C02943801230D611919D00508BDF0C246EB61A@RTWEXCH>) about 'Help
wanted with succinct subject description for non-special        ists' on
Thu, 27 Mar 2003:

>In 1967 off the coast of Vietnam, a jet landing on the aircraft carrier
>U.S.S. Forrestal was briefly illuminated by carrier-based radar. This is
>quite a normal event, however the energy from the radar caused a stray
>electrical signal to be sent to the jet weapon systems. The result was an
>uncommanded release of munitions that struck a fully armed and fuelled
>fighter on deck. The subsequent explosions killed 134 sailors and caused
>severe damage to the carrier and aircraft.

This is an appallingly bad example, insofar as it was caused by a
**fault condition**. EMC standards, and the testing itself, do not take
fault conditions into account. There is a separate subject 'EMC and
functional safety', which is incredibly complicated. If you just think
about it for a while, you will see why.

Don't let your audience think that EMI occurs only when source or victim
is faulty. EMI occurs when both would be working perfectly normally if
the EMI were not present.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk 
Interested in professional sound reinforcement and distribution? Then go to 
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!


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