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Re: EMI (was: Re: Don't trust the net too much)
On Wed, 12 Jul 1995, Paul Robichaux wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
>
> Ed Carp said:
>
> > This sounds like absolute propoganda. If you do the calculations, you'll
> > see that a 1 watt transmitter sitting 100 feet away from your target will
> > generate an EMF less than that 1000kW ERP TV transmitter array you just
> > flew over. If aircraft avionics were *that* sensitive, we'd have planes
> > falling out of the sky, and we don't.
>
> Oh, yes-- we do. The Army lost a small number (two or three) of of
> UH-60 Black Hawks in crashes where the flight control system suddenly
> commanded extreme pitch or attitude changes. Why? In all the crash
> cases, EMI from nearby TV or FM transmitters was found to be the
> proximate cause. The Army, and Sikorsky, immediately went to work to
> better shield the FCS from EMI.
>
> It's interesting to note that the Navy's SH-60, a UH-60 variant, was
> designed from the start to be EMI-immune. Ships' radars operate in the
> 10-100kW range, and that's a lot of EMI when you're landing 15-20m
> away from the radar mast.
Well, I was speaking of commercial aircraft, not military, but the point
is taken. I haven't had occasion to use my packet radio lashup on a
UH-60 -- yet ;)
--
Ed Carp, N7EKG [email protected], [email protected]
801/534-8857 voicemail 801/460-1883 digital pager
Finger [email protected] for PGP 2.5 public key [email protected]
Q. What's the trouble with writing an MS-DOS program to emulate Clinton?
A. Figuring out what to do with the other 639K of memory.