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Subject: Re: You use different lenses underwater because the speed of light is different



"David J. Littleboy" wrote in message
news:e2n3ee$eob$1@nnrp.gol.com...
> I had a friend at MIT doing submarine radio.
>
> Me: Huh? Radio waves don't propagate in water???
> Him: Sure they do, but only at low frequencies, e.g. around 1 Hz.
> Me: 1 Hz??? That's completely useless.
> Him: Not at all. All you need to transmit is one bit: fire the nuke-tipped
> missile or not.

Not quite acurate... Navy subs use VLF 3-30 kHz and ELF 40-80 Hz... The get
about 50 bps out of ELF, if I remember correctly... Enough to tell them to
do previously designated tasks... Not enough for general communication,
especially since it is one way... Enough to tell them to come to the surface
so that they can use their higher frequency radios...

http://www.fas.org/nuke/guide/usa/c3i/vlf.htm
http://www.fas.org/nuke/guide/usa/c3i/elf.htm
http://www.fas.org/man/dod-101/navy/docs/scmp/part07.htm
http://www.basicint.org/pubs/Research/1999-Y2Kpart3.htm



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You use different lenses underwater because the speed of light is different =>Re: You use different lenses underwater because the speed of light is different =>Re: You use different lenses underwater because the speed of light is different =>Re: You use different lenses underwater because the speed of light is different =>Re: You use different lenses underwater because the speed of light is different =>Re: You use different lenses underwater because the speed of light is different =>

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