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back to article US Navy boffins invent aircraft-to-sub laser phone

US Navy boffins say they have developed a method which could allow aircraft to communicate with submarines using frickin' laser beams. Dr Ted Jones of the Naval Research Laboratory has developed methods of generating acoustic effects in water by firing laser pulses into it. According to the lab: Optical properties of water can …

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erm

Wouldn't this require the plane to know the position of the sub? And aren't ermmm sub meant to keep their locations secret? Undetectable?

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Erm 2

So, the enemy won't be able to discern the sub's location from the 220dB blast then, will they. Let alone the rafts of dead marine creatures floating in the area.

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@erm

The description is that the laser generates sound waves in the water which at 220 decibels are pretty loud (compared to trying to listen for the faint sound of an enemy sub) this will mean all you need to know is the approximate location of the sub, something that using buoys also requires

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M7S
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I expected Lewis to be a bit more scathing than this. I'm genuinely disppointed.

The phrase many "hundreds of meters [sic] through air" is the sort of equivalent of "up to 8GB" nonsense peddled by ISPs, and does not sit well with the following "aircraft high above the sea", which I would take to be a sort of AWACS operating altitude.

Also its disappointing to see early on that the acoustic effects of firing a laser into the sea are not the boom of the exploding (or imploding) vessel which I am sure the Americans would prefer. Still at least its a way to counter EvilCorp's sharks.

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@Anon

One assumes the controlled focusing effect could be used to generate the pulse some distance and angle from the submarine itself, no ?

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@anon:erm2

If they waited 50 years before deploying this technology, the "rafts of dead marine creatures floating in the sea" that were killed by this technology would not, without a post mortem, be distinguishable from the rafts of dead marine creatures killed by pollution. And eventually when the sea is devoid of all life, the subs would not be detectable at all.

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baud rate

having looked at laser induced cavities in water I'm aware of a few phenomena around this, the most interesting I believe to be the oscillating bubble. A cavity/bubble created by heating (that is the process we're talking about right?) the water expands whilst it is powered, then when the light stops, the surrounding water compresses the bubble. As it compresses the gas within gets hotter and after a finite compression it begins to expand again (though obviously not to its original size because of thermodynamic losses) and so on in an oscillatory fashion until extinct. Now with all these little bubbles popping up and down and changing size, and the fact it takes a little time (ms not ns or even near fs) I'm wondering if you could even transmit anything of worth.

OK you might squeeze a little data through such a method, but encrypt it and send anything of size/worth, doubtful.

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oops - sub position given away

... by dolphins floating belly up

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I'm in the sub.

I SAID I'M IN THE SUB!!

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Thumb Up

Simple...

This technique is just perfect for sending morse code. All you have to do is turn the 1s into dashes and the 0 into dots ... and wait.

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CAO

Fast enough.

Considering that the Navy has used ELF waves, at a speed of a few characters per minute, this seems to be an acceptable data rate.

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Pirate

Bisected, cauterised porpoises wash up on beaches shortly after naval exercises in the area.

Defence sources deny any possible link.

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Grenade

One-way?

This is for sending messages TO subs, but rather useless for the subs to send messages back, no?

And wouldn't it be really easy for the enemy to intercept these signals?

"Don't move, destroyer DIRECTLY ABOVE YOU."

"Captain! The enemy has intercepted our signal!"

"Oops. Sorry. My bad."

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Pirate

Land ho!

This attempt to demonstrate ongoing prowess in submarine warfare research is obviously not at all connected with the recent reappearance of Russian subs of the US north-eastern seaboard of course. No siree, nuh-uh...

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Coat

Alternatively...

...just use a REALLY long wire...

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Coat

Until...

... they can launch the aircraft from the sub I'm not going to be impressed.

Stand-by to lauch Sky-Diver!

(MInes the one with the SHADO logo on it)

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To be more environmentally friendly

Couldn't they just strap high explosives to dolphins and detonate them in sequence to sound out Morse messages?

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@Tom Chiverton

Maybe a 220dB pulse could still give a detectable echo off even a stealth sub. And apparently the subs being stealthy use routes in known valleys in an attempt to be more discreet, so any such signal in the vicinity of one might set lights flashing. Anyway, it's not as if they're going to tell us any technical details about it, I was just supposin'...

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aircraft-to-sub laser phone....bin there done that

Many years ago I read about a new communications system for communication from aircraft to submarines...using lasers!

The difference that time round was that it relied on the principle that blue/green lasers would penetrate oceans to a depth of several hundred meters as they are attenuated less than other colours.

As I remember it died a death because you would have aircraft circling the submarine position. Bit of a give away really - and no different to this 'new' system.

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Alert

all they need to send

is "Fire"

anything else is kind of irrelevant. (unless the sub surfaces after everyone else is blown away and then decides 'what the hell' and launches anyway)

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WTF?

Active Sonar Detects with Submerged Receivers?

Let me get this straight. Let's say I am in a 688I (LA Class) attack sub when a P-3 or some other aircraft goes active via lasers to detect a Russian sub. I'm exposed by the same pulse, negating any advantage I had. One reason subs hate to go active is because it gives away their position. If I can go active and detect something 6000' away, I know that someone roughly 60,000' can pinpoint my position as I gave myself away.

Having an airdale give away a sub's position could be disasterous. Slow data rates and a few 220db pulses I can live with (better than the buoy or floating wire. Airdales going active and compromising our subs, bad. Better to do that in an area where our subs are known to NOT be in, and use skimmers' buoys to detect.

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Paris Hilton

A cunning plan but..

There's an obvious flaw looming..

If the efforts of the military are now focused on defeating international terrorism (is it just me that thinks of Crelm whenever they hear that phrase?) as organised by evil geniuses everywhere then all they need to do to cause chaos and disrupt submarine communications is to have sharks with frickin laser beams on their heads....

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Linux

220 decibel acoustic pulse

"a laser beam to generate a tailored underwater "explosion of steam" which can emit a sonic pulse at 220 decibels"

What effct would this 220 decibels acoustic pulse have on whales/dolphin population ...

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Bonus

AND you get fried fish for dinner.

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Whales

Is there an underwater office for OFCOM/FCC? If so there might be a few complaints from the neighbours...

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Please....

They've tried deafening whales with infrasound, now they're going to blind them too.

Won't someone think of the baby whales.

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FAIL

Has anyone ...

thought to ask the whales what they think of this?

I would suggest putting 10 storey high speakers just outside this boffin tank which would intermittently just blare white noise at full volume randomly 24 hours a day.

No, outside their homes maybe.

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