[PSUBS-MAILIST] Surface controlled drones

[Alan James via Personal_Submersibles]

Hi Nathan,
when they thought they had pin pointed where MH370's emergency beacon was
transmitting from, they sent down an AUV to do a grid search. It was coming up
periodically & transmitting data. All it's scanning images were then looked at.
If it had found anything of interest, there would have been coordinates with the 
image so they could then send a rov down to that point.
They have spent billions of dollars trying to find that plane.
Depending on the depth you are looking at, there are units that are towed behind boats
at a depth & scan the sea floor.
Regards Alan


________________________________
 From: Marc de Piolenc via Personal_Submersibles <personal_submersibles at psubs.org>
To: personal_submersibles at psubs.org 
Sent: Tuesday, June 3, 2014 4:50 PM
Subject: Re: [PSUBS-MAILIST] Surface controlled drones
 

Microwaves will definitely not allow you to communicate with a deeply 
submerged drone. There is a narrow range of frequencies at the lower end 
of the EM range which can penetrate a few feet into water with 
acceptable attenuation, but that won't help you at great depth. The data 
link problem is the biggest one for ROVs, and accounts for the fact that 
they are mostly tethered, with rare exceptions designed for limited 
autonomous navigation and data gathering (and those can't send data to 
the surface in real time).

For exactly the same reason, underwater navigation is also a problem.

Marc de Piolenc

On 6/3/2014 5:27 AM, Nathan.tuttle via Personal_Submersibles wrote:
> Hey I am a submersible enthusiast and an expert engineer.
>
> One thing that is bugging me is why communication with devices at great depths (the very bottom of the ocean) seems to be so hard.
>
> The thing I am working on is miniature drones fully equipped and deployed en masse to scan and collect data from the bottom of the ocean.
>
> Primarily, I want to find Amelia Earharts wreckage ;)
>
> My question is, would it be difficult to create an underwater device that can communicate via microwave to surface?
>
> Microwaves on the electromagnetic spectrum can pass through things in a line of sight manner if there is nothing obstructing them.
>
> But I am weak on my physics and maybe the several billion tons of water that it has to pass through would squelch the signal.
>
> Is there a means of telecommunication with high enough bandwidth to transfer signals from that distance and that depth?
>
> Although our earth is covered 70% of water. I think we have seen technology come to the point where a mass deployment of small controllable drones equipped with detection devices could search the sea floor.
>
> I would great appreciate your input.
>
> Sent from my iPad
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