Underwater wireless video

I need a question answered re-underwater video.
I am planning on building an R.O.V. with a video camera. My question
is: can the readily available, run-of-the-mill wireless mini video
cameras operate underwater, if in a sealed container? In other words,
will the signal transmit through water (they usually boast a 1000ft
line-of-sight range)?
Thanks
Brian
Reply to
Brian
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No, water is a conductor !
Dave
Reply to
Dave Garnett
The "big boys" use fiber optics. Jim Cameron's ROV's are all wired like that, for instance.
Just as an FYI. Designing for underwarer is infinitely more difficult thatn designing for outer space. Do your math.
Mike
Reply to
Blueeyedpop
Brian
reseach ability of RF to xmit through water at the freq of the units you're looking at.
VLF works (but check the baud rate) research land base to submarine communications
if you're planning a wired ROV ignore wireless, simply add 2-3 conductors to the unit. Most cams require power / ground / video out though I have used a DC block and shared the power conductor with video out.
if you're thinking an untethered ROV (AUV) ... research underwater modems (acoustic) they'll handle video but not the frame rate one associates with realtime (25-30fps)
if your rov is shallow depth .. tow a buoy / marker that is also an antenna feed to the unit ... that could work
- Ed
got talc ? Drysuit talc & bags
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Reply to
Ed
I know it would take a lot of power, but what about free-space optical? Avoid red because of absorption IIRC, a while back there was an idea to replace VLF comms to subs with satellite-based green lasers.
Reply to
Spam Magnet
FYI standard PPM remote control signals can penetrate water a meter or two and are used on RC subs (of the model variety). Although the depths Brian is interested in RF would be unsuitable.
If the ROV is tethered then an RF signal could be transmitted up the umbilical cord (preferable to a digital signal perhaps), perhaps even through the power cables, although noise would be something that would have to be taken care of.
Tim
Reply to
Tim Woodburn
...and the antenna size.
Reply to
Guy Macon
Thanks for the advice folks. There are wireless underwater video products out there, but at a cost much higher than my price range for this project (just doin' this for fun).
Since it will be wired for control reasons, I might as well just use a wired camera. Much cheaper I'm sure too.
Thanks!
Brian
Reply to
Brian
Excellent point. The wavelength alone for VLF is 10km - 100km. Assuming you use a 1/4 wave antenna, it's still prohibitively huge. ELF also works, but the antenna size is even bigger (100km - 1000km)
---The Mad Jesuit
Reply to
Mad Jesuit
No. The standard (legal) video transmitters operate in the 2.4GHz band. This happens to be very near, if not at, the peak absorbtion frequency of water. If you put the antenna on a surface float it will work, but not very far underwater (1-2 inches), if at all.
Tim
Reply to
Tim Jacobs

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