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Discussion Starter #1
Hi there all.

Well, many people ask if "wifi bacpac" will work underwater and guess what, GoPro will definitely answer NO to that question.
As they replied,
"... The Wi-Fi connection will be lost when one of the devices is submerged under water. Wi-Fi signals can not transmit under water. "

Although this may be correct for practical uses it's not entirely true for all cases.

Everyone knows that the curved port of GoPro "normal" housing is not goo for underwater footage, because due to light speed changes, the footage will become blurred.
Because of that, GoPro launched a flat port "Dive Housing".
All "swell".

BUT... imagine you, like me, want to shoot 3D movies... underwater.
****... the 3D GoPro housing does not have a flat lens port... so.. guess what, no use underwater.
The sync cable that will "assure" the sync between cameras will not be of use without the housing and the housing will not be of use for underwater footage
(3D for Hero 3 will not have this problem as the houses are already flat-ported)

So, my solution was to build something that would allow me to take two GoPro underwater and get the 3D footage I want.

It was basically, a ruler where I placed two GoPro supports... will do the trick.
All I have to do is to press both buttons at the same time.

****.. I'm underwater, scubadiving.. I don't need more stressful tasks... so how to solve this?

Oh, I know... let's have two "wifi bacpac" and a remote and... sync both cameras with the same remote so it will send the start/stop command to both cameras at the same time.

But GoPro says and states that WiFi will not work underwater... because of the High frequency that the remote is set on... true.

Thing is, my friends... IT DOES WORK.

Experience tells me that wi-fi signals can and are transmitted underwater, even if not in VLF and even shallower than 200ft.
The expression of the linear attenuation for the plane wave in a medium is calculated from the homogeneous Helmholtz equation.
Considering the frequency at 2.4 GHz, the attenuation assessment differs significantly depending on the origin of the values used for the permittivity calculation.
While the rigorous model predicts an attenuation of 7.2 dB / cm, the empirical model provides an additional 4 dB / cm, due to a significant difference in the imaginary parts

So... take these values... if it goes down 7.2dB /cm or even 11.2dB/cm... don't you think that they can be used as a remote for two (or more) cameras as long as they are really close to the remote?

The absorption phenomena will indeed decrease enormously the signal but if we use a setup like mine and place the transmitter just outside of the housings... I think I will not have issues.
But any way... this is just theoretical and I need to see it working to have sure ;)


Solution to shoot 3D underwater with Hero2:

- get two GoPro Hero 2;
- get two Dive Housing;
- get two Wifi Bacpac and sync with one remote;
- get two high speed SD cards with exactly the same characteristics, class 10 (6 the minimum for good HD);
- get a ruler and place the cameras side by side, well aligned (use the with o-ring to help the alignment), using one of the glued bases for each;
- get a underwater bag for the remote, if you plan to go deeper then 3meters (10feet);
- place the remote (or the remote bag) in contact with the ruler, right in the back at the middle of the cameras;
(as close to the cameras it can be, as the purpose here is not to have a remote control for a distance but a way to have the start/stop signal reach both receivers at the same time... and as I told you up there... the decrease of the signal is by the centimeter ;) )
- use it :)


Now.. for those of you that say that WI-Fi signals will not propagate underwater:
Underwater test 3D wifi

Try it! :)
And comment

6 Posts
Great solution for that need...

Excellent work!

I might be wrong but I'd bet that most people asking about the underwater wifi signal want to be able to preview/view what the camera is seeing real time using the wifi app. However, for what you want that's a very nice solution. Great job and thanks for the sweet explanation, too.
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