GoPro Underwater Wi-Fi Cable Setup


GoPro Underwater Wi-Fi Cable Setup

Posted by Paul Illsley


GoPro camera, Nexus 7 tablet, coax cable (50 feet) and waterproof case for tablet


Have you ever wanted to use your GoPro as a real-time underwater inspection device but found the Wi-Fi didnít work underwater, and you didnít really want to drill a hole in the GoPro case? Well I did so I decided to try an experiment. One nice thing about this project is you donít have to make any modifications in either the GoPro housing or viewer (Nexus 7 tablet in my case).

I picked up some RG174 coax cable and set about to find out how far this cable could transmit the Wi-Fi signal when the GoPro was underwater. I chose RG174 cable because it was cheap and easy to handle (thin and flexible). Iím sure there are other cables that will work but this one did what I needed.

I first tried 100 feet and didnít receive any signal. I then tried 75 feet and received a weak signal but not strong enough to connect to the GoPro App on my Nexus 7 tablet. I then tried 50 feet and found this was the sweet spot. I received a usable signal and the GoPro App worked well (with real time viewing and recording).


So this is how it works:

GoPro Wi-Fi broadcasts on a frequency of 2.4 GHz, unfortunately water absorbs this frequency so the Wi-Fi signal canít travel through much water before it gets absorbed (thatís why you lose Wi-Fi connection when you submerge your GoPro in water). But if you place some coax cable next to the GoPro housing and the other end next to the antenna of a Wi-Fi compatible device (Nexus 7 tablet in my case), the cable acts as a conduit for the signal to travel along so it doesn't get absorbed by the water around it.

There is only one thing you need to do to make this system work; remove the outer black plastic and braided wire shield from each end of the coax cable. The amount you remove is important; for a 2.4 GHz Wi-Fi signal, which has a wavelength of 12.5 cm (4.92 inch), you need to remove 6.3 cm (2.5 inches) of casing from each end (1/2 the wavelength). You could expose the entire 12.5 cm on each end but 6.3 fits perfect on the back of the GoPro and it works fine. You can leave the white plastic shield around the inner cable and add some glue around the open ends too seal it from water (if you want to use it for an extended period of time).

I placed one end of the cable near the internal Wi-Fi antenna on the upper part of the back of the GoPro Hero 3+ housing and taped it in place (if you were to make this a permanent setup you could glue or epoxy it in place). The other end was taped to the back of a waterproof bag housing my Nexus 7 tablet (the Wi-Fi antenna is located near the top of the tablet). I used a waterproof case because I knew it was going to be used around water and I wanted to protect the tablet.

Thatís really all there is to it. When you have this cable in place and turn on your GoPro Wi-Fi transmitter, you should be able to see and control your subnerged camera in real-time.


Parts list:

    GoPro camera and housing (with Wi-Fi capability), I used a Hero 3+ Black
    50 feet (15 metres) of RG174 coax cable
    Wi-Fi capable smart phone or tablet (Nexus 7 tablet in my case)
    Wire stripper or razor knife to trim the shielding off each end of the coax cable
    Tape or glue to hold the cables to the camera and tablet
    Waterproof bag for tablet (optional): Overboard Waterproof Bag in my case

Cable with its outer covering intact (A)
Cable with outer covering removed to expose its metal shield (B)
Cable with the metal shield removed to expose the inner plastic and wire components (C)


End of coax cable placed on the back of the GoPro camera housing
(Velcro shown in this image was used for another project)


End of coax cable placed on the back of the Nexus 7 tablet (next to the antenna)


End of coax cable placed on the back of the waterproof case (optional) containing the Nexus 7 tablet




Camera attachment ideas

1) Painterís pole camera adaptor. This allows you to attach a camera (with a standard 1/4-20 thread) directly to a painterís pole or broomstick (with a 3/4 x 5 thread) without making any modifications to the pole. A standard GoPro tripod adaptor will screw directly to this adaptor. You might want to wrap the adaptors with electrical tape after they are attached to make sure they donít come unscrewed.

2) Standard broomstick with a threaded end (the same thread as the painterís pole).

3) A standard GoPro tripod adaptor (1/4-20 thread).

4) A 24 foot telescopic pole (originally intended for cleaning leaves or snow off a roof). This pole did not have a threaded end so I inserted an eyebolt (1/4-20 thread size) down the end of the pole and drilled a hole through the pole so a second bolt could be inserted through the eye of the first bolt. The extra space around the first bolt was filled with a piece of wood to keep the eyebolt in line with the pole.

5) A 16 foot telescopic painters pole without a standard 3/4 x 5 thread end (the end was damaged and had been cut off). I simply drilled a hole through the end of the pole and inserted a 1/4-20 eye bolt through the side. I used a locking nut (with a nylon insert) to tighten the bolt to the pole after the GoPro tripod adaptor was screwed into position. The exposed eyebolt is useful for attaching additional items if required.

6) A standard GoPro tripod adaptor (1/4-20 thread size).

7) A standard photographers telescopic monopod with a 1/4-20 thread on the end.

8) A higher quality telescopic monopod with a 1/4-20 thread on the end. This monopod will accept a 1/4-20 bolt in the handle end. This is useful for adding a 1/4-20 D-Ring bolt (item 14).

9) Clamp that will accept a 1/4-20 thread bolt. This can be placed anywhere on the pole and could also be used to mount the camera in a stationary location for longer duration projects.

10) Articulating arm with 1/4-20 thread bolts on each end. This could be useful if you want to mount your camera at a specific angle (using a clamp like item #9).

11) Aluminum GoPro quick release plate with a 1/4-20 thread hole in the bottom. This could be useful if you need to quickly attach or remove your camera from the pole.

12) Compact and lightweight extension pole. This would be useful if you donít need to place the camera very deep in the water.

13) A 8.5 foot carbon fiber extension pole. This could be useful if you want good reach without a lot of weight or bulk. This pole has a male 1/4-20 thread bolt on one end and a 1/4-20 thread in the handle.

14) A 1/4-20 D-Ring bolt. This is very useful for attaching safety lines to the end of your poles.


Useful suggestions:

Consider attaching a safety line to your pole and camera; you never know when they might slip out of your hand or off the deck.

Think about securing the cable to the outside of the pole with electrical tape so it doesnít get tangled or caught on anything above or below the water.

If you want a streamlined pole without any exposed cables, consider drilling a hole in the pole near the camera and feeding the coax cable inside the pole and out the other end. Just make sure you wrap the cable with a few layers of electrical tape where it enters and exits the pole to protect the cable.

Make sure you wash all your equipment off with fresh water after use.




Underwater lights

You may want to use lights with your underwater camera so here are some suggestions.

Not only do external lights add brightness to the scene, they also help reveal the true colors of the objects being filmed. Much of the red portion of the spectrum is absorbed by water so the deeper you go, the less accurate the colors will appear.

Try and keep your lights off to the side and behind the camera. This will help decrease the potential of light reflecting off tiny particles in the water which will cause bright speckles in your image (called backscatter).

Try and choose a light with a wide angle of coverage and an even illumination across the field of coverage (not a narrow circular beam). This will provide a more even illumination across the area being photographed.

Try and angle your lights away from the camera slightly so the light doesít illuminate the water between the camera and subject. This will greatly lessen the possibility of backscatter.

Check to see what color temperature your lights have. Lights having a color temperature of around 5500K are close to that of normal sunlight; temperatures above that will appear bluer and temperatures below that will appear more orange.

Try and move relatively close to your subject. The more distance between the lights and subject, the less effect they will have.




Monitor Hood

You may find it hard to hold the pole and your monitor (smart phone or tablet) at the same time. Hereís an option I found worked quite well. In addition to allowing you to hold the pole with two hands, a monitor hood makes it much easier to view the screen in bright conditions. I added a soft neoprene camera neck strap which made the setup quite comfortable. The image above shows a monitor hood and a smart phone setup.




Keeping your cable untangled

I used a simple kite line winder to keep the cable untangled. Because RG174 coax cable is relatively thin and flexible I found 50 feet of cable fits quite well on a 6.5 inch reel. I drilled a hole the size of the cable in the side of the reel which allowed me to pass one end of the cable through (this end was attached to your phone or tablet). This allowed the remainder of the cable to be unwound and rewound without getting tangled. The reel is stored in a small nylon bag when not in use.


Posted by Paul Illsley