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

Posted by Paul Illsley