Department of Marine Science
Catalina ROVs belong to a class of ROVs affectionately known as “flying eyeballs.” They are, fundamentally, a means of steering a closed-circuit video camera around under water, so the operator of the system (the “pilot”) can actively look around under water to see what’s down there. In this respect, the video camera system is the heart and soul of this type of ROV; everything else plays a supporting role.
The overall camera system consists of a video camera, a waterproof and pressure-proof housing to protect the camera while under water, some way to get a live video image from the camera to the surface via the tether, and a TV monitor on the surface, so the pilot can see the live video image. In our case, we also needed to have the ROV record the dive video during the dive. The remainder of this page describes details of the underwater portions of our camera system, including the camera and its waterproof connection to the tether. The TV monitor portion of the camera system is described separately as part of the Pilot’s Console.
There were a number of cameras we could have chosen, but we ended up going with the original GoPro Hero camera, sometimes referred to as the “Hero 1” or the “Hero Naked.” At the time, the GoPro Hero 1 provided a good compromise among several factors important for our ROV design including: small size and weight, an available underwater housing, modest price (for both the camera and the housing), the ability to power the camera from an external battery source, the ability to extract a live video image that we could send topside to display on a TV monitor for the pilot, and the ability to record high quality 1080p HD video of each ROV dive for later review and editing by the pilot or others.
For those who may not be familiar with them, GoPros (manufactured by GoPro.com) are compact, rugged video cameras especially popular among their target audience: extreme sports enthusiasts, who strap them to their helmets, skis, surf boards, motorcycles, and other equipment to record “first person” views of their sports activities. However, they are also a popular choice for those who are adapting cameras to provide a “first person view” from radio-controlled model airplanes and other remotely controlled projects, including ROVs.
The Hero 1 we used predates the Hero 2, Hero 3, and more recent versions and is no longer sold by GoPro, but you may be able to find one at a discounted price by searching e-bay or other online sites for used camera gear. We have used later GoPro models in some of our more advanced ROV designs (for example, our Ulithi ROV uses the Hero 2), but getting the later models to transmit their video over a tether is somewhat more complicated. Several websites devoted to using GoPro cameras as “first person view” (FPV) cameras on radio-controlled model airplanes and quadcopters explain how to do it.
If you are planning to modify the Catalina design for your own purposes, be sure to consider newer GoPro models as well as alternative brands, since digital video cameras and their features are evolving quickly. This web page only describes how we used the GoPro Hero 1.
Preparing the camera
Because of space constraints in the dive housing, we found it easiest to extract our live video feed from the 30-pin GoPro bus connector located on the back of the camera, rather than getting it from the stereo jack located on the side of the camera, which is where the standard TV cables plug in. Techniques for doing this were worked out by others and made available to us and others through the GoPro User Forums. We express our gratitude to those who did this work and made our jobs so much easier.
To simplify access to the live video output from this bus connector, the Hero 1 must first be loaded with an older version of the firmware, specifically version 02.05.11. Hopefully, you’ll still be able to find this version on the GoPro support website. If you don’t do this, you’ll need to add some additional circuitry and programming to “fake” the presence of GoPro’s optional LCD backpack, which is a tiny TV screen that mounts to the back of the camera.
The instructions we provide on this website may not work unless you load version 02.05.11 of the firmware into the camera.
To change the firmware, you will first need to obtain the appropriate firmware file and put it onto the root directory of an SD card as follows:
- Download the 02.05.11 firmware.zip file from goprousers.freeforums.org and save it to your computer.
- Unzip and extract the file firmware.bin. (Do NOT rename this file; it must be “firmware.bin”)
- Place an SD card in the Hero camera, and connect the Hero camera to a computer via USB cable.
- Power on the camera, and activate the USB mode. The camera’s SD card should appear as an external drive mounted on your computer.
- Navigate to the main (root) directory/folder of the SD card.
- Drag and drop the firmware.bin file into the root directory of the SD card.
- Power down the camera and unplug it from the computer.
Now you are ready to install the firmware into the camera’s “brain.”
- While the camera is off, hold down the Shutter button (on top of the camera) and keep it pressed throughout the entire installation process.
- While still holding the Shutter button, press the Power/Mode button (on the front of the camera) once. This should power the camera on. Keep pressing the shutter button.
- While still pressing the shutter button, press the power/mode button 3 more times to cycle through the menus until the screen says “Up”. The red light will flash for 5–10 seconds while the firmware updates, then it will shut off. Note: If the red light stops after 1–2 second, repeat the firmware installation process.
- After the firmware update installation process is complete, be sure to delete firmware.bin from the SD card.
Once you have the appropriate firmware loaded, follow instructions in the camera manual to select the video recording resolution you'd like to use to record video during ROV dives. We find that 1080p works well.
The final step in preparing the camera for routine use in the ROV is to put it into its “one-button” recording mode. In one-button mode, the camera starts recording automatically whenever the camera is turned on, and stops automatically when the camera is turned off. The camera manual explains how to put the camera into one-button mode.
Threading the cat-5e through the ROV frame
Before proceeding with the rest of these camera instructions, check out the frame assembly instructions. If you decide to hide the wires inside the frame like we did, you’ll want to feed the camera end of the tether’s Cat-5e cable through the ROV frame as part of the frame assembly BEFORE you try to connect the tether to the camera housing.
Connecting the tether to the camera housing
All communication between the camera and the Pilot’s console occurs through a 50-foot length of Cat-5e computer networking cable, which is bundled along with other wires in the ROV’s tether. The following instructions assume you have already threaded the Cat-5e cable through the inside of the ROV frame or have decided that you want to run the wires on the outside of the frame.
The Cat-5e cable contains a total of 8 small wires arranged in four twisted-pairs. We used some of these wires to power the camera, others to control the camera, and still others to carry the live video signal from the camera back up to the surface. These wires must make a water-tight entry into the camera housing before they can be connected to the camera.
First, the regular back door of the GoPro dive housing for the Hero 1 will need to be replaced by an “extended” back door, such as the one that comes with the optional “LCD Backpack” or “Battery Backpack.” This extended door provides extra room needed for the small connector and printed circuit board that will be used to connect the tether wires to the 30-pin GoPro bus socket in the back of the camera. The old door can be easily popped off and the new one snapped in place, but don’t put the new one on just yet.
To provide added strength and reliability for the waterproof cable penetration, we used a modified 1/4" NPT x 5/16" barb 90-degree brass hose barb. Hose barbs are available at most hardware stores, though this particular size/shape might need to be special ordered.
We used a hack saw to shorten the threaded end of the hose barb as shown below. This was necessary to leave enough room inside the camera housing for the wires and circuit board when the door was closed.
Then we used a tiny half-round file to smooth the inside edge of the hose barb so it doesn’t cut through the wire insulation when the wires at slipped through it later.
After you are done shortening the threads and smoothing the inside lip, put some rubbing alcohol (isopropyl alcohol) on a Q-tip and swab out the inside to remove any oil or grease that might interfere with a good bond to epoxy.
The image below shows the future location and orientation of the hose barb. Note the location of the hose barb's hole through the back door relative to the door hinge.
Once you’ve figured out where to put the hole, you’ll need to drill and tap a hole in the back door to accept the 1/4" NPT threaded end of the hose barb. (Note that 1/4" is the nominal size, not the actual size; find a 1/4" (nominal) pipe tap and look up the appropriate pilot hole drill bit diameter.) To avoid shattering the plastic door, it's best to use a drill bit made specially for drilling through plastic and to start with a smaller bit and work gradually up to the correct diameter.
Pipe threads like this one are tapered, so the farther you go with the tap, the larger the diameter of the threaded hole will become. You’ll need to be careful not to go too far and make it too large. It’s best to go a little way, then test. The barb should screw in so the threads barely poke into the inside of the housing without tightening. In fact, do not tighten, or you may crack the plastic. The epoxy used in a later step will seal the threads against water leakage and take care of any slight loosness between the hose barb and the door, so there is no need to screw the hose barb in tightly.
Next you’ll want to pass the Cat-5e wires through the hose barb as shown in the photo below. This needs to be done very carefully. Inside most of these right-angle hose barbs there is a razor sharp brass edge that will cut through the wire insulation as you pass the wires through the barb. To prevent this, you must “precurl” the wires and gently push (more than pull) the wires around the corner. You'll feel it if the insulation snags. If it does, stop and try a different approach.
When you have almost, but not quite, reached the Cat-5e jacket, put the hose barb in a vice as shown below and mix some slow-curing epoxy to fill the air spaces between the wires and the interior of the hose barb. We've had good luck with J.B. Weld epoxy, because it does a good job of wetting the surfaces and creeping into nooks a crannies for a water-tight seal, though other types may work well, too. Avoid 5-minute or other quick-cure epoxies for this step, because they may not flow into all the spaces well before they start to thicken. Start at the top using a toothpick or similar to poke globs of well-mixed epoxy down in among the wires, but be very careful to keep it off the threads. Try to avoid trapping any air bubbles inside. Keep adding epoxy as you gently move the wires around to encourage the epoxy to fill all gaps. Eventually it should start dribbling out the narrow end of the hose barb. Allow this to happen. When you are confident that all the spaces between the wires and the hose barb walls are full of epoxy, slowly continue to push the wires into the hose-barb end until the jacket slides at least 1/8'-1/4" up inside the hose barb. Add a little extra epoxy around the edge to seal the cable jacket in place. Wipe excess epoxy off the wires at the threaded end of the hose barb, because these will later need to be flexible. The next couple of photos show a before and after comparison of the gluing operation.
Let the wires sit undisturbed in the hose barb for 24 hours while the epoxy cures.
Now you are ready for the second gluing operation. This time, to glue the hose barb in place in the back door of the camera housing. Feed the wires through the hole you drilled and threaded earlier in the extended back door of the camera housing. Place some JB Weld epoxy on the brass threads and screw the hose barb into place. Be sure to use enough glue to displace any air gaps and to get some extra glue forced to the outside to form a little fillet. This smooth ring of glue will create a nice waterproof seal and act as a strain relief to reduce the likelihood of cracking the plastic door. Remember not to tighten too tightly, or you’ll crack the plastic door. Let the glue harden over night before proceeding to the next step.
The ridax breakout board
The 30-pin socket located at the back of the GoPro camera provides access to the main “bus” (an important set of control wires inside the camera) and thus to many camera features. Not only can you get live video out of it, but you can also use it to supply electrical power to the camera from a remote source and use it to remotely turn the camera on or off.
To access this bus for connection to the Cat-5e wires, we used a compatible 30-pin plug and small printed circuit “breakout board” from a company called Ridax in Sweden (www.chargeconverter.com). You can buy the boards from them with the 30-pin connector already soldered in place, or you can save some mony by buying the board and plug separately and soldering them together yourself. (But be warned, this is a very tiny and delicate operation best attempted by those with considerable soldering experience, a very fine-tipped soldering iron, steady hands, and a dissecting microscope or other good magnifier.)
Through the Ridax breakout board and plug, each of the 30 tiny wires in the GoPro bus is brought out to one of the larger, easier-to-solder pads and holes arranged around the edge of the board. These are the pads to which we soldered the appropriate Cat-5e wires to connect the camera electrically with the pilot’s console at the other end of the tether. Inside the tether, all camera functions are communicated through a Cat-5e computer networking cable, which contains eight wires, some with solid colors of insulation (example: blue) and others that are white with a colored stripe (ex: white with a blue stripe, denoted white/blue).
Wiring the cat-5e to the Ridax breakout board
Once the waterproof wire penetration is complete, you are ready to work on connecting the Cat5e wires to the camera via the Ridax board.
A table below lists which wires go to which pads on the Ridax board, but before you dive into this soldering adventure, please heed the following advice:
As you solder each of the Cat-5e wires to its correct pad, keep some extra length in the wires to allow for easy removal of the camera from the housing while the Ridax board is still plugged into the back of the camera. We found it was helpful to twist the wires (like the fibers in a rope) and then coil the whole “rope” into a circle like a big spring. Of course, you also have to make sure that the wires will curl up neatly inside without getting caught in the rubber gasket or otherwise preventing the door from closing and sealing properly. Otherwise, you’ll have a flooded and destroyed camera!