Homebuilt ROVs Forum

i am wanting to use a USB webcam plugged into my laptop and just make a really long cable for the usb, i am wanting to have a 30m cable to surface. i have seen that some people are saying things like using cat6/cat5 cable but im just not sure what i should use. any better ideas or any way to make something like this possible for cheap .

Hi,

I haven't done this before, but it should be possible. You will have to use a cable with at least one twisted pair, for the data + and data - wires. If you don't use twisted pair, I would imagine that the bandwidth would be severely limited, or it might not connect at all. like you suggested, CAT5 or CAT6 would be your best bet, because they contain twisted pairs. The power draw of a webcam should not be very much, so you will probably get away with CAT5 without losing too much voltage.

To be honest though, USB was never really designed for long cables. 30m is the absolute maximum for USB 2 as far as I know (bear in mind this distance is shorter for USB 3), but you might be pushing it when factoring in a homemade cable which may introduce interference. Like I said though, I haven't done this before, I'm just speculating.

You could also try an ethernet webcam/security camera, because ethernet is designed for longer distance data transfer. The only issue is power delivery to the camera. You could use a separate power cable alongside the ethernet, or you could use PoE (Power over Ethernet). This involves sending power down an unused pair of wires in an ethernet cable. A PoE injector (a device which sends the power down the ethernet cable) can be bought fairly cheaply I believe, as well as PoE cameras (if you search around a bit). PoE normally uses around 48V though, so be careful or you might get a bit of a tingle. That will also go through the water quite easily (especially salt water), so you would need to make sure all connections are waterproof. You can get a USB to ethernet converter fairly cheaply if you don't have any free ethernet ports on the laptop.

Hope this helps, sorry I couldn't give you any definite solutions.

kinda was thinking doing this would it work???? seems to be the cheapest and the easiest to do.

From what I can see that should work, just bear in mind that you will need to use another rj45 - USB adapter on the laptop end, so it will be plugged into the USB port on the laptop, not the rj45 port. Otherwise there will be no 5v power supply to the camera. It looks like those rj45 adapters often come in pairs of a male and female USB version, so that should be easy to do.

all right kool thanks, thanks for the help now my rov will be able to see underwater

No problem, good luck with the rest of your build!

best to make sure you can power the Camera end so less problems. I used this on a 100' Cat5e cable with good results.

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