Homebuilt ROVs Forum

The problem with usb or composite cameras is cable length, any over 12' is problematic, especially if you want to record. The solution is an IP camera which can connect direct to a PC over ethernet (cat5) cable at any length, available with pan/tilt for as little as $50 and freeware like webcamXP can control it. This set up requires some computer savvy but is not beyond any one who can build a ROV

The biggest problem with doing it through software is that of lag. If you want high quality real-time video over ethernet you're talking serious computing power.

I record over standard AV cables up to a 100' without any problems.

-Steve

I've seen the video baluns to adapt rca to cat5 mentioned on here somewhere...
Are those necessary or can I just solder rca plugs onto a twisted pair in the cat5?

Soldering on RCA connectors works fine, for the most part. The longest I've gone is about 75' feet, though, using that method.

scubersteve wrote:I've seen the video baluns to adapt rca to cat5 mentioned on here somewhere...
Are those necessary or can I just solder rca plugs onto a twisted pair in the cat5?

I have been looking into baluns for a while. Here is the one I currently have my eyes on!

There is clearly more going on in that balun than a simple connection of a rca jack to an Ethernet cable...
So what is going on? What is the reasoning behind it?

The balun houses a transformer which is used to match the impedance of the coax (75 ohm) to the impedance of the CAT5 cable (100 ohm).

If you don't match impedances you don't get maximum power transfer and you may also end up with standing waves, not good in this application, useful in others.

http://www.allaboutcircuits.com/vol_2/chpt_14/6.html

They can be passive (just a transformer) or active with an amplifier to drive over longer lengths of cable. I think about 300 feet is OK with a passive balun at each end.

Martin

excellent info.
thanks

For another project I am sending HDMI 50 metres over cat6 using a powered balun. But, I am also keen on trying composite cable over a similar length. Steve, is that what you are using, composite cable? Do you convert it to coax, or composite for the full length? Do you use baluns?

Cheers

mg