CCTV Video Balun – How To Transmit Video Over Cat5
By: Steven Williams
Security cameras generally transmit video over RG59 Coax Cable, but in some cases it makes more sense to use Cat5 cable. This is especially true when trying to transmit the video signal over long distances. The solution to this situation is the CCTV video balun.
A CCTV video balun is an impedance transformer. Impedance according to this web definition, is the total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is a combination of resistance R and reactance X, measured in ohms.
In layman’s terms a CCTV video balun converts a 75 ohm video signal over to the correct 100 ohm impedance for Cat5 cable and then back 75 ohm’s again. In order for this to work you need 2 baluns. One for each end of the Cat5 cable.
Using baluns can be a real time saver too. For example: What if you are in a commercial office building and need to install a security camera You can see if there are unused Cat5 phone lines. Imagine eliminating the need run coax cable from the 1st to the 6th floor.
Another advantage of transmitting video over Cat5 cable is that you have multiple pair of wires. Typically you have 4 pairs of 22 gauge wire so you can use one cable for 4 cameras. As a side note you should either power the security cameras at the camera itself or use a separate Cat5 cable. If you don’t take this precaution, interference can occur.