Protecting Your KVM and Video Extenders From Electromagnetic Noise

KVM (keyboard-video-mouse) extenders via CAT5 may be used to remove computers from harsh or sensitive environments, or to restrict physical access to the computer. Video extension products such as VGA, DVI, S-Video or HDTV extenders via CAT5 are used to extend video displays. Each extender consists of two units – the local and remote unit, which are interconnected using a CAT5/5e/6 cable.

The low cost and easy installation of twisted pair cables such as, CAT5, CAT5e or CAT6 cable, have made them a popular choice over traditional coax cables for transmitting KVM and AV signals. However, using a type of twisted pair cable that is unsuitable for your installation environment can lead to erratic keyboard or mouse performance, data loss, and picture quality degradation, effectively undermining the purpose of your workstation or video extension.

One of the causes of signal and video quality loss when using a twisted pair cabling infrastructure is an installation environment with extreme levels of Electromagnetic Interference (or EMI, also called Radio Frequency Interference or RFI).

Electromagnetic Interference

Electromagnetic interference is an unwanted disturbance caused in an electrical circuit by electromagnetic radiation emitted from an external source.

All electronic and electrical devices produce electromagnetic radiation during operation. The current flowing in a circuit generates a magnetic field. The potential difference or voltage necessary for the current to flow, produces an electric field. Strong electrical and magnetic fields can cause one electrical device to affect another. When this is unintentional, it is known as electromagnetic interference, commonly abbreviated as EMI.