![]() Isolating video signal needs typically active technology which involves electro-optical isolation or differential amplifier with a floating ground on the input connector. Isolating video signal is more complicated than isolating audio or antenna signals, because the DC level of the video signal is important and video signals have very high frequency spectrum (normal composite video can have bandwidth from 50 Hz to 6 Mhz). Ground loop isolation in video lines Ground Loop Isolator GB0001 Cross-Talk: Ground loops can cause one signal to interfere with another, because every cable should ideally return through the corresponding shield conductor, but there's an alternative path through the other shield conductor which causes undesirable voltage differences to nearby cables.These antennas are especially adept at picking up AM broadcasts if most of the loop is vertical. Any large loop of wire makes a good AM antenna. RF Interference: Herring bone interference on video line is caused by a ground loop (that includes your coax shield) acting as an AM radio antenna.If you have light dimmers nearby those humming bars can easily become quite severe and easily visible. Hum Bars: The mains frequency (50 Hz or 60 Hz) can cause stationaly or moving horizonal humming bar to appear on the video signal (as shown on the picture above).Ground loops in the video systems can have following effects: Those have entered the cable TV signal because of ground loops in the system. The picture below is a real world example of the effects of a ground loop and what it causes a a video picture received from the cable TV network:Īd you can see that video signal has strong hummign bars and other interference in it. The same kind of bars can be also seen in computer screen, but typically they are not as visible because bars are moving so fast that you see them as some strange flashing in screen. Typically the humming can be seen as slowly vertically moving horizonal bars in normal TV video signals. Video hum maybe a problem in any system where video sources and display devices are connected to different A/C power sources with varying grounding potentials. Video hum is usually observed as bars rolling vertically through the video image, video hum may also cause video distortion or even tearing of the picture in severe cases. Video hum is low frequency (50 or 60 Hz mains frequency or it's harmonics) noise from the ground lines which has influenced the video signal, causing degradation of the displayed signal. Ground loop problems in video lines Ground Loop Isolator GB0001 What ground loops do to video linesĪs the source and destination of a video signal can be at differing ac or dc earth potentials, earth loop currents flow and cause longitudinal hum to be introduced into the video signal. VDS Single Coaxial Cable Transmission Poster! Unshielded Installations Find Your UTP Smart Cabling Solution By Distance Smart UTP Cabling Applications Smart UTP Cabling FAQ Lenses Calculator Adjust Varifocal Lens What's gorund loop and how to isolate it ? CAT5 UTP Wiring Tips
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