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Why do cables have an effect on signal quality?
Published:2014-06-26 16:36:05

The video signal is very sensitive, as it has to carry information spread over a wide spectrum of frequencies, from almost 0 Hertz (DC) to many MHz (millions of Hertz – oscillations - per second). When high frequencies are involved, proper cable termination (loading) is needed in order to equally transfer all frequencies and avoid an effect called “standing waves”, which is a result of signal reflections in the cable creating signal loss, “ghost” images and instability. The electrical energy stored in the video signal is perfectly transferred from the source to the acceptor if the cable is fully matched at both ends. Low quality cables are not suitable for good signal handling and usually have excessive built-in capacitance, which degrades the signal. When an inappropriate cable is used, quality of the signal deteriorates, details of the picture are lost, color fidelity is reduced and noise level, apparent as snow, destroys the picture. In addition, some low quality cables are not properly shielded, and do not isolate the video signal from external interference.