There are a number of options that allow for the distribution of A/V signals. The choice of which option should be used will depend on several factors, including the type of signal being distributed, the length of extension required, and the number of displays required. Distribution options include native cable distribution amplifiers, over UTP product, and over Coax products.
Native cable distribution amplifiers operate with the same cabling type that is typically used for the signal being distributed. For example, a VGA distribution amplifier will utilize VGA cabling for both the input and outputs. An advantage to this type of distribution product is that there is no need to convert the signal. Other distribution systems that use different cabling types typically require signal conversion, which presents the possibility of signal quality loss. A disadvantage to this type of distribution system is a limitation of the distance supported. These distribution devices will be bound by the length limitations of the extension electronics in the device or the signal being distributed. However, some of these distribution devices also include extenders which will allow for support of longer lengths of native cabling.
Over UTP distribution products operate by using unshielded twisted pair cabling, i.e. Cat5, Cat5e, Cat6, etc. Because the characteristic impedance of the cabling typically used for A/V signals is 75 Ohms and UTP cabling has a characteristic impedance of 100 Ohms, an over UTP distribution device must convert the A/V signal that is input to a new signal that is sent over the UTP cabling, then convert it back to the A/V signal at the display. An advantage to this type of product is that they are typically capable of supporting long extension lengths. Another advantage to using this type of distribution device is that the construction of the cable, i.e. twisted pairs, reduces crosstalk into adjacent cables. A disadvantage to using this type of distribution device is the potential for phase distortions, which can cause changes in color fidelity, audio fidelity and black-level in the background, thus lowering the quality of the image that is displayed. Another disadvantage is that the video bandwidth for these extension devices are limited by the electronics used in the distribution device. This bandwidth limitation may limit maximum resolution or supported features, such as deep color for HDMI®.
Over Coax distribution products operate by using coaxial cabling, i.e. RG59 or RG6. Because the characteristic impedance of coax cabling is the same as the native cable that is typically used for A/V signals. The matched impedance of these cable types is an advantage because there is less of an opportunity for image quality loss. Another advantage to using this type of distribution device is the predictable performance at distances equal to or less than ¼ the signal wave length in copper. A disadvantage to using this type of distribution device is that as a coax cable gets longer, it gets capacitance increases which will roll off the high frequencies and soften the displayed image. Another disadvantage is that long lengths of copper are heavy and difficult to install.
This white paper is for informational purposes only and is subject to change without notice. C2G makes no guarantees, either expressed or implied, concerning the accuracy, completeness or reliability of the information found in this document.