Telecommunication and computer cables are used in computer networks and in signal transmission using various interfaces, e.g. HDMI or USB. The most important type is the twisted-pair cable.
Computer twisted-pair cable comprises four pairs of wires placed in a common cover. Each pair is twisted lengthwise in order to minimize the impact of electromagnetic disturbances as well as mutual interferences (also known as crosstalk) on the transmission.
A twisted-pair cable may comprise:
This group also includes optical fibre cables and specialist wires for the needs of USB or HDMI cables. Their detailed parameters are defined in descriptions of particular standards.
The markings of cables of this type are defined by the IEC11801:2002 standard. Such description comes in the xx/yyTP format, where: • yy – describes a single core pair in the cable, • xx – refers to the entire cable. For instance, SF/FTP means that it’s a twisted-pair cable with each pair foiled, and an additional foil and grid shield for the entire cable.
Quality of a cable is described by its category (class), in accordance with the EN 50173 standard: from 1 to 3 and from 5e to 8.2. The higher the category, the higher the bandwidth, e.g. category 6 is for Gigabit Ethernet. What’s more, insulation colours of wires in the aforementioned four pairs are normalized as well.
Depending on the particular version, telecommunication and computer cables can be used indoors or outdoors. Cables for indoor use include e.g. self-supporting cables for overhead installations. There are also versions for non-Ethernet networks, with less pairs (e.g. one), as well as multi-pair versions for telecommunication.