The value given typically must be multiplied by the speed of light (c) to obtain units of meters per second.įor example, a cable that lists a propagation velocity of 78 gives a velocity of 0.78 X 300 X 106 - 234 X 106 meters per second. Propagation velocity ( of c): The speed at which an electrical signal travels in the cable.

Shunt Capacitance (pFft): The amount of equivalent capacitive load of the cable, typically listed in a per foot basis One of the factors limiting total cable length is the capacitive load. If termination is required in a system, the termination impedance value should match the Characteristic Impedance of the cable. When the cable is out to any length and terminated with this Characteristic Impedance, measurements of the cable will be identical to values obtained from the infinite length cable. Ready (DSR) is an indication from the Data Set (i.e., the modem or DSUCSU) that it is on.ĭCE Data Communications Equipment or a DTE Data Terminal Equipment.ĭCE One of the stickiest areas of confusion in datacom is over the terms transmit.Ĭontrol is used by the DTE and the Indication is the DCE one.Ĭrosstalk can be reduced by using low capacitance cable and shielding each pair.īeyond the obvious traits such as number of conductors and wire gauge, cable specifications include a handful of less intuitive terms.Ĭharacteristic Impedance (Ohms): A value based on the inherent conductance, resistance, capacitance and inductance of a cable that represents the impedance of an infinitely long cable. If the ground cable is not properly grounded, STP's noise-canceling functionality can be seriously compromised.Some devices are very efficient and only require one pin (some. STP cables function by drawing external interference to the shield, then getting rid of it into a grounded cable. Except in cases where the maximum pulling tension and minimum bend radius are strictly observed, these thinner cables may be torn during the installation process.įurthermore, STP cables have some other drawbacks. These cables are thin and more affordable versus the braided STP cable but they are very difficult to install. The other usual STP cables, often called foil twisted-pair cables or screened twisted-pair cables, make use of just a thinner outer foil shield. Some STP cablings make use of a thick copper braided shield which makes the cable thicker, heavier, and in turn much more difficult for installation as compared to the UTP cables. Distance from the shield to the noise source.The effectiveness of the additional covering varies according to the substance used for the shielding, such as: STP cables are often used in Ethernet networks, particularly fast-data-rate Ethernets. The additional covering in STP cable stops electromagnetic interference from leaking out of or into the cable. Techopedia Explains Shielded Twisted Pair (STP)

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