Twisted Pair Cable Overview

Twisted pair is the ordinary copper wire which connects home and many business computers to the telephone company. It is made by putting two separate insulated wires together in a twisted pattern and running them parallel to each other which helps to reduce crosstalk or electromagnetic induction between pairs of wires. Since some telephone sets or desktop locations require multiple connections, twisted pair is sometimes installed in two or more pairs, all within a single cable.

Twisted pair cable is good for transferring balanced differential signals. The practice of transmitting signals differentially dates back to the early days of telegraph and radio. The advantages of improved signal-to-noise ratio, crosstalk, and ground bounce that balanced signal transmission bring are particularly valuable in wide bandwidth and high fidelity systems.

How Does Twisted Pair Cable Work？

Twisted pair cable is widely used for telecommunications and most modern Ethernet networks. But do you know how a twisted pair cable works?

When electrical current flows through a wire, it creates a small, circular magnetic field around the wire. Noise is generated within signal lines through magnetic fields. Therefore the noise in data outlines is the consequence of the magnetic field. Within the straight cable connection, all sound current is moving in the same direction, exactly like within a regular transformer coils. Once the cable is actually twisted, their magnetic fields are opposite to each other. Thus, the two magnetic fields cancel each other and any outside magnetic fields. Due to this, the noise current in a twisted cable is lower than in an ordinary cable.

Types of Twisted Pair Cable

According to whether the cable has a shielding layer, there are two common types of twisted pair cables—shielded twisted pair cable and unshielded twisted pair cable.

Shielded Twisted Pair (STP) Cable

Shielded twisted pair (STP) cable combines the technique of shielding, cancellation and wire twisting. Each pair of wires is wrapped in a metallic foil. The four pairs of wires then are wrapped in an overall metallic braid of foil. STP cable is used to eliminate inductive and capacitive coupling. Twisting cancels out inductive coupling, while the shield eliminates capacitive coupling. This kind of cable is often applied between equipment, racks and buildings. Compared to unshielded twisted pair cable, STP will cause more attenuation. However, because in the case of balanced transmission, the complementing signals will effectively cancel out any shield currents, so the losses are negligible. Besides, although STP prevents interference better than UTP, it is more expensive and difficult to install.

Unshielded Twisted Pair (UTP) Cable

Unshielded twisted pair cable is the most commonly used cable for Ethernet connections. It consists of color-coded copper wires, but does not include any foil or braiding as insulator to protect against interference. In addition, the wires in each pair are twisted around each other. UTP cables are smaller than STP cables, which makes them easier to install, particularly in bulk or in narrow spaces. They are also cheaper than STP cables, and do not require as much maintenance, since they do not rely on outer shield. Furthermore, UTP cables can also transmit data as fast as STP cables. However, UTP cables are more prone to cause electrical noise and interference than other types of networking media. Thus, UTP cables are best used for domestic and office Ethernet connections, and in any area where there is not a high degree of electromagnetic interference.

Applications of Twisted Pair Cable

The most commonly used twisted pair cable impedance is 100 ohms. And it is widely deployed for data communications and telecommunication applications in structured cabling system. As its transmission distance&speed and bandwidth are limited, twisted pair cables are often used in telephone lines to carry voice and data channels, and local area network such as 10Base-T and 100Base-T, and so on.

Conclusion

To sum up, twisted pair cable has great potential in the field of short distance transmission in the future. It can meet necessary conditions of high efficiency, energy saving, environmental protection and many other trends in today’s society. FS.COM has been devoted to the research of twisted pair transmission technology such as Cat 7 twisted pair cable, hoping to create the highest quality products and satisfy every consumer.