With data rates expanding exponentially in recent years, there has been an influx of network cables on the market. No longer are these cables one size fits all, different cabling suits different speeds and data rates. As electrons travel through the wires inside the cabling, they carry the electrical signal to its intended destination. Unfortunately, issues can arise along the way that negatively affect network performance. When data is corrupted, lost or weakened, the problems are classified into three main groups: attenuation, noise and delays. Wi-Fi interference is not the only type of disruption you can have, but even a regular wired network cable can have interference issues.
Defined as the loss or degradation of a signal. Attenuation occurs as the signal moves further away from its source, causing it to become distorted or weak. There are a number of factors that can contribute to attenuation. The top reason among them is the length of cable being used, including path leads, the common limit for cable length is 100 meters. However, different cables have different limits, so always be aware of the type of cabling that your network uses.
- Resistance: Resistance grows when wires are longer and thinner, inhibiting the signal and dispersing the energy in the form of additional heat. It is important to control the atmospheric conditions around the cables because heat and moisture can result in failure of the network.
- Mutual Capacitance: When several wires are located near each other, they function similar to a capacitor by collecting the energy stored as a result of the wire insulation absorbing a portion of the signal. To reduce the loss of signal, high density polyethylene is often utilized in cables designed for high frequency applications. In these situations, lower frequency cabling will usually exhibit sub-par performance.
- Impedance: Resistance, capacitance and inductance combine to produce electrical impedance, which is represented in Ohms. When a signal meets high impedance, generally due to a faulty cable or improper connector, the signal bounces back and creates major problems. This is especially true with high speed networks. Zero impedance is the result of a short circuit, while infinite impedance implies that there is a cut in the cable.
When there are electrical signals on the wire that were not included in the original signal from the sender, this is referred to as noise. This can come from external or internal sources. Although twisted pair cables are intended to prevent interference, noise can be caused by variations in cable width, cable insulation or capacitance of wires or insulation. Noise can be reduced by using higher quality cables, but it will not be completely removed.
- External: Electrical interference from sources such as fluorescent lighting, motors and air conditioners, can be avoided by shielding cables or using alternatives like optical fiber.
- Internal: Cross talk has a greater effect than other types of noise. It occurs when the electric field generated by the signal moving along the conductor interferes with adjacent wires. Since this is usually an issue on patch panels and cable connectors, try to minimize the area of untwisted cable.
Cable lengths take into account the propagation delay, which is the amount of time a signal takes to travel down twisted pair cables, but excessive delay skew will impair the communication between network devices. Select high quality cables, connectors and crimps that are appropriate to your network for the best results.