Which of the following media is immune to electromagnetic interference EMI )?

In this objective, you’re expected to know a little more about the cables and connectors introduced in Objective 2.1 “Identify types of network cables and connectors”. In addition to being able to recognize the cables and connectors, you also need know about some of their characteristics, such as their speed and transmission limitations.

Exam need to know...

• Fiber

  For example: What is a benefit of fiber cable related to EMI? Which supports the maximum distance—SMF or MMF?

• Twisted-pair

  For example: What category of twisted-pair cable supports 1 Gbps? What is the maximum transmission speed of CAT 3?

• Coaxial

  For example: What is RG-6 cable used for?

Fiber

Fiber cable is more expensive and harder to work with than twisted-pair or coaxial cable. However, it has some significant advantages over other cable types, so it is being used in more and more networks.

True or false? Fiber cable is immune to EMI and RFI.

Answer: True. Fiber cable is not susceptible to signal loss from electromagnetic interference (EMI) or radio frequency interference (RFI).

Two common sources of EMI are from electric power cables or fluorescent light fixtures that are too close to signal cables. RFI interference comes from devices transmitting RF signals.

True or false? Data sent on a fiber cable can travel significantly farther than data sent on twisted-pair or coaxial cable.

Answer: True. Data sent on single-mode fiber (SMF) can travel the farthest without needing a repeater. Data sent on multi-mode (MMF) fiber can travel farther than data sent on twisted-pair or coaxial cable, but not as far as SMF cable.

For comparison, the maximum distances of different cables without using a repeater are as follows:

• SMF—up to 40 Km

• MMF—up to 2 Km

• Twisted-pair—up to 100 meters

• Coaxial—185 meters or 500 meters, depending on the cable type

Twisted-pair

Twisted-pair cable comes in many different types and categories. All categories come in both unshielded twisted-pair (UTP) and shielded twisted-pair (STP) versions. The STP version provides some protection against EMI and RFI, but it isn’t as effective as fiber cable against this interference.

True or false? If you need to run twisted-pair cable close to fluorescent lights, you should use UTP cable.

Answer: False. Fluorescent array lighting is a known source of interference, so STP cable is the best choice.

UTP cable is highly susceptible to signal loss from EMI and RFI. STP cable provides some protection against EMI and RFI, but it isn’t as effective as fiber cable.

True or false? CAT 5e cable supports a maximum transfer rate of 10 Gbps.

Answer: False. CAT 5e cable supports a maximum transfer rate of 1 Gbps.

The maximum transfer rates of various categories are as follows:

• CAT 3—10 Mbps

• CAT 5—100 Mbps

• CAT 5e—1000 Mbps (1 Gbps)

• CAT 6—10 Gbps

True or false? Plenum rated cable is fire retardant and reduces hazardous fumes from a fire.

Answer: True. Plenum rated cable should be used when cable is run through a plenum. It is fire retardant and reduces hazardous fumes from a fire.

A plenum, or plenum space, is the open space where heated and/or air conditioned air is forced through a building. Cables are commonly routed through these plenum spaces. The standard jacket covering used for cables is made of polyvinyl chloride (PVC), and it will emit toxic fumes if it burns. PVC cable should never be used in a plenum space because the toxic fumes are sent through the building from the heating and ventilation system.

Coaxial

The two types of coaxial cable mentioned in the objectives are RG-6 and RG-59. RG-6 cable commonly uses an F-type screw-on connector, and RG-59 normally uses a BNC twist-on connector, although both cable types can use either connector.

True or false? RG-6 cable is commonly used for cable television distribution and supports the transmission of both analog and digital data.

Answer: True. RG-6 supports both analog and digital data.

RG-59 supports analog or digital data, although it is susceptible to high-frequency losses, so it is not used for cable television transmissions. Cable TV companies often provide Internet access through the same cable used for television channels. RG-6 cable is often used for these connections. When customers subscribe to broadband Internet in addition to cable television, a splitter is used to send one output to televisions and another output to a cable modem for the Internet connection.

Optical Fibre Is Immune To EMI

Fibre optic cables are non-metallic... they transmit signals using pulses of light in glass threads! As a result, they are immune to Electro-Magnetic Interference and Radio Frequency Interference. In other terms, the integrity of signals is not affected by electrical noise in the environment.

In copper cables, the integrity of signals can be affected by electrical noise. This can also reduce speed of transmission as larger numbers of lost and/or corrupted data packets can lead to excessive levels of retransmission.

Attenuation loss can be as low as 0.2 dB/km in optical fibre cables, allowing transmission over long distances without the need for repeaters (than you will have with copper systems to ensure satisfactory performance over long distances with higher data rate).

Fibre connections isolate data from dangerous increases in ground potential, ground loops, and electrical EMI/RFI (radio-frequency interference). It also removes a potential security vulnerability, as data cannot be read from the magnetic field around the cable.

Fibre Optic Eliminates The Spark Hazard

As they don’t carry current, fibre cables can’t generate even the smallest spark. This is a considerable advantage in explosive environments such as chemical plant or oil refineries as it increases the safety of your installation. We will recommend this specific Fanless Intel Mini PC as it integrates 2 fibre optic GbE LAN ports, which will enable you to get a direct connexion to a fibre backbone.

Which type of media is immune to EMI?

What cable is immune to electromagnetic interference EMI?

Which of the following media types is the most prone to EMI electromagnetic interference )?

Are coaxial cables immune to EMI?