Knowledge Bank

8P8C

The 8 position 8 contact (8P8C) connector is a modular connector commonly used to terminate twisted pair and multi-conductor flat cable. These connectors are commonly used for Ethernet over twisted pair, registered jacks and other telephone applications. Also called RJ45

ANSI/TIA-568

It is a set of telecommunications standards from the Telecommunications Industry Association (TIA). The standards address commercial building cabling for telecommunications products and services.

ISO/IEC

The International Organization for Standardization (ISO) is an international standard-setting body composed of representatives from various national standards organizations. ISO has formed two joint committees with the International Electrotechnical Commission (IEC) to develop standards and terminology in the areas of electrical and electronic related technologies.

ANSI

American National Standards Institute

American Wire Gauge (AWG)

A standard system for designating wire diameter.

Attenuation

The decrease in magnitude of a signal as it travels through any transmitting medium, such as a cable.

Attenuation Constant

A rating for a cable or other transmitting medium, which is the relative rate of amplitude decrease of voltage or current in the direction of travel. It is measured in decibels per unit of length of cable.

ACR (Attenuation Crosstalk Ratio)

The difference between attenuation and crosstalk, measured in dB, at a given frequency. An Important characteristic in networking transmission to assure that signal sent down a twisted pair is stronger at the receiving end of the cable than are any interference signals imposed on that same pair by crosstalk from other pairs.

AXT (Alien Crosstalk)

AXT is interference caused by other cables routed close to the cable of interest as opposed to signals contained in the same cable.

Bandwidth

The difference between the upper and lower limits of a given band of frequencies. Expressed in Hertz.

Bend Radius

Radius of curvature that a fiber optic or metallic cable can bend without any adverse effects.

Bonded Cable

Round PVC insulated conductors that are placed side by side and chemically joined in a single plane.

Braid

Woven bare metallic or tinned copper wire used as shielding for wires and cables and as ground wire.

Balanced Line

In telecommunications and professional audio, a balanced line or balanced signal pair is a transmission line consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits.

Balun

Device for matching an unbalanced coaxial transmission line to a balanced two-wire system. Can also provide impedance transformation, as 30 ohm balanced to 75 ohm unbalanced.

Bandwidth

The difference between the upper and lower limits of a given band of frequencies expressed in Hertz.

Barrel

The portion(s) of a terminal or contact that is crimped.

Baud

Unit of data transmission speed meaning bits per second (500 baud - 500 bits per second).

Bend Loss

A form of increased attenuation caused by (a) having an optical fiber curved around a restrictive radius of curvature or (b) micro bends caused by minute distortions in the fiber imposed by externally induced perturbations.

Bend Radius

Radius of curvature that a fibre optic or metallic cable can bend without any adverse effects.

Bit

One binary digit

Boot

A form placed around wire termination of a multiple contact connector to hold the liquid potting compound before it hardens. Also a protective housing, usually made from a resilient material, that prevents moisture entry into a connector.

Buffer

A protective coating over an optical fibre.

Bunch Strand

Conductors twisted together with the same lay and direction without regard to geometric pattern.

Cable

An assembly of one or more conductors or fiber optic strands within a protective sheath.

CATV

Community Antenna Television

CCTV

Closed-circuit television

Cable

An assembly of one or more conductors or fiber optic strands within a protective sheath.

Cabling

The method by which a group of insulated conductors is mechanically assembled or twisted together.

Capacitance

The ability of a dielectric material between conductors to store electricity when a difference of potential exists between the conductors. The unit of measurement is the farad, which is the capacitance value that will store a charge of one coulomb when a one-volt potential difference exists between the conductors. In ac, one farad is the capacitance value which will permit one ampere of current when the voltage across the capacitor changes at a rate of one volt per second.

Capacitance Reactance

The opposition to alternating current due to the capacitance of a capacitor, cable, or circuit. It is measured in ohms and is equal to 1/6.28fC where f is the frequency in Hz and C is the capacitance in farads.

Capacitor

Two conducting surfaces separated by a dielectric material. The capacitance is determined by the area of the surfaces, type of dielectric, and spacing between the conducting surfaces.

Cat 5 (Category 5)

Category 5 cable, commonly referred to as Cat 5, is a twisted pair cable for computer networks. The cable standard provides performance of up to 100 MHz and is suitable for most varieties of Ethernet over twisted pair.

Cat 6 (Category 6)

A cable commonly referred to as Cat 6, is a standardized twisted pair cable for Ethernet and other network physical layers that is backward compatible with the Category 5/5e and Category 3 cable standards. The cable standard also specifies performance of up to 250 MHz compared to 100 MHz for Cat 5 and Cat 5eThe cable standard also specifies performance of up to 250 MHz compared to 100 MHz for Cat 5 and Cat 5e.

Cable Length

The Cable Length test verifies that the copper cable from the transmitter to receiver does not exceed the maximum recommended distance of 100 meters in a 10BASE-T/100BASE-TX/1000BASE-T network.

Cellular Polyethylene

Expanded or "foam" polyethylene, consists of individual closed cells of inert gas suspended in a polyethylene medium, resulting in a desirable reduction of the dielectric constant.

Circular Mil

A term used to define cross sectional area using an arithmetic short-cut in which the area of a round wire is taken as "diameter in mils (.001")" squared; hence, one circular mil is equal to pi/4 square mils.

Coaxial Cable

A cable consisting of two cylindrical conductors with a common axis or a cylindrical transmission line consisting of a conductor centred inside a metallic tube of shield, separated by a dielectric material, and covered by an insulating jacket.

Cladding

A low refractive index material that surrounds the core of an optical fiber causing the transmitted light to travel down the core and protects against surface contaminant scattering.

Concentric Stranding

A group of uninsulated wires twisted together and containing a center core with subsequent layers spirally wrapped around the core to form a single conductor.

Conductivity

The ability of a material to allow electrons to flow, measured by the current per unit of voltage applied. It is the reciprocal of resistivity.

Conductor

An uninsulated wire or combination of wires suitable for carrying electric current. Or, a material that offers low resistance to the flow of electrical current.

Cord

A very flexible insulated cable.

Composite Cable

A cable containing more that one gauge size or a variety of circuit types.

Connector

A coupling device that provides an electrical and mechanical connection or disconnection between two circuits.

Contact

The conducting part of a connector that acts with another such part to complete or break a circuit also known as terminals.

Contact Durability

Endurance measured by the number of insertion and withdrawal cycles that a connector withstands while remaining within its specified electrical and mechanical performance levels.

Contact Insertion Force

The amount of force required to insert a contact into the connector housing.

Continuity

A continuous path for the flow of current in an electrical circuit.

Crosstalk

In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, inductive, or conductive coupling from one circuit or channel to another.

Current, Alternating (AC)

An electric current that periodically reverses direction of electron flow. That rate at which a full cycle occurs in a given unit of time (generally a second) is called the frequency of the current.

Current, Direct (DC)

Electrical current whose electrons flow in one direction only. It may be constant or pulsating as long as its movement is in the same direction.

Current Loop

A two wire transmit/receive interface.

Data Center

A data center is a facility used to house computer systems and associated components, such as telecommunications and storage systems.

Decibel (dB)

One-tenth of a bel. It is equal to 10 times the logarithm of the power ratio, 20 times the log of the voltage ratio, or 20 times the log of the current ratio. One decibel is the amount by which the pressure of a pure sine wave of sound must be varied in order for the change to be detected by the average human ear. The decibel can express an actual level only when comparing with some definite reference level that is assumed to be zero dB.

Delay Line

A transmission line or equivalent device designed to delay a wave or signal for a specific length of time.

Delay Skew

The Delay Skew is used to find the difference in propagation delay between the fastest and slowest set of wire pairs over 100 mtr length.

Dielectric

Non-conducting barriers that protect individual conductors from accidental contact with other conductors (a "short circuit") and allow uninterrupted flow or current.

Dielectric

An insulating (nonconducting) medium. Non-conducting barriers that protect individual conductors from accidental contact with other conductors (a "short circuit") and allow uninterrupted flow or current.

Dielectric Breakdown

Any change in the properties of a dielectric that causes it to become conductive normally a catastrophic failure of insulation because of excessive voltage.

Dielectric Constant

Also called permittivity. The property of a dielectric which determines the amount of electrostatic energy that can be stored by the material when a given voltage is applied to it.

Dielectric Heating

The heating of an insulating material when placed in a ratio-frequency field, caused by internal losses during the rapid polarization reversal of molecules in the material.

Dielectric Loss

The power dissipated in a dielectric as the result of the friction produced by molecular motion when an alternating electric field is applied.

Digital Signal

An electrical signal which possesses two distinct states (on/off, positive/negative).

Distortion

Any undesired change in a wave form or signal.

Distribution Cable

In a CATV system, the transmission cable between the distribution amplifier and the drop cable.

Dispersion

The cause of bandwidth limitations in an optical fiber. Dispersion causes a broadening of input pulses along the length of the fiber. Two major types are (a) mode dispersion caused by differential optical path lengths in a multimode fiber, and (b) material dispersion caused by a differential delay of various wavelengths of light in a wave guide material.

Bend Loss

A form of increased attenuation caused by (a) having an optical fiber curved around a restrictive radius of curvature or (b) microbends caused by minute distortions in the fiber imposed by externally induced perturbations.

Drain Wire

In a cable the uninsulated wire laid over the component or components and used as a ground connection.

Drop Cable

In a CATV system, the transmission cable from the distribution cable to a dwelling.

ELFEXT (Equal level far end crosstalk)

ELFEXT measures the FEXT with attenuation compensation.

Far End Crosstalk (FEXT)

FEXT measures the interference between two pairs of a cable measured at the far end of the cable with respect to the interfering transmitter.

Gain

The increase of voltage, current, or power over a standard or previous reading. Usually expressed in decibels.

Gauge

A term used to denote the physical size of a wire.

Gigahertz (GHz)

A unit of frequency equal to one billion hertz.

GND

Abbreviation for Ground.

Ground

An electrical connection to the earth, generally through a ground rod. Also a common return to a point of zero potential such as metal chassis in radio equipment.

Graded-Index

A type of optical fiber in which the refractive index of the core is in the form of a parabolic curve, decreasing toward cladding. This type of fiber provides high bandwidth capabilities.

Ground Loop

A completed circuit between shielded pairs of a multiple pair created by random contact between shields.

Ground Potential

A circuit, terminal, or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system.

Headroom

The amount by which a cable ACR exceeds 10 dB. The TIA/EIA 568B standard states a minimum of 10 dB of ACR is required for Category 5 certification.

High Frequency

The band from 3 to 30 MHz in the radio spectrum, as designated by the Federal Communications Commission.

Hertz (Hz)

The unit of frequency, one cycle per second.

HF

High Frequency.

IF

Abbreviation for Intermediate Frequency.

Impedance

The total opposition a circuit, cable, or component offers to alternating current flow. It includes both resistance and reactance and is generally expressed in ohms and designated by the symbol z.

Impedance Characteristic

In a transmission cable of infinite length, the ratio of the applied voltage to the resultant current at the point the voltage is applied. Or the impedance which makes a transmission cable seem infinitely long, when connected across the cable's output terminals.

Impedance High

Generally, the area of 25,000 ohms or higher.

Impedance Low

Generally, the area of 1 through 600 ohms.

Impedance Match

A condition whereby the impedance of a particular circuit cable or component is the same as the impedance of the circuit, cable, or device to which it is connected.

Impedance Matching Sub

A section of transmission line or pair of conductors cut to match the impedance of a load. Also called matching sub.

Inductance

A property of a conductor or circuit which resists a change in current. It causes current changes to lag behind voltage changes and is measured in henrys.

Induction

The phenomenon of a voltage, magnetic field, or electrostatic charge being produced in an object by lines of force from the source of such fields.

Induction Heating

Heating a conducting material by placing it in a rapidly changing magnetic field. The changing field induces electric currents in the material and I2Rlosses account for the resultant heat.

Injection Laser Diode

Sometimes called the semiconductor diode. A laser in which lasing occurs at the junction of n-type and p-type semiconductor material.

Input

A signal (or power) which is applied to a piece of electric apparatus or the terminals on the apparatus to which a signal or power is applied.

Hum

A term used to describe the 60- or 120 cycle per second noise present in the sound of some communications equipment. Usually hum is the result of undesired coupling to a 60 cycle source or to the defective filtering of 120 cycle ripple output of a rectifier.

Impedance

The total opposition a circuit, cable, or component offers to alternating current flow. It includes both resistance and reactance and is generally expressed in ohms and designated by the symbol z.

Insertion Loss

A measure of the attenuation of a device by determining the output of a system before and after the device is inserted into the system. Insertion loss increases with distance and frequency.

Insulation

A material having good dielectric properties which is used to separate close electrical components, such as cable conductors and circuit components.

Insulation Displacement Technology (IDT)

A wire termination technique in which an insulated wire is pressed into a terminal slot smaller that the conductor diameter, displacing the insulation, and forming an electrical contact between the terminal and the conductor.

Insulation Stress

The molecule separation pressure caused by a potential difference across an insulator. The practical stress on insulation is expressed in volts per mil.

Interface

The region where two systems or a major and a minor system meet and interact with each other.

Interference

Disturbances of an electrical or electromagnetic nature that introduces undesirable responses into other electronic equipment.

Intermediate Frequency

A frequency to which a signal is converted for ease of handling.

Jacket

Pertaining to wire and cable, the outer protective covering (may also provide additional insulation).

KEV

1000 electron volts.

KPSI

Tensile strength in thousands of pounds per square inch.

KV

Abbreviation for Kilovolt (1000 volts).

KVA

Abbreviation for Kilovolt ampere.

KW

Abbreviation for Kilowatt.

Laser

A coherent source of light with a narrow beam and a narrow spectrum bandwidth (about 2nm).

Lay

Pertaining to wire and cable, the axial distance required for one cabled conductor or conductor strand to complete one revolution about the axis around which it is cabled.

Lay Direction

The direction of the progressing spiral twist in a cable while looking along the axis of the cable away from the observer. The lay direction can be either "left" or "right".

Leakage

the undesirable passage of current over the surface of, or through, an insulator.

LF

Abbreviation for Low Frequency.

Life Cycle

A test to determine the length of time before failure in a controlled, usually accelerated, environment.

Light Emitting Diode (LED Source)

A semiconductor device that emits incoherent light formed by the P-N junction. Light intensity is roughly proportional to electrical current flow.

Line Drop

A voltage loss occurring between any two point in a power or transmission line. Such loss, or drop, is due to the resistance, reactance, or leakage of the line.

Line Equalizer

A reactance (inductance and/or capacitance) connected in series with a transmission line to alter the frequency-response characteristics of the line.

Line Level

Refers to the output voltage level of a piece of electronic equipment. Usually expressed in decibels (e.g.. 0 dBv).

Line Voltage

The value of the potential existing on supply or power line.

Load

A device that consumes power from a source and uses that power to perform a function.

Loaded Line

A transmission line that has lumped elements (inductance or capacitance) added at uniformly spaced intervals. Loading is used to provide a given set of characteristics to a transmission line.

Long-wire Antenna

Any conductor length in excess of one-half of a wavelength. In a residential television installation, a horizontal run or unshielded lead-in will act as a long-wire antenna and introduce additional signal on top of the regular antenna signal causing ghosts.

Loss

The portion of energy applied to a system that is dissipated and performs no useful work.

Low Frequency

A band of frequencies extending from 30 to 300 kHz in the radio spectrum, designated by the Federal Communications Commission.

NEXT (Near-End Crosstalk)

NEXT is a measure of the ability of a cable to reject crosstalk, so the higher the NEXT value, the greater the rejection of crosstalk at the local connection. It is generally expressed in decibels per feet or decibels per 1000 feet and varies with the frequency of transmission.

PSNEXT (Power Sum Near End Crosstalk)

PSNEXT is a NEXT measurement which includes the sum of crosstalk contributions from all adjacent pairs as an algebraic sum of the NEXT of the three wire pairs as they affect the fourth pair in a four-pair cable Power Sum ELFEXT (PSELFEXT)

Power Sum ACR (PSACR)

Power Sum ACR (PSACR) done in the same way as ACR, but using the PSNEXT value in the calculation rather than NEXT.

Propagation Delay

The Propagation Delay is the time it takes for the signal to be sent from one end and received by the other end.

Return Loss

Return Loss is the measurement (in dB) of the amount of signal that is reflected back toward the transmitter. The reflection of the signal is caused by the variations of impedance in the connectors and cable and is usually attributed to a poorly terminated wire.

Structured cabling

It is a office or building or campus cabling infrastructure that consists of a number of standardized smaller elements (hence structured) called subsystems

Twisted Pair

Twisted pair cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility.

Wiremap

The wiremap test is used to identify physical errors of the installation; proper pin termination at each end, shorts between any two or more wires, continuity to the remote end, split pairs, crossed pairs, reversed pairs, and any other mis-wiring.