FIBER OPTIC CENTER GLOSSARY
There are 56 names in this directory beginning with the letter V.
A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test (formerly designated FR-1).
A glue joint in which one side is thicker than the other as a result of poor machining or uneven application of pressure.
A press designed for laminating or veneering in which the panel is placed inside of a flexible bag connected to a vacuum pump.
Any void between the insulated conductors of a cable or between a cable core and its covering. See also interstice.
A tap system for 10BASE5 systems that does not require cutting and splicing the cable. This system uses a sharp pin that pierces the insulator and contacts the center conductor of the thick 10BASE5 cable.
Vapor Axial Deposition (VAD)
A method of optical fiber manufacturing where a the end of a bait rod is used to grow a preform of oxidized soot.
Vapor Phase Soldering
A soldering process that uses the latent heat of vaporization of a liquid as its energy source.
Variable optical attenuator (VOA)
A fiber system attenuator with adjustable attenuation; often used to test system performance by increasing attenuation until the system fails.
Vector-Sum Excitation Linear Predictor (VSELP)
VSELP refers to a technique that digitally codes and significantly compresses voice signals, increasing radio channel capacity by reducing the amount of information that needs to be transmitted.
Velocity of Light
The velocity of light is 300.000 km/s in vacuum. In a medium it depends on the refractive index and the wavelength.
Velocity of Propagation (VP)
The speed of an electrical signal down a length of cable compared to speed in free space expressed as a percent. It is the reciprocal of the square root of the dielectric constant of the cable insulation.
Vertical-cavity surface-emitting laser (VCSEL)
A high-speed, low-cost laser operating at the 850-nm wavelength that is used for applications such as Gigabit Ethernet where the modulation rate of current LEDs is insufficient.
Very High Frequency (VHF)
A Federal Communications Commission designation for the band from 30 to 300 MHz in the radio spectrum.
Real time communications via video between two or more users at separate locations.
A rack mountable connector with a recessed female receptacle and an outer concentric female receptacle.
A rack mounted device used to manually route video signal. Usually consists of a panel containing several video jacks of normal or non-normal configurations.
Video on demand
A video service that allows users to select a program and begin viewing it at any time. It can allow VCR-like playback control.
Video over IP
The transmission of video programming over an IP network. If the source programming is digital, it is encapsulated into IP packets. Otherwise, it is digitized and usually compressed. It can then be converted back to analog by equipment at the customer�s premises or viewed on a digital television.
Video Pair Cable
A transmission cable containing low-loss pairs with an impedance of 125 ohms. Used for TV pick ups, closed circuit TV, telephone carrier circuits, etc.
Video Patch Cord
A flexible coaxial cable with Video Plugs on both ends, used to connect two Video Jacks.
A cable mounted connector with a recessed make plug and an outer concentric housing, The Video Plug is designed to mate with a Video Jack.
Measure of fluid thickness or resistance to flow expressed in poise or centipoise. Water is one centipoise. Thicker fluids have higher numbers. 30 weight oil has a viscosity of 400 centipoise (cps).
Electromagnetic wavelengths, ranging from 380-770 nm, that are visible to the human eye.
Visual fault locator
A device that couples visible light into the fiber to allow visual tracing and testing of continuity. Some are bright enough to allow finding breaks in fiber through the cable jacket.
DuPont trademark for a series of fluoroelastomers based on the copolymer of unylidene fluoride and hexafluoropropylene.
VLF (Very Low Frequency)
The spectrum extending from 10 kHz to 30 kHz, as designated by the Federal Communications Commission (FCC).
A speech-compression device used to convert speech into digital signals. Vocoders are usually characterized by the bandwidth required, such as 8 or 13 kb/s.
Any of the frequencies that are audible to the human ear. For telephone transmission the range is generally from 300 to 3,400 Hz.
A designation for a facility capable of carrying signals with a frequency range of 200 - 4000 Hertz.
Volatile organic compound (VOC)
Any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, ammonium carbonate, and excluding any �exempt compound� which participates in atmospheric photochemical reactions. The VOC is a measured or calculated number that reflects the amount of volatile organic material that is released from a product as it dries.
Unit of electromotive force. It is the difference of potential required to make a current of one ampere flow through a resistance of one ohm.
The term most often used to designate electric pressure that exists between two points and is capable of producing a flow of current when a closed circuit is connected between the two points.
Test to determine voltage at which insulation fails at a given temperature and time.
(1) The highest voltage that can be continuously applied to a wire in conformance with the standard or specification; ( 2) The system voltage printed on the wire or cable.
Voltage Standing Wave Ratio (VSWR)
1)The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of a mismatched radio frequency transmission line.��2)The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of a mis-matched radio frequency transmission line.
The electrical resistance between opposite faces of a one cm. cube of insulating material, commonly expressed in ohms-centimeter.
A chemical reaction in which the physical properties of an elastomer are changed by reacting it with sulfur or other crosslinking agents.