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L

L - Symbol for inductance.


Lacing and harnessing - A method of grouping wires by securing them in bundles of designated patterns.


Lacquer - A liquid resin or compound applied to textile braid to prevent fraying, moisture absorption, etc.


Lag - The image retention of an object after the object has been scanned. Sometimes, it causes smearing effect.


Lambda - Individual wavelengths as a result of DWDM.


Laminated tape - A tape consisting of two or more layers of different materials bonded together.


LAN (local area network) - A user-owned, user-operated, high-volume data transmission facility connecting a number of communicating devices within a single building or campus of buildings.


Laser (light amplification by stimulated emission of radiation) - A device that produces coherent light with a narrow range of wavelengths


Laser diode - A semiconductor diode that emits coherent light.


Laser-optimized multimode fiber (LOMMF) - Laser-optimized 50-micron multimode fiber. Uses an enhanced bandwidth capable of supporting 10 Gigabit Ethernet at 850 nm using VCSEL technology. This is also a restricted mode launch, so it avoids the pulse spreading due to DMD. Also referred to as OM3-grade fiber.


LATA (local access and transport area) - One of 161 USA geographical subdivisions used to define local as opposed to long distance telephone service.


Launch angle - The angle between the radiation vector and the axis of an optical fiber.


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 twist in the cable as indicated by the top strands while looking along the axis of the cable away from the observer. Described as right hand or left hand.


Layer - Consecutive turns of a coil lying in a single plane.


L Band - The band of frequencies between 390 and 1,550 megahertz.


Lbf - Pound force.


LCL (longitudinal conversion loss) - A measurement of balance in a cable. Measured by applying a common-mode signal to the cable and measuring the differential at the near end.


LCTL (longitudinal conversion transfer loss) - Measured by applying a common-mode signal to a cable and measuring it at the far end of the cable. (Same as LCL but measures at far end.)


LDAP (Lightweight Directory Access Protocol) - An Internet protocol that e-mail programs use to look up contact information from a server.


Leaching and non-leaching - In a leaching wire the plasticizer will migrate when exposed to heat. A non-leaching wire will retain its plasticizer under extreme temperature conditions and remain flexible after baking.


Lead - A wire, with or without terminals, that connects two points in a circuit.


Lead cured - A cable that is cured or vulcanized in a metallic lead mold.


Lead-in - The conductor that provides the path for RF energy between the antenna and the radio and television receiver.


Leakage current - An undesirable flow of current through or over the surface of an insulating material.


Leakage distance - The shortest distance along an insulation surface between conductors.


Leap - Cisco proprietary wireless security protocol.


Leased line - A line intended for data communications that is leased from a telephone company. Leased lines are conditioned to a variety of specifications to keep impairments at a minimum. See also DIAL-UP.


LED (light-emitting diode) - Semiconductor device, much more reliable than an incandescent lamp, used for status display purposes in electronics equipment.


Length of lay - The axial length of one turn of the helix of a wire or member.


Level - A measure of the difference between a quantity or value and an established reference.


Level control - Main iris control. Used to set the auto iris circuit to a video level desired by the user. After setup, the circuit will adjust the iris to maintain this video level in changing lighting conditions. Turning the control toward high will open the iris, toward low will close the iris.


LF (low frequency) - A band of frequencies extending from 30 to 300 kHz in the radio spectrum, designated by the Federal Communications Commission.


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


Lightning ground cable - A specially stranded single conductor cable connecting lightning rods (air terminals) protecting buildings to adequate ground, such as grounding rods.


Light source - An object capable of emitting light. In fiber optics, the light source is normally a LED or a laser.


Light wave - The term used to describe the signal providing communication over optical fiber.


Limits of error - The maximum deviation (in degrees or percent) of the indicated temperature of a thermocouple from the actual temperature.


Limpness - The ability of a cable to lay flat or conform to a surface as with portable or microphone cables.


Line balance - The degree to which the conductors of a cable are alike in their electrical characteristics with respect to each other, to other conductors and to ground.


Line driver - A signal converter which conditions the digital signal transmitted by an RS-232 interface to ensure reliable transmission beyond the 50 ft. RS-232 limit and often up to several miles; it is a baseband transmission device.


Line drop - A voltage loss occurring between any two points in a power transmission line. Such loss, or drop, is due to the resistance, 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 fault - A fault such as an open circuit, short circuit or ground in an electrical line or circuit.


Line hit - An electrical surge, dip or transient that causes spurious signals in a circuit.


Line level - The level of a signal at a certain point on a transmission line. Usually expressed in decibels.


Line lock - To synchronize the field sync pulses, of an AC powered camera, to the frequency of the voltage input (line voltage).


Line loss - A total of the various energy losses occurring in a transmission line.


Line noise - Sustained high-frequency voltage excursions due to static electricity or RF interference from various sources.


Line turnaround - The reversal of transmission on a half-duplex circuit.


Line unbalance - Unequal loads on the phase lines of a multi-phase feeder.


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


Linearity - The property of a transmission medium or of an item of equipment that allows it to carry signals without introducing distortion.


Line voltage - The value of the potential existing on a supply or power line.


Link - Communications circuit or transmission path connecting two points.


Litz wire - Very fine, e.g. #44 AWG bare copper, each strand is enamel insulated. Used for low inductance coil windings.


LLC (logical link control) - Defined by IEEE 802.2, it is the upper half of the second layer of the OSI model. It interfaces with the MAC and the network layer.


LLDPE (linear low-density polyethylene) - Usually used as cable jacketing.


Load - A device that consumes or converts the power delivered by another device.


Load cell cable - Small multi-conductor shielded cables for connecting load cells with instruments in electronic strain gauges. It’s also used for weighing and force measurement applications.


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.


Loading - See LOADED LINE.


Lobe - In the multi-use communication loop, one of two separately driven sections of a loop. In the local area network, the section of cable that attaches a device to a wiring concentrator (access unit).


Loc-trac - Alpha’s registered trademark for a zipper tubing closure track that does not require any sealants to keep it closed, even during extreme flexing.


Local area network (LAN) - A network that is located in a localized geographical area (e.g., an office, building, complex of buildings or campus) and whose communications technology provides a high-bandwidth, low-cost medium to which many nodes can be connected.


Local exchange, local central office - The exchange or central office in which the subscriber’s lines terminate.


Local line, local loop - A channel connecting the subscriber’s equipment to the line terminating equipment in the central office; usually a metallic circuit (either 2-wire or 4-wire).


LOMMF (laser-optimized multimode fiber) - Laser-optimized 50-micron multimode fiber, sometimes referred to as next-generation fiber, has enhanced bandwidth capable of supporting 10 Gigabit Ethernet at 850 nm using VCSEL technology. This is also a restricted mode launch so it avoids the pulse spreading due to DMD. Also called OM3.


Long-haul network - A network most frequently used to transfer data over distances from several thousand feet to several thousand miles. These networks can use the international telephone network to transmit messages over most or part of these distances.


Logging cable - Usually FEP/Tefzel self-supporting instrumentation cable. Generally dropped through borings in subsurface mining or well applications.


LCL (longitudinal conversion loss) - A measurement of balance in a cable. Measured by applying a common- mode signal to the cable and measuring the differential at the near end.


LCTL (longitudinal conversion transfer loss) - Measured by applying a common-mode signal to a cable and measuring it at the far end of the cable. (Same as LCL but measures at far end.)


Longitudinal shield - A tape shield, flat or corrugated, applied longitudinally with the axis of the cable.


Longitudinal shrinkage - A term generally applied to shrink products denoting the axial length lost through heating in order to obtain the recovered diameter.


Longitudinal wrap - Tape applied longitudinally with the axis of the core being covered.


Long wall machine - A mining machine used to undercut coal.


Loop - A closed circuit unidirectional signal path connecting input-output devices to the system.


Loop resistance - The total resistance of two conductors measured round trip from one end. Commonly used term in the thermocouple industry.


Loop test - A long line test where a good line is connected to a faulty line to form a loop in which measurements will locate the fault.


Looping - A term indicating that a high-impedance device has been permanently connected in a parallel to a video source.


Loopback, loopback test - Type of diagnostic test in which the transmitted signal is returned to the sending device, after passing through all of or a portion of ad at a communications link or network; this allows a technician (or built-in diagnostic circuit) to compare the returned signal with the transmitted signal. This comparison provides the basis for evaluating the operational status of the equipment and the transmission paths through which the signal traveled.


Loss – (1) The portion of energy applied to a system that is dissipated and performs no useful work. (2) Reduction in signal strength, expressed in decibels; also attenuation; opposite of GAIN.


Loss factor - The power factor times the dielectric constant.


Low bond insulation - An insulation that exhibits small bond strength to the conductors.


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


Low-loss dielectric - An insulating material that has a relatively low dielectric loss, such as polyethylene or Teflon. Dielectrics with tan δ below 0.01 (approximately) are considered low-loss materials.


Low-noise cable - A cable specially constructed to eliminate spurious electrical disturbances caused by capacitance changes or self-generated noise induced by either physical movement or adjacent circuitry.


Low tension - Low voltage, as applied to ignition cable.


Low voltage – (1) In the National Electrical Code, an electromotive force rated nominal 24 volts, nominal or less, supplied from a transformer, converter or battery. (2) In power system voltage ratings, a class of nominal system voltages 1,000 or less.


LPF - Low pass filter. A filter that greatly attenuates signals of higher than a specified frequency, but passes with minimal attenuation all signals lower in frequency.


LS (LOW SMOKE) - An optional rating for UL Listed cable types that also pass low smoke requirements contained in UL Standards. A cable that meets the requirements can be marked “LS.”


LSZH - Abbreviation for low smoke, zero halogen. Sometimes also written LS0H (0=zero).


Lumen - A unit of measurement for light output.


Lux - A unit of measuring the intensity of light (1 FC = 10 lux).


LV - Low voltage.


LWAPP - Light Weight Access Point Protocol.