Glossary of Common Fiber Optic Terms: R - Z

Common Fiber Terms A-E

Common Fiber Terms F-L

Common Fiber Terms M-P

Common Fiber Terms: R-Z

R:

Rack Panels
Framework or boxes to hold patch panels and other cable management devices.

Rayleigh Scattering
Scattering by refractive index fluctuations (inhomogeneities in material density or composition) that are small with respect to wavelength. Referred to as backscatter.

Receiver
A device which detects an optical signal, converts into an electronic form, then processes it further so it can be used by electronic equipment. From the standpoints of components, it can be viewed as a combination of detector and single processing electronics.

Receiver I.C.
Consists of photodiode which converts the signal to an elec­tronic one which feeds into an amplifier bringing the signal back to a level.


Receiver Sensitivity (expressed in dBm)
This tells how much optical power the photo-detector must receive to achieve a specified base band per­formance, such as a specified bit-error rate of signal-to-noise ratio.

Reflection
The abrupt change in direction of a light beam at an interface between two dissimilar media so that the light beam returns into the media from which it originated.

Refraction
The bending of a beam of light at an interface between two dissimilar media or in a medium whose refractive index is a continuous function of position (graded index medium).

Repeater (fiber optic)
A device which detects a weak signal in a fiber optic communication system, amplifies it, cleans it up, and retransmits it in optical form. Also known as a regenerator.

Return Loss
Expressed in negative value (-dB), this refers to the amount of back reflection. The lower the dB value, the better the connector and polish finish on the connector ferrule.

RF (Radio Frequency)
The frequency spectrum from 15kHz to 100GHz.

RFI (Radio Frequency Interference)
Electromagnetic radiation in the radio frequency spectrum fiom 15kHz to 100GHz. The best shielding material against RFI is copper and aluminum alloys. The term "EMI" should not be used in place of RFI since shielding materials for the entire electromagnetic frequency spectrum are not available.

Riser
Pathways for indoor cables that pass between floors. It is normally a vertical shaft or space. Also a fire-code rating for indoor cable.
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S:

Scattering
A property of glass that causes light to deflect from the fiber and contributes to optical attenuation.

Scribe Tool
Also called a cutting tool or breaking tool, consisting of cut­ting blade usually made from tungsten carbide or a diamond. Application is to break/scribe fiber @90? without lips or hackles or angular irregularities.

Selco Lenses
Segments of optical fibers specially designed to function as lenses.

Semi-Graded Index
An optical fiber with refractive index profile interme­diate between step-index and graded index. Strictly speaking, this might be considered a type of graded-index fiber with refractive index profile some­what steeper than normal.

Signal-to-Noise Ratio
The ratio of the power of the signal to that of background noise, usually measured in decibels. This is a common measure of the quality of analog electronics or transmission systems.

Simplex Cable
A single cable structure with a single fiber.

Singlemode
One type of low-loss optical waveguide with a very small Core (2-9 microns). It requires a laser source for input signals becauuse of the very small entrance aperture. The core diameter of a single-mode is designed to accept a one mode(wavelength) from the light source .

Skew Rate
A ray somethimes refered to as a dominant ray, that never intersects the axis of fiber while being internally reflected (in contrast with a meridional ray).

Splice
A permanent junction between two optical-fiber ends.

Splice Housing (Fiber Optics)
A housing designed to protect a splice in an optical fiber from damage by the environment, such as from the applica­tion of stress on the fiber. It also can seal the splice fiom environmental agents such as water which could cause it to deteriorate.

Star Coupler (fiber optics)
A coupler in which many fibers are brought together to a single optical element in which their signals are mixed. The mixed signals are then transmitted back through all the fibers. The name comes from the geometric arrangement

Step-Index
An optical fiber in which there is a discontinuous (step-function) change in refractive index at the boundary between fiber core and cladding. Such fibers have a large numerical aperture (light accepting angle), and are simple to connect. but have lower bandwidth than other types of optical fibers.

Stripper
Mechanical tool used to remove buffer coatings from fibers.

STTL
Standard TTL (see TTL)

Swage
To displace metal by pressure.

Switch (fiber optics)
A device for rerouting signals from one optical fiber into others.
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T:

Tap (fiber optic)
A coupler in which part of the light carried by one fiber is split off and inserted into another fiber, essentially the same as a Tee coupler.

Tee Coupler (fiber optic)
A fiber optic coupler in which three fiber ends are joined together, and a signal transmitted from one fiber is split between the other two. A conceptual drawing looks like the letter T, which accounts for the name.

Telecommunications Closet (TC)
An enclosed space for housing telecommunications equipment, cable terminations, and cross-connects. The closet is the recognized cross-connect between the backbone and horizontal cabling.

Termination tools
Tools used in preparing optical fibers for spliciug and/or installation of connectors.

Tight Buffered Cable
a protective coating extruded tightly over fiber for mechanical and environmental protection. The coating material is either nylon or PVC. This buffering offers excellent physical and flexing properties, but higher micro-bending sensitivity.

Time-Division multiplexing
A digital technique for combining two or more signals into a single stream of data by interleaving bits from each signal. Bit one might be from signal one, bit two from signal two, etc.

Total Internal Reflection
The total reflection that occurs when light strikes an interface at angles of incidence greater than the critical angle.

Transmitter (fiber optics)
A light source (LED or diode laser) which is combined with electronic circuitry to drive it. A transmitter operates directly from the signal generated by other electronic equipment to produce the drive current needed for LED or diode laser.
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W:

Wavelength-Division Multiplexing
Combination of two or more signals so they can be transmitted over a common optical path, usually over a single fiber; by a technique in which the signals are generated by light sources having different wavelengths. For example, one signal might be transmitted at 850 nanometers and a second at 1300 nanometers.

WDM
Wave Division Multiplexing. Multiplexing is done by combining different wavelengths over one optical fiber simultaneously. Each wavelength is capable of carrying a certain amount of information.

White Light
A mixture of colors of visible light that appears white to the eye. In theory, a mixture of three colors is sufficient to product white light.
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Z:

Zero-Dispersion Wavelength
Wavelength at which the chromatic dispersion of an optical fiber is zero. Occurs when waveguide dispersion cancels out material dispersion.

Glossary of Common Fiber Optic Terms: M - P

Common Fiber Terms A-E

Common Fiber Terms F-L

Common Fiber Terms: M-P

M:

Macrobending
In an optical fiber, all macro deviations of the axis from a straight line.

Material Dispersion
The dispersion associated with a non-monochromatic light source due to the wavelength dependence of the refractive index of a material or of the light velocity in this material.

Mating Sleeve
A mechanical media termination device designed to align and join fiber optic connectors of the same type. Often referred to as a coupling, bulkhead, or interconnect sleeve.

Mechanical Splicing
Joining two fibers together by permanent or temporary mechanical means (vs. fusion splicing or connectors)

Megahertz (MHz)
A unit of frequency that is equal to one million cycles per second.

Meridional Ray
A ray that passes through the axis of a fiber while being internally reflected (in contrast with a skew ray) and is confined to a single plane.

Microbending Loss
In an optical fiber, loss caused by sharp curvatures involving local axial displacements of a few micrometers and spatial wavelengths of a few millimeters. Such bends may result from fiber coating, cabling, packaging, installation, etc.

Micron
A unit of length equal to one-millionth (10 E-6) of a meter (same as a micrometer).

Modal Dispersion
Pulse spreading due to multiple light rays traveling different distances and speeds through an optical fiber.

Mode
A stable condition of oscillation in a laser. A laser can operate in one mode (singlemode) or in many modes (multimode). The theoretical underpinnings are extremely complex; the main practical implications are in beam quality.

Mode Changing
In a optical fiber, the exchange of power among modes.

Mode Conditioning Patchcord
a duplex multimode cord that has a small length of singlemode fiber at the start of the transmission leg. The basic principle behind the cord is that you launch your laser into the small section of single mode fiber. The other end of the singlemode fiber is cou­pled to multimode section of the cable with the core offset from the center of the multimode fiber. The laser light thus misses the "dip" and this new launch condition more closely mimics a standard LED launch. The bonus is that you still retain the speed advantages of using a laser.

Mode Filter
A device to remove high order modes to simulate equilibrium mode distribution in a short length of optical fiber.

Mode Scrambler
A device for inducing mode coupling in an optical fiber.

Modulation
Coding of information onto the carrier frequency. This includes amplitude, frequency, or phase modulation techniques.

Monomode
See Singlemode

Multifiber Cable
In general usage, a fiber optic cable which containsmany fibers which transmit signals independently and are housed in separate substructures within the cable or otherwise isolated from one another. This term is usually not applied to bundles of fibers which together transmit single signal.

Multimode
An optical waveguide with a relatively much larger core (commonly 50 to 62.5 micron) than the singlemode waveguide core (2 to 9 microns) and which permits approximately 1000 modes to propagate through the core compared to only one mode through a singlemode fiber.

Multiplexer
A device which combines two or more separate signals for transmission through a single fiber. Optical multiplexers combine signals at different wavelengths. Electronic multiplexers combine signals electronically before being converted into optical form.
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N:

Nanometer
One-Billionth of a meter (10 E-9) (same as a millimicrometer).

Non-Silica Glasses
A glass in which the primary constituent is a material other than silica (silicon dioxide). The term is sometimes applied to mean non-oxide glasses, those which do not contain oxide compounds. In fiber optics, some of these materials are used for fibers transmitting mid-infrared wavelengths.

Numerical Aperture
NA The numerical aperture of an optical fiber defines a characteristic of the fiber in terms of it's acceptance of light. The "degree of openess", "light gathering ability" and "acceptance cone" are all terms describing this characteristic.
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O:

OFNP
Optical Fiber, Non-conductive, Plenum rated.

OFNR
Optical Fiber, Non-conductive, Riser rated.

OM1 Fiber Classification (FDDI)
OM1 is legacy (FDDI) grade fiber originally designed for use with LEDs and tend to be 62.5/125 types.  OFL Bandwidth (LED) 850/1300nm (MHz.km) is 200 / 500.  

OM2 Fiber Classification (50/125)
OM2 fibers enable maintenance and extension to existing 50/125 cabling.  OFL Bandwidth (LED) 850/1300nm (MHz.km) is 500 / 500

OM3 Fiber Classification (10Gb/s)
OM3 fibers can support 10 Gb/s over 300 meters and are recommended for all new network builds for link distances up to 300 meters. OFL Bandwidth (LED) 850/1300nm (MHz.km) is 1500 / 500, and Effective Laser Launch Bandwidth at 850nm is 2000 mhz.km.  

Optical Attenuation Meter (Attenuator)
Device which measures the loss or Attenuation of an optical fiber, fiber optic cable, or a fiber optic system. Measurements generally are made in decibels.

Optical Break
The breaking of an optical fiber in such a way which predictably produces flattened surfaces that are perpendicular to the longitudinal axis of the fiber. Sometimes referred to as a mirror-like surface across the entire end surface.

Optical Return Loss (ORL)
a reflection that travels down the fiber back to the source. In high speed systems this is undesirable because it can interfere with the transmission. Also referred to as “back reflection”.

Optical Time Domain Refectometer (OTDR)
A method for characterizing a fiber via an optical pulse transmitted through the fiber. The resulting backscatter and reflections are measured as a function of time. The OTDR is useful in measuring attenuation, in distance and identification of defects and other losses.

Output Power (LED)
Radiant power expressed in watts.
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P:

Patch Panel
Flat strip of material with adapters for interconnections. Generally 6, 8, or 12 per panel. See Rack Panels

Patchcord
A length of cable with connectors at both ends. Also known as jumpers.

PE
Abbreviation used to denote polyethylene. A type of plastic material used for outside plant cable jackets.

Photodiode
A diode designed to produce photocurrent by absorbing light. Photodiodes are used for the detection of optical power and for the conversion of optical power into electrical power.

Pigtail
A short length of optical fiber with one connector on one end and no connector on the other end.

Pin Photodiode
A semiconductor diode light detector in which a region of intrinsic silicon separates the p and n materials. It offers particularly fast response and is often used in optic systems.

Plastic Clad SiIica (PCS)
A step index optical fiber in which a silica core is covered by a transparent plastic cladding of lower refractive index that of the core. The plastic cladding is usually a soft material, although hard-clad versions have recently been introduced. Offers good radiation resistance.

Plastic Fibers
Optical fibers in which both core and cladding are made of plastic material. Typically their transmission is much poorer than that of glass fibers, and their lowest losses are in the visible region.

Plenum
An air-handling space such as that found above drop-ceiling tiles or in raised floors. Also, a fire code rating for indoor cable.

Polarization-Maintaining Fiber
A singlemode optical fiber which maintains the polarization of the light which entered it, normally by including some birefringence within the fiber itself. Normal singlemode fibers, and all other types, allow polarization to be scrambled in light transmitted through them.

Polishing
A step in the connectorization process that creates a flat even surface on the ferrule face. Quality is measured in terms of back reflection reduction. Also referred to as “finish”

Polyethylene (PE)
A type of plastic material used for outside plant cable jackets.

Polyvinyl-chloride (PVC)
A type of plastic material used for cable jacketing. Typically used in flame-retardant cables.

Pulse Dispersion (pulse spreading)
The separation or spreading of the input characteristics of the optical signal that appears along the length of the optical fiber and limits the useful transmission bandwidth of the fiber. Expressed in time and distance a nanoseconds per kilometer. Three basic mechanisms for dispersion are the material effect, the waveguide effect, and the multimode effect.

Pulse Suppressor
A launching fiber used to take up the unmeasurable beginning (dead zone) of an OTDR.

PVC
Abbreviation used to denote polyvinyl-chloride. A type of plastic material used for cable jacketing. Typically used in flame-retardant cables.

PVDF
Abbreviation used to denote polyvinyldiflouride. A type of material used for cable jacketing. Often used in plenum-rated cables.

Common Fiber Terms R-Z

Glossary of Common Fiber Optic Terms: F - L

Common Fiber Terms A-E

Common Fiber Terms: F-L

F:

Fan-out
A multi-fiber cable constructed in a tight buffered tube design. At a termination point, cable fibers must be separated from the cable to their separate connection positions.

Ferrule
A component of fiber optic connections that holds a fiber in place and aids in it's alignment. It is the protruding portion of the connector, made of Ceramic, Stainless Steel, or Polymer, and is polished during the connection process to form a smooth finish.

Fiber Buffer
Material used to protect an optical fiber or cable from physical damage. providing mechanical isolation or protection. Fabrication techniques include both tight jacket, or loose tube buffering, as well as multiple buffer layers.

Fiber Optic Cable
A sub-assembly made up of several optical fibers incorporated into an assembly of organic materials arranged for providing the necessary tensile strength, external protection, and handling properties comparable to those of equivalent diameter coaxial cables.

Fiber Optics
The technique of conveying light or images through a particular configuration of glass or plastic fibers. Fiber optics can be categorized roughly into three groups: incoherent, coherent and specialties.

   1. Incoherent fiber optics will transmit light|like a pipe will water|but not an image.
   2. Coherent fiber optics can transmit an image through the perfectly aligned small (12 micron) clad optical fibers (image carrying).
   3. Specialty fiber optics combines some aspects of a and b.

Fiber Sensor
A sensing device in which the active sensing element is in an optical fiber or an element attached directly to an optical fiber. The quantity being measured changes the optical properties of the fiber in way that can be detected and measured. For example, pressure changes induced in a fiber by acoustics can change the amount of light transmitted by a fiber.

Field Installable (fiberoptics)
Nominally, a fiber optic splice or cable is field installable if it can be mounted by technicians working in the field without a lab-full of equipment at hand. Different manufacturers define the term differently.

Finish
Refers to the polish results on the end of the ferrule. Better the Finish, the less the back reflectance.

Frequency-Division Multiplexing
The combination of two or more signals at different frequencies so they can be transmitted as one signal. This can be done electronically, or it can be done optically by using two or more light sources of different wavelengths. The optical version is better known as wavelength division multiplexing.

Fresnel Relflection
Reflection losses that are incurred at the input and output faces of the fiber and are due to the difference in refractive index between the core glass and the immersion medium.

FTTH
“Fiber to the Home" FTTH is where fiber will be brought directly to the side of your home to support your cable TV, telephone service and internet needs. It looks much like the utility box that you currently have on the side of your home, only with fiber jumpers inside.


Furcation Tubing
A protective tubing used to protect exposed fiber. Commonly used in terminating multi-fiber cable or “fan out” situations.

Fusion splicer
A high precision piece of equipment that allows the user to 'melt' or fuse the ends of two optical fibers together to create one continous fiber. There is typically very low loss at this junction. Alignment of fibers can be by manual or automatic manipulation. The fusing takes place by electrical discharge between two electrodes.
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G:

Gigahertz (GHz)
A unit of frequency that is equal to one billion cycles per second.

Graded Index Fiber
An optical fiber in which the refractive index changes gradually between the core and cladding, in a way designed to refract light so it stays in the fiber core. Such fibers have lower dispersion and hence broader bandwidth than step-index fibers.
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H:

Hard-Clad Silica Fluid
A liquid with refractive index that matches that of the core or cladding of an optical fiber. It is used in coupling light into or out of optical fibers and can help in suppressing reflections at glass surfaces.

Hybrid Cable
A fiber optic cable containing two or more different types of fiber, such as 62.5um multimode and singlemode.
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I:

Index Matching Gel
A gel material with an index of refraction close to that of glass that reduces reflections caused by refractive-index differences.

Index of refraction
The ratio of light velocity in a vacuum to its velocity in a given transmission medium.

Infrared
Those wavelengths that extend beyond 770 nanometers. Infrared is used extensively in the transmission of light through optical waveguides. These light wavelengths are invisible and harmful to the naked eye.

Insertion Loss
Total optical power loss caused by insertion of an optical component such as a connector, splice, or coupler into a previously continuous path.

Interconnect Sleeve
A mechanical media termination device designed to align and join fiber optic connectors, designed to be mounted on a panel. Often referred to as a coupling, bulkhead, or mating sleeve.

Interferometer Test
A test used to determine the quality of the ferrule surface using three measurements.

   1. The angle of the cut or radius on the end of a connector which determines actual back reflection values or characteristics.
   2. The undercut or protrusion of the fiber. This is mea­sured against the ferrule end face determining how well the physical contact will be.
   3. The position of the fiber in relation to cut or curve, called the apex.

Intrinsic Joint Loss
Loss caused by fiber parameter (e.g.: core dimensions, profile parameter) mismatches when two non identical fibers are joined.
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J:

Jumper
A length of cable with connectors at both ends. Also known as patchcords.
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K:

Kevlar
Strands of aramid yarn used to provide strain relief in cable assemblies.

Kilometer (km)
One thousand meters, or approximately 3281 feet. The kilometer is a standard unit of length measurement in fiber optics. Conversion is 1 ft. = 0.3048
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L:

LAN
A Local Area Network. A network which does not utilize outside telco company lines.

Large-Core Fiber
An optical fiber with a comparatively large core, usually a step-index type. Usually, 400 micrometers or more (see Step Index).

Laser
An acronym for Light Amplification by the Stimluated Emission of Radiation, applied to a wide range of devices which produce light by that principle. Compared other light sources, laser light covers a narrow range of wavelengths. tends to be coherent, and is emitted in a directional beam.

Launch Fiber
A fiber used in conjunction with a source to excite the modes of another fiber in a particular way. Launching fibers are most often used in test systems to improve the precision of measurements. See “Pulse Suppressor”

LED (Light-Emitting Diode)
A semiconductor device in which light is produced when current carriers combine at a p-n junction. The emission is spontaneous and there are no feedback mirrors, unlike diode lasers. Output is lower in power than from diode lasers, reflecting the use lower operating currents. Generally LEDs are less expensive than diode lasers, and can operate at shorter wavelengths without the rapid degradation that occurs with visible-wavelength diodes.

Loose Buffer Cable
Loose buffered designs Consist of a loose tube surrounding a coated fiber. It also includes a Kevlar? braid as the strength member for improved flexibility.

LSTTL (Low Power Schottky TTL)
Utilizes a diode-clamped transistor to lower power requirememts.

Common Fiber Terms M-P

Common Fiber Terms R-Z

Glossary of Common Fiber Optic Terms: A - E

Common Fiber Terms: A-E

A:

A.T.C. (Automatic Threshold Control)
Electric control circuit which regulates the input current to an LED to prevent it from being overdriven.

Absorption Losses
Losses caused by impurities principally transition metals and neighboring elements (Cr, Mn, Fe, Co, Ni), and also by water as well as intrinsic material absorption.

Acceptance Angle
Any angle measured from the longitudinal center line up to the maximum acceptance angle of an incident ray that will be accepted by the waveguide. The maximum acceptance angle is depend­ent on the indices of refraction of the two mediums.

Adapter
A mechanical media termination device designed to align and join fiber optic connectors. Often referred to as a coupling, bulkhead, or interconnect sleeve.

Angle on Incidence
The angle between an incident ray and the normal to a reflecting surface.

Aramid Yarn
Fibers, yellow, that provide cable tensile strength, support, and additional protection of the optical fiber bundles. KevlarÒ is a particular brand of aramid yarn. Often refered to as central strength member.

Armor
Protective material in cable made of corrugated steel.

ATM
A method of data multiplexing that can provide large, instantaneous bandwidths for busy traffic while permitting slow traffic to use that bandwidth between bursts. Very short, fixed-length packets or cells are used to transmit information. Its basic cell is 53 bytes long.


Attenuation
a measure of the decrease in energy transmission (loss of light) expressed in dB/Km. When in optical wave guides it is primarily due to absorption losses and scattering losses.

Avalanche photodiode (APD)
A type of semiconductor detector operated at high voltages. When incident light generates photoelectron from the material, the high voltage across the device accelerates the elec­tron enough to cause avalanche of other electrons, effectively amplifying the signal. An avalanche photodiode could be seen as similar to a solid state photo-multiplier.

Axial Ray
A ray passing through the axis of the optical waveguide without any internal reflection.
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B:

Back Reflection
An undesirable characteristic in singlemode fiber transmission. Reflectance of light pulse back towards the transmitted source. Also referred to as Optical Return Loss (ORL).

Backscattering
See “Back Reflection”

Bandwidth
The capacity of an optical fiber to transmit information expressed in bits of information transmitted in a specific time period for a specific length of optical wave guide. (Usually expressed in megabits/sec./km.) Bandwidth is limited by pulse spreading or broadening due to dispersion, so that adjacent pulses overlap and cannot be distinguished. (see Pulse Dispersion)

Beamsplitter
A device which divides a beam of light passing through it into separate beams going in two different directions. Some types affect polarization of the beam, while others do not. Various splitting ratios are possible. (eg., 90-10, 70-30, 50-50, etc.)

Bend Radius
Maximum bend allowed before physical damage is incurred. Generally expressed for two conditions, loaded (under tensile load) or unloaded.

Bit
An electrical light pulse whose presence or absence indicates data. The capacity of the optical waveguide to transmit information through the waveguide without error is expressed in bits per second per unit length.

Bragg Gratings, Fiber
Fiber that is treated to back reflect a particular wavelength, called the Bragg Wavelenth. See technical notes: Fiber Bragg Gratings

Buffer
Material used to protect an optical fiber or cable from physical damage and providing mechanical isolation or protection. Fabrication techniques include both tight jacket, or loose tube buffering, as well as multiple buffer layers.

Bulkhead Attenuator
A mechanical media termination device designed to align and join fiber optic connectors, designed to be mounted on a panel, and that contains an attenuation device.

Bulkhead Connector
A mechanical media termination device designed to align and join fiber optic connectors, designed to be mounted on a panel. Often referred to as a coupling, bulkhead, interconnect or mating sleeve.
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C:

Card-Edge Connector
Designed for printed circuit boards for blind mating of connectors.

Central Member
The center component of a cable used to provide strength. Commonly referred to as “Central Strength Member”

Chromatic Dispersion
Spreading of a light pulse caused by the difference in refractive indices at different wavelengths.

Cladding
A low refractive index, glass or plastic that surrounds the core of a fiber. Optical cladding promotes total internal reflection for the propagation of light in a fiber.

Collimation
A process in which a divergent or convergent beam of radiation is converted into a beam with the minimum divergence as possible, preferably parallel.

Composite Cable
A cable containing both fiber and copper conductors.

Connector
A junction which allows users to connect / disconnect cables or devices.

Core
The light conducting portion of a fiber, defined by its high refraction index. The core is the center of a fiber, surrounded by concen­tric cladding of lower refractive index.

Core Eccentricity
A measure of the displacement of the center of the core relative to the cladding center.

Core Ellipticity (non-circularity
A measure of the departure of the core from roundness.

Coupler (fiber optic)
A coupler is a device which joins together three or more fiber ends, for example, splitting the signal from one fiber so it can be transmitted to two or more other fibers. Directional , star, and tee couplers are the most common varieties.

Coupling Loss
The power loss suffered when coupling light from one optical device to another.
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D:

Dark Current
The output current that a photodiode emits in the absence of light.

Data Link (fiber optic)
A fiber optic signal transmission system which carries information in digital or (sometimes) analog form. Usually this term refers to short-distance communications, spanning distances of less than a kilometer.

Data Rate
The maximum number of bits of information that can be transmitted per second, as in a data transmission link. Typically expressed as megabits per second (Mbps)

dBm
Decibels relative to one milliwatt. A positive number indicates the power is above one milliwatt; a negative number indicates the power is below. This unit has become common in fiber optic communication sys­tems because the power of light sources used with optical fibers is on the order of one milliwatt.

Decibel
The standard unit used to express the ratio of two power 1evels. It is used in communications to express either a gain or loss in power between the input and output devices.

Demultiplexer
A device which separates two or more signals that have been multiplexed together for transmission through a single fiber. (See multiplexer.)

Detector
A transducer that provides an electrical output signal in response to an incident optical signal. The current is dependent on the amount of light received and the type of device.

Detector-Amplifier
A device in which an optical detector is packaged together with electronic amplification circuitry.

Dielectric
Non-metallic, and therefore, non-conductive. Glass fibers are considered dielectric. A dielectric cable contains no metallic components.

Diode Adapter Receptacle
Designed to house LED or PlN/APD diodes in a receptacle which allows the mating plug to position the fiber for an optimum coupling efficiency.

Directional Coupler (fiber optics)
A fiber coupler is directional if it preferentially transmits light in one direction.

Dispersion
Spread of the signal delay in an optical waveguide. It consists of various components: modal dispersion, material dispersion, and waveguide dispersion. As a result of its dispersion, an optical waveguide acts as a low-pass filter for the transmitted signals.

Divergence
The spreading out of a laser beam with Distance, measured as an angle.

Doppler Shift
A change in the wavelength of light caused by the motion of an object emitting (or reflecting) the light. Motion toward the observer causes a shift toward shorter wavelengths, while motion away causes a shift toward longer wavelegths.

Driver I.C
An amplifier in an integrated circuit used to increase signal current to the LED for greater transmission distance.

Duplex Cable (fiber optics)
A cable which contains two optical fibers in a single cable structure. Light is not coupled between the two fibers: typically one is used to transmit signals in one direction and the other used to transmit in the opposite direction.

Duplex Connector (Fiber optics)
A connector which simultaneously makes two connections, joining one pair of optical fibers with another.
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E:

E.C.L. (Emitted-Coupled Logic)
Method of data transmission which uses negative logic. -0.8V is "1" and -1.6V is "0".

Electromagnetic Interference (EMI)
The frequency spectrum of electromagnetic radiation extending from subsonic frequency to X-rays. This term should not be used instead of the term "RFI" (see RFI) (Shielding materials for the entire EMI spectrum are not readily available.)

EMP (Electromagnetic Pulse)
An extremely strong short lived magnetic field resulting from a nuclear explosion could cause a damaging magnetic field at a distance of 1500-3000 miles.

End Finish
Quality of the surface of an optical fiber's end, commonly described as mirror, mist, hackle, chipped, cracked or specified by final grit size in polishing. (1um, .3um, etc.). See “Polish”

End Separation Loss
The optical power loss of a fiber and source, detector or another fiber (see Frensel Reflection).

Extinction ratio
a performance standard measurement of polarization maintaining (PM) fiber. The measurement of light entering and exiting a fiber indicates how well the fiber maintains polarization.

Extrinsic joint Loss
Loss caused by imperfect alignment of fibers in a connector or splice. Contributors include angular misalignment, lateral offset, end separation and end finish. Generally synonymous with Insertion loss.

Common Fiber Terms F-L

Common Fiber Terms M-P

Common Fiber Terms R-Z

CCTV Glossary of Common Terms and Definitions

Closed-Circuit Television (CCTV)

A collection of cameras, tv/monitors, and recording devices directly connected together via cables or other direct means (such as wireless transmitters/receivers).

Alarm Input
Some cameras and DVRs have the ability to accept alarm inputs. These are inputs from standard sensor devices such as, Passive Infra-red (PIR) detectors, door contacts, active beams etc. or relay outputs from intruder alarm panels, or  access control panels. Alarm input circuits can come in a number of forms, but most are commonly self powered, so will operate with a passive switch style circuit. However, in some cases, they expect to be provided with power (normally 12V) as the signal of open or closed.

Alarming
Ability of CCTV equipment to respond to an input signal, normally a simple contact closure. The response will vary depending on your equipment type.

Ambient Light Level
The amount of background light in any given situation.

Analog Signal
Most CCTV cameras, although internally working with digital components, produce a standard analog signal. This is where the image is represented by a variable voltage level and frequency timings. In the USA, the standard used is called NTSC. In the UK and Europe, the standard for the analog signal output from CCTV cameras is called PAL.

Annunciator
An audible and/or visual signaling device.

Aperture
The aperture of a lens, is the area that allows light to pass into the lens. Lenses with large apertures allow more light in than lenses with small apertures.

Aperture Correction 

Compensation for the loss in sharpness of detail because of the finite dimensions of the image elements or the dot-pitch of the monitor.

Aspect Ratio
The ratio between the the height and width of an image.

Auto Iris
Cameras with an Auto Iris feature have the ability to compensate for large variations in light levels. This is particularly useful for cameras that need to compensate for changes from bright sunlight to dark shadows (ex. near the front door of a building with the door opening and closing a lot). The auto iris circuitry is normally linked to a motorized iris drive that physically opens and shuts the iris on the lens.




Automatic Gain Control (AGC)
This is a feature of many CCTV cameras to help keep the strength of the output signal constant, even with varying light levels. In other words, it boosts signal strength at low light levels, and caps it at higher levels.

Automatic Level Control (ALC)
Allows the camera to either bring out detail in bright areas of the image, or bring out more detail in the darker areas, depending on how it is set up. This is often useful where the view has a window in the background, where the sunlight is causing the image of the room to be much darker than required.

Automatic Terminating (Auto-terminating)
Video signals are normally transmitted along co-axial cable, which require a terminating resistor at either end. If the signal is looped through a piece of equipment that has an input and an output, then it should be terminated if it is the final piece of equipment, but not terminated if it is in between other equipment. Some appliances have a manual switch for this setting, while others automatically detect if termination is required and applies the additional resistor as necessary.

Automatic White Balance
Automatically adjusts the color settings to maintain the quality of the white areas of an image.

Back Focus
Alignment of the rear of the lens to the imaging device.

Back Light Compensation
Automatically adjusts the image to compensate for bright sunlight or bright lights, to give more detail on the darker areas of the image. (ex- Can focus on a persons face, even if there is a bright light coming from behind them).


Balanced Signal
This is a method of transmitting audio or video signals over a pair of wires, (ex- twisted pair cable) by sending two equal, but opposite signals. This system minimizes external interference, and maintains signal quality.

Balun
Short for Balanced - Unbalanced. It is a device used to interface between balanced lines and unbalanced lines.Typically used for Cat5e to Coax cable. 

 

Bandwidth 

A measure of the carrying capacity of information over a network. Video, for example, takes up more bandwidth to transmit over a network than text would.

 

Bar Test Pattern 

This is a special test pattern for adjusting color TV receivers or color encoders. The upper portion consists of vertical bars of saturated colors and white. The power horizontal bars have black and white areas and I and Q signals.

 

BNC Connector 

BNC is a bayonet style connector for coaxial cable that is most commonly used for CCTV installations. The 3 types of connector types are Compression, Crimp and Twist.

Burn-In (burn)
An image which persists in a fixed position in the output signal of a camera tube after the camera has been turned to a different scene or, on a monitor screen. This is why it's a good idea to use CCTV specific monitors, vs a standard monitor.

Charge Coupled Device (CCD)
One of the two main types of image sensing device used in cameras. It operates by converting light energy into electrical charge.




Chromaticity 
The color quality of light which is defined by the wavelength (hue) and saturation. Chromaticity defines all the qualities of color except its brightness.

Chrominance
This refers to the part of the video signal that contains the color information.

C Mount Lens / CS Mount Lens
C Mount lens has a flange back distance of 17.5mm while the CS Mount lens has a flange back distance of 12.5mm. C mount lenses therefore have a longer focal distance.

Co-Axial Cable (Coax)
This refers to cable that has a central conductor, surrounded by a shield sharing the same axis. The shield can be made from a variety of materials including, braided copper, or lapped foil.There are various standards for specific types of coax cable. RG59 is the most common used cable for CCTV application. You can also get a siamese coax, which includes 2 wires for power.

Composite Video
A full video signal that combines picture signal and synchronisation pulses.

Compression
Digital video pictures can be compressed with a number of techniques. These include: JPEG and JPEG-2000 (for still images), M-JPEG and MPEG (for moving pictures).

Depth of Field
Depth of field or depth of focus refers to the range of distance from the camera that is in good focus. The smaller the aperture of the lens, the longer the depth of field. However, less light coming into the lens, means that the image will be dimmer, so the camera needs to compensate by increasing the gain. For example, the best (longest) depth of field would be obtained on a bright, sunny day, with a very small aperture on the camera. In this case the imaging device still gets a reasonable amount of light, even with a small aperture. The worst (shortest) depth of field would be in a dark room, with a large aperture. To improve depth of field, the best approach is to increase the amount of light on the subject, or use a more sensitive camera, like an IR Camera


Digital Versatile Disk (DVD)
This is an optical disk,  the same size as a CD, used for storing data of various formats. Including video, audio and computer data.


Digital Video Recorder (DVR)
This is a device that records video signal digitally. Normally this is on a large hard drive in the machine. 

Direct Drive (DD)
Some auto iris lenses require a DC signal from the camera. These are known as direct drive lenses.


Electronic Iris (EI)
This is an electronic implementation of an auto iris. It uses electronics to simulate the effect of opening and closing the iris, by increasing or decreasing the effective shutter time of the camera.

External Sync
External sync allows a piece of equipment to take its video synchronization from another unit, so that it can align itself with the system as a whole.

Focal Length
The distance between the center of a lens, or its secondary principal point and the imaging sensor. Lower lengths give a greater field of view and less magnification. Longer lengths give a narrower field of view and greater magnification. The table below gives an approximate value for the angle of the field of view for lenses of various focal lengths. 30˚ is considered to be a normal view, telephoto (longer) lenses have lower angles. Most CCTV cameras have one of the 3 sizes of imaging devices listed below, 1/4", 1/3" or 1/2".

Frame
Refers to a full TV picture. The PAL signal transmits 25 full frames per second.

Gamma Correction
This is an adjustment to ensure that variations in light input, produce a corresponding output in light intensity.

Ghost
This refers to poor image quality, where the primary signal is weak, allowing a secondary signal to interfere with the picture.

Hertz (Hz)
Cycles per second.

Impedance
The total opposition offered by a device to the flow of an alternating current (measured in Ohms).

Infra Red (IR)
Low frequency light below the visible spectrum. This is often used for covert or semi-covert surveillance to provide a light source for cameras to record images in dark or zero light conditions. 


Interlacing
PAL video signals transmit odd and even lines alternately. This is a 2:1 interlace. The two sets of lines are combined to form each single frame.

Internal Sync
Devices with internal sync, have an internal crystal to provide sync pulses, without needing reference from any external device.

IP Waterproof Rating (IP66 - IP68)
IP ratings are a BSi standard measurement for how waterproof something is. Many cameras or camera housings are designed for outdoor use, and therefore need to be waterproof to some degree. The details of the tests are defined in BS EN 60529 : 1992. The IP number has two digits, and optional letters after them.

Iris
A mechanical device that adjusts to vary the amount of light passing through the lens of a camera. Think of it like the iris of your eye. When it's dark outside, the iris opens bigger to let more light in.



JPEG
JPEG is a standard for coding/compression of still pictures. It is used in the CCTV systems to compress and store individual frames of video.

Line Amplifier
This device takes a weak video signal as its input and outputs a new stronger version of the same signal. These are useful/necessary for transmitting video over very long cable runs. This is sometimes known as a video line corrector.

Line Fed Camera
This refers to the use of equipment that can provide power to the camera and take the video signal along the same cable. It normally involves placing an "encoder" unit at one end and a "decoder" unit at the other. These units effectively combine and then split the power from the video signal at either end of the cable run.

Liquid Crystal Display (LCD)
This is a technology used for flat screen displays. Aside from being smaller and lighter, it also has the advantage of using less power than traditional cathode ray tube screens.


Looping
This refers to connecting an additional device in parallel with an existing video cable. For example, when driving a video recorder as well as a monitor from the same video signal, simply by T'ing off the cable.

Luminance
This refers to the part of a video signal that carries the monochrome information. i.e. brightness information.


Lux
This is a measure of the amount of light striking a surface. i.e. the luminus flux density at a surface. One lux is one lumen per square metre. Cameras for use in good lighting conditions, or in daylight would normally be rated at 2 Lux or more. Cameras with a Lux rating of 0.2 Lux or less would be considered low-light cameras. It is not possible to get good colour definition in low light levels, so in general low light cameras are always monochrome. However, day/night cameras use electronics to switch from colour during the daytime, to monochrome during night or low light conditions. Many low light cameras are also infra-red sensitive, so that infra-red illumination can be used. Particularly useful in zero light conditions.


Matrix Switcher
This is a device that allows any of its camera inputs to be switched to one or more of its monitor outputs. The outputs can also be video recorders.

Monitor
A device used to view video pictures. These devices don't normally have television RF frequency receivers. They normally have composite, or component video inputs.

Monochrome
Refers to a black and white image rather than color.

MPEG
MPEG is a standard used for coding and compression of moving images. It is now used widely for the compression of video images. However MPEG isn't just one standard. They have developed several standards for different uses. For example MPEG-2 is used for DVD's and set top boxes. MPEG-4 was developed for multi-media applications for fixed and mobile web applications.

Multiplexer
A device that takes inputs from 2 or more video channels and combines them into one signal. This is often done by using time division multiplexing, which interleaves frames from each channel in such a way that they can be split out again. Frequency division multiplexing uses different frequencies to achieve the separation of the signals.

Network Camera (IP Camera)
This refers to a camera that is designed to record pictures and transmit them directly over a computer network or dialup internet connection. Network cameras normally do not have any analog video outputs. The images are encoded directly in one of the standard compression techniques, such as JPEG or MPEG.

NTSC
The standard for TV signals developed by the National Television Standards Committee in the USA. The UK and Europe, use a similar, but different standard known as PAL.

PAL
This is the standard for TV signals used in the UK. It stands for Phase Alternating Line.

Pinhole Lens
This is a type of lens with a very small aperture. Normally used for covert applications, where it can easily hide behind or within another object.

Pixel
A pixel refers to an individual area on the surface of the imaging device, normally a CCD. It is made from photosensitive material which converts light into electrical energy. In the context of a display monitor, a pixel is also referred to as an individual area on the surface of the screen which converts electrical energy to visible light.


Roll
This is a fault condition on a video signal which refers to loss of vertical synchronization. It causes the picture to continuously move up or down.

SECAM
The system used for TV signals in France.

Shutter
The shutter in a camera is the device that controls the time period for which light is gathered by the collecting device. Old cameras used mechanical shutters. However modern cameras use electronic circuits to perform the same function with no moving parts.

Television Lines (TVL)
This is a measure of the resolution of a video device. Higher number is higher resolution. 380 TVL is considered medium resolution. 480 TVL or greater is considered high resolution.

Varifocal (Zoom)
This refers to a type of lens that has the facility to change the focal length. This allows adjustment of the magnification and field of view of a camera.

Video Motion Detection
This is a feature that detects motion within a video signal. Normally this is used to trigger recording of images. Advanced video motion detection systems have the facility to adjust the sensitivity and object size that will trigger the system. They also allow the image to be blocked out, such that only certain areas of the image are taken into account when scanning for motion.

Wide Area Network (WAN)
 Multiple LANs connected together, usually over a great distance, to share information.

Wavelets
This is a compression technique used to give high compression without degrading the image quality.

Zoom Lens
A lens that may be effectively used as a wide angle, standard or telephoto lens by varying the focal length of the lens.

Discount-Low-Voltage.com/CCTVSecurityProducts

Common HDMI Cable Terms for your TV cable

Common HDMI Terms:

First things first, what is HDMI?
HDMI (High Definition Multimedia Interface) is the first and only industry supported, uncompressed, all-digital audio/video interface. HDMI delivers a crystal clear, all-digital audio and video signal through a single cable, greatly simplifying the cabling process and provides a high quality home theater experience. An HDMI cable provides an interface between any audio/video source (DVD player, DVR, Gaming console) and an audio and/or video monitor (Television, PC).

What are "Gold Plated" connectors?
Gold plating refers to the connectors. Most HDMI connectors nowadays have gold plated, corrosion resistant connectors. The main purpose is to reduce corrosion that would impede signal transfer.

What's the difference between HDMI and DVI?
HDMI and DVI are the exact same as one another, image-quality-wise. The principal differences being that HDMI carries audio and uses a different type of connector. HDMI can be a big advantage since your only running 1 wire, making your installation easier and with less clutter. I personally prefer to work with the HDMI cables as well, since the connector is smaller and easier to work with. Here you can see the size difference:

What is AWG?
AWG (American Wire Gauge) is a standardized wire gauge system used since 1857 for the diameter of wire. The lower the number, the larger the size of the cable. For example, a 22awg wire is significantly larger than a 28awg wire.

What size AWG should I use?
As a general rule of thumb, HDMI cables 15ft or less can use a 28awg wire, while anything longer than that would benefit from a 22 or 24 awg wire. That will insure you don't have any signal loss.

What are Ferrite Cores and what do they do?
Ferrite cores are are a barrel shaped device (see picture below) that assists in signal transfer and help eliminate interference.

1080i vs 1080p
1080 refers to the vertical lines of resolution (1920 x 1080). Both 1080i and 1080p have 1,080 lines of resolution, but the way the picture gets conveyed onto the screen is different. 1080i conveys the images in an interlaced format. As the picture is being "painted" on the screen, the odd-numbered lines of resolution appear on your screen first, followed by the even-numbered lines--all within 1/30 of a second. 1080p conveys all of the lines of resolution sequentially in a single pass, which makes for a smoother, cleaner image, especially when watching sports and other motion-intensive content.

Bandwidth
Bandwidth is the carrying capacity of a data. High-bandwidth connections are also known as high-speed connections, because they can transmit large quantities of data very quickly. HDMI has extremely high bandwidth capacity: up to 10.2 gigabits per second.

Component Cable
Component video cables are commonly referred to as R, G, B (red, green, blue) and consists of 3 separate cables (usually connected together) that distribute the 3 primary color components to the display.

Compression
Technologies designed to increase the carrying capacity of a data connection by compacting the data stream at one end and re-expanding it at the other end. One of the advantages of HDMI over other connection technologies is its enormous carrying capacity, which makes compression unnecessary.

Deep Color
The expanded bandwidth of HDMI 1.3 is allowing manufacturers to design displays with much greater Color Depth. These new “Deep Color” monitors will be capable of rendering many more distinct hues than current displays – up to trillions of colors rather than thousands or millions.

DTV
Digital televisions, the successor technology to analog TV, are televisions capable of receiveing a ditigal terrestrial or cable broadcast signal.

HD
HD (High Definition) is usually used to describe any device capable of generating or displaying a signal with a resolution of at least 720 vertical lines.


HDCP
HDCP (High-bandwidth Digital Content Protection) is a form of digital copy protection, developed by Intel to prevent copyrighted audiovisual content.

HD-DVD
High-definition DVD, one of two potential successor technologies to the DVD. A high-density optical disc format designed for the storage of high-definition video. HDMI is the interconnect standard for HD-DVD players.

HDMI Repeater
An HDMI repeater is a device that both receives and sends HDMI signals, such as an AV receiver. A/V receivers are considered HDMI repeaters.

HDMI Source
HDMI source refers to a device that sends an HDMI signal. Examples would be a DVD player or Set-top box.

HDMI Version 1.0, 1.1, 1.2, 1.3, 1.4?
HDMI devices are manufactured to adhere to various versions of the specification, in which each version is given a number. Each subsequent version of the specification is backward-compatible and uses the same kind of cable but increases the bandwidth and/or capabilities of what can be transmitted over the cable. A product listed as having an HDMI version does not necessarily mean that it will have all of the features that are listed for that version, since some HDMI features are optional, such as Deep Color and xvYCC.


HDTV
An HDTV (High Definition Television) is a TV capable of displaying a 720p signal or better.


Mini HDMI Connector
A miniature HDMI connector, introduced in HDMI 1.3, designed for use in mobile and hand held products where space is at a premium. The Mini HDMI Connector is pin-for-pin compatible with the larger Standard HDMI Connector and completely compatible as well. The Mini HDMI Connector is referred to as the Type C Connector in the HDMI specification.

MPEG
MPEG is part of a family of audio/video codecs developed by the Motion Picture Experts Group. The majority of TV content, including cable, broadcast, and satellite, is currently transmitted in the MPEG-2 format. HD-DVD and Blu-ray disc players, along with some recently launched satellites, rely on the newer and more powerful MPEG-4 format.

NTSC
The legacy analog television broadcast system used in the US, being replaced by the ATSC digital system.

Refresh Rate
The frequency with which a video image is refreshed, expressed as either frames per second (i.e. 60 fps) or as an equivalent frequency (i.e. 60 Hz). Faster refresh rates tend to render smoother motion sequences. Refresh rates for broadcast TV vary by region – for example, European HD systems run at 50 Hz.

Set-top Box
A device for decoding incoming AV signals, such as programs from a cable or satellite TV network. Many models also include DVR (digital video recorder) technology. Virtually all STBs now rely on HDMI output.


YCbCr Color
A family of color spaces, used in some HD applications, where color is expressed using a luma component plus red and blue chroma components, rather than by describing absolute color values, as in the RGB color model. Also known as YPbPr color. 

 Now you know it all and where to get your HDMI cables from.

Thanks!

"By Mercy Salinas"