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Fibre-optics can be seen as a replacement for copper wire systems for communication and signal transmission. It can span long distances and provide the backbone for many network systems. Other systems users include television services, network on university campuses, between office buildings, industrial plants and electric utility companies.

Lately we see the new telecoms providers as well as Telkom installing large infrastructure to carry fibre networks all over our country. These networks have a special fibre deployment method called blown fibre. This is when the fibre cores are blown into the pipes as needed.

Fibre-Optic Cables – Multi-mode

Multi-mode fibre has a large core, up to 50 microns in diameter. As a result, some of the light rays that make up the digital pulse may travel a direct route, whereas others zigzag a they bounce off the cladding. These alternative pathways cause the different groupings of light rays, referred to as modes, to arrive separately at a receiving point. The pulse, an aggregate of different modes, begins to spread out, losing its well-defined shape. The need to leave spacing between pulses to  prevent overlapping limits bandwidth, that is, the amount of information that can be sent. Consequently, this type of fibre is best suited for transmission over shorter distances, up to 12km.

Fibre-Optic Cables – Single–Mode

Single-mode fibre has a narrow core (8 microns or less) and the index of refraction between the core and the cladding changes less than it does for multi-mode fibre. Light thus travels parallel to the axis, creating very low pulse dispersion.


Why Use Fibre Optic Cable?

Fibre Optic is a technology that uses glass (or plastic) threads (fibres) to transmit data. A fibre optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves. There many options available today to transmit Video Voice and Data. You could use Cat 5 cable, Radio, Co-Ax cable but none are as secure as Fibre.
Fibre optic cable is used as a replacement to cable systems and has several advantages over copper cable.

Immune to interference: Any form of EMI or EMC interference does not affect Fibre optic cabling. It’s unique characteristics make it immune to cross-talk, radio and electrical disturbances, allowing you to lay it where you need it, without having to worry about the proximity to electrical systems.

Lightning Protection:
A Big advantage of fibre is that it is non conductive and thus isolates the remote equipment from the local equipment and therefore protects the equipment from longitudinal induced lightning currents.

Security: Fibre is secure as it is not possible to tap into the fibre along a route. Fibre can carry a large amount of data in digital form with no deterioration of signal. Optical losses are far less than losses that could be experienced in copper cable or on radio links. Thus making it ideal over longer distances.  Fibre is also suitable for shorter distances from 100meter upwards to 100km and more by adding additional equipment.

Weight: a Great advantage of fibre is its lightweight construction. This is especially useful when fibre is used down mineshafts or in large buildings, on cranes. Cost savings on transport and handling is a great advantage.

Fibre cable construction
Fibre Optic Cables were introduced into South Africa around the late 70’s. ATC set up a manufacturing plant to produce the product locally. There are many differently constructed cables available. Be sure to select one with the ruggedness suitable for the application.

In general a Fibre optic cable consists of a rugged plastic outer Sheath some with an additional inner Tube supported with Kevlar for strength and then with a multiple individual single core fibres coated with a with 125 micron clading. Each fibre can measure 50 micron for multimode applications and 8 micron for single mode applications. These cables are suitable for use on mines, industrial sites, Airports and long distance communication. Application for CCTV, IP Networks and Access control are found in shopping centers factories and the like. Lately the advantages of fibre are realized in the ordinary domestic areas for intercoms security video monitoring.

(POF): Another form of fibre called Plastic optical fibre (or Polymer optical fibre) an optical fibre which is made out of plastic. These fibres are suitable for lower data rates and shorter distances.

Since the late 1990s however, much higher-performance POF based fibres has begun to appear in the marketplace. This lends itself to be looked at again in the light of the increasing domestic market. This fibre has a much larger core diameter as much as 1mm and light is transmitted through the complete core of the fibre. POF has been called the “consumer” optical fibre because the fibre and associated optical links, connectors, and installation are all inexpensive.

Fibre cable application  

Fibre cables can be laid underground, or strapped to existing infrastructure and are even used down mineshafts.

Connection and joining of fibre cable is a precision job done with special tools  needed and thus has to be done by the installer who will terminate the cable on a patch panel. From there a patch lead is used that connect to the equipment. These patch leads come in single or duplex fibre almost like twin flex with the connecters already fitted and can be connected by the user.

Plastic Optical Fibre is more suited in the domestic environment as it is easier to install and to terminate a  crimping pliers with a cutting and polishing kit can be purchased at a reasonable cost. It is more suited for domestic applications as the installation distances of a link rarely exceed 100m. 

Fibre-optics can be seen as a replacement for copper wire systems for communication and signal transmission. It can span long distances and provide the backbone for many network systems. Other system users include television services, network on university campuses, between office buildings, industrial plants, and electric utility companies. Lately we see the new telecoms providers as well as Telkom installing large infrastructure to carry fibre networks all over the country. These networks have a special fibre deployment method called blown fibre. This is when the fibre cores are blown into the pipes as needed.

How does it work

Think of a fibre cable in terms of very long cardboard tube that is coated with a mirror on the inside. If you shine a flashlight in one end you can see light come out at the far end - even if it’s been bent around a corner because the light is reflected by the mirror finish inside the tube.

Light pulses move easily down the fibre-optic line because of a principle known as total internal reflection. This principle of total internal reflection states that when  the angle of incidence exceeds a critical value, light cannot get out of the glass; instead, the light bounces back in. When this principle is applied to the construction of the fibre-optic strand, it is possible to transmit information down fibre lines in the form of light pulses.

The core must have a very clear and pure material for the light or in most cases near infrared light (850nm, 1300nm and 1500nm) is used. The core can be Plastic  (used for very short distances) but most are made from glass. Glass optical fibre is almost always made from pure silica, but some other materials, such as  fluorozirconate, fluoroaluminate, and chalcogenide glasses, are used for longer-wavelength infrared applications. Fibre optic cable functions as a “light guide,”  guiding the light introduced at one end of the cable through to the other end.

The light source can either be a light-emitting diode (LED) or a laser. The light source is pulsed on and off, and a lightsensitive receiver on the other end of the cable converts the pulses back into the digital ones and zeros of the original signal. Even laser light shining through a fibre optic cable is subject to loss of strength,  primarily through dispersion and scattering of the light, within the cable itself. The faster the laser fluctuates, the greater the risk of dispersion. Light strengtheners, called repeaters, may be necessary to refresh the signal in certain applications.

While fibre optic cable itself has become cheaper over time - a equivalent length of copper cable cost less per meter but does not carry have the same data capacity.

In order to use fibre optic cable we need special terminating devices. To produce the light use is made of LED technology  for shorter distances and lasers for longer distances and higher data rates. On the receive side light sensitive devices that detect the light and convert it into an electrical signal are used. These devices come in various shapes and sizes and with different connecters.

Mainly 3 Fibre types are used:
Single mode fibre has the best performance characteristics and the highest data throughput see the fibre specs. Because of the smaller diameter fibre used the cost of the connectors, installation terminating equipment etc. all make the installation more expensive.

Multimode fibre is used for analog video transmission and digital transmitter and receiver units making it more cost effective. Transmission range is reduced to 3km for 850nm optics and 12km for 1300nm optics the later being more expensive to terminate but still suitable for analog video transmission.

Then POF work at much shorter distances within the 100m range but terminating the cables are easier thus reducing installation costs but also with reduced bandwidth. However Siemens has now developed a new modulation method that enable bandwidths up to the Gigibit range however this equipment will be expensive for the near future.

Fibre has a large core, up to (50 microns in diameter). As a result, some of the light rays that make up the digital pulse  may travel a direct route, whereas others zigzag as they bounce off the cladding. These alternative pathways cause the different groupings of light rays, referred to as modes, to arrive separately at a receiving point. The pulse, an aggregate of different modes, begins to spread out, losing its well-defined shape. The need to leave spacing between pulses to prevent overlapping limits bandwidth, that is, the amount of information that can be sent. Consequently, this type of fibre is best suited for transmission over shorter distances, up to 12km. Bandwidth approaches 500Mb/km the colour of multi mode patch cord is usually Orange.

Fibre has a narrow core (8 microns or less), and the index of refraction between the core and the cladding changes less than it does for multi-mode fibre. Light thus travels parallel to the axis, creating very low pulse dispersion. Bandwidth in the Gigabit range. The color of single mode patch cords are usually Yellow.

Entity is something that has no dependencies; it can “stand alone”. Referred to as a table top unit or peace of equipment. These units can be mounted in pole mounted boxes with separate or built in power supplies. Rack mount - is a standardized frame or enclosure for mounting multiple equipment modules. Each module has a front panel that is 19” wide, including edges or ears that protrude on each side which allow the module to be fastened to the rack frame with screws.

Security quality
There is no specification for the quality required for security therefore we often see video recordings where the image is of a crime perpetrator is not recognisable making the video useless. It is important to note that the camera position and degree of zoom can make all the difference to an installation. If you want to see the bird in a tree then it is necessary to have the whole tree in the picture and not the full landscape. The position of the sun is just as important. Sun rays reflecting into the camera lens can totally blank out a picture making it useless.

Broadcast quality
(http://encyclopedia2.thefreedictionary.com/broadcast+quality+video) This is usually referred to as picture quality suitable for broadcast. We are used to the normal analogue TV picture quality and compare all other video pictures to this. Lately we have DSTV and DVD quality which is a compressed form of video with excellent results. This compression is also used in Digital Video Recorders Normally called MPEG-4 or H.264/MPEG-4 . To obtain similar quality in a security system we have to use good quality cameras with at least 640 lines per frame. It is essential to eliminate long lengths of copper wire as this reduces the picture quality. Analogue video on fibre over distances up to 2km is acceptable for this quality, however digital video on fibre will give a better result and there will be no degradation of signal quality or any noise due to attenuation and can be transmitted over 24km with little effort. The use of IP based systems can be considered on application. IP systems rarely provide real time video which could be a problem in some applications, however higher resolution cameras are available.

H.264 is perhaps best known as being one of the codec standards for Blu-ray Discs; all Blu-ray players must be able to decode H.264. It is also widely used by streaming internet sources, such as videos from ‘Vimeo’, YouTube and the iTunes Store, web software such as the Adobe Flash Player and Microsoft Silverlight, broadcast services for DVB and SBTVD, direct-broadcast satellite television services, cable television services, and real-time videoconferencing.

The most used broadcast option and also the most widely available. Units are easily obtainable and very cost effective. ADD offers from 1 to 3 channel equipment in this category for fixed and dome (PTZ) cameras. Both multi-mode and single-mode are available. Card frames can handle up to 30 channels on a 3U level

Analog Circuit
A circuit or device having an output that is proportional to the input; “analogue device”; “linear amplifier”. An analogue video signal will instantly modulate the light  luminance (brightness) in a fibre as the picture intensity changes this is done up to 6 million times a second capturing the chrominance (colour) and all the picture detail.

Analogue signals
Signals that are continually changing, as opposed to being digitally encoded.

Signals encoded into discrete bits. Multiplexers fall into this category. These are units that can transmit and receive multiple video, audio and data channels on 1 fibre. Mostly used when an existing site wants to add more cameras and only has a limited amount of already installed fibre left. ADD offers 4, 8, 16 and 32 channel units.

Radio Broadcast
A common method of broadcasting video but can be limited in area. Very dependent on the layout and geography of an area. A further consideration is that only a limited amount of channels are available for use and an area (i.e. mine) can quickly become saturated.

Lan Based Broadcasting
Also known as IP video Has become very popular because of its ease of use and familiarity of the technology to people. Many sites are Lan based and a myriad of  cameras, transmitters, receivers and software options are available in today’s market. This has a tendency to limit itself as bandwidth quickly gets exhausted, especially if high quality recordings are called for. Dedicated lan networks are recommended.

Din Rail
Is a standardised 35mm wide metal rail with hat-shaped cross section. It is widely used for mounting circuit breakers and industrial control equipment inside  equipment racks. It is also used to house fibre interface units, power supplies, video transmitters etc.

Fibre optic networks can operate at high speeds - up into the gigabits/second.

Large data carrying capacity normally expressed as data throughput in bits per second. Also referred to as the range of signal frequencies or bit rate within which a fibre optic component, link or network will operate.

EMI Electromagnetic interference
Also called radio frequency interference or RFI, is a disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit or cables. Lightning is the biggest contributor to this interference.

Is a general systems concept, typically defined as a continuum describing the degree to which a system’s components may be separated and recombined. It refers to both the tightness of coupling between components, and the degree to which the “rules” of the system architecture enable (or prohibit) the mixing and matching of components.

Video and Audio
Our video products deliver crisp, clear, full-speed streaming video over fibre-optic. ADD’s video products have a proven reliability record with more than 10,000 links installed in the field. Available in single and multi-channel configurations. Audio and contact closure cards provide total CCTV / security solutions.

Access control
Is a system which enables an authority to control access to areas and resources in a given physical facility or computer-based information system. An access control system, within the field of physical security, is generally seen as the second layer in the security of a physical structure. It can be a gate controlled by an  electronic lock by which access is gained into a security area.

Is simply that part of a signal that one can hear once it is converted into sound waves. The specifications normally go beyond the normal audio range. A normal person can hear sound waves from 20cycles per second to approximately 7000cycles per second. The audio specifications for HIFI equipment specify signals from 10 – 20000cycles. As an interest the normal POTS telephone has a specification of 200 to 3400cycles per second.

Digital video
In relation to fibre digital video as opposed to analogue video is the conversion of the analogue signal into a data stream and sending light pulses down the fibre. These pulses are recovered on the receive side as ones and zeros eliminating any interference along the way. Whereas a analogue signal can become noisy as the distance increases the digital signal is recovered without noise. Digital video uses a high data rate to send video signals across fibre this lends itself to also include audio and data signals on the same fibre.

Digital Data
Is to refer to more than one concept. It can refer to discrete-time signals that have a discrete number of levels, for example a sampled and quantified analogue signal, or to the continuous-time waveform signals in a digital system, representing a bit-stream. In the first case, a signal that is generated by means of a digital  modulation method, which is considered as, converted to an analogue signal, while it is considered as a digital signal in the second case.

Power Supply Unit
Is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy (e.g., mechanical, chemical, solar) to electrical energy. A regulated power supply is  one that controls the output voltage or current to a specific value; the controlled value is held nearly constant despite variations in either load current or the voltage  supplied by the power supply’s energy source.

Video Recorder
A digital video recorder (DVR) or personal video recorder (PVR) is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device. The term includes set-top boxes with recording facility, portable media players (PMP) with recording facility, recorders (PMR as camcorders that record onto memory cards) and software for personal computers which enables video capture and playback to and from disk. A television set with built-in digital video-recording facilities was introduced by LG in 2007 followed by other manufacturers.

(Process Field Bus) is a standard for field bus communication in automation technology and was first promoted (1989) by BMBF (German department of education and research). It should not be confused with the PROFINET standard for Industrial Ethernet. Data rates of up to 500kb/s are standard for this communication system. This bus system is normally driven by RS485 interface units.

In telecommunications, (Recommended Standard 232) is a standard for serial binary single-ended data and control signals connecting between a DTE (Data Terminal Equipment) and a DCE (Data Communication Equipment). It is commonly used in computer serial ports. The standard defines the electrical  characteristics and timing of signals, the meaning of signals, and the physical size and pin out of connectors. This standard is no longer supported by your normal  PC. The USB port has taken over most of its function.

lso known as TIA/EIA-485 or RS-485, is a standard defining the electrical characteristics of drivers and receivers for use in balanced digital multipoint systems. The standard is published by the ANSI Telecommunications Industry Association/Electronic Industries Alliance (TIA/EIA). Digital communications networks implementing the EIA-485 standard can be used effectively over long distances (up to 1 km) and in electrically noisy environments. Multiple receivers may be connected to such a network in a linear, multi-drop configuration. These characteristics make such networks useful in industrial environments and similar applications. Only two wires are needed to carry the this signal and the protocol operates in a half duplex mode. Like talking to your mother in Law. When she speaks you shut up.

Is a common short form and former official title of American National Standards Institute (ANSI) standard ANSI/TIA/EIA-422-B and its international equivalent ITU-T Recommendation T-REC-V.11, also known as X.27. These technical standards specify the electrical characteristics of the balanced voltage digital interface circuit. RS-422 provides for data transmission, using balanced or differential signalling, with unidirectional/non-reversible, terminated or non-terminated transmission lines, point to point, or multi-drop. In contrast to EIA-485 (which is multi-point instead of multi-drop), EIA-422/V.11 does not allow multiple drivers but only multiple receivers. This is a 4 wire system that allow but rarely used data communication in both directions at the same time.

Data circuit
In telecommunication, is the transmission media and the intervening equipment used for the transfer of data between data terminal equipments (DTEs).

Sometimes referred to as X21, is an interface specification for differential communications introduced in the mid 1970s by the ITU-T. X.21 was first introduced as a means to provide a digital signalling interface for telecommunications between carriers and customers’ equipment. This includes specifications for DTE/DCE physical interface elements, alignment of call control characters and error checking, elements of the call control phase for circuit switching services, and test loops. This communication is similar to RS422 with the addition of a sync clock signal pair added to the connector. All data is then synced to the clock signal.

MUX a multiplexer or MUX
Occasionally the terms muldex or muldem are also found for a combination multiplexer-de-multiplexer, is a device that performs multiplexing; it selects one of many analogue or digital input signals and forwards the selected input into a single data line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output.

An electronic multiplexer makes it possible for several signals to share one device or resource, for example one A/D converter or one communication line, instead of having one device per input signal.

On the other end, a demultiplexer (or demux) is a device taking a single input signal and selecting one of many data-output-lines, which is connected to the single input. A multiplexer is often used with a complementary demultiplexer on the receiving end.

An electronic multiplexer can be considered as a multiple-input, single-output switch, and a demultiplexer as a single-input, multiple-output switch. The schematic symbol for a multiplexer is an isosceles trapezoid with the longer parallel side containing the input pins and the short parallel side containing the output pin. The schematic on the right shows a 2-to-1 multiplexer on the left and an equivalent switch on the right. The sel wire connects the desired input to the output.
In telecommunications, a multiplexer is a device that combines several input information signals into one output signal, which carries several communication channels, by means of some multiplex technique. A demultiplexer is in this context a device taking a single input signal that carries many channels and separates those over multiple output signals.

Telephone Circuit
Is any line, conductor, or other conduit by which information is transmitted. A dedicated circuit, private circuit, or leased line is a line that is dedicated to only one use. Originally, this was analog, and was often used by radio stations as a studio/transmitter link (STL) or remote pickup unit (RPU) for their audio, sometimes as a backup to other means. Later lines were digital, and used for private corporate data networks.
The opposite of a dedicated circuit is a switched circuit, which can be connected to different paths. A POTS or ISDN telephone line is a switched circuit, because it can connect to any other telephone number.

On digital lines, a virtual circuit can be created to serve either purpose, while sharing a single physical circuit.

Video Server
Is a computer based device (also called a ‘host’) dedicated to recording and delivering video.

Video Decoder
is a device or software that enables video compression and/or decompression for digital video. The compression usually employs lossy data compression. Historically, video was stored as an analogue signal on magnetic tape. Around the time when the compact disc entered the market as a digital-format replacement for analogue audio, it became feasible to also begin storing and using video in digital form, and a variety of such technologies began to emerge.

Fiber media converters
Are simple networking devices that make it possible to connect two dissimilar media types such as twisted pair with fiber optic cabling. They were introduced to the industry nearly two decades ago, and are important in interconnecting fiber optic cabling-based systems with existing copper-based, structured cabling systems. They are also used in MAN access and data transport services to enterprise customers.

Patch cable
Is an electrical or optical cable, used to connect (“patch-in”) one electronic or optical device to another for routing. Devices of different types (ie: a switch connected to a computer, or switch to router) are connected with patch cords. Patch cords are usually produced in many different colours so as to be easily distinguishable, and are relatively short, perhaps no longer than two metres. Types of patch cords include microphone cables, headphone extension cables, XLR connector, RCA connector and ¼” TRS connector cables (as well as modular Ethernet cables), and thicker, hose-like cords (snake cable) used to carry video or amplified signals. However, patch cords typically only refer to those short ones used with patch panels. In optical systems these patch cords come in single mode (Yellow Colour) or multimode (orange Colour).

Attenuator electronic
Is normally a non active electronic device that reduces the amplitude or power of a signal without appreciably distorting its waveform.

An attenuator is effectively the opposite of an amplifier, though the two work by different methods. While an amplifier provides gain, an attenuator provides loss, or gain less than 1.

Attenuators are usually passive devices made from simple voltage divider networks. Optic attenuators are devices that plug in series with a patch cord or panel to reduce to optic light level. It is necessary where receive equipment is installed at a short distance from the transmitter and a overdrive condition occurs. This is usually resolved in the planning phase of an installation.

Attenuator Fibre
A device that reduces signal power in a fibre optic link by inducing loss.

Attenuation in a fibre cable
The reduction in optical power as it passes along a fibre, usually expressed in decibels (dB). See optical loss. Various fibre types will have a different attenuation. See the fibre loss table. Can also be described as cable loss.

Attenuation Coefficient
Characteristic of the attenuation of an optical fibre cable per unit length, in dB/km.

Patch Panel
Is a panel, typically rack mounted, that houses cable connections. One typically shorter patch cable will plug into the front side, whereas the back holds the connection of a much longer and more permanent cable. The assembly of hardware is arranged so that a number of circuits, usually of the same or similar type, appear on jacks for monitoring, interconnecting, and testing circuits in a convenient, flexible manner. This is suitable for optic cables where bulkheads are used in the patch panel and the patch cords can easily connect to the front of the panel.

Monitoring System
In systems engineering is a process within a distributed system for collecting and storing state data.

That portion of fibre optic attenuation resulting of conversion of optical power to heat.

Average power
The average signal strength over time of a modulated signal. It is important to maintain a constant average power of a signal in order to prevent fluctuations in compensation of optic receive power in the receiver circuitry.

Return loss back reflection, optical
Light reflected from the cleaved or polished end of a Fibre caused by the difference of refractive indices of air and glass. Typically 4% of the incident light. Expressed in dB relative to incident power.

The scattering of light in a fibre back toward the source, used to make OTDR measurements. This is normally caused by poor joints, sharp corners or mismatched connectors in the cable

Bending loss, micro-bending loss
Loss in fibre caused by stress on the fibre bent around a restrictive radius.

Bit-error rate (BER)
The fraction of data bits transmitted that are received in error. The acceptable BER of a data link is normally specified using a communication standard and can be 1 in 10 power -9 bits. Tests normally run clear on fibre.

An electrical or optical pulse that carries 2 states of information.

a device used to temporary store erratic data to allow a receiver to clock it out at a constant rate.

Optic Cable
One or more fibres enclosed in protective coverings and strength members.

Cable Plant, Fibre Optic
The combination of fibre optic cable sections, connectors and splices forming the optical path between two terminal devices.

Chromatic dispersion
The temporal spreading of a pulse in an optical waveguide caused by the wavelength dependence of the velocities of light.

The lower refractive index optical coating over the core of the fibre that “traps” light into the core.

Optic Connector
A device that provides for a demountable connection between two fibres or a fibre and an active device and provides protection for the fibre.

The centre of the optical fibre through which light is transmitted.

An optical device that splits or combines light from more than one Fibre.

Cutback method
A technique for measuring the loss of bare fibre by measuring the optical power transmitted through a long length then cutting back to the source and measuring the initial coupled power.

Cutoff wavelength
The wavelength beyond which single-mode Fibre only supports one mode of propagation.

Optical power referenced to 1 milliwatt. 0dBm = 1 milliwatt

Decibel (dB)
A unit of measurement of power which indicates relative power on a logarithmic scale, sometimes called dBr. dB=10 log ( power ratio), dBv = 20Log (Voltage Ratio)

Optic Detector
A photodiode that converts optical signals to electrical signals.

The temporal spreading of a pulse in an optical waveguide. May be caused by modal or chromatic effects.

Erbium-doped Fibre amplifier, an all optical amplifier for 1550 nm SM transmission systems.

Edge-emitting diode (E-LED)
A LED that emits from the edge of the semiconductor chip, producing higher power and narrower spectral width.

End finish
The quality of the end surface of a fibre prepared for splicing or terminated in a connector.

Equilibrium modal distribution (EMD)
Steady state modal distribution in multimode Fibre, achieved some distance from the source, where the relative power in the modes becomes stable with increasing distance.

IBM standard for connecting peripherals to a computer over fibre optics. Acronym for Enterprise System Connection.

Excess loss
The amount of light lost in a coupler, beyond that inherent in the splitting to multiple output fibres.

Fibre Amplifier
An all optical amplifier using erbium or other doped fibres and pump lasers to increase signal output power without electronic conversion.

Fibre Distributed Data Interface, 100 Mb/s ring architecture data network.

A precision tube which holds a Fibre for alignment for interconnection or termination. A ferrule may be part of a connector or mechanical splice.

Fibre tracer
An instrument that couples visible light into the Fibre to allow visual checking of continuity and tracing for correct connections.

Fibre identifier
A device that clamps onto a Fibre and couples light from the fibre by bending, to identify the fibre and detect high speed traffic of an operating link or a 2 kHz tone injected by a test source.

Fibre optics
Light transmission through flexible transmissive fibres for communications or lighting.

Common abbreviation for “Fibre optic.”

Optical Loss
The amount of optical power lost as light is transmitted through Fibre, splices, couplers, etc.

Optical return loss, back reflection
Light reflected from the cleaved or polished end of a Fibre caused by the difference of refractive indices of air and glass. Typically 4% of the incident light. Expressed in dB relative to incident power.

Fusion splicer
An instrument that splices fibres by fusing or welding them, typically by electrical arc.

Graded index (GI)
A type of multimode fibre which used a graded profile of refractive index in the core material to correct for dispersion.

Index profile
The refractive index of a fibre as a function of cross section.

Insertion loss
The loss caused by the insertion of a component such as a splice or connector in an optical Fibre.

The protective outer coating of the cable.

Jumper cable
A short single Fibre cable with connectors on both ends used for interconnecting other cables or testing.

Laser diode, ILD
A semiconductor device that emits high powered, coherent light when stimulated by an electrical current. Used in transmitters for singlemode Fibre links.

Launch cable
A known good Fibre optic jumper cable attached to a source and calibrated for output power used as a reference cable for loss testing. This cable must be made of Fibre and connectors of a matching type to the cables to be tested.

Light-emitting diode, LED
A semiconductor device that emits light when stimulated by an electrical current. Used in transmitters for multimode Fibre links.

Fibre optic Link
A combination of transmitter, receiver and Fibre optic cable connecting them capable of transmitting data. May be Analogue or digital.

Long wavelength
A commonly used term for light in the 1300 and 1550 nm ranges.

Loss budget
The amount of power lost in the link. Often used in terms of the maximum amount of loss that can be tolerated by a given link.

The additional amount of loss that can be tolerated in a link after the transmitter and receiver specifications have been taken into consideration. One would normally require 33% safe margin.

Mechanical splice
A semi-permanent connection between two fibres made with an alignment device and index matching fluid or adhesive.

Micron (μm)
A unit of measure, 10-6 m, used to measure the core of a fibre.

Used in Fibre optic inspection. A microscope used to inspect the end surface of a connector for flaws or contamination or a fibre for cleave quality.

A single electromagnetic field pattern that travels in Fibre. Mode field diameter: A measure of the core size in single mode fibre. Mode filter: A device that removes optical power in higher order modes in fibre. Mode scrambler: A device that mixes optical power in Fibre to achieve equal power distribution in all modes. Mode stripper: A device that removes light in the cladding of an optical fibre. Modal dispersion: The temporal spreading of a pulse in an optical waveguide caused by modal effects.

Nanometer (nm)
A unit of measure , 10-9 m, used to measure the wavelength of light.

A system of cables, hardware and equipment used for communications.

Numerical aperture (NA)
A measure of the light acceptance angle of the Fibre.

Optical amplifier
A device that amplifies light without converting it to an electrical signal.

Optical Fibre
An optical waveguide, comprised of a light carrying core and cladding which traps light in the core.

Optical loss test set (OLTS)
An measurement instrument for optical loss that includes both a meter and source.

Optical power
The amount of radiant energy per unit time, expressed in linear units of Watts or on a logarithmic scale, in dBm (where 0 dB = 1 mW) or dB* (where 0 dB*=1 microwatt).

Optical switch
A device that routes an optical signal from one or more input ports to one or more output ports.

Optical time domain reflectometer
(OTDR) An instruments that used backscattered light to find faults in optical fibre and infer loss.

Overfilled launch
A condition for launching light into the fibre where the incoming light has a spot size and NA larger than accepted by the fibre, filling all modes in the Fibre.

A semiconductor that converts light to an electrical signal, used in Fibre optic receivers.

A short length of fibre attached to a fibre optic component such as a laser or coupler.

Plastic optical Fibre (POF)
An optical fibre made of plastic.

Plastic-clad silica (PCS) Fibre
A fibre made with a glass core and plastic cladding.

Power budget
The difference (in dB) between the transmitted optical power (in dBm) and the receiver sensitivity (in dBm).

Power meter, Fibre optic
An instrument that measures optical power emanating form the end of a fibre.

The large diameter glass rod from which fibre is drawn.

Receive cable
A known good fibre optic jumper cable attached to a power meter used as a reference cable for loss testing. This cable must be made of fibre and connectors of a matching type to the cables to be tested.

A device containing a photodiode and signal conditioning circuitry that converts light to an electrical signal in fibre optic links.

Refractive index
A property of optical materials that relates to the velocity of light in the material.

Repeater, regenerator
A device that receives a fibre optic signal and regenerates it for retransmission, used in very long fibre optic links.

The change of direction of light after striking small particles that causes loss in optical fibres.

Short wavelength
A commonly used term for light in the 665, 790, and 850 nm ranges.

A laser diode or LED used to inject an optical signal into Fibre.

Splice (fusion or mechanical)
A device that provides for a connection between two fibres, typically intended to be permanent.

Splitting ratio
The distribution of power among the output fibres of a coupler.

Steady state modal distribution
Equilibrium modal distribution (EMD) in multimode Fibre, achieved some distance from the source, where the relative power in the modes becomes stable with increasing distance.

Step index Fibre
A multimode fibre where the core is all the same index of refraction.

Surface emitter LED
A LED that emits light perpendicular to the semiconductor chip. Most LEDs used in data communications are surface emitters.

Talkset, Fibre optic
A communication device that allows conversation over unused fibres.

Preparation of the end of a fibre to allow connection to another fibre or an active device, sometimes also called “connectorisation”.

Test cable
A short single fibre jumper cable with connectors on both ends used for testing. This cable must be made of fibre and connectors of a matching type to the cables to be tested.

Test kit
A kit of fibre optic instruments, typically including a power meter, source and test accessories used for measuring loss and power.

Test source
A laser diode or LED used to inject an optical signal into fibre for testing loss of the fibre or other components.

Total internal reflection
Confinement of light into the core of a fibre by the reflection off the core-cladding boundary.

A device which includes a LED or laser source and signal conditioning electronics that is used to inject a signal into fibre.

Vertical cavity surface emitting laser, a type of laser that emits light vertically out of the chip, not out the edge.

Visual fault locator
A device that couples visible light into the fibre to allow visual tracing and testing of continuity. Some are bright enough to allow finding breaks in fibre through the cable jacket.

A linear measure of optical power, usually expressed in milliwatts (mW), microwatts (*W) or nanowatts (nW).

A measure of the colour of light, usually expressed in nanometres (nm) or microns (*m).

Wavelength division multiplexing
(WDM) A technique of sending signals of several different wavelengths of light into the fibre simultaneously.

Working margin
The difference (in dB) between the power budget and the loss budget (i.e. the excess power margin).


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