Octet - In packet-switched networks, a grouping of eight bits; similar but not identical by byte.
OD - Outside diameter.
ODBC (open database connectivity) - ODBC is a widely accepted application programming interface (API) for databases using structured query language (SQL).
ODI (open data link interface) - Novell’s media-and-protocol-independent communications specification providing a standard interface that allows transport protocols to share a network interface card without conflict.
OEM - Original equipment manufacturer.
OFDM - Orthogonal frequency division multiplexing.
OFDM - Orthogonal frequency division multiplexing.
OFHC - Oxygen-free high-conductivity copper.
OFL (overfilled launch) - Standard for MMF when used with LEDs (uses 100 percent of core).
Ohm - (W) The electrical unit of resistance. The value of resistance through which a potential difference of one volt will maintain a current of one ampere.
Ohm’s law - Stated E=IR, I=E/R, or R=E/I where E is voltage, I is current and R is resistance.
OID - Object ID.
Oil aging - Cable aged in an accelerated manner by placement in an oil bath and heated to a preset temperature for a stated time.
OLT (optical line terminator) - In EFM applications, an aggregation device, usually located at the CO, that uses passive optical splitting from one fiber from a CO Ethernet switch to individual fibers feeding homes.
OM3 - ISO/IEC 11801 specification for laser optimized multimode fiber type for 10 Gbps applications.
Online computer - A computer used for online processing.
ONT (optical network terminal) - Fiber terminal outside a residence in FTTH application. Conversion point from fiber to copper.
ONU (optical network unit) - In an EPON system the ONU provides the functionality to connect the fiber owned by the service provider to the media in the residence.
Open architecture - An architecture that is compatible with hardware and software from any of many vendors. Contrast with CLOSED ARCHITECTURE.
Open cell - Foamed or cellular material with broken cell walls. Air fills in the spaces in the material. Usually softer and less expensive than closed cell material.
Open circuit - A break in an electrical circuit so that there can be no current flow.
Optical conductor - Materials that offer a low optical attenuation to transmission of light energy.
Optical connector - Connector designed to connect and disconnect either single or multiple optical fibers repeatedly. Optical connectors are used to connect fiber cable to equipment and interconnect cables. (Examples are: ST, SC, SMA, etc.)
Optical cross-connect - A cross-connect unit used for circuit administration and built from modular cabinets. It provides for the connection of individual optical fibers with optical fiber patch cords.
Optical encoder - A device whose position is determined by a photoelectric device and converted to an electrical data output.
Optical fiber connector - See OPTICAL CONNECTOR.
Optical fiber duplex adapter - A mechanical media termination device designed to align and join two duplex connectors.
Optical fiber duplex connection - A mated assembly of two duplex connectors and a duplex adapter.
Optical fiber duplex connector - A mechanical media termination device designed to transfer optical power between two pairs of optical fibers.
Optical fiber - Any filament or fiber, made of dielectric materials that is used to transmit light signals; optical fiber usually consists of a core, which carries the signal and cladding, a substance with a higher refractive index than the core, which surrounds the core and serves to reflect the light signal. See also FIBER OPTICS.
Optical interconnect - An interconnection unit used for circuit administration and built from modular cabinets. It provides interconnection for individual optical fibers, but unlike the optical cross connect panel, it does not use patch cords. The optical interconnect provides some capability for routing and rerouting circuits, but is usually used where circuit rearrangements are infrequent.
Optical splice - A fiber optic splice provides the means by which two or 24 fiber optic cable ends are permanently joined together. Two types of optical splices are fusion and mechanical.
Optical transceiver - An optical device which both transmits and receives data over optical fiber.
Optical waveguide - A fiber used for optical communications. Analogous to a waveguide used for microwave communications.
Optimization - The procedure used in the design of a system to maximize or minimize some performance index.
ORL - Optical return loss.
OS/2 - An operating system developed by IBM, largely relegated to niche uses and virtualization applications.
Oscillatory surge - A surge that includes both positive and negative polarity values.
Oscilloscope - Test instrument for visually showing the changes in a varying voltage by means of a line made on a fluorescent screen using the deflection of a beam of cathode rays.
OSHA (Occupational Safety and Health Act) - Federal Law #91-596 or 1970 charging all employers engaged in business affecting interstate commerce to be responsible for providing a safe working place. It is administered by the Department of Labor. OSHA regulations are published in Title 29, Chapter XVIII, Part 1910 of the CFR and the Federal Register.
OSI (open systems interconnection) - The OSI reference model for a logical structure for network operations standardized with the ISO; a 7-layer network architecture being used for the definition of network protocol standards to enable any OSI-compliant computer or device to communicate with any other OSI-compliant computer or device for an exchange of information.
OSMOSIS - The diffusion of fluids through membranes.
OTDR (Optical Time Domain Reflectometer) - An instrument that locates faults in optical fibers or infers attenuation from backscattered light measurements.
Out gassing - Dissipation of gas from a material.
Outdoor termination - A cable termination intended for use where it is not protected from direct exposure to either solar radiation or precipitation.
Outlet box, telecommunications - A metallic or nonmetallic box mounted within a wall, floor or ceiling and used to hold telecommunications outlets, connectors or transition devices.
Outlet/connector, telecommunications - A connecting device in the work area on which horizontal cable terminates.
Out-of-band signaling - A method of signaling which uses a frequency that is within the pass band of the transmission facility, but outside of a carrier channel normally used for information transmission.
Output - The useful power to signal delivered by a circuit or device.
Overall diameter - Finished diameter of a wire or cable.
Overcoat conductor - A stranded conductor made from individual strands of tin-coated wire stranded together and then given an overall tin coat.
Overlap - The amount the trailing edge laps over the leading edge of a spiral tape wrap.
Oxygen index - A test to rate flammability of materials in a mixture of oxygen and nitrogen. More formally referred to as limiting oxygen index (LOI).
Ozone - An extremely reactive form of oxygen, normally occurring around electrical discharges and present in the atmosphere in small but active quantities. In sufficient concentrations it can break down certain insulations.