A metallic ring which will be mechanically shaped to pro-vide retention of the coaxial cable braid and jacket onto "F" type connectors. They are usually incorporated into these connectors.[Arr11] Crimp Tool
A tool used to provide retention of an "F" type connector onto the braid and jacket of a drop cable.[Arr11]
In geometric optics, at a refractive boundary, the smallest angle of incidence at which total internal reflection occurs. [Fib111]
Distance along a specific cable to cause worst-case mismatch reflection. A function of frequency-attenuation-velocity of propagation parameters of specific cable types. CRL Certificate Revocation List
The physical connection between patch panels or punch-down blocks that facilitates connections from systems and feeds to drops. [Lin07] Connections between terminal blocks on the two sides of a distribution frame or between terminals on a terminal block (also called straps). Also called cross-connection or jumper. [Fib111]
A form of television signal distortion where modulation from one or more television channels is imposed on another channel or channels. Also referred to as XMOD.
Cross-gain Modulation (XGM)
A technique used in wavelength converters where gain saturation effects in an active optical device, such as a semiconductor optical amplifier (SOA), allow the conversion of the optical wavelength. Better at shorter wavelengths (e.g. 780 nm or 850 nm). [Fib111] Cross-phase Modulation (XPM)
A fiber nonlinearity caused by the nonlinear index of refraction of glass. The index of refraction varies with optical power level which causes different optical signals to interact. [Fib111]
Ownership of two or more kinds of communications outlets by the same individual or business. The FCC prohibits television stations and telephone companies from owning cable systems in their service areas. Television networks are prohibited from owning cable systems anywhere in the U.S. Crosstalk
Noise passed between communications cables or device elements. 1) Undesired coupling from one circuit, part of a circuit, or channel to another. 2) Any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates and undesired effect in another circuit or channel. [Fib111]
Cathode Ray Tube
The process of recovering the plaintext of a message or the encryption key without access to the key.
An algorithm used to transfer text between plaintext and ciphertext.
Common Scrambling Algorithm
Call State Control Function
CSD Circuit Switched Data
CSMA/CD Carrier Sense Multiple Access with Collision Detection; a network control protocol in which (a) a carrier sensing is used and (b) while a transmitting data station that detects another signal while transmitting a frame, stops transmitting that frame, waits for a jam signal, and then waits for a random time interval before trying to send that frame again. [Fib111]
Channel Service Unit; A digital interface device that connects end-user equipment to the local digital telephone loop. CSU is frequently coupled with DSU (see below) as CSU/DSU. [Sat07]
Circuit Switched Voice
Carrier-to-noise-Temperature ratio. [Sat07]
CTB Composite Triple Beat CTIA
Cellular Telecommunications Industry Association
CTP Compliance Test Plan
Clear To Send; in a communications network, a signal from a remote receiver to a transmitter that it is ready to receive a transmission. [Fib111] Current, Alternating (AC)
An electric current that periodically reverses the direction of electron flow. The rate at which a full cycle occurs in a given unit of time (generally a second) is called the frequency of the current.[Arr11] Current, Direct (DC)
Electrical current whose electrons flow in one direction only. It may be constant or pulsating as long as the movement is in the same direction.[Arr11] Custom Local Area Signaling Services (CLASS)
This term refers to a set of voice telephony services that make use of information about the calling or called numbers. Examples are caller ID, Automatic recall (*69), anonymous call rejection, etc.
Customer Premises Equipment (CPE)
Equipment at the end user's premises; MAY be provided by the end user or the service provider.
Customer Service Representative (CSR)
Customer service representative.
A technique of measuring optical fiber attenuation by measuring the optical power at two points at different distances from the test source. [Fib111]
That frequency beyond which no appreciable energy is transmitted. It may refer to either an upper or lower limit of a frequency band.
In single-mode fiber (SMF), the wavelength below which the fiber ceases to be single-mode. [Fib111]
CVC Code Verification Certificate
CW Control Word
Continuous Wave; usually refers to the constant optical output from an optical source when it is biased (i.e., turned on) but not modulated with a signal. [Fib111]
One complete sequence of values of an alternating wave starting at zero, increasing to a maximum positive value, decreasing to zero, increasing to a maximum negative value, and decreasing to zero again. Also called a Hertz (Hz). [Arr11] Cyclic Redundancy Check (CRC)
An algorithm to detect data corruption.
A format for component digital video tape recording working to the ITU-R 601, 4:2:2 standard using 8-bit sampling. [Fib111] D2
The VTR standard for digital composite (coded) NTSC or PAL signals that uses data conforming to SMPTE 244M. [Fib111] D3
A composite digital video recording format that uses data conforming to SMPTE 244M. [Fib111] D5
An uncompressed tape format for component digital video which has provisions for HDTV recording by use of 4:1 compression. [Fib111]
An ISDN Data channel is a data connection between the telephone company's switching equipment and a customer's ISDN equipment. It carries telephone connection information—signals to tell your equipment that a call is coming in and carry dialing and call handling information to the phone company's equipment— and can also be used to carry multiple low-speed data connections using the X.25 packet-switching protocol. DAC
Digital-to-Analog Converter; a device used to convert digital signals to analog signals. [Fib111]
Digital-to-Analog Converter (DAC) Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/d
Demand-Assigned Multiple Access; A highly efficient means of instantaneously assigning telephony channels in a transponder according to immediate traffic demands. [Sat07] Dark Current
The current through the photodiode in the absence of light, when it is operated in photoconductive mode. The dark current includes photocurrent generated by background radiation and the saturation current of the semiconductor junction. Dark current must be accounted for by calibration if a photodiode is used to make an accurate optical power measurement, and it is also a source of noise when a photodiode is used in an optical communication system. [Wki11] Dark fiber
Unused fiber-optic cable that has been deployed but does not have the proper electronic and optical equipment to carry optical (light) signals. Generally considered to be extra fiber that will support future demand for communications capacity. DASE Digital Application Software Environment
The movement of encoded information by means of electrical transmission systems. The transmission of data from one point to another over communication channels.
A technique that saves storage space by eliminating gaps, empty fields, redundancies, or unnecessary data to shorten the length of records or blocks.
Data Dependent Jitter (DDJ)
Also called data dependent distortion. Jitter related to the transmitted symbol sequence. DDJ is caused by the limited bandwidth characteristics, non-ideal individual pulse responses, and imperfections in the optical channel components. [Fib111] Data Link
A fiber optic transmitter, cable and receiver that transmits digital data between two points.[Arr11] Data Link Layer
Layer 2 in the Open System Interconnection (OSI) architecture; the layer that provides services to transfer data over the transmission link between open systems.
The number of bits of information in a transmission system, expressed in bits per second (b/s or bps), and which may or may not be equal to the signal or baud rate. [Fib111]
Data Over Cable Service Interface Specifications (DOCSIS®)
Specification for transmission of data over a cable network that has been approved by the ITU as an international standard. DOCSIS® was developed by CableLabs and a consortium of North American multi-system cable operators.
DAVIC Digital Audio Visual Council
dB Decibel DBA
Dynamic Bandwidth Allocation
A measure of spurious signal level. The level is measured relative to the nominal unmodulated carrier level.[Arr11] dBi
Decibel-isotropic; a unit of measure that expresses a ratio of power, measured in decibels, referring to the gain or loss relative to a dipole antenna.[Arr11] dBµV
dB micro volts. A measurement of ‘x dBµV’ indicates that the signal is x dB above one microvolt in 75 ohms. To convert x microvolts to dBµV: dBµV = 20 log (x microvolts). [Blo10] dBm
dB milli volts. A measure of signal amplitude. 0 dBmV is equivalent to 1 mV RMS across the given impedance (usually 75 Ohms).[Arr11]. dBmV and dBµV are expressions of power that contain an upper case “V”. This does not mean they are expressions of voltage. They are expressions of power. When all the power scales (dBm, dBmV and dBµV) are laid next to each other, it is easy to see that each track on a dB for dB basis. A power measurement of ‘x dBmV’ indicates that a particular signal is x dB greater than (‘above’) 1 millivolt in 75 ohms. A negative dBmV value indicates that the signal is x dB less than (‘below’) 1 millivolt in 75 ohms. To convert x millivolts to dBmV: dBmV = 20 log (x millivolts)[Blo10] dBRL
Return loss as measured with a TDR and expressed in dB. It is the ratio of power levels between an outgoing pulse and its reflection. This unit of measure can assist in determining the severity of a cable fault.[Arr11] DBS Direct Broadcast Satellite; also referred to as SATCOM-DBS. An alternative to cable and analog satellite reception that uses a fixed 18-inch dish focused on one or more geostationary satellites. DBS units receive multiple channels of multiplexed video and audio signals as well as programming information and related data. Also known as digital satellite system. [Fib111] dBW
The ratio of the power to one Watt expressed in decibels. [Sat07] DC
Direct current. See also current, direct. DCD
Duty Cycle Distortion Jitter [Fib111] DC Power Block
A device which stops the flow of dc power but permits passage of higher frequency ac signals. [Cha07]
Digital Certificate Authorization Agreement
Data Circuit-terminating Equipment. 1) In a data station, the equipment that performs functions such as signal conversion and coding, at the network end of the line between the data terminal equipment (DTE) and the line, and may be a separate or an integral part of the DTE or of intermediate equipment. 2) The interfacing equipment that may be required to couple the data terminal equipment (DTE) into a transmission circuit or channel and from a transmission circuit of a channel into the DTE. [Fib111]
Digital Cable Ready
Discrete Cosine Transform [Fib111] DDE-1 Declarative Data Essence DDJ
Data Dependent Jitter [Fib111] Dead Zone
Period of time after a reflected pulse is detected before another feature may be measured.[Arr11] De-BPSK
Differential Binary Phase Shift Keying [Sat07] Decibel (dB)
A unit to measure the relative levels of current, voltage or power. An increase of 3 dB indicates a doubling of power, an increase of 10 dB indicates a 10x increase in power, and an increase of 20 dB indicates a 100x increase in power.
The standard unit used to express the ratio of two power levels. It is used in communications to express either a gain or loss in power between the input and output devices. [Sat07] Decipherment
A procedure applied to ciphertext to translate it into plaintext.
The offset angle of an antenna from the axis of its polar mount as measured in the meridian plane between the equatorial plane and the antenna main beam. [Sat07]
Declarative Data Essence (DDE-1)
A standard by SMPTE (Society of Motion Picture and Television Engineers) formalizing Advanced Television Enhancement Forum (ATVEF).
A device used to convert data by reversing the effect of previous coding. [Fib111] Decryption
A procedure applied to ciphertext to translate it into plaintext. Decryption Key
The key in the cryptographic algorithm to translate the ciphertext to plaintext.
Digital Enhanced Cordless Telecommunications
Reinstatement of a uniform baseband frequency response following demodulation. [Sat07] De-Emphasis
The restoration of a pre-emphasized signal wave to its original form (see Pre-Emphasis). [Cha07] Deep Well GaAs
Processing of Gallium Arsenide (GaAs) based III-V semiconductor material to create a quantum well, rib, or trench within the material for use as a waveguide suitable for optical transmission. [Rob91]
Schematic GaAs-AIGaAs Rib Waveguide, with loss mechanisms indicated: (1) epilayer roughness, (2) substrate leakage, (3) rib sidewall roughness, and (4) defect and impurity absorption. Rib width W, and height h are shown. Courtesy of IEEE Journal of Quantum Electronics, Volume 27, Number 3, March 1991, “Low-Loss III-V Semiconductor Optical Waveguides”, Robert J. Deri and Eli Kapon
The elapsed time between the instant when user information is submitted to the network and when it is received by the user at the other end. Delay Distortion
Distortion resulting from non-uniform speed of transmission of the various frequency components of a signal; i.e., the various frequency components of the signal have different times of travel (delay) between the input and the output of a circuit. Also known as Group Delay Distortion.
An effect of multi-path for a digital interface in which multiple reflections of the same signal arrive at the receiver at different times, creating a noticeable degradation in signal quality.
The point of demarcation between equipment and facility or between outside plant facilities and premises distribution.[Arr11] Demodulation
The extraction of the modulation or information from a radio-frequency current.
Breakdown of television viewers by such factors as age, sex, income levels, education and race.
A module that separates two or more signals previously combined by compatible multiplexing equipment. [Fib111]
Dense Wavelength Division Multiplexing (DWDM)
A technology that provides, in fiber, the equivalent of frequency division multiplexing in metallic wire. Separate parallel channels are transmitted on a single fiber, with one wavelength for each channel. Current products enable 16 channels of 2.5Gb each for a total of 50Gb per fiber. DWDM can operate over existing single-mode fiber, and therefore reduce upgrade costs. DWDM permits transmission of closely spaced wavelengths in the 1550 nm region over a single optical fiber. Wavelength spacings are usually 100 GHz or 200 GHz which corresponds to 0.8 nm or 1.6 nm. DWDM bands include the C-Band, the S-Band, and the L-Band. See also Coarse Wavelength Division Multiplexing (CWDM). [Fib111]
DWDM Diagram courtesy of Fiber Optics Info, http://www.fiber-optics.info/fiber_optic_glossary/d