Glossary Terms Beginning C

0-9 : A : B : C : D : E : F : G : H : I : J : K : L : M

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C/N: See Carrier-to-noise ratio.
Capacity: Satellite bandwidth or channel.
Carrier; carrier frequency: Continuous (usually high-frequency) electromagnetic wave which can be modulated by a baseband signal to carry information; main frequency on which a voice, data or video signal is sent.
Carrier-to-noise ratio: C/N: the ratio of the received carrier power and the noise power in a given bandwidth, expressed in dB. Cascading Concatenating connection of devices.
C-band: Frequencies in the 4-6 GHz range, used both for terrestrial microwave links and satellite links.
CCIR-601: Recommendation developed by the CCIR for the digitization of colour video signals; now ITU-R BT.601
CDMA: Code division multiple access: refers to a multiple-access scheme where the transmission process uses spread-spectrum modulations and orthogonal codes to avoid the signals interfering with one another.
Centre frequency: Frequency of the centre of a channel on a satellite transponder.
CEPT: Conference Europeane des Administrations des Postes et des Telecommunications.
CES: Coast earth station: alternative term for LES in INMARSAT system.
CFR: Code of Federal Regulations (US).
Chain: Transmission path; usually in an SNG uplink referring to the equipment that makes up the transmission channel.
Channel: Specific frequency range in which a signal is transmitted in a satellite transponder.
Check-bits: Data bits added for error detection.
Chip-set: Set of integrated circuit devices which form the heart of a compression encoder.
Chrominance: Colour signal.
CIF: Common intermediate format: developed so that computerized video images could be shared from one computer to another. An image that is digitized to CIF format has a resolution of 352 × 288 or 352 × 240, which is essentially one-half of CCIR-601.
Circular polarization: Geometric plane in which the electromagnetic signals are transmitted. Circular polarization can be either clockwise (left-hand circular polarization, or LHCP) or counter-clockwise (right-hand circular polarization, or RHCP).
Clamp: Video processing circuit that removes the energy dispersal signal component from the video waveform.
Clarke Belt; Clarke Orbit: Geostationary orbit; named in honour of Arthur C. Clarke.
Clean carrier: Unmodulated carrier signal.
Cleanfeed: Studio audio output transmitted to the remote site so that the reporter is able to conduct a two-way dialogue with the studio presenter. Also called IFB, mix-minus, return sound or return audio.
Cliff-edge effect: Describes the fact that digital signals suffer from achieving either perfect results or nothing: as a digital signal passes a particular threshold, the signal fails catastrophically with no warning.
Coax: Coaxial cable, used for carrying signals at frequencies from video baseband up to IF.
Codec: COder/DECoder: a device which converts an analogue signal into or from a digital signal.
Coding delay: See Latency.
Coding order: Order in which a group of pictures is coded in a digital compression process.
Coefficient: Mathematical term for a number with a particular algebraic significance.
Co-located: Where a number of satellites share the same geostationary orbital assignment.
Common carrier: Regulated telecommunications company which will carry signals for a fee; common carriers include telephone companies as well as owners of communications satellites.
Companding: COMpressing/exPANDING: a noise-reduction technique that applies compression at the transmitter and complementary expansion at the receiver.
Compression: Process of removing redundant data to minimize the use of bandwidth, ideally without visibly or audibly degrading the programme.
Convolutional code: Type of error correction code used in digital coding.
Cross-modulation: Form of signal distortion in which modulation from one or more RF carrier(s) is imposed on another carrier.
Cross-polar discrimination: XPD: measurement of immunity from interference from signals on the opposite polarization; describes the ratio of (wanted) signals on the desired polarization compared to the (unwanted) signals on the opposite polarization.
Cross-polar interference: XPI: interference from signals in the same transponder (IPs) or adjacent transponders, and signals at similar frequencies but on the opposite polarization – related to XPD
Cross-strapping: Process on-board a satellite where an uplinked signal in one frequency band is converted to a different frequency band for the downlink, e.g. C-band uplink to Ku-band downlink.
Cross-talk: Unwanted leakage of signal from one channel to another.