To use the glossary, simply click below on the first letter of the term of interest:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Q

QAM

Quadrature Amplitude Modulation.

QCIF

Quarter Common Intermediate Format. Describes a subset of the type of coded video signals transmitted when using ITU-T H.261 and H.263 coding methods. See CIF.

QoS

Quality of Service which includes technical performance parameters like differential phase, latency, phase jitter or error distribution, together with worst-case performance values for each.

QPSK

Quadrature Phase Shift Keying, a modulation method used for digital satellite transmission.

Quantization

The process of dividing a continuous range of signal values into larger, less granular, contiguous parts, a unique value being assigned to each part. The process assigns the same digital value to two or more of the original adjacent digital values. Quantizing is used as part of a lossy coding algorithm.

 

Quantizers may be linear, non-linear or dynamic, depending upon the circumstances and application.

R

R - Y

Red minus luminance (Y). One of the two color signals used in encoding television signals.

RADSL

Rate-Adaptive Digital Subscriber Line, a form of xDSL, it provides full duplex asymmetrical connectivity at 7.0 Mbps from the network, and 1 Mbps to the network over distances up to 5.5 Km (3.4 miles). This type of transmission supports telephony over the same physical pair as does ADSL. Like a standard dial-up modem, RADSL can change its maximum bit rate in response to changing line conditions.

Rapid Deployment System

A telecommunications system often including videoconferencing and a variety of data capabilities, packaged in air-transportable containers and permitting rapid setup. These systems are intended for establishing telecommunications and videoconferencing in emergency and crisis situations.

RBOC

Regional Bell Operating Company (USA)

Receive-Only Codec

A video codec able only to receive communications signals and process them for local output. Primarily used at receive locations in point-to-multipoint or broadcast applications such as DBS where two-way communication with the sending location is not required. Security systems also use receive-only codecs.

Recursive filtering

A method of motion video noise reduction developed by the BBC; the hardware was known as a Digital Noise Reducer (DNR), manufactured by Pye (UK). Random noise is identified by its lack of connection to similar values of picture elements adjacent to it or, between successive video frames and at similar coordinates. Such pixels identified as noise may then be removed by replacing them with the average value of the surrounding pixels.

Redundancy (telecommunications)

Alternative and/or duplicate transmission paths, routes, equipment and power in various combinations to enhance the reliability of a telecommunications infrastructure.

Redundant (information)

Video data information that does not change over a certain time interval (temporally redundant) or video data information where a given pixel is surrounded with similar pixels (spatially redundant).

Reed-Solomon Code

A forward-error correction technique used for satellite transmission and CD recordings, especially effective for error bursts.

Restricted Channel

A digital communications channel for which each p or B channel (ITU-T usage) gives a usable capacity of 56 Kbps instead of 64 Kbps. Still sometimes used in North America, this is a remnant of the ones-density limitation of early T1 carrier facilities.

RFI (project management usage)

Request For Information.

RFI (electro-magnetic usage)

Radio Frequency Interference.

RFP

Request For Proposal.

RFQ

Request For Quotation.

RGB Video Signal

A video signal where the red (R), green (G) and blue (B) picture components are present as individual signals. Synchronization information may be separate or included with the G signal.

RGB/N

An RGB video signal based on the NTSC 525-line scanning rates.

RGB/P

An RGB video signal based on the PAL 625-line scanning rates.

RISV

Reference Impairment System for Video. RISV is used to simulate video compression impairments, independent of the compression scheme in preparation for P.910 video subjective testing.

RJ-11

USOC Registered Jack #11; a North American standard 4-wire modular telephone jack.

RMS

Root Mean Square

ROM

Read-Only Memory. A type of semiconductor memory device that stores unalterable data or program information. ROMs are best suited to large volume applications, and are often programmed using a custom mask as part of the IC lithography process.

RTP

Real-time Transport Protocol.

RTSP

Real-Time Streaming Protocol.

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