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To use the glossary, simply click on the first letter of
the term of interest below:
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.
To use the glossary, click on the first letter of
the term of interest:
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© 2006 - 2008 Acleris
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