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  • Acleris' -- Telecommunications Glossary -- IDSL to IXC
    UK IEEE Institute of Electrical and Electronics Engineers New York City USA formerly IRE Institute of Radio Engineers Interoperability The degree of compatibility among devices required to operate with one another with reference to a specified feature set or standard This is an important consideration when mixing non ITU T compliant systems from different manufacturers or when mixing ITU T compliant systems from different manufacturers which often may support different capabilities allowable within the standards Remember that many ITU T systems revert to the highest common denominator for interability IP Internet Protocol packet transmission standard for the transmission of data voice video and other information over the Internet IP PBX IP Private Branch Exchange A telephone data and video switching system usually located on customer premises and belonging to the user Makes use of technologies like VoIP H 323 and Ethernet IR InfraRed that portion of the electromagnetic spectrum adjacent to the visible light spectrum and with longer wavelengths IR is often used for optical communications over FOTS or through the air IRD Integrated Receiver Decoder the device to receive and decode television signals from DTH direct to home broadcast satellites or MMDS wireless cable systems IRE Scale Units Institute of Radio Engineers scale units A standard measure of NTSC video signal amplitudes for which 140 IRE scale units equals 1 00 volt peak to peak ISDN Integrated Services Digital Network see also BRI and PRI A switched digital service using a 16 Kbps D channel for signaling and two or more 64 Kbps or 56 Kbps some US B channels for data transmission ISM Industrial Scientific and Medical unlicensed radio bands ISO International Standards Organization Geneva CH ITU R formerly CCIR An International Telecommunications Union United Nations international telecommunications standards setting body specializing in radio spectrum usage ITU T

    Original URL path: http://acleris.com/info/glossary2-i.html (2016-04-29)
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  • Acleris' -- Telecommunications Glossary -- JPEG to Ku-Band
    for storage and transmission of a wide variety of still graphics image formats Currently used by digital cameras and is commomly used for graphics on the Internet In telecommunications and videoconferencing JPEG may be used in conjunction with fully compliant ITU T codecs and includes both lossy and lossless modes Note that so called motion JPEG is a proprietary method of motion video transmission and is not a standard K Kbps Kb s Kilobits thousands of bits per second One kilobit contains 1 024 bits 2 10 bits KBps KB s KiloBytes thousands of bytes or octets per second One kilobyte contains 1 024 bytes 2 10 bytes Key A sequence of symbols applied to data in order to provide encryption Sometimes referred to as the seed KG Key Generator A device external to a codec or other telecommunications equipment for maintaining the security of classified communications using encryption techniques Provides much better security than DES and is generally used only by the military NASA NATO and some military contractors KHz KiloHertz analog thousands of cycles per second Ku band A microwave frequency band When used for satellite links the frequencies assigned are uplink to the satellite 14 0 14

    Original URL path: http://acleris.com/info/glossary3.html (2016-04-29)
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  • Acleris' -- Telecommunications Glossary -- LAN to LZW
    audio and or visual communications In shared bandwidth transmission environments it is possible to encounter latency which varies dynamically caused by perhaps a single user accessing or originating multi megabyte sized files or accessing high bandwidth streaming signals LCD Liquid Crystal Display A very low power device capable of displaying characters words and symbols often built into a telecommunications equipment control panels LCP Link Control Protocol PPP usage LCR Least Cost Routing LDAP Lightweight Directory Access Protocol developed at the University of Michigan as a front end to the more complex ITU T X 500 directory protocol formalized in 1995 in RFC 1777 It includes five models data organization security function and topology It is useful for a wide range of uses including simple dialing directories and indexing large databases LEC Local Exchange Carrier LEO Low Earth Orbit non geosynchronous satellites used for communications and other purposes Lip Sync The maintenance of sound i e speech exactly in step with movement in a visual image e g talking heads A common cause is different transmission paths and transmission technologies for the sound and image signals Within codec hardware the processing time for the video portion of the signal is about 100 times longer than the audio processing time Consequently codecs usually incorporate adjustable audio delay circuitry to delay equalize the two signals to maintain lip sync LMCS Local Multipoint Communication System another version of MMDS or wireless cable TV a term used in Canada Data rates can be as high as 155 Mbps compared to 64 Kbps cell phones and depending on jurisdiction may operate between 2 GHz and 42 GHz with up to 3 GHz of spectrum available LMDS Local Multipoint Distribution Service a broader band higher frequency version of MMDS or wireless cable TV Data rates can be

    Original URL path: http://acleris.com/info/glossary3-l.html (2016-04-29)
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  • Acleris' -- Telecommunications Glossary -- Mbps to MWS
    estimated vectors must terminate within the image while in H 263 they may extend outside the image bounds Important at lower transmit bit rates optional in H 261 MPEG Motion Pictures Experts Group an ISO image standards group MPEG1 MPEG1 is the first of a family of motion video and audio compression standards It provides DCT lossy compression with rather high quality It is intended for broadcast quality applications with resolutions based upon the CCIR now ITU R 601 standard for video coding It uses three coding protocols Intraframe coding or I Pictures no prediction P Pictures incorporating motion prediction from the previous video image and B Pictures bi directional prediction which include motion prediction one frame ahead as well as from the previous frame MPEG2 has largely supplanted MPEG1 MPEG2 MPEG2 is the second in a family of motion video and audio compression standards The result of a natural evolution from MPEG1 it provides DCT lossy compression ranging from low to rather high quality although not as good as MPEG1 It is intended for broadcast quality applications with resolutions based upon the CCIR now ITU R 601 standard for video coding It uses three coding protocols Intraframe coding or I Pictures no prediction P Pictures incorporating motion prediction from the previous video image and B Pictures bi directional prediction which include motion prediction one frame ahead as well as from the previous frame MPEG2 also has a coding mode at 24 frames per second matching that of motion picture film useful for offline image encoding MPEG2 has largely supplanted MPEG1 and is used for coding multimedia images from CD ROM DVD broadcasting pay TV and high quality videoconferencing MPEG2 also includes more coding decision points than MPEG1 permitting rather fine control of image quality over time in response to the needs of other channels in applications like DBS This standard is also known as ITU T H 262 MPEG3 The MPEG3 standard was intended as an ultra high quality solution that was abandoned during development and therefore does not exist However the term MPEG3 is sometimes incorrectly used to describe MPEG2 layer 3 audio MP3 MPEG4 MPEG4 is an ISO standard intended to satisfy the needs of content authors network service providers and end users It is a multifaceted extensible standard and is an attempt to provide all things to all people It covers sprites speech synthesis streaming video multimedia and many other aspects including a foreground background coding technique which will likely supplant MPEG2 for broadcast applications as it uses about one half the bandwidth for equivalent quality The most common version found in the PC environment is known as MPEG4 Part 3 which includes moving images and sound MPEG4 Part 10 AVC An ISO motion video compression standard using advanced video coding a foreground background coding technique intended for high quality and HDTV applications The ISO work was merged with that of ITU T work on same subject and is known as H 264 which see MSDSL

    Original URL path: http://acleris.com/info/glossary3-m.html (2016-04-29)
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  • Acleris' -- Telecommunications Glossary -- NBS to Octet
    U V W X Y Z N NBS The former US National Bureau of Standards See NIST NCP Network Control Protocol PPP usage NEBS Network Equipment Building Standards A set of standards for equipment to be installed in telco central offices NIC Network Interface Card PC usage often referring to an Ethernet 10 100 1000baseT device NIST US National Institute of Standards and Technology formerly US National Bureau of Standards NBS Noise reduction electroacoustic In acoustic echo cancellers AECs a type of filtering which reduces the amplitude of noise sources within a teleconference room transmitted to a distant conference room NTSC The National Television System Committee 525 line color television standard used in North America and Japan It is synonymous with CCIR System M NTT Nippon Telephone and Telegraph the principal Japanese common carrier As AT T has done in the USA so NTT has produced many of the transmission standards used in Japan Nyquist Criterion From sampling theory for a sine wave the sampling frequency must be no less than twice the maximum signal frequency O OC1 Optical Carrier level 1 51 84 Mbps OC3 Optical Carrier level 3 155 52 Mbps Octet 8 bits of data European usage

    Original URL path: http://acleris.com/info/glossary3-no.html (2016-04-29)
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  • Acleris' -- Telecommunications Glossary -- P.800 to PWT
    added as appropriate at different locations PAD Packet Assembler Disassembler PAL Phase Alternate Line the European 625 line 25 frame per second color television standard PAM Pulse Amplitude Modulation a sampled analog signal which may exist as an intermediate step prior to the signal s coding and quantizing Passband A range of frequencies passed by a device or network PBX Private Branch eXchange A telephony data switching system usually located on customer premises and belonging to the user In contrast to Centrex which is largely located on the common carrier s premises Some modern PBXs provide effective switched digital interfaces for operation of switched 64 56 Kbps and ISDN videoconferencing Some contemporary PBXs also provide VoIP encoding for VPN communications between an organization s offices PCB Printed Circuit Board An electronic assembly which is plugged into the main frame assembly of a complex electronic device or which may be used as the principle element of a simple electronic device PCM Pulse Code Modulation a basic form of digital modulation where an analog signal is sampled with each sample being quantized independently of the other samples PCS Personal Communications Services PDA Personal Digital Assistant PDU Protocol Data Unit PEL Picture ELement Picture Element The smallest discrete part of a video image the size of which is controlled by the analog to digital conversion sampling process and subsequent other compression processes The more picture elements per line the higher the resolution of the image To convert the number of H pixels to a close approximation of TV lines of resolution for the NTSC system simply multiply the number of H pixels by 0 78 Furthermore each 80 TV lines of resolution NTSC requires 1 MHz of analog bandwidth for transmission PID Premises Interface Device a filtering and splitter device for interfacing bidirectional

    Original URL path: http://acleris.com/info/glossary3-p.html (2016-04-29)
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  • Acleris' -- Telecommunications Glossary -- QAM to RTSP
    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

    Original URL path: http://acleris.com/info/glossary4.html (2016-04-29)
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  • Acleris' -- Telecommunications Glossary -- SDSL to Syndrome
    from voice only to full multimedia conferencing multipoint is also included SGML Standard Generalized Markup Language the superset from which HTML was derived SMDS Switched Multi megabit Data Service a cell relay wireless technology for providing data between 1 5 Mbps and 45 Mbps SLIP Serial Line Interface Protocol an Internet access method Compare with PPP SMPTE Society of Motion Picture and Television Engineers SNA System Network Architecture IBM usage SNMP Simple Network Management Protocol TCP IP SNR Signal to Noise Ratio Softswitch A concept that was perhaps first formalized by the ITU T Working Party developing the nascent T 130 series recommendations in the mid 1990s Several key concepts included distributed network intelligence distributed switching time and space and the separation of the multimedia content and the switching logic layers Now there is an industry consortium promulgating standards based aspects including H 323 Videoconferencing and Multimedia SIP Session Initiation Protocol RTP Real time Transport Protocol RTSP Real Time Streaming Protocol MGCP Media Gateway Control Protocol Depending upon the point of view of the particular industry sector Softswitch technology may result in the replacement of the end office switch for the CLEC for the provision of telephony and facsimile At the other extreme Softswitch can be a flexible intelligent packet switching arrangement in a mixed multimedia environment Internet services like VoIP will also likely be part of this technology mix once the quality of service issues are fully resolved SONET Synchronous Optical NETwork Spatial Filtering In video compression removal of redundant information on a line by line basis by discarding diagonally adjacent pixels Also known as field subsampling loop filtering H 261 H 263 usage SPL Sound Pressure Level in acoustic measurement SQCIF Sub Quarter Common Intermediate Format Describes a subset of the type of coded video signals transmitted when

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