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Bearer Capability
Bearer Capability in telecommunications is one of the Information Elements (fields) of the Q.931 SETUP message. It is used by the calling party to specify the kind of B channel that is being requested. Description For example, if a Bearer Capability of Speech is specified, then the network is free to select a set of facilities that are able to provide this service (including, in this case, analogue trunks and routes involving echo cancellers or DCME). If, on the other hand, a Bearer Capability of Unrestricted Digital Information is specified, then the network is required to set up the call using only end-to-end digital facilities (without the use of robbed-bit signalling, echo cancellers, DCME nor A-law An A-law algorithm is a standard companding algorithm, used in European 8-bit PCM digital communications systems to optimize, i.e. modify, the dynamic range of an analog signal for digitizing. It is one of two versions of the G.711 standar ... to mu-law conversion), or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B Channel
{{for, Indonesian television network formerly known as B-Channel, RTV (Indonesian TV network) B channel (bearer) is a telecommunications term which refers to the ISDN channel in which the primary data or voice communication is carried. It has a bit rate of 64 kbit/s in full duplex. The term is applied primarily in relation to the ISDN access interfaces ( PRA or PRI and BRA or BRI), since deeper in the PSTN network an ISDN bearer channel is essentially indistinguishable from any other bearer channel. Apart from any transmission errors, the purpose of the network is to carry the contents of the B channel transparently between the endpoints of the call. Exceptions to this general principle include: *If one or more trunks on the route between the endpoints employs Robbed Bit Signalling, this will result in frequent bit errors in the least-significant bit of bytes transported by the channel, effectively limiting the channel to 56 kbit/s. *If the call has been established as a long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echo Canceller
Echo suppression and echo cancellation are methods used in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. In addition to improving subjective audio quality, echo suppression increases the capacity achieved through silence suppression by preventing echo from traveling across a telecommunications network. Echo suppressors were developed in the 1950s in response to the first use of satellites for telecommunications. Echo suppression and cancellation methods are commonly called acoustic echo suppression (AES) and acoustic echo cancellation (AEC), and more rarely line echo cancellation (LEC). In some cases, these terms are more precise, as there are various types and causes of echo with unique characteristics, including acoustic echo (sounds from a loudspeaker being reflected and recorded by a microphone, which can vary substantially over time) and line echo (electrical impulses caused by, e.g., coupling between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-law Algorithm
An A-law algorithm is a standard companding algorithm, used in European 8-bit PCM digital communications systems to optimize, i.e. modify, the dynamic range of an analog signal for digitizing. It is one of two versions of the G.711 standard from ITU-T, the other version being the similar μ-law, used in North America and Japan. For a given input x, the equation for A-law encoding is as follows: F(x) = \sgn(x) \begin \dfrac, & , x, < \dfrac, \\ ex \dfrac, & \dfrac \leq , x, \leq 1, \end where is the compression parameter. In Europe, . A-law expansion is given by the inverse function: The reason for this encoding is that the wide |
