quadbit

quadbit Telecom Definition

A set of four bits. Some line coding techniques encode blocks of 4 bits of data at a time, rather than 1 or 2 bits.The 4B/5B technique, for example, encodes a 4-bit block of data into a 5-bit block of signal in order to provide sufficient clocking pulses and signal transitions to synchronize the network and to provide some level of error detection. 4B/5B is used in 100Base-TX, 100Base-FX, and Fiber Distributed Data Interface (FDDI) LANs. Compare to nibble. See also 4B/5B, line coding, and synchronization.
Referring to a modulation technique that impresses 4 bits on a baud, so that the bit rate is quadruple the baud rate. Such a technique employs 16 signal states. 16-QAM is a quadbit technique achieved by defining two amplitude values for each of eight phase shifts. See also 16-QAM, amplitude, amplitude modulation, baud, baud rate, bit, bit rate, dibit, modulation, phase, QAM, quartet, signal, tribit, and unibit.

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