Also found in: Encyclopedia, Wikipedia.
2B1Q2 Binary 1 Quaternary
References in periodicals archive ?
Users planning to build their own NT1 can use the AT&T Microelectronics T7252A four-wire transceiver, the T7262/63 2B1Q chip set, and the T7270 to interconnect the subscriber to the network.
Although there are several line code schemes which could provide the basic two-wire transport mechanism for user data, the 2B1Q scheme has been adopted by ANSI and major European PTTs, and has been acknowledged by the CCITT and European Telephone Standards Institute (ETSI).
Systems designed to comply with the ANSI specification for 2B1Q can be expected to operate satisfactorily on 98% of all non-loaded subscriber loops in the North American two-wire loop plant.
Also, 2B1Q loops should not contain faults that would violate normal voice grade POTS standards.
The service performance objectives of the 2B1Q system were chosen to allow the local telephone company service provider to assign the ISDN loop facility from a normal POTS database.
The AT&T 2B1Q transceiver performance is not sensitive to the details of cable makeup.
2B1Q is guaranteed to run on 99% of the worst wires surveyed by Bellcore in the telephone-loop plant in 1983.
Due to an unfortunate collision of names, 2B1Q and 2B+D are frequently confused.
2B+D bits can be transmitted over a pair of wires by many line codes, such as 2B1Q, AMI, TCM, or 4B3T.
2B1Q stands for "two bits in one quaternary"--meaning two bits transmitted in one four-level symbol.
Today's ANSI standard specifies that the 144 kb/s payload of 2B1Q be formatted into 2B+D.
When told a certain piece of equipment handles 2B+D, remember to ask: "But does it use the 2B1Q line code?