2B1Q

Two-binary, one-quaternary (2B1Q) is a line code used in the U interface of the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) and the high-bit-rate digital subscriber line (HDSL).[1] 2B1Q is a four-level pulse-amplitude modulation (PAM-4) scheme without redundancy, mapping two bits (2B) into one quaternary symbol (1Q). Symbol rate is half of data rate.

A competing encoding technique in the ISDN basic rate U interface, mainly used in Europe, is 4B3T.

  1. ^ Reeve, Whitham D. (1995). Subscriber Loop Signaling and Transmission Handbook. IEEE Telecommunications Handbook Series. IEEE Press. ISBN 0780304403.