Bit-synchronous operation

Bit synchronous operation: Operation in which data circuit terminating equipment (DCE), data terminal equipment (DTE), and transmitting circuits are all operated in bit synchronism with a clock.

Note 1: In bit synchronous operation, clock timing is usually delivered at twice the modulation rate, and one bit is transmitted or received during each clock cycle.

Note 2: Bit synchronous operation is sometimes erroneously referred to as digital synchronization.

Source: from Federal Standard 1037C and from MIL-STD-188