baud (Bd)

The unit of step rate is Baud (Bd), named after the French telegrapher Emile Baudot (1845-1903). A baud is understood to be a signal of fixed duration, e.g. 1 bit or 1 character per unit of time.

Multiplying the number of bits per state by the baud rate gives the transmission speed. Only if two state changes are coded with one bit, the baud rate is equal to the bit rate. If several signal elements are transmitted within one step duration when special coding methods are used, both quantities deviate from each other.

The transmission rate is the number of discrete states or signal events that are transported in a given unit of time. For example, if a signal is modulated in four phases using quadrature amplitude modulation( QAM), the step rate is one quarter of the transmission rate.