The number of times per second that a system, especially a data transmission channel, changes state. In the particular case of a binary channel, the baud rate is equal to the bit rate, i.e.
In the general case, however, the baud rate is equal to the number of data elements transmitted per second and with more complex modulation techniques each element can represent four or more bits at the same time (see quadrature amplitude modulation). The rate was named for J. M. E. Baudot.