Baud

In telecommunications, Baud is the unit to measure the symbol rate. If one symbol can be transmitted per second, this is equal to one Baud. The unit is named after Jean-Maurice-Émile Baudot a French telecommunications engineer who invented the Baudot code. The Baud rate is different from the gross bit rate, measured in bits/second.

Various electric signal schemes invented in the 20th century such as Phase-shift keying can make bit rates much higher than signal rates. In another example, gigabit ethernet has a symbol rate of 125MBd. Gigabit ethernet uses pulse-amplitude modulation and can transmit two bits of payload data per symbol. Gigabit ethernet uses four balanced pairs for transmission.

It can transmit ${\rm {125\;MBd\cdot 2\;{\tfrac {bit}{symbol}}\cdot 4=1000\;{\tfrac {Mbit}{s}}}}$.