# 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 innvented the Baudot code. The Baud rate is different from the gross bit rate, measured in bits/second. As an 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 wires for transmission. It can transmit $\rm 125 \;MBd \cdot 2 \;\tfrac{bit}{symbol} \cdot 4 = 1000 \;\tfrac{Mbit}{s}$.