Bit Rate from Baud

In a digital communication system, the baud rate tells you how many signal symbols are sent each second, while each symbol can represent several bits if the alphabet has more than two symbols. The term log2(M) gives the number of bits encoded by one symbol because there are M possible symbol choices, and each added bit doubles the number of distinct patterns. Multiplying symbol rate by bits per symbol therefore gives the total bit rate in bits per second.

Use this formula when a modulation scheme is described by its symbol rate and the number of signal states per symbol, such as in PSK, QAM, or other digital modulation systems. It is useful whenever you need to convert from baud to throughput in bits per second.

• Treating baud and bit rate as the same thing even when each symbol carries multiple bits
• Using log10 or ln instead of log2
• Forgetting that M must be the number of distinct symbols in the modulation alphabet