Baud and Data Rates

2.3 Baud and Data Rates

Emile_BaudotYou may have heard the term ‘baud rate’ used in relation to modems. Baud rate is the speed at which data is transmitted over a channel. It is named after the French scientist: Emil Baudot, who devised one of the earliest data transmission codes, ie: Baudot Code. At low speeds one baud is equivalent to one bit per second, therefore, a 1200 baud channel will transmit data at the rate of 1200 bits per second.

When the transmission rate of a line is defined for DCE the term baud is often used. If used correctly baud indicates the number of line signal changes per second, therefore, if each transmitted signal is either a one or a zero then baud rate and the actual transmission rate, ie: bits per second (bps) are the same. However, there are many instances when the line signal can take on more than two states and as such each signal can be used for more than one single bit.

Baud versus Data Rates

Baud rate is the measurement of signal units required to transmit the data. The ideal is to create an efficient system using as few signals as possible. The fewer signals there are, the less bandwidth is required to move data.

Baud rate determines the amount of bandwidth required in communications links.

Bit Rate or Data Transmission Rate (DTR) is measured in bits per seconds (bps). The data transmission rate indicates how long it will take to transmit the data, in terms of the user and computer this is the most important information, because DTR is used to compare speeds and performance.

Note: Baud rate will always be less than or equal to the DTR.

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