Baud rate and bits per second

By Andy Walker

Question:What’s the difference between "baud" and "bits per second" when it comes to my modem speed? --G.B.S.

Answer: The modem speed measurement baud is different from bits per second.

"The word baud is no longer relevant when describing throughput of modern modems, and was largely misunderstood by the computing masses, even in the days of 2400 to 9600 bps modems," explained Dan MacRae of Calgary in an e-mail note.

MacRae referred me to a useful explanation from a document on the Calgary Board of Education's internal bulletin board. Here's an excerpt: "A modem's carrier is a rather simple signal, of a pre-defined frequency, which it transmits constantly over the phone line during a connection ... Baud refers to the number of times per second the modem carrier changes. Bits per second refers to the number of data bits that can be inserted into a second of data transmission. There is a difference between a modem's bit rate and its baud rate when each change in the carrier (which is baud) contains multiple bits of information."