Serial Digital Interface (SDI) is a standard for digital video transmission over coaxial cable. The most common data speed is 270 megabits per second (Mbps). However, speeds of up to 540 Mbps are theoretically possible. Standard 75-ohm cable is used. This is the same type of coaxial cable used in most home television (TV) installations.
The SDI standard uses data words that are 8 or 10 bits in length. Signals are uncompressed and are self-synchronizing between the source (transmitter) and destination (receiver). Most errors caused by noise or interference can be detected, and the lost data recovered by means of a specialized code called the Hamming code. A signal in SDI can contain up to four independent digital audio signals along with the video signal.
SDI also stands for the Strategic Defense Initiative, a U.S. space defense initiative.