Strategic Defense Initiative (SDI)

also called Star Wars

Proposed U.S. strategic defense system against nuclear attacks. Announced as a 20-year, $20 billion effort by Pres. Ronald Reagan in 1983, SDI was intended to defend the U.S. from a full-fledged Soviet attack by intercepting ICBMs in flight. The interception was to be effected by technology not yet developed, including space- and ground-based laser stations and air- and ground-based missiles. The space component of SDI led to its being derisively dubbed “Star Wars” after the popular film. Though the program was roundly criticized by opposition politicians and arms-control advocates as unworkable and as a dangerous violation of the Antiballistic Missile (ABM) Treaty of 1972, Congress granted initial funding for it. Early development efforts were largely unsuccessful, and with the fall of the Soviet Union in 1991 the concept lost urgency. During the Bush and Clinton administrations, ballistic missile defense was scaled back to focus on protecting the U.S. from limited attack by a “rogue” state or a single accidentally launched missile. In 2002 the U.S. withdrew from the ABM treaty to begin active testing of a limited antimissile program. See also antiballistic missile.

SDI

(1) (Serial Digital Interface) A physical interface widely used for transmitting digital video in various formats. For electrical transmission, it uses a high grade of coaxial cable and a single BNC connector with Teflon insulation. It also uses optical fibers with ST, SC and FC connectors. Following are the common digital formats transmitted over SDI. See ITU-R BT.601, BNC connector, fiber-optic connectors and serial interface.

 Standard Definition     Aspect  Transfer
 SD-SDI                  Ratio   Rate

 Digitized NTSC (4FSC)    4:3    143 Mbps
 Digitized PAL (4FSC)     4:3    177 Mbps
 Component ITU-R BT.601   4:3    270 Mbps
 Component ITU-R BT.601  16:9    360 Mbps

 High Definition
 HD-SDI

 Component ITU-R BT.709  16:9  1,485 Mbps

An SDI Video Capture Board

Blackmagic Design's DeckLink HD card supports SD-SDI and HD-SDI. Two of the four BNC connectors are input ports and two are output. At 4:2:2 color sampling, SD-SDI and HD-SDI use only one line for in and one for out. However, HD-SDI with 4:4:4 sampling requires two lines for in and two for out. (Image courtesy of Blackmagic Design Pty. Ltd, www.blackmagic-design.com)

(2) (Switched Digital International) An AT&T dial-up service providing 56 and 64 Kbits/sec digital transmission to international locations.

(3) (Single Document Interface) A Windows function that allows an application to display only one document at a time. SDI requires the user to load another instance of the application to work with two or more documents. Contrast with MDI.

(4) (Standard Drive Interface) A hard disk interface for VAX computers.

(5) (Strategic Defense Initiative) A high-tech defense system for the U.S. proposed during the Reagan administration in the 1980s.

1.	(library)	SDI - Selective Dissemination of Information.
2.	(programming)	SDI - Single Document Interface.