Although much of this section describes basic video and facsimile technologies that have not changed over the years, newer material is also included. For example, international agreement was reached recently on the use of 1920 1080 as a common image format for high-definition (HD) production and program exchange. The 1920 1080 format has its roots in the CCIR (Consultative Committee in International Radio) sampling standard and brings international compatibility to a new level.

Set-top boxes and high-definition or digital-ready TV sets will be the mechanism that brings digital technology to the consumer for the next several years as the transition from analog to digital takes place. In the United States, three modulation techniques have become standards in a particular application: vestigial sideband (VSB) for terrestrial, quadrature amplitude modulation (QAM) for cable, and quaternary phaseshift keying (QPSK) for direct-to-home satellite.

With Internet facsimile, store-and-forward facsimile occurs when the sending and receiving terminals are not in direct communication with one another. The transmission and reception takes place via the store-andforward mode on the Internet using Internet e-mail. In this mode, the facsimile protocol stops at the gateway to the Internet. It is reestablished at the gateway leaving the Internet. Real-time facsimile is covered by Recommendation T.38 approved by the International Telecommunications Union, Telecommunications (ITU-T) in 2002. R.J.

In This Section:

On the...