National Datacast Incorporated (NDI) was a pioneer in

data broadcasting Datacasting (data broadcasting) is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital terrestrial television (DTT), but may also be applied ...

. It was a for-profit

subsidiary A subsidiary, subsidiary company or daughter company is a company owned or controlled by another company, which is called the parent company or holding company. Two or more subsidiaries that either belong to the same parent company or having a s ...

of the

Public Broadcasting Service The Public Broadcasting Service (PBS) is an American public broadcaster and non-commercial, free-to-air television network based in Arlington, Virginia. PBS is a publicly funded nonprofit organization and the most prominent provider of educati ...

(PBS), which had a minority stake in the final years of this subsidy. It handled

datacasting Datacasting (data broadcasting) is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital terrestrial television (DTT), but may also be applied ...

on PBS

TV station A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV) operator, that transmits video content and audio content via radio waves directly from a transmitter on the earth ...

s throughout the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. Services using

ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...

digital TV Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advanc ...

included

MovieBeam MovieBeam was a video on demand service started by The Walt Disney Company, specifically its subsidiary Buena Vista Datacasting, LLC. Movies were sent wirelessly into the subscriber's home by embedding digital data (datacasting) within local Publ ...

and

UpdateTV Qterics (formerly Broadcast Data Corporation and later UpdateLogic Incorporated ) is a company which has developed a system for datacasting firmware upgrades to digital television devices. It appears that UpdateTV is the only product the compan ...

. UpdateTV continues to be operated by its present owner, Qterics,

leasing A lease is a contractual arrangement calling for the user (referred to as the ''lessee'') to pay the owner (referred to as the ''lessor'') for the use of an asset. Property, buildings and vehicles are common assets that are leased. Industrial ...

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

to other companies for the purpose of automatic television firmware updates. National Datacast was formed in 1988 based on PBS' early work in

closed caption Closed captioning (CC) and subtitling are both processes of displaying text on a television, video screen, or other visual display to provide additional or interpretive information. Both are typically used as a transcription of the audio po ...

ing for the hearing impaired. It used

NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...

horizontal line 21, which is at the end of the

vertical blanking interval In a raster scan display, the vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time between the end of the final visible line of a frame or field and the beginning of the first visible line of the next fram ...

, and thus, potentially visible as blinking black and white bars at the top of the screen in the

overscan Overscan is a behaviour in certain television sets, in which part of the input picture is shown outside of the visible bounds of the screen. It exists because cathode-ray tube (CRT) television sets from the 1930s through to the early 2000s were h ...

area. This artifact can often be seen when viewing old footage on modern televisions or PCs that no longer crop the overscan area. Uniquely, NDI may also have used other horizontal lines in the vertical blank for other types of data transmission. It ceased operations in 2015.https://bento.cdn.pbs.org/hostedbento-prod/filer_public/PBS_About/Files%20and%20Thumbnails/Finances/2015%20PBS%20Financial%20Report.pdf

References

Public Broadcasting Service Television organizations in the United States Mass media companies established in 1988 Mass media companies disestablished in 2015 Technology companies established in 1988 Technology companies disestablished in 2015 1988 establishments in the United States 2015 disestablishments in the United States {{PBS-stub