Introduction to Digital TV and DVRMay 6, 2020
Digital TV consists of several formats and standards, the most celebrated being high definition digital TV (HDTV). Besides the HDTV formats, it also includes a series of formats known collectively as standard definition TV, which is more like conventional analog TV, in use since the 1940s, but offers additional features such as the ability to bundle multiple programs in one signal and potentially less distortion and interference.
High definition TV marks a more dramatic departure from traditional TV. In contrast to analog TV with its 525 horizontal lines per frame, HDTV offers, depending on the format, either 720 or 1,080 horizontal lines, providing much clearer images and detail. HDTV can also provide wide format viewing, much as movie theaters do, and fewer signal distortions. A standard analog television receives modulated radio waves that it reconstructs into a nearly square picture. HDTV, on the other hand, receives signals digitally as binary electronic signals, which the receiver then translates into a stream of images virtually free from broadcast distortion. Like analog signals, digital signals can be transmitted by broadcast, cable, or satellite. HDTV provides a 16/9 width-to-height ratio compared to the 4/3 ratio of conventional TV. HDTV also delivers digital sound, comparable in quality to an audio compact disc.
Digital TV hardware employs state-of-the-art computer technology to make it efficient and highly functional. Digital TV transmitters use computer technology to compress the signals for broadcast, allowing them to send two programs in one broadcast channel. Analog technology can deliver only one program per channel. Reciprocal technology must be present on the receiving end to interpret the digital signal.
Even though the Federal Communications Commission (FCC) decreed that all commercial broadcasts be offered digitally by 2002-and that all analog broadcasts must cease by 2006-bickering over standards has made for an underwhelming debut by digital TV. Setting technical standards has been complicated by the diverse range of business interests in the digital medium. In addition to television set manufacturers, other industries vying to have their positions heard included broadcasting stations, broadcast equipment makers, cable system operators, computer display manufacturers, and software developers. Often what was most beneficial to one of those industries was disadvantageous to others. For instance, computer hardware companies fought for a standard that would allow existing computer display technology to work readily with digital TV, but most broadcasters and traditional TV manufacturers preferred technology closer to existing TVs. Indeed, more than once, standards were all but agreed upon, only to have one or more parties to the agreement break ranks and lobby for changes. At the urging of companies involved, the FCC has maintained a largely hands-off role, but regulators have been irked by the manufacturers’ inability to resolve the disputes and get products on the market.
In November 2005, the U.S. Senate, in a budget bill, gave broadcasters until April 7, 2009 to end traditional analog transmissions and provided $3 billion to help those with older TV sets buy digital-to-analog converter boxes so they could receive a signal once conversion to digital becomes permanent. The month before, the House approved a December 31, 2008 deadline for analog and $1 billion for the converter boxes. The matter went to a House-Senate conference committee for final resolution of differences between the bills.
Some alternatives for receiving digital TV, however, don’t involve buying a new display. Instead, some manufacturers have developed set-top conversion boxes that allow digital signals to be received by analog TVs. Such devices are necessary as analog broadcasting is phased out, because the TV set replacement rate is likely to lag behind the adoption of digital standards.