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In the United States, digital television broadcasts, or DTV, can be received via cable, via internet, via satellite, or via digital terrestrial television — much like analog television broadcasts have been. Full-power analog television broadcasts, however, were required by U.S. federal law to cease by June 12, 2009. Low-power, Class A, and TV Translator stations are not currently[ when? ] required to cease analog broadcasts. Also by law, digital broadcasts — when transmitted as over-the-air signals — must conform to ATSC standards. it is unclear whether satellite operators are free to use their own proprietary standards;[ citation needed ] and many standards exist for Internet television (most are proprietary).
The United States of America (USA), commonly known as the United States or America, is a country comprising 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the most populous city is New York City. Most of the country is located contiguously in North America between Canada and Mexico.
Digital television (DTV) is the transmission of television audiovisual 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 advancement and represented the first significant evolution in television technology since color television in the 1950s. Modern digital television is transmitted in high definition (HDTV) with greater resolution than analog TV. It typically uses a widescreen aspect ratio in contrast to the narrower format of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit up to seven channels in the same bandwidth as a single analog channel, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2006. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more widely used standards:
Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fiber-optic cables. This contrasts with broadcast television, in which the television signal is transmitted over the air by radio waves and received by a television antenna attached to the television; or satellite television, in which the television signal is transmitted by a communications satellite orbiting the Earth and received by a satellite dish on the roof. FM radio programming, high-speed Internet, telephone services, and similar non-television services may also be provided through these cables. Analog television was standard in the 20th century, but since the 2000s, cable systems have been upgraded to digital cable operation. James VanDamager, the original Cable God, invented CATV in 1948 in Milpitas, California.
The U.S. opted to adhere to ATSC standards for broadcast digital television. These standards define, among other things, format and transmission criteria that ensure consistency, accessibility, and fairness for consumers and equipment manufacturers alike in the U.S., as well as international compatibility.
Advanced Television Systems Committee (ATSC) standards are a 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 standard, used mostly in the United States, Mexico and Canada. Other former users of NTSC, like Japan, have not used ATSC during their digital television transition because they adopted their own system called ISDB.
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The five main ATSC formats of DTV currently[ when? ] broadcast in the U.S. are:
Standard-definition television is a television system which uses a resolution that is not considered to be either high or enhanced definition. SDTV and high-definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions.
NTSC, named after the National Television System Committee, is the analog television color system that was used in North America from 1954 and until digital conversion, was used in most of the Americas ; Myanmar; South Korea; Taiwan; Philippines; Japan; and some Pacific island nations and territories.
Most digital television sets sold in the U.S. use a display with a 16:9 aspect ratio to optimally display HDTV-formatted content. Lower-resolution sources like regular DVDs may be upscaled to the native resolution of the TV.
The aspect ratio of an image describes the proportional relationship between its width and its height. It is commonly expressed as two numbers separated by a colon, as in 16:9. For an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this same length unit, the height will be measured to be y units.
Most Americans get digital television broadcasts via cable or satellite.[ citation needed ] Digital cable television systems with an active channel capacity of 750 MHz or greater, are required by the FCC to follow ANSI/SCTE transmission standards with the exception of cable systems that only pass through 8 VSB modulated signals. Digital television sets (equipped with ATSC tuners) are often capable of viewing a baseline set of unencrypted digital programming, known as basic cable or low-tier channels, which typically include local network television affiliates. According to FCC regulations, the remaining encrypted channels must be viewable with a receiver equipped with a CableCARD.[ citation needed ]
The Federal Communications Commission (FCC) is an independent agency of the United States government created by statute to regulate interstate communications by radio, television, wire, satellite, and cable. The FCC maintains jurisdiction over the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security.
CableCARD is a special-use PC Card device that allows consumers in the United States to view and record digital cable television channels on digital video recorders, personal computers and television sets on equipment such as a set-top box not provided by a cable television company. The card is usually provided by the local cable operator, typically for a nominal monthly fee.
Digital television transmissions over-the-air (OTA) are available in metropolitan areas in the U.S., often carrying both standard-definition and high-definition (HDTV) transmissions of the same stations. [ failed verification ] As of the analog shut-off date of June 12, 2009, all full power OTA stations in the U.S. by law either transmitted their broadcasts digitally, or shut down.
Many stations used the switch to digital transmission as an opportunity to transition from 480i broadcasts to digital HD OTA broadcasts (either in 720p or 1080i), though this change is voluntary.
Within a distance of 35 to 40 miles from the broadcast stations, it is possible that a simple antenna (such as "rabbit ears") may be adequate to receive a DTV broadcast signal OTA—at least some of the time for some of the channels. Any television equipped with an ATSC tuner may display DTV broadcasts properly. Some customers discovered that terrain, trees, rain, snow, wind, and movement of people around the room interfere with reception to one degree or another, from signals breaking up to total loss of signal. (Few modern ATSC-equipped televisions or converter boxes have internal antennas, in contrast to analog sets available in years past).
Broadcast TV signals in the United States are horizontally polarized.
It was estimated that as of April 2007, 28% of American households had an HDTV set, a total of 35 million sets, and that 86% of owners were highly satisfied with the HDTV programming [ when? ] broadcast in both digital and analog and major networks broadcast in HD in most markets.All TV stations currently
While many in the industry wanted a flexible or delayed deadline, the FCC forced the issue at the behest of Congress. Congress wanted to reclaim some of the spectrum used for analog and repurpose that for emergency services. They also wanted to auction off bandwidth between 76-88 MHz frequencies (channels 5 and 6) and old analog UHF channels 60 to 69, and channels 52 to 59 by mandating DTV tuners be phased into all new TV sets.[ citation needed ] Many transition dates were proposed, but Congress finally fixed February 17, 2009 (later extending it until June 12, 2009), in law as the maximum end date for analog television authorizations. Because this date comes after the NCAA's Bowl Championship Series and the NFL's Super Bowl XLIII, there will be less of a chance of an acute hardware shortage from people waiting until the last minute to purchase an ATSC tuner than there would have been with a January 1 cutoff.[ citation needed ]
In March 2008, the FCC requested public comment on turning over the bandwidth occupied by analog television channels 5 and 6 (76–88 MHz) to extend the FM broadcast band when the digital television transition was to be completed in February 2009 (ultimately delayed to June 2009). This proposed allocation would effectively assign frequencies corresponding to the existing Japanese FM radio service (which begins at 76 MHz) for use as an extension to the existing North American FM broadcast band.
Ultimately, VHF Channels 5 and 6 were retained for digital broadcast television use after the transition, though the FCC had continued researching the possibility of re-allocating the two channels to an expanded FM band.[ citation needed ]
On August 22, 2011, the United States' Federal Communications Commission announced a freeze on all future applications for broadcast stations requesting to use channel 51,to prevent adjacent-channel interference to the A-Block of the 700 MHz band. On December 16, 2011, Industry Canada and the CRTC followed suit in placing a moratorium on any future Channel 51 television station applications.
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On May 8, 2008, FCC Chairman Kevin J. Martin announced the agency would test run the transition to digital terrestrial television in Wilmington, North Carolina, beginning September 8, 2008. This test run was to work out problems that might have occurred before the complete transition.
8VSB is the modulation method used for broadcast in the ATSC digital television standard. ATSC and 8VSB modulation is used primarily in North America; in contrast, the DVB-T standard uses COFDM.
Terrestrial television is a type of television broadcasting in which the television signal is transmitted by radio waves from the terrestrial (Earth-based) transmitter of a television station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in the United States it is called broadcast or over-the-air television (OTA). The term "terrestrial" is used to distinguish this type from the newer technologies of satellite television, in which the television signal is transmitted to the receiver from an overhead satellite, cable television, in which the signal is carried to the receiver through a cable, and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television channels with frequencies between about 52 and 600 MHz in the VHF and UHF bands. Since radio waves in these bands travel by line of sight, reception is limited by the visual horizon to distances of 40–60 miles (64–97 km).
The Integrated Services Digital Broadcasting is a Japanese standard for digital television (DTV) and digital radio used by the country's radio and television networks. ISDB replaced NTSC-J analog television system and the previously used MUSE Hi-vision analogue HDTV system in Japan, and will be replacing NTSC, PAL-M and PAL-N in South America and the Philippines. Digital Terrestrial Television Broadcasting (DTTB) services using ISDB-T started in Japan in December 2003 and in Brazil in December 2007 as a trial. Since then, many countries have adopted ISDB over other digital broadcasting standards.
Digital cable is the distribution of cable television using digital video compression for distribution. The technology was originally developed by General Instrument before being acquired by Motorola and subsequently acquired by ARRIS Group. Cable companies converted to digital systems during the 2000s, around the time that television signals were converted to the digital HDTV standard, which was not compatible with earlier analog cable systems. In addition to providing higher resolution HD video, digital cable systems provide expanded services such as pay-per-view programming, cable internet access and cable telephone services. Most digital cable signals are encrypted, which reduced the high incidence of cable theft which occurred in analog systems.
The All-Channel Receiver Act of 1962 (ACRA), commonly known as the All-Channels Act, was passed by the United States Congress in 1961, to allow the Federal Communications Commission to require that all television set manufacturers must include UHF tuners, so that new UHF-band TV stations could be received by the public. This was a problem at the time since the Big Three television networks were well-established on VHF, while many local-only stations on UHF were struggling for survival.
A tuner is a subsystem that receives radio frequency (RF) transmissions like radio broadcasts and converts the selected carrier frequency and its associated bandwidth into a fixed frequency that is suitable for further processing, usually because a lower frequency is used on the output. Broadcast FM/AM transmissions usually feed this intermediate frequency (IF) directly into a demodulator that convert the radio signal into audio-frequency signals that can be fed into an amplifier to drive a loudspeaker.
QAM is a digital television standard using quadrature amplitude modulation. It is the format by which digital cable channels are encoded and transmitted via cable television providers. QAM is used in a variety of communications systems such as Dial-up modems and WiFi. In cable systems, a QAM tuner is linked to the cable in a manner that is equivalent to an ATSC tuner which is required to receive over-the-air (OTA) digital channels broadcast by local television stations when attached to an antenna. Most new HDTV digital televisions support both of these standards. QAM uses the same 6 MHz bandwidth as ATSC, using a standard known as ITU-T Recommendation J.83 Annex B ("J.83b").
An ATSCtuner, often called an ATSC receiver or HDTV tuner is a type of television tuner that allows reception of digital television (DTV) television channels transmitted by television stations in North America, parts of Central America and South Korea that use ATSC standards. Such tuners may be integrated into a television set, VCR, digital video recorder (DVR), or set-top box that provides audio/video output connectors of various types.
A digital channel election was the process by which television stations in the United States chose which physical radio-frequency TV channel they would permanently use after the analog shutdown in 2009. The process was managed and mandated by the Federal Communications Commission for all full-power TV stations. Low-powered television (LPTV) stations are going through a somewhat different process, and are also allowed to flash-cut to digital.
A digital television adapter (DTA), commonly known as a converter box, is a television tuner that receives a digital television (DTV) transmission, and converts the digital signal into an analog signal that can be received and displayed on an analog television set. The input digital signal may be over-the-air terrestrial television signals received by a television antenna, or signals from a digital cable system. It normally does not refer to satellite TV, which has always required a set-top box either to operate the big satellite dish, or to be the integrated receiver/decoder (IRD) in the case of direct-broadcast satellites (DBS).
A coupon-eligible converter box (CECB) was a digital television adapter that met eligibility specifications for subsidy "coupons" from the United States government. The subsidy program was enacted to provide over-the-air television viewers with an affordable way to continue receiving free digital over-the-air television services after the nation's television service transitioned to digital transmission and analog transmissions ceased. The specification was developed by the National Telecommunications and Information Administration (NTIA), with input from the broadcast and consumer electronics industries as well as public interest groups.
Analog passthrough is a feature found on some digital-to-analog television converter boxes. Boxes without analog passthrough only allow digital TV to be viewed on older, analog-only TVs. Those with analog passthrough allow both digital and analog television to be viewed on older TVs.
The digital transition in the United States was the switchover from analog to exclusively digital broadcasting of terrestrial television television programming. According to David Rehr, then president and CEO of the National Association of Broadcasters, this transition represented "the most significant advancement of television technology since color TV was introduced." For full-power TV stations, the transition went into effect on June 12, 2009, with stations ending regular programming on their analog signals no later than 11:59 p.m. local time that day.
In North American digital terrestrial television broadcasting, a distributed transmission system is a form of single-frequency network in which a single broadcast signal is fed via microwave, landline, or communications satellite to multiple synchronised terrestrial radio transmitter sites. The signal is then simultaneously broadcast on the same frequency in different overlapping portions of the same coverage area, effectively combining many small transmitters to generate a broadcast area rivalling that of one large transmitter or to fill gaps in coverage due to terrain or localised obstacles.
TV radio, TV band radio, and TV audio radio are common names for a type of radio receiver that can play the audio portion of a TV channel. The actual name of the device may comprise a list of all frequency bands the device can receive, one or two of which includes the TV channel bands.
ATSC 3.0 is a major version of the ATSC standards for television broadcasting created by the Advanced Television Systems Committee (ATSC). ATSC 3.0 comprises around 20 standards covering different aspects of the system and in total will have over 1,000 pages of documentation.
Certain commenters have urged the Commission to give a "hard look" to a proposal that the Commission re-allocate TV Channels 5 and 6 for FM broadcasting73 FR 28400, 28403