8VSB is the 8-level vestigial sideband modulation method adopted for terrestrial broadcast of the ATSC digital television standard in the United States and Canada. Single-sideband modulation (SSB) is a refinement of the technique of amplitude modulation designed to be more efficient in its use of electrical power and bandwidth. ... The Advanced Television Systems Committee (ATSC) is the group that helped to develop the new digital television standard for the United States, also adopted by Canada, Mexico, and South Korea and being considered by other countries. ... It has been suggested that Digital terrestrial television be merged into this article or section. ...

Throughput

In the 6MHz (megahertz) channel used for broadcast ATSC, 8VSB carries 19.39Mb (megabits) of usable data per second, although the actual transmitted bit rate is significantly higher due to the addition of forward error correction codes. The eight signal levels are selected with the use of a trellis encoder. There are also the similar modulations 2VSB, 4VSB, and 16VSB. 16VSB was notably intended to be used for ATSC digital cable, but quadrature amplitude modulation (QAM) has become the industry standard instead. MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ... The megabit is a unit of information storage, abbreviated Mbit or sometimes Mb. ... In telecommunications and computing, bit rate (sometimes written bitrate) is the frequency at which bits are passing a given (physical or metaphorical) point. It is quantified using the bit per second (bit/s) unit. ... It has been suggested that this article or section be merged with Error correction and detection. ... 2VSB is an abbreviation for 2-level vestigial sideband modulation, capable of transmitting one bit (21=2) at a time. ... 4VSB is an abbreviation for 4-level vestigial sideband modulation, capable of transmitting two bits (22=4) at a time. ... 16VSB is an abbreviation for 16-level vestigial sideband modulation, capable of transmitting four bits (24=16) at a time. ... Digital cable is a term for a type of cable digital television that delivers more channels than possible with analog cable by using digital video compression. ... Quadrature amplitude modulation (QAM) is a modulation scheme which conveys data by changing (modulating) the amplitude of two carrier waves. ...

Power saving advantages

A significant advantage of 8VSB for broadcasters is that it requires much less energy to cover an area comparable to that of the earlier NTSC system, and it is reportedly better at this than the most common alternative system, COFDM. Some stations can cover the same area while transmitting at an effective radiated power nearly ten times lower. While NTSC and most other analog television systems also use a vestigial sideband technique, the unwanted sideband is filtered much more effectively in ATSC 8VSB transmissions. 8VSB uses a Nyquist filter to achieve this, though the filter also causes the transmission to be very "noisy." Receivers must sample the incoming signal at very precise intervals to properly interpret the 8-level signal. Improper timing results in receiving useless information, so this makes reception in moving vehicles nearly impossible due to the Doppler effect. Reed-Solomon error correction is the primary system used to retain data integrity. NTSC is the analog television system in use in Korea, Japan, United States, Canada and certain other places, mostly in the Americas (see map). ... Orthogonal frequency division modulation (OFDM, also called orthogonal frequency division multiplexing) is a technique for the modulation of digital information onto an analog carrier electromagnetic (e. ... In radio telecommunications, effective radiated power or ERP is determined by subtracting system losses from system gains. ... A sample refers to a value or set of values at a point in time and/or space. ... The Doppler effect, named after Christian Andreas Doppler, is the apparent change in frequency or wavelength of a wave that is perceived by an observer moving relative to the source of the waves. ... Reed-Solomon error correction is a coding scheme which works by first constructing a polynomial from the data symbols to be transmitted and then sending an over-sampled plot of the polynomial instead of the original symbols themselves. ...

In summer of 2005, the ATSC published standards for Enhanced VSB, or E-VSB [1]. This will allow DTV reception on low power handheld receivers with smaller antennas in much the same way DVB-H does in Europe. 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Disputes over ATSC's further use

There has been a continuing lobby for changing the modulation for ATSC to COFDM, the way DVB-T is transmitted in Europe, and ISDB-T in Japan. However, the FCC has continued to assert that 8VSB is the better modulation for use in U.S. digital television broadcasting. In 2000, it denied a petition for rulemaking from Sinclair Broadcast Group requesting the change. Because of continued adoption of the 8VSB-based ATSC standard in the U.S., a switch to COFDM is now unlikely. Congress passed a law mandating that all analog terrestrial transmissions in the US will be turned off in February 2009, and 8VSB tuners are increasingly widespread in new TVs due to FCC tuner mandates, effectively mooting this debate. Modulation is the process of varying a carrier signal, typically a sinusoidal signal, in order to use that signal to convey information. ... DVB-T stands for Digital Video Broadcasting - Terrestrial and it is the DVB European consortium standard for the broadcast transmission of digital terrestrial television. ... Europe is conventionally considered one of the seven continents of Earth which, in this case, is more a cultural and political distinction than a physiographic one, leading to various perspectives about Europes borders. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The FCCs official seal. ... The Sinclair Broadcast Group (SBG) NASDAQ: SBGI is the operator of the largest number of local television stations in the United States with a total of 59 stations across the country in 38 (mostly) small and medium markets. ... The abbreviation FCC can refer to: Face-centered cubic (usually fcc), a crystallographic structure Federal Communications Commission, a US government organization Farm Credit Corporation/Farm Credit Canada, a Canadian government organization Families with Children from China, an adoption support organization Florida Christian College, a college in central Florida Fresno City...

8VSB vs DVB-T's COFDM

In 2001, a technical report compiled by the COFDM Technical Group concluded that COFDM did not offer any significant advantages over 8VSB. * The report recommended in conclusion that receivers be linked to outdoor antennas raised to roughly 30 feet (9 m) in height. A foot (plural: feet) is a non-SI unit of distance or length, measuring around a third of a meter. ... The metre, or meter, is a measure of length, approximately equal to 3. ...

• Neither 8VSB nor COFDM performed acceptably in most indoor test installations. ^[1]

However, there were questions whether the COFDM receiver selected for these tests, a transmitter monitor[2] lacking normal front end filtering, colored these results. Retests that were performed using the same CODFM receivers with the addition of a front end band pass filter gave much improved results for the DVB-T receiver, but further testing was not pursued.[3]

The debate over 8VSB versus COFDM modulation is still ongoing. Proponents of COFDM argue that it resists multipath far better than 8VSB. Early 8VSB DTV (digital television) receivers often had difficulty receiving a signal in urban environments. However, newer 8VSB receivers are far better at dealing with multipath. Moreover, 8VSB modulation requires less power to transmit a signal the same distance. In less populated areas, 8VSB often pulls ahead of COFDM because of this. In urban areas, however, COFDM still offers better reception than 8VSB. Digital television (DTV) uses digital modulation and compression to broadcast video, audio and data signals to television sets. ...

Shortage of ATSC-8VSB instruments

While ATSC 8VSB consumer receivers for use with HDTV Television sets are available, test and measuring instruments for ATSC 8VSB receivers remain elusive and are extremely expensive. The lowest priced is full featured Equipment from Modulation Sciences, which is about 20% of the cost of Spectrum analyzers sold today with 8VSB capability. ^[2] A spectrum analyzer is a device used to examine the spectral composition of some electrical, acoustic, or optical waveform. ...

Bifurcation of digital transmission systems

The United States is also notable for creating a separate transmission system for digital radio. An in-band on-channel (IBOC) system developed by iBiquity will be used instead of the Eureka 147 Digital Audio Broadcast system that has been selected in Europe. This is partially due to the fact that the L band normally used for that technology is unavailable in the U.S. However, the American IBOC system uses COFDM, as does Eureka 147 and another standard known as Digital Radio Mondiale. This article needs to be cleaned up to conform to a higher standard of quality. ... In-band on-channel (IBOC) is a method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency. ... iBiquity is a company formed by the merger of USA Digital Radio and Lucent Digital Radio, with the goal of creating an in-band on-channel (IBOC) digital radio system for the United States. ... Eureka 147 is a protocol for digital radio broadcasting originally developed in Europe, but now being deployed in many countries around the world. ... Digital Audio Broadcast or DAB is a standard for digital radio broadcast developed by EUREKA as a research project for the European Union. ... L band (20-cm radar long-band) is a portion of the microwave band of the electromagnetic spectrum ranging roughly from 0. ... Digital Radio Mondiale (DRM) is an international non-profit consortium committed to designing and implementing an open-source platform for digital radio broadcasting around the world, especially on shortwave. ...

References

1. ^ 8VSB/COFDM Comparison Report
2. ^ 8VSB Analyzer

External links

• What exactly is 8-VSB anyway?