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3. Testimonials - don't know anybody that has bought a 8vsb? Wrong! If the 8vsb is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about 8vsb then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
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6. Returns - still worried that even after all of the above your 8vsb wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your 8vsb then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the 8vsb site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about 8vsb, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your 8vsb, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
8VSB is the 8-level
vestigial sideband modulation method adopted for terrestrial broadcast of the ATSC digital television standard in the
United States,
Canada, and other countries.
Throughput
In the 6 MHz (megahertz) channel used for broadcast ATSC, 8VSB carries 19.39
Mbit/s of usable data, 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 modulation. 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
de facto industry standard instead.
Power saving advantages
A significant advantage of 8VSB for broadcasters is that it requires much less power 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 of approximately 10% of analog broadcast power. 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 (signal) 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.
In summer of
2005, the ATSC published standards for Enhanced VSB, or E-VSB . This will allow DTV reception on low power handheld receivers with smaller antennas in much the same way
DVB-H does in Europe.
Disputes over ATSC's use
For some period of time, there had been a continuing lobby for changing the modulation for ATSC to COFDM, the way
DVB-T is transmitted in
Europe, and Integrated Services Digital Broadcasting#ISDB-T in
Japan. However, the
Federal Communications Commission has always held that 8VSB is the better modulation for use in U.S. digital television broadcasting. In a 1999 report, the Commission found that 8VSB has better threshold or carrier-to-noise (C/N) performance, has a higher data rate capability, requires less transmitter power for equivalent coverage, and is more robust to impulse and phase noise.{{Citation | title = DTV REPORT ON COFDM AND 8-VSB PERFORMANCE
| url = http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/reports/dtvreprt.pdf
| publisher = FCC Office of Engineering and Technology
| accessdate = 2007-03-04
-->, September 30, 1999.
As a result, it denied in 2000 a
petition for rulemaking from Sinclair Broadcast Group requesting the change. (Since then, further improvements to VSB reception technologies have also quelled this challenge.) Because of continued adoption of the 8VSB-based ATSC standard in the U.S., and a large growing ATSC receiver population, a switch to COFDM is now essentially impossible. 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 ATSC tuner#U.S Government mandates, effectively ending this debate.
8VSB vs COFDM
The previously cited FCC Report also found that COFDM has better performance in dynamic and high level static multipath situations, and offers advantages for single frequency networks and mobile reception. Nonetheless, 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 foot (unit of length) (9
metre) in height. Neither 8VSB nor COFDM performed acceptably in most indoor test installations. 8VSB/COFDM Comparison Report
However, there were questions whether the COFDM receiver selected for these tests − a transmitter monitor lacking normal front end filtering − colored these results. Retests that were performed using the same COFDM 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.
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 may outperform COFDM because of this. However, in some urban areas, as well as for mobile use, COFDM may offer better reception than 8VSB. In order to broaden the application of VSB, several "enhanced" VSB systems are now in development, most notably E-VSB, A-VSB, and
MPH (VSB).
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.
References
See also
External links
- What exactly is 8-VSB anyway?
8VSB is the 8-level vestigial sideband modulation method adopted for terrestrial broadcast of the
ATSC digital television standard in the United States, Canada, and other countries.
Throughput
In the 6 MHz (
megahertz) channel used for broadcast ATSC, 8VSB carries 19.39 Mbit/s of usable data, 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 modulation. 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
de facto industry standard instead.
Power saving advantages
A significant advantage of 8VSB for broadcasters is that it requires much less power 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 of approximately 10% of analog broadcast power. 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 (signal) 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.
In summer of
2005, the ATSC published standards for Enhanced VSB, or
E-VSB . This will allow DTV reception on low power handheld receivers with smaller antennas in much the same way
DVB-H does in Europe.
Disputes over ATSC's use
For some period of time, there had been a continuing lobby for changing the modulation for ATSC to COFDM, the way DVB-T is transmitted in
Europe, and
Integrated Services Digital Broadcasting#ISDB-T in
Japan. However, the Federal Communications Commission has always held that 8VSB is the better modulation for use in U.S. digital television broadcasting. In a 1999 report, the Commission found that 8VSB has better threshold or carrier-to-noise (C/N) performance, has a higher data rate capability, requires less transmitter power for equivalent coverage, and is more robust to impulse and phase noise.{{Citation | title = DTV REPORT ON COFDM AND 8-VSB PERFORMANCE
| url = http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/reports/dtvreprt.pdf
| publisher = FCC Office of Engineering and Technology
| accessdate = 2007-03-04
-->, September 30, 1999.
As a result, it denied in 2000 a
petition for rulemaking from
Sinclair Broadcast Group requesting the change. (Since then, further improvements to VSB reception technologies have also quelled this challenge.) Because of continued adoption of the 8VSB-based ATSC standard in the U.S., and a large growing ATSC receiver population, a switch to COFDM is now essentially impossible. 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 ATSC tuner#U.S Government mandates, effectively ending this debate.
8VSB vs COFDM
The previously cited FCC Report also found that COFDM has better performance in dynamic and high level static multipath situations, and offers advantages for single frequency networks and mobile reception. Nonetheless, 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 foot (unit of length) (9
metre) in height. Neither 8VSB nor COFDM performed acceptably in most indoor test installations. 8VSB/COFDM Comparison Report
However, there were questions whether the COFDM receiver selected for these tests − a transmitter monitor lacking normal front end filtering − colored these results. Retests that were performed using the same COFDM 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.
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 may outperform COFDM because of this. However, in some urban areas, as well as for mobile use, COFDM may offer better reception than 8VSB. In order to broaden the application of VSB, several "enhanced" VSB systems are now in development, most notably E-VSB,
A-VSB, and
MPH (VSB).
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.
References
See also
External links
- What exactly is 8-VSB anyway?
8VSB - Wikipedia, the free encyclopedia
8VSB is the 8-level vestigial sideband modulation method adopted for terrestrial broadcast of the ATSC digital television standard in the United States, Canada, and other countries ...
8VSB
Acronym Finder: 8VSB stands for 8-Level Vestigial Sideband (US ATSC broadcast standard) ... What does 8VSB stand for? 8-Level Vestigial Sideband (US ATSC broadcast standard)
8VSB - Wikipédia
8VSB nyaeta metode vestigial sideband modulation 8 hambalan nu dipake keur siaran terestrial standar televisi digital ATSC di Amerika Sarikat, Kanada, katut nagara sejenna.
8VSB Modulator
8VSB ATSC Test modulator ... 8VSB- Single and Multi Channel 8VSB Modulators for Product Development and Digital Signage
Wegner, 8VSB Signal Processing
8VSB OFF-AIR PROCESSORS : Space efficient processors for cable operators managing off-air HDTV signals. WEGENER 8VSB transport stream multiplexers enable cable operators to easily ...
Product information - Ktech VSB-ENC-200 Broadcast 8VSB Modulator
Headquartered in the UK and with associates sales and support offices in the USA, Spain, China and Hong Kong Techex has been supplying products, solutions and consultancy to the ...
TVB590 DVB-T / DVB-H / 8VSB / QAM / QPSK / DVB-S2 / ISDB-T Modulator ...
TELEVIEW TVB590 DVB-T / DVB-H / 8VSB / QAM / QPSK / DVB-S2 Modulator PCI Card ... QUESTER QAM (DVB-C) Modulator; AMIGO 8VSB (ATSC) Modulator; DVM 5000 DVB-H/DVB-T Modulator; DVM ...
8VSB: Information from Answers.com
8-VSB ( 8 -level V estigial S ide B and) The modulation technique used for digital TV (DTV) in the U.S
8VSB Modulator , Multi channel ATSC modulator, ATSC modulator, Digital ...
8VSB Modulator , Multi channel ATSC modulator, ATSC modulator, Digital Signage , RF modulator, Test modulator, Digital Modulator
8VSB - What does 8VSB stand for? Acronyms and abbreviations by the ...
Acronym Definition; 8VSB: 8-Level Vestigial Sideband (US ATSC broadcast standard)
