DTV transition
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The DTV transition (or Broadcast Digital Transition) is the switchover from analog (the traditional method of transmitting television signals) to exclusively digital broadcasting of free television programming. The transition from analog to digital television has been described by David Rehr, president and CEO of the National Association of Broadcasters, as representing "the most significant advancement of television technology since color TV was introduced."[1]
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[edit] United States
The transition from the analog NTSC format to the digital ATSC format will be completed on February 17, 2009, as set by Congress.[2] Congress mandated the conversion to all-digital television broadcasting for full-power broadcasters, also known as the digital television (DTV) transition, because all-digital broadcasting will free up frequencies to be auctioned by the US federal government to the highest bidder. Of the eighteen channels (52 - 69), four (60, 61, 68, 69) will be held for reallocation to public safety communications (such as police, fire, and emergency rescue). In addition, some of the freed up frequencies will be used for advanced commercial wireless services for consumers, such as Qualcomm's planned use of former UHF channel 55 for its MediaFLO service.[2]
Digital TV uses a more efficient transmission technology that allows broadcast stations to offer improved picture and sound quality, as well as offer more programming options through multiple broadcast streams (multicasting). Television stations have been preparing for the transition from analog to DTV since the late 1990s, when they began building digital facilities and airing digital channels alongside regular analog broadcasts. Today, 1,609 out of 1,745 full power television stations nationwide offer digital programming, however, most of the smaller, low-power broadcasters, for whom switching to digital would be cost prohibitive, will still be permitted to transmit in analog for several years to come. [3] Since the majority of US viewership is no longer using over-the-air antennae to receive signals, but has switched to cable and satellite, the impact will be much smaller on current NTSC receivers which will continue to use NTSC content and devices after the cut-off date. Set-top boxes will enable existing over-the-air NTSC only receivers to watch over-the-air ATSC signals.
A major concern is that the broadcast technology used to transmit ATSC signals called 8VSB has problems receiving signal inside buildings and in urban areas, largely due to multipath reception issues which cause annoying ghosting and fading on analogue images, but can lead to intermittent signal or no reception at all on ATSC programs.[4]. DTV broadcasts exhibit a digital cliff effect, by which viewers will receive either a perfect signal or no signal at all with little or no middle ground. Digital transmissions do contain additional data bits to provide error correction for a finite number of bit errors; once signal quality degrades beyond that point, recovery of the original digital signal becomes impossible.
The maximum power for DTV broadcast classes is also substantially lower; one-fifth of the legal limits for the former full-power analogue services. A hundred-kW analogue station on channel 2-6 would therefore be faced with the choice of either lowering its power by 80% (to the twenty kilowatt limit of low-VHF DTV) or abandoning a channel which it occupied since the 1950s in order to transmit more signal power on the less-crowded UHF TV band. Unfortunately, the higher frequencies perform poorly in areas where signals must travel great distances and encounter significant terrestrial obstacles.
The Consumer Electronics Association has set up a website called Antenna Web[5] to identify means to provide the correct signal reception to over-the-air viewers. The TV Fool website[6] provides geographic mapping and signal data to allow viewers to estimate the number of channels which will be gained or lost as a result of digital transition; while it estimates that marginally more stations will be gained than lost by viewers, this varies widely with viewers of low-VHF analogue signals in distant-fringe areas among the most adversely affected.
When the transition is complete, channels 2 through 51 will be used for digital television broadcasts, and channels 52 through 69 will be reclaimed for other uses.[7]
The rules requiring digital must-carry access on cable and satellite systems are still being worked out by the FCC and Congress due to technical issues with available channel capacity and replacement of analog/SD signals with Digital/HDTV signals.[8]
[edit] Coupon program
The Department of Commerce's National Telecommunications and Information Administration (NTIA) has launched the Digital-to-Analog Converter Box Coupon Program, as authorized in the Digital Television Transition and Public Safety Act of 2005.[10]
Beginning January 1, 2008, all U.S. households will be eligible for two $40 USD coupons to be used toward the purchase of two digital-to-analog converter boxes.[11].
These coupons may be redeemed toward the purchase of a digital-to-analog converter at brick and mortar, on-line, and telephone retailers that have completed the NTIA certification process.[12] After applying the coupons, boxes will range in price from $0 for the DTVPal up to $40 for some of the boxes by GE, LG and other manufacturers.
[edit] United Kingdom
The DTV transition began in the United Kingdom as FreeView broadcasting additional standard definition[SD] programming using DVB-T. The United Kingdom has a phased switchover based upon region.[13]
[edit] Digital-to-analog converters
After the switch from analog to digital broadcasts is complete, analog TVs will be incapable of receiving over-the-air broadcasts without the addition of a set-top converter box. Consequently, a digital-to-analog converter, an electronic device that connects to an analog television, must be used in order to allow the television to receive digital broadcasts.[14] The box may also be called a "set-top" converter, "digital TV adapter" (DTA), or "digital set-top box" (DSTB).[15]
[edit] References and notes
- ^ Broadcasters Prepare For DTV Transition. TWICE (January 7, 2008). Retrieved on 2008-03-23.
- ^ a b All-Digital Television Is Coming (And Sooner Than You Think!). Retrieved on 2008-03-23.
- ^ What is Digital Television? for the public, by DTV Answers. Accessed 11 May 2007.
- ^ http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/reports/dtvreprt.pdf
- ^ http://www.antennaweb.org Antenna Web
- ^ TV fool
- ^ http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-275789A1.pdf
- ^ The BRIDGE
- ^ TV Converter Box Coupon Program Website - Frequently Asked Questions (FAQs)
- ^ Digital-to-Analog Converter Box Coupon Program. NTIA.gov. Retrieved on 2008-02-15.
- ^ TV Converter Box Coupon Program Website
- ^ TV Converter Box Coupon Program Website - Locate a Converter Box Retailer near you
- ^ Digital - Switchover. BBC (March 23, 2008). Retrieved on 2008-03-23.
- ^ A television commercial shown on American television featuring This Old House announces that this is true.
- ^ What is a set-top converter box?. Digital TV Facts (2007). Retrieved on 2008-03-23.
[edit] External links
- DTVAnswers.com: What you need to know about the February 17, 2009 switch to DTV.
- National Association of Broadcasters
- DTV Transition
- Consumer oriented FCC site
- FCC regulatory information on the DTV transition
- Federal Coupon Program
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