Comparison analog vs digital

DTV has several advantages over analog TV, the most significant being that digital channels take up less bandwidth, and the bandwidth needs are continuously variable, at a corresponding reduction in image quality depending on the level of compression as well as the resolution of the transmitted image. This means that digital broadcasters can provide more digital channels in the same space, provide high-definition television service, or provide other non-television services such as multimedia or interactivity. DTV also permits special services such as multiplexing (more than one program on the same channel), electronic program guides and additional languages (spoken or subtitled). The sale of non-television services may provide an additional revenue source.

Digital and analog signals react differently to interference. For example, common problems with analog television include ghosting of images, noise from weak signals, and many other potential problems which degrade the quality of the image and sound, although the program material may still be watchable. With digital television, the audio and video must be synchronized digitally, so reception of the digital signal must be very nearly complete; otherwise, neither audio nor video will be usable. Short of this complete failure, “blocky” video is seen when the digital signal experiences interference.

Analog TV started off with monophonic sound, and later evolved to stereophonic sound with two independent audio signal channels. DTV will allow up to 5.1 audio signal channels, with broadcasts similar in quality to movie theaters and DVDs.

Effect on existing analog technology

Television sets with only analog tuners cannot decode digital transmissions. When analog broadcasting over the air ceases, users of sets with analog-only tuners may use other sources of programming (e.g. cable, recorded media) or may purchase set-top converter boxes to tune in the digital signals. In the United States, a government-sponsored coupon was available to offset the cost of an external converter box. Analog switch-off (of full-power stations) took place on December 11, 2006 in The Netherlands,June 12, 2009 in the United States,July 24, 2011 in Japan,August 31, 2011 in Canada,February 13, 2012 in Arab states, May 1, 2012 in Germany, October 24, 2012 in the United Kingdom and Ireland,and October 31, 2012 in selected Indian cities.Completion of analog switch-off is scheduled for December 10, 2013 in Australia,December 31, 2014 in the whole of India,by 2015 in the Philippines and Uruguay, and by 2017 in Costa Rica.

Disappearance of TV-audio receivers

Prior to the conversion to digital TV, analog television broadcast audio for TV channels on a separate FM carrier frequency from the video signal. This FM audio signal could be heard using standard radios equipped with the appropriate tuning circuits.

However, after the relatively recent transition of many countries to digital TV, no portable radio manufacturer has yet developed an alternative method for portable radios to play just the audio signal of digital TV channels. (DTV radio is not the same thing.)

Environmental issues

The adoption of a broadcast standard incompatible with existing analog receivers has created the problem of large numbers of analog receivers being discarded during digital television transition. An estimated 99 million unused analog TV receivers are currently in storage in the US alone and, while some obsolete receivers are being retrofitted with converters, many more are simply dumped in landfills where they represent a source of toxic metals such as lead as well as lesser amounts of materials such as barium, cadmium and chromium.

While the glass in cathode ray tubes contains an average of 3.62 kilograms (8.0 lb) of lead[unreliable source?] (amount varies from 1.08 lb to 11.28 lb, depending on screen size but the lead is “stable and immobile”) which can have long-term negative effects on the environment if dumped as landfill, the glass envelope can be recycled at suitably equipped facilities. Other portions of the receiver may be subject to disposal as hazardous material.

Local restrictions on disposal of these materials vary widely; in some cases second-hand stores have refused to accept working color television receivers for resale due to the increasing costs of disposing of unsold TVs. Those thrift stores which are still accepting donated TVs have reported significant increases in good-condition working used television receivers abandoned by viewers who often expect them not to work after digital transition.

In Michigan, one recycler has estimated that as many as one household in four will dispose of or recycle a TV set in the next year. The digital television transition, migration to high-definition television receivers and the replacement of CRTs with flatscreens are all factors in the increasing number of discarded analog CRT-based television receivers.

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