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Advantages to conversion
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 cost in image quality depending on the level of compression). 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. In many cases, viewers perceive DTV to have superior picture quality, improved audio quality, and easier reception than analog.
Disadvantages to conversion
The analog switch-off ruling, which so far has met with little opposition from consumers or manufacturers, would render all non-digital televisions obsolete on the switch-off date, unless connected to an external off-the-air tuner, analog or digital cable, or a satellite system. An external converter box (an ATSC tuner) can be added to non-digital televisions to lengthen their useful lifespan. Several of these devices have already been shown, and while few are currently available, American industry and government statements predict that low-cost units will be available in January 2008.
Some existing analog equipment will be less functional with the use of a converter box. For example, television remote controls will no longer be effective at changing channels, because that function will instead be handled by the converter box. Similarly, video recorders for analog signals (including both tape-based VCRs and hard-drive-based DVRs) will not be able to select channels, limiting their ability to automatically record programs via a timer or based on downloaded program information. Also, older, handheld televisions, which rely primarily on over-the-air signals, and battery operation, will be rendered impractical, since the proposed converter boxes are not portable, nor powered with batteries. Portable radios which feature the ability to listen to television audio on VHF channels 2-13 would also lose their ability to function, while television stations which formerly broadcast on Channel 6 and were able to have their analog audio heard on common radios using a quirk in the system where their audio could be heard on the far end of the FM band at 87.7, would lose the ability for commuters to listen to their broadcasts.
If new TVs contain only an ATSC tuner, it prevents older devices, such as VCRs and video game consoles with only an analog RF output, from connecting to the TV. Connection would require an analog to digital converter box, which is the opposite as what is currently being sold. Such a box would also likely introduce additional delay into the video signal.
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